South China Sea Arbitration and Its Legal Impact

Introduction

The South China Sea Arbitration is one of the most important decisions ever issued under the United Nations Convention on the Law of the Sea. Its legal importance is often misunderstood. The Tribunal did not decide who owns the Spratly Islands, Scarborough Shoal, or any other disputed land feature. It did not draw a maritime boundary between China and the Philippines. Its central role was more precise: it clarified what UNCLOS permits and forbids when a State claims maritime rights based on history, geography, environmental control, or law enforcement activity (South China Sea Arbitration, 2016; Talmon, 2022).

The case began in January 2013, when the Philippines brought arbitration against China under Annex VII of UNCLOS. China refused to participate and argued that the Tribunal had no jurisdiction. Beijing’s position was that the dispute was really about territorial sovereignty and maritime delimitation, two matters that the Tribunal could not decide under the way the case had been framed. China also argued that the Philippines had breached prior commitments to negotiate and that China’s 2006 declaration under Article 298 excluded the dispute from compulsory adjudication (People’s Republic of China, 2014).

That objection created the first major legal question: could an UNCLOS tribunal decide issues about maritime entitlements without deciding sovereignty over land? The Tribunal answered yes. It separated sovereignty over land features, which remained outside its jurisdiction, from the legal capacity of those features to generate maritime zones under UNCLOS. This distinction gave the case its doctrinal force. A tribunal may ask what a reef, rock, or island can generate under the Convention without deciding which State owns it (South China Sea Arbitration, 2015; South China Sea Arbitration, 2016).

This point matters far beyond the Philippines and China. Many maritime disputes are politically linked to territorial disputes. If every territorial disagreement automatically blocked UNCLOS jurisdiction, compulsory dispute settlement under Part XV would be weakened whenever it was needed most. The South China Sea Arbitration showed that careful pleading can isolate legal questions about maritime zones, environmental duties, and State conduct, even when sovereignty remains contested.

The best-known part of the award concerns China’s nine-dash line. For decades, that line had been used to express broad Chinese claims across much of the South China Sea. The exact legal meaning of the line was often unclear. It appeared at different times as a claim to historic rights, sovereign rights, jurisdiction, or control over resources. The Tribunal treated this ambiguity as a legal problem. UNCLOS allocates maritime rights through defined zones: territorial sea, exclusive economic zone, continental shelf, and high seas. A claim to historic rights over resources inside another State’s EEZ cannot override that structure (South China Sea Arbitration, 2016; Klein, 2020).

The award did not say that history is irrelevant in the law of the sea. That would be too broad. Historic bays, historic title, traditional fishing, and long-standing usage may still matter in specific legal settings. The narrower finding was stronger: historic usage cannot create rights that contradict the EEZ and continental shelf regime created by UNCLOS. In practical terms, China could not rely on the nine-dash line to claim living and non-living resources in areas where UNCLOS gives sovereign rights to the Philippines (South China Sea Arbitration, 2016; Reichler, 2019).

A second major contribution concerns Article 121 of UNCLOS. That provision distinguishes islands capable of generating full maritime zones from rocks that cannot sustain human habitation or economic life of their own. The Tribunal found that none of the relevant Spratly features could generate an EEZ or continental shelf. This was not a technical footnote. It changed the legal map. If those features cannot generate 200-nautical-mile entitlements, large areas claimed by China fall within the maritime entitlements of nearby coastal States or outside any claim based on those features (South China Sea Arbitration, 2016; Villamizar Lamus, 2020).

The reasoning on Article 121 also limited the legal effect of artificial island-building. A reef cannot become a fully entitled island because a State builds runways, harbours, military installations, or reclaimed land on it. The legal classification depends on the feature’s natural condition. This matters because modern technology allows States to transform reefs physically. UNCLOS does not allow them to transform those reefs legally into sources of vast maritime zones (UNCLOS, 1982; South China Sea Arbitration, 2016).

The environmental findings are equally important. The Tribunal found that China had breached duties to protect and preserve the marine environment, especially through large-scale construction and land reclamation on coral reef systems. These findings gave practical force to Part XII of UNCLOS. They showed that environmental obligations in the law of the sea are not decorative principles. They can operate as concrete duties requiring prevention, due diligence, cooperation, and environmental assessment where serious marine harm is foreseeable (South China Sea Arbitration, 2016; Boyle, 2020).

The case also shows the limits of international adjudication. The award is final and binding between the parties under UNCLOS Article 296 and Annex VII. China’s rejection does not erase that legal status. At the same time, the award has not ended coercive incidents, competing patrols, or dangerous confrontations in the South China Sea. This is the hard lesson: international law can clarify rights with precision, but enforcement still depends on diplomacy, political pressure, reputational cost, institutional support, and the conduct of States (Klabbers, 2024; Talmon, 2022).

The South China Sea Arbitration should not be treated as a complete solution to the South China Sea disputes. It is not. It left sovereignty unresolved. It did not settle all maritime boundaries. It did not create a regional security arrangement. Its lasting value is different. It narrowed the range of lawful maritime claims under UNCLOS, rejected excessive historic-rights claims, clarified the legal status of maritime features, strengthened marine environmental obligations, and confirmed that non-participation cannot by itself defeat compulsory proceedings.

This article examines those legal effects in depth. It argues that the South China Sea Arbitration is best understood as a structural decision about the integrity of UNCLOS. The award protects the Convention against claims that would replace treaty rules with historical ambiguity, artificial construction, or unilateral control. Its impact lies not only in what it decided for the Philippines and China, but also in the legal discipline it gives to future disputes over maritime rights, islands, reefs, resources, and environmental harm.

1. The case and the legal dispute

1.1 The South China Sea legal setting

The South China Sea dispute is not one single dispute. It is a cluster of territorial, maritime, environmental, security, and resource conflicts occupying the same geographic space. China, the Philippines, Vietnam, Malaysia, Brunei, and Taiwan claim different rights over islands, reefs, rocks, low-tide elevations, fisheries, seabed resources, and navigation routes. The legal problem is that these claims do not operate on the same level. Some concern ownership of land territory. Others concern maritime zones generated by coasts or features. Others concern conduct at sea, including fishing restrictions, coast guard activity, seabed exploration, and construction on reefs.

That distinction controls the whole case. Territorial sovereignty decides which State owns a land feature. The law of the sea decides what maritime entitlements a land feature can generate. A State may claim title over a reef or island, but that does not automatically give it an exclusive economic zone or continental shelf. UNCLOS makes entitlement depend on the legal character of the feature, not on the political weight of the claimant (UNCLOS, 1982; South China Sea Arbitration, 2016).

The arbitration arose because the Philippines treated China’s conduct as a violation of UNCLOS, not merely as a dispute over ownership. This choice mattered. UNCLOS does not settle the title to land territory. It does, however, regulate maritime zones, resource rights, environmental duties, navigation, artificial islands, and dispute settlement. By focusing on those treaty questions, the Philippines brought the case within the legal architecture of Part XV and Annex VII (South China Sea Arbitration, 2015; Talmon, 2022).

The regional setting made that strategy significant. Fisheries are central to the livelihoods of coastal communities and to the economies of the claimant States. Hydrocarbon exploration also created tension because offshore energy blocks may lie within one State’s claimed exclusive economic zone while another State asserts historic rights or jurisdiction over the same waters. These are not abstract doctrinal issues. If a State prevents fishing vessels, blocks petroleum surveys, or deploys coast guard vessels inside another State’s EEZ, the dispute becomes a concrete question of sovereign rights under Articles 56 and 77 of UNCLOS (UNCLOS, 1982; Rothwell and Stephens, 2016).

Navigation gives the dispute a wider international dimension. The South China Sea is a major maritime corridor. Commercial shipping, naval movement, coast guard patrols, and surveillance activities all occur in a legally crowded environment. UNCLOS does not give coastal States complete control over the EEZ. It grants resource rights and specific jurisdictional powers, while preserving navigation and overflight freedoms for other States. The legal structure is one of allocated competences, not exclusive dominion over the sea (Churchill, Lowe and Sander, 2022).

Artificial island construction made the dispute more acute. Reclamation works can transform a reef’s appearance, but they cannot change its original legal status. A low-tide elevation does not become a natural island because concrete, sand, ports, runways, or military infrastructure are placed on it. This point is crucial because modern engineering can alter facts on the water faster than courts or diplomats can respond. The Tribunal treated the natural condition of the feature as the legally relevant baseline (South China Sea Arbitration, 2016).

Environmental harm added another layer. Coral reefs are not incidental scenery in this case. They were part of the legal dispute because UNCLOS Part XII requires States to protect and preserve the marine environment. Large-scale reef destruction, harmful harvesting of endangered species, and land reclamation on fragile marine ecosystems raised issues of due diligence and prevention. The award gave environmental obligations a practical role in maritime disputes, rather than treating them as soft background principles (Boyle, 2020; South China Sea Arbitration, 2016).

The legal setting is best understood as a conflict between two models of maritime order. One model relies on broad historical narratives and strategic control. The other relies on treaty-defined maritime zones, feature classification, and coastal State entitlements. The arbitration tested which model could prevail within the UNCLOS system.

1.2 The Philippines’ claims

The Philippines did not ask the Tribunal to award it sovereignty over the Spratly Islands or Scarborough Shoal. That would have failed at the jurisdictional threshold. Instead, it asked for declarations on the legal effects of China’s claims and actions under UNCLOS. The case was built around entitlement, not title.

The first target was the nine-dash line. The Philippines argued that China could not claim historic rights to resources in areas where UNCLOS gives the Philippines sovereign rights over the EEZ and continental shelf. The argument was not that Chinese fishermen or navigators had never used the South China Sea. The argument was that historic usage could not defeat a treaty regime that allocates maritime rights through measured zones and defined entitlements (South China Sea Arbitration, 2016; Klein, 2020).

The second target was the status of specific maritime features. The Philippines asked the Tribunal to determine which features were low-tide elevations, which were rocks, and which, if any, could generate an EEZ or continental shelf. This was not a technical detour. Feature status determines the legal reach of maritime claims. A submerged feature or low-tide elevation cannot produce the same legal consequences as a naturally formed island above water at high tide. A rock under Article 121(3) may generate a territorial sea, but not a 200-nautical-mile EEZ or continental shelf (UNCLOS, 1982; Villamizar Lamus, 2020).

The third target was Chinese conduct. The Philippines challenged interference with fishing, obstruction of petroleum activities, construction works, damage to reefs, and actions around Scarborough Shoal. These claims placed State behaviour at the centre of the case. The Tribunal was not only asked to interpret maps. It was asked to decide whether concrete acts at sea breached treaty obligations (South China Sea Arbitration, 2016).

This pleading strategy was legally sharp because it separated three questions that political debate often merges. Who owns a feature? What maritime zone can that feature generate? What conduct is lawful in the surrounding waters? Only the first question was outside the Tribunal’s mandate. The second and third could be answered under UNCLOS if they did not require a sovereignty ruling or boundary delimitation (South China Sea Arbitration, 2015; Talmon, 2022).

A practical example shows the point. If Mischief Reef is a low-tide elevation within the Philippines’ EEZ and continental shelf, it cannot be appropriated as land territory in the same way as an island, nor can it generate its own maritime zones. The legal conclusion concerns the feature’s status and maritime consequences, not an award of territorial title. That is why the Tribunal could rule on certain features without deciding sovereignty over the Spratly group as a whole (South China Sea Arbitration, 2016).

The Philippines also used the compulsory settlement system of UNCLOS to offset a major power imbalance. It could not force China into bilateral concessions. It could not bring China before the ICJ without consent. Annex VII offered a treaty-based route because both States were parties to UNCLOS. The case illustrates how a smaller State can use legal process to discipline maritime claims, even when compliance later depends on political pressure and diplomatic support (Reichler, 2019; Talmon, 2022).

This was not a risk-free strategy. The Philippines had to avoid asking too much. A request for boundary delimitation would have triggered China’s Article 298 declaration. A request for sovereignty over islands would have fallen outside UNCLOS. The strength of the case came from restraint. The submissions were designed to obtain legally useful declarations without crossing jurisdictional lines.

1.3 China’s rejection of arbitration

China rejected the proceedings and maintained that the Tribunal lacked authority. Its position rested on several connected objections.

The first was sovereignty. China argued that the Philippines had disguised a territorial dispute as a law of the sea case. In Beijing’s view, the Tribunal could not classify features or assess maritime zones without first deciding who owned the relevant islands and reefs. Since UNCLOS does not allocate sovereignty over land territory, China said the case fell outside the Convention (People’s Republic of China, 2014).

The second was maritime delimitation. China argued that the Philippines’ submissions would require the Tribunal to determine overlapping maritime entitlements and effectively draw a boundary. China had filed an Article 298 declaration in 2006, excluding compulsory procedures for maritime delimitation and related matters. On that basis, China treated the arbitration as barred by the Convention’s own exceptions (People’s Republic of China, 2014; Talmon, 2022).

The third was prior negotiation. China relied on bilateral exchanges and regional instruments, including the ASEAN-China Declaration on the Conduct of Parties in the South China Sea. It argued that the Philippines had committed to negotiation and could not unilaterally shift the dispute into arbitration. The Tribunal later treated those instruments as insufficient to exclude Part XV procedures in the way China claimed (South China Sea Arbitration, 2015).

The fourth was consent. China insisted that it had never accepted arbitration over these matters. The Tribunal’s answer was grounded in the structure of UNCLOS. Consent was not sought on a case-by-case basis. By becoming a party to the Convention, China had accepted Part XV procedures within the limits set by the treaty. The real question was not political consent to this particular case, but jurisdiction under the Convention (South China Sea Arbitration, 2015).

China’s refusal to appear did not stop the proceedings. Annex VII permits a case to continue when one party does not participate. That rule does not give the applicant an automatic win. The Tribunal still had to test jurisdiction, admissibility, evidence, and legal reasoning. It considered China’s public statements, diplomatic notes, and position papers as expressions of China’s objections (South China Sea Arbitration, 2016; Talmon, 2022).

This procedural posture gave the case an unusual character. China was absent as a litigant but present through its legal objections. The Tribunal had to answer arguments that China did not formally plead before it. That made the jurisdictional phase especially important and explains why the award has been studied not only for its conclusions on maritime rights, but also for its treatment of non-appearance, burden of proof, and procedural fairness (Talmon, 2022).

A fair reading must concede that China’s objections touched real legal sensitivities. The South China Sea dispute does include unresolved sovereignty claims. It does include possible delimitation issues. The decisive point was narrower: did the Philippines’ specific submissions require the Tribunal to decide those excluded matters? The Tribunal concluded that most of them did not. That conclusion opened the door to the merits.

1.4 What the award did not decide

The award’s authority depends on its limits. It did not decide ownership of the Spratly Islands, Scarborough Shoal, or any other disputed land feature. It did not say that the Philippines owns them. It did not say that China owns them. It did not rule on the territorial claims of Vietnam, Malaysia, Brunei, or Taiwan. Sovereignty over land remained untouched (South China Sea Arbitration, 2016).

It also did not draw a maritime boundary. No line was placed on a map dividing the Chinese and the Philippine maritime zones. The Tribunal avoided delimitation by addressing entitlement first. If a feature cannot generate an EEZ or continental shelf, it cannot create the kind of overlapping 200-nautical-mile claim that would require boundary delimitation. This was one of the most important moves in the award (South China Sea Arbitration, 2016; Talmon, 2022).

Nor did the Tribunal rule on every Chinese activity in the region. It assessed specific acts, specific maritime areas, and specific UNCLOS provisions. Some matters were outside the jurisdiction. Others depended on the status of the feature involved, the location of the conduct, and the nature of the legal right allegedly breached. The award was broad in consequence, but not unlimited in scope.

The Tribunal also avoided deciding general questions of military balance or regional security. Some incidents could be examined as law enforcement, environmental harm, or interference with resource rights. Broader military activities raised jurisdictional limits under Article 298. This distinction matters because the South China Sea is often discussed as a security crisis, while the award dealt only with legal questions that could be anchored in UNCLOS (South China Sea Arbitration, 2015; South China Sea Arbitration, 2016).

What the Tribunal did decide was still substantial. It held that China’s historic-rights claims, as applied within the nine-dash line, were incompatible with UNCLOS, where they exceeded the maritime zones allowed by the Convention. It classified several maritime features and clarified their capacity to generate maritime entitlements. It found that China had interfered with Philippine rights in certain areas. It identified breaches of marine environmental obligations. It also found that certain conduct had aggravated the dispute during the proceedings (South China Sea Arbitration, 2016).

The award should be read as a decision about legal consequences under UNCLOS, not as a final settlement of the South China Sea. That narrower reading is not a weakness. It is the reason the award has lasting value. By refusing to decide sovereignty or draw boundaries, the Tribunal preserved the jurisdictional limits of UNCLOS while still clarifying how the Convention constrains excessive maritime claims and unlawful conduct at sea.

2. Jurisdiction under UNCLOS Part XV

2.1 Annex VII arbitration

UNCLOS Part XV creates a compulsory dispute settlement system, but it does not send every dispute to the same court. Article 287 allows States to choose among the International Tribunal for the Law of the Sea, the International Court of Justice, Annex VII arbitration, or special arbitration under Annex VIII. If States have not accepted the same forum, or if a State has made no valid choice, Annex VII arbitration becomes the default procedure (UNCLOS, 1982).

That default rule was decisive. The Philippines and China were both parties to UNCLOS, but they had not accepted the same compulsory forum for this dispute. The Philippines could not force China before the ICJ without a separate basis of consent. It also could not rely on ITLOS jurisdiction unless the treaty conditions were met. Annex VII supplied the procedural route because UNCLOS itself made that route available when party choices did not match (South China Sea Arbitration, 2015).

Annex VII arbitration is not optional diplomacy. It is a treaty mechanism accepted in advance by States Parties, subject to the Convention’s limits. Once a dispute falls within Part XV and no applicable exception removes it, a respondent State cannot block proceedings merely by refusing to appoint an arbitrator or declining to appear. The system would have little practical value if a State could defeat jurisdiction by silence or absence (Klein, 2005; Talmon, 2022).

The legal force of Annex VII also depends on restraint. It does not give tribunals general authority over every dispute connected to the sea. The tribunal must identify a dispute concerning the interpretation or application of UNCLOS. It must also respect the Convention’s exclusions and optional exceptions. In this case, that meant the Tribunal had to separate treaty questions from sovereignty and boundary questions with care (South China Sea Arbitration, 2015).

This explains why the jurisdictional phase was not a procedural formality. It was the gateway to the entire case. If the dispute had been treated as one about territorial sovereignty or maritime delimitation, China’s objections would have been much stronger. If the dispute could be characterized as one about maritime entitlements, environmental duties, fisheries, and the legal effect of historic-rights claims under UNCLOS, the Tribunal could proceed.

2.2 Article 288 and Convention disputes

Article 288(1) gives an UNCLOS tribunal jurisdiction over any dispute concerning the interpretation or application of the Convention. The key question was not whether the South China Sea dispute had a political background. It plainly did. The key question was whether the Philippines’ specific submissions required the Tribunal to interpret and apply UNCLOS.

China argued that the real dispute was territorial sovereignty. The Tribunal rejected that broad characterization. It did not ask who owned the Spratly Islands or Scarborough Shoal. It asked what legal consequences flowed under UNCLOS if certain maritime features were low-tide elevations, rocks, or islands. It also asked whether China’s claims and conduct were compatible with the Convention’s rules on maritime zones, fisheries, environmental protection, and navigation (South China Sea Arbitration, 2015; South China Sea Arbitration, 2016).

This approach followed a functional test. The Tribunal looked at the real subject matter of each submission. The political context did not control jurisdiction. Nor did China’s preferred description of the dispute. A sovereignty dispute in the background did not automatically remove treaty questions in the foreground. That distinction gave Article 288 practical effect.

The Tribunal’s reasoning was especially important for mixed disputes. Many law of the sea disputes involve facts that touch land sovereignty, security, resources, and maritime entitlements at once. If the mere presence of a sovereignty issue were enough to defeat jurisdiction, Part XV would be easy to evade. A State could block compulsory settlement by attaching every maritime dispute to an unresolved territorial claim.

The Tribunal avoided that result by treating the Philippines’ claims individually. Some submissions could be heard. Others required closer analysis. The award on jurisdiction and admissibility did not assume jurisdiction over everything. It examined whether each claim could be decided without ruling on sovereignty or drawing a boundary (South China Sea Arbitration, 2015). This claim-by-claim method gave the decision greater legal credibility.

A useful example is feature classification. Deciding that a feature is a low-tide elevation is not the same as deciding which State owns it. Deciding that a rock cannot generate an EEZ is not the same as assigning sovereignty over the rock. These are legal consequences under UNCLOS. The Tribunal could answer them while leaving territorial title unresolved.

2.3 China’s non-appearance

China refused to participate in the arbitration, but non-appearance did not halt the case. Annex VII, Article 9 provides that the absence of a party or failure to defend its case is not a bar to the proceedings. The same provision requires the tribunal to satisfy itself that it has jurisdiction and that the claim is well founded in fact and law (UNCLOS, 1982).

This rule protects both sides. It prevents a respondent State from destroying compulsory dispute settlement through non-participation. It also prevents the applicant State from winning by default. The tribunal must independently test the case. That duty becomes more demanding when one party is absent because the adversarial process is weaker (Rosenne, 2006; Talmon, 2022).

The Tribunal took China’s position seriously despite China’s absence. It considered China’s 2014 Position Paper, diplomatic communications, public statements, and other official materials. Those materials were not formal pleadings, but they allowed the Tribunal to engage with China’s objections. This was essential to procedural fairness and to the award’s authority (South China Sea Arbitration, 2015).

Non-appearance also affected the evidence. The Tribunal could not cross-examine Chinese witnesses or test a full Chinese evidentiary record. To compensate, it appointed experts, requested additional materials, questioned the Philippines, and examined public records. The Tribunal did not treat China’s absence as consent to the Philippines’ factual allegations (South China Sea Arbitration, 2016).

This point matters because criticism of the award sometimes suggests that the case was one-sided. Procedurally, it was one-sided because China chose not to appear. Legally, it was not a default judgment. The Tribunal still had to prove jurisdiction to itself and verify whether the Philippines’ claims met the required standard.

China’s non-appearance created a second problem: legitimacy. A judgment or award may be valid even when rejected by one party, but public authority is harder to maintain when a major power refuses to take part. The Tribunal’s response was to make the reasoning unusually detailed. The jurisdictional award and final award repeatedly addressed China’s objections because the legal audience extended beyond the two parties (Talmon, 2022).

2.4 The duty to exchange views

Article 283 of UNCLOS requires parties to a dispute to proceed expeditiously to an exchange of views regarding settlement by negotiation or other peaceful means. This obligation is not decorative. It prevents States from rushing into litigation without first giving diplomacy a serious chance.

China argued that the Philippines had not satisfied this requirement. Beijing emphasized that the parties had long dealt with South China Sea issues through bilateral exchanges and that China consistently preferred negotiation. The Philippines answered that years of diplomatic communication had shown that further exchanges would not resolve the dispute. It also argued that the parties disagreed not only over substance, but over the method of settlement itself (South China Sea Arbitration, 2015).

The Tribunal treated Article 283 as a practical obligation, not an endless negotiation requirement. The parties must exchange views, but they do not have to continue talking when it is clear that positions are fixed and no settlement method is mutually acceptable. A State cannot use Article 283 to keep a dispute permanently outside adjudication by repeating that negotiation is the only acceptable path.

The facts mattered. The Philippines and China had exchanged views over many years through diplomatic notes, bilateral consultations, ASEAN-related processes, and public statements. Those exchanges showed a persistent disagreement. China wanted bilateral negotiations. The Philippines eventually chose arbitration. The Tribunal concluded that the obligation had been met because the parties had already reached an impasse on both the dispute and the method of resolving it (South China Sea Arbitration, 2015).

This interpretation respects the balance of Part XV. UNCLOS encourages negotiated settlement, but it also creates compulsory procedures when negotiation fails. If Article 283 required indefinite diplomatic engagement, compulsory dispute settlement would become dependent on the respondent State’s willingness to move beyond talks.

The better reading is narrower. Article 283 requires genuine communication before litigation. It does not require success. It does not require a weaker State to remain locked in negotiations when the legal disagreement has hardened, and no common settlement method exists.

2.5 Prior agreements and negotiation clauses

China also relied on Articles 281 and 282 of UNCLOS. These provisions limit compulsory procedures where States have agreed to settle a dispute by another peaceful means, or where another binding procedure applies. The argument was that bilateral statements, regional instruments, and the 2002 ASEAN-China Declaration on the Conduct of Parties in the South China Sea required negotiation and excluded arbitration.

This was one of China’s strongest objections because UNCLOS does allow States to choose alternative settlement methods. If the parties had made a binding agreement to use negotiation only, and to exclude further procedures, the Tribunal’s jurisdiction could have been blocked. The issue was not whether negotiation had been mentioned. The issue was whether the relevant instruments legally excluded Part XV arbitration (South China Sea Arbitration, 2015).

The Tribunal found that they did not. The 2002 Declaration on Conduct was treated as a political instrument aimed at restraint, confidence-building, and eventual negotiation of a code of conduct. It did not contain a clear exclusion of compulsory dispute settlement under UNCLOS. Nor did the bilateral materials show a binding agreement to make negotiation the exclusive method for all relevant disputes (South China Sea Arbitration, 2015).

This reasoning is important for regional diplomacy. States often use political declarations to manage sensitive disputes. Such texts may create expectations and diplomatic commitments. They do not automatically waive treaty rights to compulsory settlement. Exclusion of Part XV procedures requires a clear legal effect. Ambiguous language about negotiation, restraint, or friendly settlement is not enough.

Article 281 also requires attention to the phrase “where no settlement has been reached.” The provision does not allow negotiation clauses to operate as permanent shields unless the parties have agreed that no further procedure may be used. The Tribunal read the relevant instruments as encouraging negotiation, not as forbidding arbitration after negotiations failed (UNCLOS, 1982; South China Sea Arbitration, 2015).

Article 282 did not remove jurisdiction either. There was no separate binding procedure between China and the Philippines that would replace the UNCLOS mechanism for the specific claims before the Tribunal. Regional diplomacy remained available, but it did not extinguish the Philippines’ treaty right to initiate Annex VII proceedings.

The legal lesson is precise: UNCLOS respects negotiated settlements, but it does not let political declarations defeat compulsory procedures by implication. A State seeking to exclude Part XV must show a legally binding agreement with sufficiently clear terms.

2.6 Article 298 exceptions

Article 298 allows States to exclude certain disputes from compulsory procedures. China made such a declaration in 2006. It excluded disputes concerning maritime boundary delimitation, historic bays or titles, military activities, and certain law enforcement activities. The Tribunal had to decide whether the Philippines’ submissions fell within those exceptions (People’s Republic of China, 2014; South China Sea Arbitration, 2015).

This was the hardest jurisdictional issue in the case. The Philippines could not defeat Article 298 by clever drafting alone. If the substance of a claim involved delimitation, historic title, or excluded military activity, the Tribunal had to decline jurisdiction. The Tribunal’s task was to identify the real legal character of each submission.

The result turned on distinctions that are technical but essential. Historic rights are not the same as historic title. Maritime entitlement is not the same as delimitation. Law enforcement activity is not always military activity. Each distinction determined whether the Tribunal could proceed.

2.6.1 Historic title and historic rights

China argued that the dispute involved a historic title and was excluded by Article 298. The Tribunal drew a narrower line. Article 298 refers to disputes involving historic bays or titles. Historic title suggests sovereignty over maritime areas, often linked to historic waters treated as internal waters or territorial waters. The Philippines’ claim was different. It challenged China’s asserted historic rights to resources within the nine-dash line, especially where those claims exceeded the maritime zones allowed by UNCLOS (South China Sea Arbitration, 2015; South China Sea Arbitration, 2016).

That distinction allowed jurisdiction. The Tribunal treated the nine-dash line not as a claim to historic title over waters, but as a claim to historic rights over resources and jurisdictional control. Such rights, if claimed beyond UNCLOS limits, raised a question about the interpretation and application of the Convention. They were not automatically excluded by Article 298.

The merits later made the point sharper. The Tribunal held that UNCLOS superseded incompatible historic-rights claims where the Convention allocated maritime entitlements to coastal States. A claim to resource rights in another State’s EEZ could not survive merely because it was historically asserted (South China Sea Arbitration, 2016; Klein, 2020).

This distinction has broader significance. A State cannot avoid UNCLOS review by labelling a resource claim as historical. The legal content of the claim matters. If the claim is really about sovereign title to waters, Article 298 may exclude it. If it is about resource rights beyond treaty limits, a tribunal may still have jurisdiction.

2.6.2 Entitlement and delimitation

China’s delimitation objection required the Tribunal to distinguish between determining entitlements and delimiting overlapping zones. Maritime entitlement asks what zones a coast or feature can generate. Delimitation asks how overlapping entitlements between States should be divided.

The Tribunal held that it could decide the first question without deciding the second. Classifying a feature under Article 121 does not draw a boundary. It only determines the maximum legal effect that the feature may have. If a feature cannot generate an EEZ or continental shelf, there may be no overlapping entitlement requiring delimitation in the relevant area (South China Sea Arbitration, 2015; South China Sea Arbitration, 2016).

This reasoning was central to the award. The Philippines did not ask the Tribunal to allocate overlapping maritime spaces between the parties. It asked whether certain features were legally capable of generating overlapping entitlements at all. That question fell within UNCLOS interpretation and did not require a boundary line.

The distinction also prevented Article 298 from becoming too broad. If every question about entitlement were treated as delimitation, tribunals could not classify features whenever boundary consequences might follow. That would make Article 121 difficult to enforce in contested areas. The Tribunal preserved a space for legal classification without crossing into boundary-making.

There is a legitimate criticism here. Entitlement findings can affect future delimitation by shrinking or eliminating possible claims. Yet legal effect is not the same as legal identity. Many judicial findings influence later negotiations or disputes. That does not convert every preliminary legal question into delimitation.

2.6.3 Law enforcement and military activity

Article 298 also excludes certain disputes concerning military activities and law enforcement activities. These exceptions required the Tribunal to characterize China’s conduct carefully.

Some conduct could be examined as law enforcement or interference with resource rights. For example, actions affecting fishing, petroleum exploration, or access to Scarborough Shoal raised questions under UNCLOS provisions governing EEZ rights, traditional fishing, and navigation-related obligations. Other incidents risked falling within military activity, especially where naval vessels, security operations, or coercive State conduct were involved (South China Sea Arbitration, 2015; South China Sea Arbitration, 2016).

The Tribunal did not adopt a single label for all Chinese activity. That would have been legally careless. It looked at the nature of each incident. Coast guard operations, fisheries enforcement, construction activity, and military conduct do not all fall into the same jurisdictional category.

The military activities exception posed a special difficulty because States may describe conduct differently. One State may call an incident law enforcement. Another may call it military coercion. The Tribunal had to assess the character of the activity objectively, using available evidence and the legal context.

Some submissions were limited or excluded because of these concerns. Others survived because they could be decided as disputes about environmental protection, resource interference, or the legal status of maritime features. This claim-specific approach avoided an overbroad assertion of jurisdiction.

The result shows why Article 298 must be read with precision. It protects sensitive matters that States chose to exclude. It does not remove every dispute involving government vessels, maritime pressure, or strategic consequences.

2.7 Indispensable third parties

China argued that other claimants were indispensable third parties. Vietnam, Malaysia, Brunei, and Taiwan all had interests in the South China Sea. A decision affecting the legal status of features or maritime entitlements could influence their positions. The question was whether that influence made their participation legally necessary.

International adjudication cannot decide the rights of absent third parties if those rights form the very subject matter of the decision. This principle is associated with the Monetary Gold doctrine. It protects States from having their legal rights determined without consent (Monetary Gold, 1954; East Timor, 1995).

The Tribunal concluded that the absent claimants were not indispensable. It did not decide sovereignty over features claimed by them. It did not delimit boundaries involving them. It did not decide their territorial rights. The legal questions concerned the compatibility of China’s claims and conduct with UNCLOS in relation to the Philippines (South China Sea Arbitration, 2015).

The distinction is narrow but workable. A decision may affect the interests of third States without deciding their legal rights. Many international judgments have practical consequences for non-parties. That alone does not make them indispensable. The bar is higher: the tribunal must be unable to decide the case without first determining the legal responsibility or rights of the absent State.

Feature classification illustrates the point. If a tribunal says that a certain reef is a low-tide elevation or that a feature cannot generate an EEZ, that finding may matter to several States. But it does not decide which State owns the feature. Nor does it allocate maritime zones among all claimants. The absent States remain free to maintain their sovereignty claims and to argue their own boundary positions in other settings.

Taiwan’s position created an additional sensitivity because Itu Aba was central to the Article 121 analysis. The Tribunal examined the natural capacity of the feature, not sovereignty over it. That allowed the Tribunal to address its legal status under UNCLOS without deciding Taiwan’s territorial claim or legal personality questions.

This part of the award is important for future disputes. If all potentially interested coastal States had to participate before any UNCLOS tribunal could classify a feature or assess a maritime claim, compulsory settlement would often be impossible in semi-enclosed seas. The Tribunal avoided that paralysis while preserving the rule that absent States cannot have their rights directly adjudicated.

2.8 Good faith and abuse of process

China argued that the Philippines acted in bad faith and abused legal process by framing the dispute to avoid sovereignty and delimitation. The objection deserves careful treatment. Strategic pleading is not automatically abusive. All applicants frame claims to fit the jurisdiction of the forum they choose. The legal issue is whether the framing distorts the real dispute or asks the tribunal to decide matters beyond its authority indirectly.

The Philippines’ strategy was deliberate. It avoided sovereignty. It avoided boundary delimitation. It focused on historic rights, feature status, maritime entitlements, environmental harm, and interference with treaty rights. That was not improper by itself. A State may choose claims that fall within a tribunal’s jurisdiction and leave other claims unresolved (South China Sea Arbitration, 2015; Talmon, 2022).

The abuse argument would have been stronger if the Tribunal could not answer the submissions without deciding sovereignty or drawing a boundary. That was the core test. The Tribunal found that most submissions could be decided within UNCLOS. The Philippines did not ask the Tribunal to award title to territory, nor did it ask for a boundary line disguised as entitlement analysis.

Good faith also works both ways. A State cannot use negotiation rhetoric to block every legal process indefinitely. Nor can a State rely on the existence of a broader political dispute to avoid narrower treaty obligations. The Convention assumes that disputes may have political dimensions. Part XV would be ineffective if politics alone removed jurisdiction.

At the same time, the Philippines’ approach had consequences. By narrowing the case to UNCLOS questions, it obtained a legally powerful award but not a full settlement. Sovereignty remained unresolved. Delimitation remained unresolved. Enforcement remained difficult. The strategy succeeded in litigation, but it could not substitute for regional settlement.

The better conclusion is that the Philippines used a lawful procedural design, not abuse. It selected claims that an UNCLOS tribunal could decide. China was entitled to challenge that characterization. The Tribunal was required to test it. The award’s jurisdictional reasoning stands or falls on that testing, not on whether the Philippines gained a strategic advantage by choosing arbitration.

3. Historic rights and the nine-dash line

3.1 The nine-dash line as a legal claim

The nine-dash line was legally difficult because it was never expressed with stable precision. At different moments, it appeared as a claim to islands, a claim to adjacent waters, a claim to historic rights, a claim to sovereign rights over resources, or a claim to a special maritime space under Chinese control. That uncertainty was not a minor drafting problem. It affected jurisdiction, the merits, and the ability of other States to know what legal claim they were expected to accept or resist.

China’s official language often refers to sovereignty over islands in the South China Sea and “relevant waters,” together with sovereign rights and jurisdiction in surrounding maritime areas. The problem was that this formulation did not clearly identify the source, extent, or legal character of the claimed rights. If the line merely indicated sovereignty over land features, the legal issue would be territorial title. If it asserted rights over waters and seabed beyond zones allowed by UNCLOS, the issue became treaty incompatibility. If it claimed historic rights to resources, the Tribunal had to decide whether such rights survived the Convention (People’s Republic of China, 2014; South China Sea Arbitration, 2016).

Ambiguity gave China diplomatic flexibility, but it weakened the legal defensibility of the claim. International law requires more than historical assertion. A maritime claim must identify its legal basis, its spatial reach, and its relationship with the rights of other States. A line on a map cannot by itself create sovereignty, sovereign rights, or jurisdiction over a semi-enclosed sea. Nor can it replace the treaty rules governing territorial seas, exclusive economic zones, and continental shelves (Beckman, 2013; Rothwell and Stephens, 2016).

The Tribunal treated the line by looking at how China had used it in practice. Chinese vessels, official statements, objections to Philippine petroleum activities, fisheries enforcement, and diplomatic protests suggested that China was asserting rights to living and non-living resources beyond maritime zones generated by its mainland coast or any lawfully entitled island. The legal question was not the cartographic history of the line alone. The question was what China claimed to do inside it (South China Sea Arbitration, 2016).

This method avoided a trap. The Tribunal did not need to give the line one fixed meaning for all purposes. It only needed to decide whether any claim to historic rights, sovereign rights, or jurisdiction beyond UNCLOS limits could be valid against the Philippines. Once framed that way, the dispute became a direct test of the Convention’s allocation of maritime entitlements.

The nine-dash line also created a notice problem for neighbouring States. Vietnam, Malaysia, Brunei, Indonesia, and the Philippines could not assess the legality of the claim if its content shifted depending on context. The law of the sea depends on ascertainable zones. Baselines, territorial seas, EEZs, and continental shelves are measured through legal criteria. A vague historical envelope across the sea is hard to reconcile with that structure (UNCLOS, 1982; Churchill, Lowe and Sander, 2022).

The award’s treatment of the line should not be reduced to a rejection of Chinese history. The Tribunal did not deny that Chinese fishermen and navigators had long used parts of the South China Sea. It rejected the use of history as a legal device to claim resource rights in areas where UNCLOS gives rights to other coastal States (South China Sea Arbitration, 2016).

3.2 UNCLOS as a complete allocation system

The Tribunal’s central reasoning was that UNCLOS provides a comprehensive system for allocating maritime rights. The Convention defines the territorial sea, contiguous zone, exclusive economic zone, continental shelf, high seas, and the international seabed Area. These zones are not political preferences. They are legal categories that distribute authority between coastal States and other States (UNCLOS, 1982).

That structure was the reason the historic-rights claim failed. UNCLOS gives coastal States sovereign rights over natural resources in the EEZ and continental shelf. It also preserves freedoms of navigation, overflight, laying of cables and pipelines, and other internationally lawful uses of the sea. A claim to historic resource rights across areas already allocated by the Convention would disturb that balance. It would allow one State to retain exceptional rights inside another State’s EEZ without a clear treaty basis (South China Sea Arbitration, 2016; Klein, 2020).

The Tribunal did not say that every pre-existing maritime practice disappeared when UNCLOS entered into force. Some historic claims remain legally relevant, especially historic bays or historic title where the law recognizes them. Traditional fishing rights may also survive in narrow settings, depending on location and legal context. The holding was more specific: any historic rights to resources in areas that UNCLOS now allocates as another State’s EEZ or continental shelf are superseded if they are incompatible with the Convention (South China Sea Arbitration, 2016).

This reasoning protects the bargain behind the EEZ. During the negotiation of UNCLOS, coastal States accepted a legal compromise. They received extensive resource rights up to 200 nautical miles, but they did not receive full sovereignty over those waters. Other States retained important freedoms. Historic claims cutting across that arrangement would reintroduce uncertainty into a system designed to replace open-ended assertions with measured entitlements (Churchill, Lowe and Sander, 2022).

The decision also limited the role of unilateral maps. UNCLOS does not allocate maritime rights through historical sketches, national atlases, or domestic declarations alone. It allocates them through coasts, baselines, distance, natural prolongation, feature status, and agreed rules. A map may evidence a claim. It does not prove that the claim is lawful (Beckman, 2013; South China Sea Arbitration, 2016).

The legal consequence was direct. China could claim maritime zones generated by its mainland coast and by any land features over which it might lawfully have sovereignty, subject to UNCLOS. It could not claim additional resource rights merely because those waters fell inside a dashed line. The Convention supplied the controlling framework.

3.3 Historic rights before UNCLOS

Historic use and historic legal entitlement are not the same. This distinction was decisive. Evidence that Chinese fishermen sailed, traded, fished, named features, or used parts of the South China Sea did not automatically establish an exclusive legal right against other coastal States. Many people used the sea. Shared use is not the same as sovereign control.

Before UNCLOS, much of the water beyond narrow territorial seas was treated as high seas. Fishing and navigation in those areas were commonly exercises of high seas freedoms, not evidence of exclusive historic rights. The Tribunal found that Chinese fishermen and navigators had historically been active in the region, but similar activities were also carried out by others. That pattern supported historic use, not exclusive entitlement (South China Sea Arbitration, 2016).

A historic legal claim normally requires stronger elements. The State must show authority exercised over the area as of right, continuity over time, and acquiescence by other States. Mere presence by private fishermen is not enough. Nor is occasional official reference, naming practice, or general historical association. The legal claim must be public, consistent, and accepted or at least tolerated by affected States in a way that supports legal recognition (Symmons, 2019; Tanaka, 2019).

The Tribunal found no sufficient evidence that China had exercised exclusive control over the waters or resources inside the line before UNCLOS. There was no settled pattern of Chinese administration over the waters as a maritime space. There was no convincing evidence that neighbouring States had acquiesced in Chinese exclusive rights. Historic activity existed, but legal exclusivity did not (South China Sea Arbitration, 2016).

This part of the award is important because historical narratives can easily become overextended. States often rely on old maps, voyages, fishing traditions, administrative acts, and cultural memory to support modern maritime claims. Those materials may matter in territorial disputes over land features. They do not automatically generate rights over broad maritime spaces.

The difference is practical. A fisherman’s use of a fishing ground may support a claim that traditional fishing should be respected in a specific area. It does not justify sovereign rights over the seabed, exclusion of other coastal States, regulation of foreign vessels, or interference with another State’s petroleum activities. The legal weight of history depends on the specific right being claimed (South China Sea Arbitration, 2016; Rothwell and Stephens, 2016).

The Tribunal’s approach also avoided treating the South China Sea as historically empty except for China. The region had long been used by coastal communities from several States. International law cannot convert one State’s historical use into regional control when the factual record shows plural use and no general acceptance of exclusivity.

3.4 EEZ and continental shelf consequences

Rejecting the nine-dash line preserved the legal architecture of the 200-nautical-mile EEZ and continental shelf. That was the award’s most important systemic effect. If a broad historic-rights claim could override UNCLOS zones, the EEZ would become unstable wherever a State could produce historical evidence of navigation, fishing, tribute, maps, or administrative interest.

The EEZ gives the coastal State sovereign rights over natural resources in the water column and seabed. The continental shelf gives rights over seabed and subsoil resources, including hydrocarbons and minerals. These rights exist by operation of law. They do not depend on occupation, proclamation, or historical control in the same way territorial sovereignty might (UNCLOS, 1982; Tanaka, 2019).

For the Philippines, this meant that areas within 200 nautical miles of its coast could not be subjected to Chinese resource claims unless China could identify a lawful UNCLOS entitlement overlapping those areas. The dashed line itself was not enough. Nor could historic fishing or navigation establish a superior claim to seabed resources within the Philippine continental shelf (South China Sea Arbitration, 2016).

The result was not simply anti-China. It protects every coastal State, including China, against excessive claims by others. If historic-rights arguments could defeat EEZs, then any State with a long maritime tradition could challenge neighbouring coastal entitlements. UNCLOS would lose the predictability that made the EEZ acceptable to both coastal and maritime powers.

This point is often missed in political commentary. The award did not create special rights for the Philippines. It applied a general treaty rule. Coastal States receive resource rights within defined maritime zones. Other States retain freedoms protected by the Convention. Neither side may replace that allocation with vague historical claims (Klein, 2020; Churchill, Lowe and Sander, 2022).

The continental shelf implications are especially significant. Seabed rights are not based on historic fishing or surface navigation. They arise from the coastal State’s land territory and the legal rules on natural prolongation and distance. A State cannot claim another State’s continental shelf resources through historical presence in the waters above them (UNCLOS, 1982; South China Sea Arbitration, 2016).

The decision also reduced the legal value of coercive presence. Patrols, warnings, survey interference, or administrative declarations cannot create lawful maritime rights where UNCLOS does not provide them. Physical control at sea may alter facts temporarily. It does not alter the treaty basis of entitlement.

3.5 Impact on other coastal States

The award binds only the Philippines and China, but its reasoning matters to every coastal State facing excessive maritime claims in the South China Sea. Vietnam, Malaysia, Brunei, and Indonesia were not parties. Their rights were not adjudicated. Yet the legal analysis gives them a vocabulary for challenging claims that exceed UNCLOS limits.

Vietnam has an obvious interest because it contests sovereignty over the Paracel and Spratly Islands and faces overlapping claims in nearby waters. The award does not decide Vietnam’s territorial claims, but it supports the argument that maritime entitlements must be derived from UNCLOS, not from a broad historical line. It also strengthens the view that many small features cannot generate extensive maritime zones (South China Sea Arbitration, 2016; Churchill, Lowe and Sander, 2022).

Malaysia and Brunei benefit from the same logic in relation to their continental shelf and EEZ claims. If resource rights are allocated by UNCLOS, then historical assertions cannot lawfully cut across their 200-nautical-mile entitlements without a valid maritime entitlement generated by land territory. This is particularly relevant for offshore energy activity and continental shelf submissions.

Indonesia’s position is different because it does not claim the Spratly Islands. Its concern has centred on waters near the Natuna Islands, where Chinese fishing and enforcement activity has sometimes been linked to historic-rights language. The award supports Indonesia’s legal position that waters generated by the Natuna Islands must be assessed under UNCLOS, not under a vague historical claim extending into another State’s EEZ (Beckman, 2013; Klein, 2020).

The award also affects ASEAN diplomacy. It gives regional States a legal baseline for negotiations with China. A code of conduct may help reduce incidents, but it cannot lawfully dilute rights already granted by UNCLOS. Political arrangements may manage behaviour; they cannot validate maritime claims that contradict the Convention.

There is also a litigation effect. Future tribunals are not formally bound by the award as precedent in the common-law sense. Even so, the reasoning will be difficult to ignore. It is detailed, treaty-based, and directed at recurring problems: historic rights, feature status, maritime entitlements, and the relationship between law and power in semi-enclosed seas (Talmon, 2022; Tanaka, 2019).

For other coastal States, the award’s value lies in legal discipline. It does not hand them automatic victories. It does not settle their boundaries. It does not decide sovereignty over disputed islands. What it does is narrow the legal field. Claims must be translated into UNCLOS categories. Historic narratives must meet legal standards. Resource rights must be tied to valid maritime entitlements. That is why the decision remains central to the legal future of the South China Sea.

4. Maritime features under Article 121

4.1 Feature status before sovereignty

The Tribunal’s treatment of maritime features followed a strict sequence. It did not begin by asking which State owned each feature. It first asked what each feature was under UNCLOS. That order was crucial. A feature’s legal capacity depends on its physical and functional character, not on the identity of the sovereign.

This approach allowed the Tribunal to avoid a sovereignty ruling. It could decide that a reef was a low-tide elevation, or that a high-tide feature was a rock under Article 121(3), without deciding which State had title to it. The legal question was limited: what maritime zones can this type of feature generate under the Convention? That question concerns entitlement, not ownership (South China Sea Arbitration, 2016; Talmon, 2022).

Article 121 sets the basic framework. Paragraph 1 defines an island as a naturally formed area of land, surrounded by water, above water at high tide. Paragraph 2 states that islands generally generate the same maritime zones as other land territories. Paragraph 3 limits that rule by providing that rocks unable to sustain human habitation or economic life of their own have no exclusive economic zone or continental shelf (UNCLOS, 1982).

The Tribunal’s sequence was legally efficient. If a feature is submerged at high tide, it cannot be an island. If it is a low-tide elevation outside any territorial sea, it cannot generate its own maritime zones. If it is above water at high tide but falls within Article 121(3), it may have a territorial sea but no EEZ or continental shelf. Each step narrows the legal consequences before any sovereignty question becomes necessary.

That method also reduced the risk of disguised delimitation. The Tribunal did not draw a boundary. It asked which features were legally capable of creating maritime entitlements. Once that capacity was defined, the possible area of overlap became much smaller. This was one of the most important jurisdictional and substantive moves in the award (South China Sea Arbitration, 2015; South China Sea Arbitration, 2016).

The point is simple but often missed. Sovereignty over a feature does not decide the size of the sea around it. A State may own a rock, but that does not make the rock a source of a 200-nautical-mile zone. The Convention controls the legal effect.

4.2 Low-tide elevations

Low-tide elevations occupy an awkward place in the law of the sea. They are naturally formed areas of land surrounded by and above water at low tide, but submerged at high tide. Article 13 of UNCLOS gives them limited legal relevance. If a low-tide elevation lies wholly or partly within the territorial sea of the mainland or an island, its low-water line may be used as a baseline. If it lies outside the territorial sea, it has no territorial sea of its own (UNCLOS, 1982).

This rule had major consequences for Mischief Reef and Second Thomas Shoal. The Tribunal found that both were low-tide elevations. They were not islands. They were not rocks. They could not generate a territorial sea, EEZ, or continental shelf by themselves. Their legal significance depended on their location within maritime zones generated by other land territory (South China Sea Arbitration, 2016).

Mischief Reef was especially important because China had built installations there. Construction did not change the legal classification. A low-tide elevation remains a low-tide elevation even if a State places structures on it. Artificial works may create facts on the ground, but they do not create natural land territory for the purposes of maritime entitlement (UNCLOS, 1982; South China Sea Arbitration, 2016).

The Tribunal also found that Mischief Reef lies within the Philippines’ exclusive economic zone and continental shelf. That conclusion mattered because coastal States have sovereign rights over resources in those zones and jurisdiction over artificial islands, installations, and structures. A foreign State cannot acquire independent maritime entitlements by constructing facilities on a submerged reef located in another State’s EEZ and continental shelf (South China Sea Arbitration, 2016).

Second, Thomas Shoal raised similar issues. As a low-tide elevation, it could not create maritime zones of its own. Its relevance came through the surrounding maritime entitlements of the Philippines. Chinese interference around that area had to be assessed against the Philippines’ rights under the Convention, not against any entitlement generated by the shoal itself.

The broader lesson is direct. Submerged features and low-tide elevations cannot be used as legal anchors for expansive maritime claims. Modern construction can make them operationally important. It cannot make them legally equivalent to islands.

4.3 Rocks and islands

Article 121(3) became one of the most debated parts of the award. The provision appears short, but it carries large consequences. If a high-tide feature is an island under Article 121(1) and does not fall within Article 121(3), it may generate an EEZ and continental shelf. If it is a rock unable to sustain human habitation or economic life of its own, it is limited to a territorial sea (UNCLOS, 1982).

The Tribunal interpreted Article 121(3) by focusing on capacity, not present political use. The question was not simply what people had done on a feature after military occupation, external supply, or artificial improvement. The question was what the feature could sustain in its natural condition. This made the analysis historical, geographic, ecological, and economic at the same time (South China Sea Arbitration, 2016).

The decision was significant because earlier international courts often avoided a full interpretation of Article 121(3). In delimitation cases, small islands were sometimes given reduced effect without a detailed ruling on their status as rocks. The Tribunal could not avoid the issue because feature status was central to the Philippines’ submissions. Villamizar Lamus treats the award as a clarification of Article 121 rather than a rupture with prior jurisprudence, which is the better reading (Villamizar Lamus, 2020).

The Tribunal did not treat size alone as decisive. A small feature is not automatically a rock. Nor is a larger feature automatically a fully entitled island. The relevant inquiry is the capacity to sustain human habitation or economic life of its own. Fresh water, soil, vegetation, shelter, food sources, exposure to storms, historical settlement, and dependence on outside supply all become relevant.

The legal standard was demanding. It required more than temporary survival, military presence, or extractive activity. The feature had to be capable of supporting a stable human community or an economic life not dependent on outside resources. This interpretation sharply limited the maritime effect of remote reefs and small coral formations in the Spratly group (South China Sea Arbitration, 2016; Tanaka, 2019).

4.3.1 Human habitation

Human habitation under Article 121(3) does not mean that a few people can physically stay on a feature for a period of time. If that were enough, almost any reef with a shelter, generator, and supply boat could qualify. The Tribunal looked for capacity to support a settled community in a meaningful sense.

Military personnel, coast guard units, lighthouse staff, scientific teams, and temporary officials do not prove that a feature can sustain human habitation. Their presence usually depends on outside supply, State funding, rotation, infrastructure, and strategic purpose. Such an occupation may show control or administrative interest, but it does not show a natural capacity for ordinary human settlement (South China Sea Arbitration, 2016).

The Tribunal also distinguished survival from habitation. People can survive in extreme places with enough external support. That does not mean the place sustains habitation of its own. Article 121(3) asks about the feature’s capacity, not the logistical capacity of the State occupying it.

Historical evidence was relevant but not conclusive. The Tribunal examined records of fishermen, small groups, officials, and temporary occupants. It looked for signs of stable residence, family life, local community, and ordinary social existence. The evidence did not show that the Spratly features had supported such communities in their natural condition (South China Sea Arbitration, 2016).

Itu Aba was the strongest candidate for full island status. It has fresh water and is larger than many other Spratly features. Even there, the Tribunal concluded that the evidence did not prove capacity to sustain a stable human community without external support. That finding remains controversial, but it reflects the Tribunal’s strict reading of Article 121(3) (Talmon, 2022; Villamizar Lamus, 2020).

The practical effect is important. States cannot create an EEZ by stationing personnel on an otherwise incapable feature. Strategic occupation is not the same as habitation in the legal sense.

4.3.2 Economic life of their own

The second limb of Article 121(3) concerns economic life. A feature may be unable to sustain human habitation but still arguably support an economic life of its own. The Tribunal gave this phrase independent meaning, but not an easy one.

Economic value is not enough. Many reefs have value because nearby waters contain fish, the seabed may contain resources, or the location has military and navigational importance. That does not mean the feature itself has economic life of its own. The economic activity must be connected to the feature’s own capacity, not merely to the surrounding maritime zone that the feature is being used to claim (South China Sea Arbitration, 2016).

This distinction prevents circular reasoning. A State cannot say that a feature generates an EEZ because the surrounding EEZ would contain valuable resources. Article 121(3) asks if the feature can sustain economic life before the EEZ is granted. The potential wealth of the waters cannot be used to justify the legal entitlement to those same waters (Churchill, Lowe and Sander, 2022).

Fishing around a reef also requires careful treatment. Fishing may show that the surrounding waters are productive. It does not necessarily show that the feature itself supports an economy. Traditional fishing expeditions, seasonal visits, or extraction by passing vessels do not create an economic life belonging to the feature. They are uses of the sea.

The Tribunal also rejected activities dependent on outside supply or State sponsorship as proof of the economic life of the feature itself. Military bases, administrative outposts, subsidized settlements, and externally supported installations may have economic effects, but those effects come from State policy. They do not demonstrate natural capacity (South China Sea Arbitration, 2016).

Guano extraction, turtle harvesting, clam collection, and fishing appeared in the historical record. The Tribunal treated such activity as intermittent exploitation rather than a self-sustaining economy. That approach matters because many remote maritime features have been visited for extraction. Occasional extraction is not the same as an economy rooted in the feature itself.

The result was restrictive but coherent. Article 121(3) would be almost meaningless if any resource use near a feature allowed it to generate an EEZ and continental shelf. The Tribunal’s interpretation preserves the provision’s limiting function.

4.3.3 Natural condition

The Tribunal assessed features in their natural condition. This was essential because several features had been altered by reclamation, dredging, construction, and military development. Without a natural-condition rule, States could manufacture maritime entitlements by changing geography.

UNCLOS supports this approach. Article 121 refers to a “naturally formed” area of land. Artificial islands do not have the status of islands and do not possess a territorial sea of their own. They may generate safety zones in certain circumstances, but they do not create EEZs or continental shelves (UNCLOS, 1982).

Land reclamation cannot upgrade a reef into a fully entitled island. A runway, port, radar station, harbour, housing unit, desalination plant, or power generator may make occupation easier. None of these proves that the original feature could sustain habitation or economic life of its own. The legal baseline remains the feature before artificial transformation (South China Sea Arbitration, 2016).

This rule has strong policy logic. If artificial enhancement could create maritime entitlements, powerful States would gain incentives to build on reefs and low-tide elevations to expand jurisdiction. The maritime order would shift from law-based entitlement to engineering capacity. That would undermine the stability of UNCLOS.

The natural-condition inquiry also protects weaker coastal States. A State with greater construction capacity should not be able to enlarge maritime claims by physically altering features near another State’s EEZ. The Convention assigns maritime zones through legal criteria, not through the scale of reclamation works.

The Tribunal’s approach does not make artificial islands irrelevant. They may matter for environmental obligations, safety zones, navigation risks, and violations of coastal State rights. They simply cannot become natural islands for the purpose of generating maritime zones.

4.4 The Spratly Islands

The Tribunal found that none of the Spratly features considered in the arbitration could generate an EEZ or continental shelf. This was one of the award’s most consequential findings. It meant that even the strongest high-tide features in the group were legally limited under Article 121(3) (South China Sea Arbitration, 2016).

The Tribunal examined the features individually and also rejected the idea that the Spratly Islands could be treated collectively as a unit capable of generating maritime zones. UNCLOS does not allow a group of scattered features to be converted into an archipelagic unit for a continental State in the same way an archipelagic State may draw archipelagic baselines under Part IV. China could not treat the Spratlys as a single maritime generator merely by grouping them politically or historically (UNCLOS, 1982; South China Sea Arbitration, 2016).

This finding sharply reduced the possibility of overlapping entitlements with the Philippines’ EEZ. If Spratly features had generated EEZs, large areas would have involved competing 200-nautical-mile claims and possible delimitation. By finding that they did not, the Tribunal could identify areas where the Philippines’ entitlements existed without overlap with those features.

The finding also limited the legal effect of occupation. Several States occupy features in the Spratlys. Occupation may matter for sovereignty disputes, administration, and security. It does not alter Article 121. A State cannot enlarge a feature’s maritime reach by placing personnel, buildings, or infrastructure on it.

The Spratly analysis has drawn criticism because some consider the Tribunal’s reading of habitation and economic life too strict, especially regarding Itu Aba. That criticism deserves attention. Still, the award’s reasoning is anchored in a concern that small, remote, externally supplied features should not project vast maritime zones into semi-enclosed seas. Without that limit, Article 121(3) would have little practical effect (Talmon, 2022; Villamizar Lamus, 2020).

The practical result was large. Much of the area that might have been claimed through Spratly-based EEZs could no longer be treated that way under the Tribunal’s analysis. Claims had to be based on valid entitlements generated by mainland coasts or fully qualifying islands, not on the Spratly group as a whole.

4.5 Scarborough Shoal

Scarborough Shoal required separate treatment because it raised issues different from the Spratlys. It is not a large island capable of supporting an ordinary settlement. It consists of rocks above water at high tide, surrounding a lagoon. The Tribunal treated it as capable of generating a territorial sea, but not an EEZ or continental shelf (South China Sea Arbitration, 2016).

The shoal mattered especially for fishing. Filipino fishermen had traditionally fished there, as had Chinese fishermen. The Tribunal found that traditional fishing rights existed in the territorial sea of Scarborough Shoal and that China had unlawfully prevented Filipino fishermen from exercising those rights after gaining control of access to the area (South China Sea Arbitration, 2016).

This finding did not decide sovereignty over Scarborough Shoal. It also did not give the Philippines exclusive control over the shoal. The ruling was narrower: where traditional fishing rights existed, China could not exclude Filipino fishermen in the way it did. This makes Scarborough Shoal different from areas treated mainly as part of the Philippines’ EEZ.

The territorial sea context is important. Traditional fishing rights may have a different legal status in territorial waters than in the EEZ. The EEZ is a treaty-created zone with coastal State resource rights. Traditional fishing in territorial seas has a more specific historical and local character. The Tribunal’s reasoning reflected that difference (South China Sea Arbitration, 2016; Tanaka, 2019).

Scarborough Shoal also raised law enforcement issues. Chinese control at the shoal involved government vessels and restrictions on access. The Tribunal had to assess those acts without treating the matter as a sovereignty dispute. It focused on the legality of excluding traditional fishermen and on navigation-related conduct, not on ownership of the shoal.

This separate treatment prevents analytical confusion. Scarborough Shoal cannot be treated as identical to Mischief Reef, Second Thomas Shoal, or the Spratly features. Its legal role came from its above-water rocks, possible territorial sea, and traditional fishing rights. The Spratly analysis centred more heavily on Article 121(3), low-tide elevations, and the absence of EEZ-generating features.

4.6 Effects on maritime claims

The classification of features reshaped the legal map. Once the relevant Spratly features were found, unable to generate EEZs or continental shelves, many possible overlaps disappeared. The Philippines’ maritime entitlements from its main archipelago could be assessed without giving a competing 200-nautical-mile effect to small offshore features controlled or claimed by China (South China Sea Arbitration, 2016).

This had direct consequences for Mischief Reef and Second Thomas Shoal. As low-tide elevations within the Philippines’ EEZ and continental shelf, they could not serve as independent sources of Chinese maritime rights. Chinese construction or presence there could be assessed against Philippine coastal State rights under UNCLOS (South China Sea Arbitration, 2016).

The doctrinal effect is broader than the bilateral dispute. Article 121 limits the capacity of small features to distort maritime zones. Without that limit, tiny rocks could project large EEZs and continental shelves into areas already close to other States’ coasts. The Tribunal’s approach favours proportionality in the structure of maritime entitlement, even before formal delimitation begins.

The award also reduces incentives for artificial expansion. If construction cannot upgrade legal status, then reclamation loses value as a method of maritime claim-building. It may still have military or administrative value, but not entitlement-generating value. This distinction is essential for the integrity of the Convention.

For future disputes, the key lesson is that maritime claims must begin with lawful feature classification. A State cannot rely on occupation, history, infrastructure, or strategic importance alone. It must show that the feature meets the Convention’s criteria and that the claimed maritime zones follow from those criteria.

The Tribunal’s findings do not bind third States as parties. Vietnam, Malaysia, Brunei, and Taiwan remain outside the award’s operative binding force. Yet the reasoning matters because it offers a detailed method for evaluating small maritime features in contested seas. Legal advisers and tribunals will have to engage with it, even if they later accept, distinguish, or criticize parts of its analysis.

The final effect is conceptual. The award moved the debate away from maps filled with lines and toward legal capacity under UNCLOS. It asked what each feature naturally is, what it can sustain, and what maritime zones the Convention allows it to generate. That method is less politically dramatic than sovereignty rhetoric, but it is more disciplined and legally durable.

5. Marine environmental obligations

5.1 Coral reefs and reclamation

The environmental part of the award is one of its most important contributions, although it receives less attention than the nine-dash line and Article 121. The Tribunal treated coral reef destruction as a legal injury under UNCLOS, not as a secondary ecological concern. China’s land reclamation and construction activities at several reefs were assessed against Part XII of the Convention, especially the duties to protect and preserve the marine environment and to prevent serious damage under State control (UNCLOS, 1982; South China Sea Arbitration, 2016).

The facts were serious. Large-scale dredging, land reclamation, harbour works, artificial island construction, and the installation of infrastructure altered fragile reef systems. Coral reefs are not ordinary seabed terrain. They are living marine ecosystems that support biodiversity, fisheries, coastal protection, and biological productivity. Damage to them can be long-lasting or irreversible. The Tribunal relied on scientific evidence to conclude that China’s activities caused severe harm to coral reef environments (South China Sea Arbitration, 2016).

The legal issue extended beyond physical damage to include due diligence. Under UNCLOS, a State must not only avoid direct pollution from its own vessels. It must regulate activities under its jurisdiction or control when those activities risk serious harm to the marine environment. That includes construction, dredging, harvesting, and other operations carried out by State organs, State-linked actors, or private actors whose conduct the State fails to prevent or control (South China Sea Arbitration, 2016; Boyle, 2020).

This is why the reclamation findings matter beyond the South China Sea. They show that environmental obligations in UNCLOS are operational rules. They require planning, control, assessment, and prevention. A State cannot rely on strategic need, administrative control, or infrastructure policy to avoid the Convention’s environmental limits.

The Tribunal also rejected the idea that sovereignty uncertainty excuses environmental damage. Even where States disagree over ownership of features, they remain bound by duties to protect the marine environment. Part XII applies across maritime zones and is not suspended because a reef is disputed. A State cannot destroy an ecosystem first and leave legal title for later.

Artificial island construction made the problem sharper. Reclamation did not only damaged reefs; it also attempted to create permanent physical facts in contested waters. The award drew a clear line between physical alteration and legal entitlement. The construction did not upgrade the maritime status of the features, and the environmental harm remained legally relevant regardless of the strategic function of the installations (UNCLOS, 1982; South China Sea Arbitration, 2016).

5.2 Article 192 and positive duties

Article 192 of UNCLOS states that States have the obligation to protect and preserve the marine environment. The wording is broad, but the Tribunal treated it as legally meaningful. It is not a slogan. It imposes duties that can be applied to concrete conduct where marine ecosystems are damaged or placed at serious risk (UNCLOS, 1982; South China Sea Arbitration, 2016).

The obligation has two sides. First, States must avoid conduct that harms the marine environment. Second, they must take active measures to protect it. The first side is negative: do not degrade the marine environment through harmful activities. The second is positive: regulate, supervise, cooperate, assess risks, and act with due diligence where harm is foreseeable.

The Tribunal’s reasoning helped develop Article 192 into a practical rule. China’s large-scale construction and failure to prevent destructive harvesting were not treated as matters outside legal review. They were examined as breaches of a general environmental obligation made specific by the facts. The damage to coral reefs, the scale of the works, and the ecological vulnerability of the area turned Article 192 into a concrete standard (South China Sea Arbitration, 2016).

The later climate advisory proceedings before ITLOS confirmed the wider importance of this interpretation. In those proceedings, the Philippines relied on the South China Sea award to argue that Article 192 contains both an active duty to protect the marine environment and a duty not to degrade it. ITLOS later confirmed that Article 192 has a broad scope and must be read with other provisions of Part XII, including obligations to prevent, reduce, and control pollution of the marine environment (ITLOS, 2024).

This matters because Article 192 operates as an entry point for modern environmental disputes under the law of the sea. It can address reef destruction, pollution, biodiversity damage, and climate-related harm to marine systems. It does not give tribunals unlimited environmental jurisdiction, but it allows legal scrutiny when a State’s conduct threatens marine ecosystems protected by UNCLOS (Boyle, 2020; ITLOS, 2024).

The award also gave Article 192 an ecological dimension. The marine environment is not protected only as a resource for human use. Coral reefs, endangered species, and marine habitats have legal relevance because they are part of the environment that States must protect and preserve. This broad reading strengthens the connection between UNCLOS, biodiversity protection, and sustainable use.

5.3 Article 194 and due diligence

Article 194 requires States to take all measures necessary to prevent, reduce, and control pollution of the marine environment. It also requires States to ensure that activities under their jurisdiction or control are conducted so as not to cause damage by pollution to other States and their environment, and so that pollution does not spread beyond areas where they exercise sovereign rights (UNCLOS, 1982).

The Tribunal treated Article 194 as part of a due diligence framework. Due diligence does not demand perfect prevention of every harm. It demands reasonable, serious, and proactive conduct proportionate to the risk. The more dangerous the activity and the more vulnerable the environment, the higher the standard of care expected of the State (South China Sea Arbitration, 2016; Boyle and Redgwell, 2021).

This approach connects UNCLOS to the broader no-harm principle in international environmental law. The no-harm rule requires States to prevent significant transboundary environmental damage arising out of activities within their jurisdiction or control. The International Court of Justice has treated prevention, vigilance, and environmental assessment as central elements of modern environmental responsibility (Pulp Mills, 2010; Certain Activities, 2015).

In the South China Sea, the harm was not speculative. The Tribunal found serious damage to coral reef systems caused by dredging and construction. It also considered China’s failure to stop the destructive harvesting of endangered species by Chinese fishermen. These activities were sufficiently linked to Chinese control, tolerance, or failure of regulation to engage the State’s obligations under Part XII (South China Sea Arbitration, 2016).

Article 194 should not be read as a narrow anti-pollution provision limited to chemicals or oil. UNCLOS defines pollution broadly, covering the introduction by humans of substances or energy into the marine environment that results or is likely to result in harmful effects. Physical destruction of marine habitats, sedimentation caused by dredging, and large-scale ecological disruption can fall within that protective logic when the effects damage marine life, ecosystems, or legitimate uses of the sea (UNCLOS, 1982; Tanaka, 2019).

The due diligence standard also has an institutional side. A State must have laws, enforcement capacity, monitoring systems, and administrative control sufficient to address foreseeable risks. It is not enough to say that harmful conduct was carried out by private fishermen or contractors if the State knew of the harm and failed to act. Knowledge, control, and regulatory failure are central to responsibility (South China Sea Arbitration, 2016).

This part of the award is valuable because it prevents environmental obligations from becoming ceremonial. Part XII requires conduct before damage becomes irreversible. In fragile reef systems, waiting for complete destruction before acting defeats the purpose of the Convention.

5.4 Environmental impact assessment

Environmental impact assessment is one of the main tools used to make prevention effective. Article 206 of UNCLOS requires States to assess the potential effects of planned activities when they have reasonable grounds to believe that those activities may cause substantial pollution or significant and harmful changes to the marine environment. The results must be communicated in the manner provided by the Convention (UNCLOS, 1982).

The Tribunal found that China had not met its obligations concerning assessment and communication in relation to major construction works. The scale of reclamation, the sensitivity of coral reefs, and the likelihood of severe ecological harm made environmental assessment essential. A State carrying out large works in such conditions cannot lawfully proceed as if environmental consequences are incidental (South China Sea Arbitration, 2016).

The link with the ICJ’s decision in Pulp Mills is important. The Court held that where there is a risk of significant transboundary harm, conducting an environmental impact assessment is a requirement under general international law. The Court did not prescribe one universal method, but it made clear that assessment must occur before the activity is implemented, not after damage has already occurred (Pulp Mills, 2010).

ITLOS has also strengthened this preventive logic. In its advisory work, it has treated environmental assessment as part of due diligence under UNCLOS, especially where activities may produce significant harm to the marine environment. This confirms that assessment is not merely a domestic administrative step. It is an international legal obligation when the risk threshold is met (Responsibilities and Obligations in the Area, 2011; ITLOS, 2024).

For reef construction, an adequate assessment would need to examine sediment plumes, coral mortality, habitat loss, effects on fish stocks, endangered species, cumulative impacts, and alternatives to the planned works. It would also require monitoring and public communication, where the Convention demands reporting. A paper assessment prepared after political decisions have already been taken would not satisfy the preventive function of Article 206.

The South China Sea award is particularly useful because it ties assessment to concrete marine harm. It does not treat EIA as a box-ticking requirement. The assessment obligation matters because coral reefs are vulnerable, damage is difficult to reverse, and scientific evidence can identify risks before construction begins.

The practical lesson is blunt. Large-scale marine construction in disputed waters creates legal risk. A State must assess environmental consequences, control contractors and officials, cooperate where appropriate, and communicate relevant findings. Failure to do so can breach UNCLOS even if sovereignty over the underlying feature remains unresolved.

5.5 Endangered species and fisheries

The award also addressed destructive harvesting practices, especially the extraction of giant clams and damage to coral reefs. These activities were not separate from the environmental case. They showed how biodiversity protection, fisheries management, and marine habitat preservation overlap under UNCLOS (South China Sea Arbitration, 2016).

Giant clam harvesting was especially damaging because extraction methods involved breaking or scarring reef structures. The harm was not only the removal of individual specimens. It included the destruction of reef habitat that supports wider marine life. The Tribunal found that Chinese authorities were aware of harmful practices by Chinese fishermen and failed to prevent them adequately (South China Sea Arbitration, 2016).

This finding matters for State responsibility. A State may breach environmental obligations not only by acting directly, but also by failing to regulate private conduct under its jurisdiction or control. When authorities know that vessels or nationals are damaging protected marine ecosystems and do not take reasonable enforcement measures, the omission itself becomes legally significant (South China Sea Arbitration, 2016; Boyle and Redgwell, 2021).

Fisheries law under UNCLOS is built around conservation as well as exploitation. Coastal States have rights to manage living resources in the EEZ, but those rights come with duties to conserve stocks and avoid overexploitation. Other States also have obligations to cooperate in conservation and to respect applicable rules. Destructive practices undermine both biodiversity and sustainable fisheries (UNCLOS, 1982; Tanaka, 2019).

The award’s treatment of endangered species also connects UNCLOS with other environmental regimes. The Convention on Biological Diversity and CITES are not substitutes for UNCLOS, but they help show the broader legal context in which marine species and habitats are protected. UNCLOS Part XII can absorb ecological concerns that were once treated as peripheral to maritime law (CBD, 1992; CITES, 1973; South China Sea Arbitration, 2016).

The fisheries dimension should not be reduced to conservation language alone. In the South China Sea, fisheries are tied to food security, coastal livelihoods, and regional stability. Destructive harvesting harms ecosystems and intensifies political conflict because it damages the shared resource base on which several coastal communities depend.

The Tribunal’s approach gives future claimants a stronger legal pathway. A State challenging destructive conduct does not need to show only interference with its economic rights. It can also invoke marine environmental obligations where the conduct damages habitats, protected species, or ecological systems. That dual route is important in semi-enclosed seas, where ecological harm often crosses political boundaries.

The broader message is that UNCLOS does not separate resource use, biodiversity, and environmental protection into sealed compartments. Fisheries, endangered species, coral reefs, and coastal State rights interact. The South China Sea award made that interaction legally visible and showed that marine environmental duties can carry real consequences in disputes dominated by sovereignty and security narratives.

6. Fishing, navigation, and due regard

6.1 Traditional fishing rights

Scarborough Shoal raised a question that was different from the legal status of the Spratly features. The Tribunal did not decide who owns the shoal. It examined a narrower issue: could China lawfully prevent Filipino fishermen from accessing a traditional fishing ground that had long been used by communities from the Philippines and China?

The answer was no. The Tribunal found that Filipino fishermen had exercised traditional fishing at Scarborough Shoal and that China unlawfully interfered with that practice after gaining effective control of access to the area (South China Sea Arbitration, 2016). The finding protected a specific local practice. It was not a ruling on sovereignty.

That distinction matters. Traditional fishing at Scarborough Shoal is not the same as a broad claim to historic rights across the South China Sea. The first concerns artisanal use in a defined maritime space. The second would undermine the EEZ regime if used to claim resources inside another State’s treaty-based maritime zone. The Tribunal accepted the former and rejected the latter.

The ruling also avoided turning traditional fishing into a general exception to coastal State rights. It did not create a right for foreign industrial fleets to fish freely in another State’s EEZ. Nor did it authorize claims over seabed resources, petroleum exploration, or maritime jurisdiction. Its scope was narrow: small-scale fishing linked to long-standing practice at Scarborough Shoal.

This part of the case gives the law a human dimension. The dispute was not only about maps, patrol vessels, and hydrocarbon blocks. It also concerned fishermen whose livelihoods depended on access to waters used before the crisis intensified. The Tribunal protected that practice without deciding territorial title, which shows how international adjudication can address concrete harm while staying within jurisdictional limits (Tanaka, 2019).

6.2 EEZ rights and due regard

The exclusive economic zone is a zone of shared legal functions. The coastal State has sovereign rights over natural resources. Other States keep important freedoms, including navigation, overflight, and the laying of submarine cables and pipelines. Neither side has complete control. UNCLOS manages that coexistence through due regard (UNCLOS, 1982).

Article 56(2) requires the coastal State to respect the rights and duties of other States. Article 58(3) requires other States to respect the coastal State’s rights and duties. This reciprocal structure prevents the EEZ from becoming either a territorial sea or high seas. It is a functional zone, built around allocated competences (Churchill, Lowe and Sander, 2022).

The Tribunal applied that structure to actual conduct. China’s interference with Philippine petroleum exploration and fishing activities was not treated as a mere political incident. It was assessed as a possible breach of rights granted by UNCLOS. Where the Philippines had sovereign rights over resources in its EEZ and continental shelf, another State could not lawfully obstruct those activities without a valid legal entitlement of its own (South China Sea Arbitration, 2016).

Petroleum exploration shows the point clearly. Continental shelf rights exist by operation of law. A coastal State does not need to occupy the seabed or proclaim each block before its legal entitlement exists. If another State prevents surveys, drilling preparations, or exploration support in that area without a lawful overlapping claim, it interferes with rights protected by Articles 56 and 77 (UNCLOS, 1982).

Fishing follows the same logic, with different details. In the EEZ, the coastal State controls access to living resources and must manage conservation. Foreign vessels do not have a free-standing right to fish there. Once the nine-dash line was found incompatible with UNCLOS, where it exceeded treaty limits, China could not rely on it to regulate or restrict fishing inside the Philippine EEZ (South China Sea Arbitration, 2016).

Navigation requires a separate analysis. Foreign vessels may pass through another State’s EEZ. The coastal State cannot treat that zone as territorial waters. Yet navigational freedom does not include a right to block lawful resource activity, create collision risks, or use government vessels to intimidate operators. Due regard requires practical respect for the legal rights being exercised by others (Rothwell and Stephens, 2016).

Due regard is not vague politeness. It asks concrete questions: what right is being exercised, how serious is the interference, what risk is created, and could the activity have been conducted in a less disruptive way? In the South China Sea, that standard matters because fishing, exploration, patrols, surveillance, and navigation often occur in the same waters.

6.3 Safety of navigation

The case also involved unsafe conduct at sea. This issue receives less attention than historic rights, but it is central to maritime stability. Dangerous manoeuvring can turn a legal dispute into a collision, an injury, or a military crisis.

UNCLOS works alongside the Convention on the International Regulations for Preventing Collisions at Sea. The collision regulations require proper lookout, safe speed, risk assessment, and action to avoid collision. They are not optional rules of courtesy. They are technical rules with legal consequences (COLREGs, 1972; UNCLOS, 1982).

The Tribunal found that Chinese law enforcement vessels had created serious collision risks during incidents involving Philippine vessels near Scarborough Shoal. The problem was not only political pressure. It was navigational danger. A State cannot use unsafe manoeuvring as a method of maritime assertion and then treat the result as ordinary enforcement conduct (South China Sea Arbitration, 2016).

This point matters because many confrontations in the region are carried out by coast guard vessels rather than warships. A white hull does not remove legal responsibility. Blocking, shadowing, crossing ahead at close range, surrounding another vessel, or forcing sudden course changes may breach safety duties even if no shot is fired.

Obstruction can also engage several legal regimes at once. If a vessel blocks access to fishing grounds, interrupts a resupply mission, interferes with petroleum activity, or creates a collision risk, the same conduct may raise issues of due regard, EEZ rights, navigational safety, and dispute aggravation. Legal classification depends on the facts, not on the label used by the State involved (Tanaka, 2019).

The Tribunal’s reasoning separates lawful presence from unlawful pressure. A government vessel may monitor, protest, communicate warnings, and maintain presence. It may not create danger at sea as a tool of coercion. In a crowded maritime corridor, that line is not technical. It is essential to prevent escalation.

6.4 Coast Guard conduct

Coast guards and maritime militia have become central to the South China Sea dispute. They allow States to apply pressure below the level of open naval conflict. They can block access, escort fishing fleets, challenge survey vessels, control approaches to reefs, and maintain a constant presence around contested features.

UNCLOS was not drafted for the full scale of modern grey-zone operations, but its rules still apply. Coast guard conduct can affect fisheries, navigation, environmental protection, artificial islands, resource exploration, and the rights of coastal States in the EEZ. The legal question is not only which vessel appears on the scene. It is what the vessel does and which legal interest it affects (UNCLOS, 1982; South China Sea Arbitration, 2016).

The Tribunal did not treat every government vessel operation as military activity. That would allow States to avoid legal scrutiny too easily. It also did not assume that every coercive act was ordinary law enforcement. The better method is functional: examine the vessels involved, the conduct used, the rights affected, and the operational context.

Maritime militia activity creates a harder problem. Fishing vessels may act privately, commercially, or with varying degrees of State support and coordination. If they damage reefs, obstruct access, or operate as part of a pressure campaign, questions arise about attribution and due diligence. A State may be responsible where vessels act under its instructions, direction, or control. Even where direct attribution is difficult, failure to prevent known harmful conduct may still breach due diligence obligations (ILC, 2001; South China Sea Arbitration, 2016).

The environmental findings illustrate this point. Chinese authorities were found to have tolerated or failed to prevent destructive harvesting by Chinese fishermen. That reasoning matters because States cannot always hide behind the private status of vessels when the conduct is known, repeated, and harmful.

Grey-zone activity also blurs the line between law enforcement and coercion. Genuine law enforcement is permitted where the State has jurisdiction. It becomes legally problematic when enforcement language is used to assert unlawful claims, exclude another State from its own EEZ, or create dangerous confrontations without a valid legal basis.

The practical conclusion is strict. Coast guard operations require legal discipline. Vessel colour, institutional label, or strategic purpose does not excuse unsafe navigation, unlawful interference with resource rights, or toleration of environmental harm.

7. Binding force and compliance

7.1 Final and binding status

The 2016 arbitral decision is final and binding between the Philippines and China. Article 296 of UNCLOS provides that decisions rendered by a court or tribunal with jurisdiction under Part XV are final and must be complied with by the parties. Annex VII, Article 11 confirms the same rule for arbitral decisions (UNCLOS, 1982).

This binding force is limited but real. It applies between the parties and to the particular dispute. It does not formally bind Vietnam, Malaysia, Brunei, Indonesia, Taiwan, Japan, Australia, the United States, or the European Union. Those actors may rely on the Tribunal’s reasoning, cite it, endorse it, or use it in diplomatic practice, but they are not parties to the operative ruling.

China’s rejection after the case does not alter the legal status of the decision. By joining UNCLOS, China accepted the Convention’s dispute settlement system subject to the treaty’s limits and exceptions. Once the Tribunal found jurisdiction and ruled on the claims before it, non-acceptance by the losing party did not operate as a veto (South China Sea Arbitration, 2016; Talmon, 2022).

The distinction between binding force and wider influence is important. The decision is not legislation for the whole world. Yet it has become one of the leading interpretations of UNCLOS on historic rights, Article 121, environmental duties, and EEZ interference. Its authority outside the parties depends on the strength of its reasoning and the extent to which States and institutions continue to rely on it.

If a respondent State could erase an Annex VII ruling simply by refusing to accept it, compulsory dispute settlement under UNCLOS would lose much of its value. Finality protects the system from that result.

7.2 Non-compliance and legal validity

Compliance and validity are separate issues. A State may reject a decision politically while remaining legally bound by it. China’s position affects enforcement, diplomacy, and regional behaviour. It does not turn the Tribunal’s decision into a legal nullity under UNCLOS (South China Sea Arbitration, 2016; Talmon, 2022).

This is one of the hard lessons of international adjudication. There is no automatic enforcement authority comparable to domestic courts. Implementation depends on diplomatic pressure, reputational cost, alliance policy, repeated invocation in international forums, domestic legal measures, and the behaviour of other States at sea (Klabbers, 2024).

That does not make the ruling irrelevant. Legal validity can shape the field even without full compliance. It gives the Philippines a defined legal baseline. It gives third States a treaty-based basis for rejecting excessive maritime claims. It also changes the argumentative burden. After 2016, the nine-dash line could no longer rely on ambiguity in the same way. Any defence of it must confront a detailed rejection grounded in UNCLOS.

Non-compliance also carries reputational costs. A State that rejects a binding decision may weaken its credibility when it invokes international law in other disputes. It may face coordinated diplomatic responses and closer scrutiny of its maritime conduct. These effects may be gradual, but they are not meaningless.

The realistic assessment is neither romantic nor dismissive. The ruling did not end confrontations. It did not compel immediate policy change by China. Yet it remains legally relevant because the validity of an international decision does not depend on voluntary acceptance by the State that lost.

7.3 China’s legal counter-narrative

China’s post-2016 position has remained consistent. It argues that the Tribunal lacked jurisdiction, that the decision is null and void, and that China neither accepts nor recognizes it. The same themes appeared before the ruling: territorial sovereignty, maritime delimitation, lack of consent, prior commitments to negotiation, and abuse of process (People’s Republic of China, 2014; People’s Republic of China, 2016).

The sovereignty objection remains the centrepiece. China maintains that the Tribunal could not address the Philippines’ submissions without first deciding ownership of maritime features. Since UNCLOS does not determine title to land territory, Beijing argues that the case fell outside the Convention. The Tribunal answered that it could decide specific questions of maritime entitlement and conduct without assigning sovereignty (South China Sea Arbitration, 2015; South China Sea Arbitration, 2016).

The delimitation objection is closely related. China treats the case as an indirect attempt to allocate maritime space. The Tribunal drew a line between entitlement and delimitation. It classified features and assessed their legal capacity to generate maritime zones. It did not draw a maritime boundary. That distinction remains one of the main points of disagreement between China’s position and the Tribunal’s reasoning (Talmon, 2022).

China also continues to rely on negotiation. It argues that the Philippines bypassed agreed diplomatic channels and escalated the dispute by bringing arbitration. The Tribunal rejected that view because the relevant instruments did not clearly exclude Part XV procedures, and years of exchanges had failed to settle the dispute or produce agreement on another binding method (South China Sea Arbitration, 2015).

The abuse-of-process argument is more nuanced. China says the Philippines artificially repackaged sovereignty and delimitation issues as UNCLOS claims. The Philippines plainly framed the case to fit the jurisdiction. That is not unlawful by itself. The decisive question was whether the Tribunal could answer the submissions without deciding excluded matters. It concluded that most claims could be resolved within the Convention.

China’s counter-narrative also serves political functions. It supports domestic messaging, preserves room for diplomatic manoeuvre, and prevents the ruling from becoming an uncontested regional baseline. For legal analysis, though, non-recognition is not an answer to the reasoning. The objections must be tested against UNCLOS.

7.4 Philippine policy after 2016

Philippine policy after 2016 has moved through different phases. Under President Rodrigo Duterte, Manila often softened public reliance on the decision in favour of engagement with China, economic cooperation, and bilateral management of tensions. The legal position was not formally abandoned, but it was not always used as the centre of foreign policy (Batongbacal, 2019; Storey, 2020).

Under President Ferdinand Marcos Jr., the decision returned to the centre of Philippine maritime policy. Manila has relied more openly on the ruling, strengthened defence cooperation with partners, and publicized incidents involving Chinese vessels. The legal strategy is now linked to public documentation, diplomatic protest, and operational presence (Department of Foreign Affairs of the Philippines, 2024).

In 2024, the Philippine Department of Foreign Affairs described the 2016 ruling as a reaffirmation of UNCLOS and as protection for the rights of the Philippines as a coastal State and seafaring nation. That language matters because it places the decision within continuing policy, not as a symbolic victory from the past (Department of Foreign Affairs of the Philippines, 2024).

This approach combines law with statecraft. Diplomatic protests cite the ruling. Public release of maritime incidents builds credibility. Defence cooperation increases deterrence. Legal argument gives these actions a treaty-based foundation. None of those tools alone is sufficient, but together they make it harder for unlawful claims to become normalized.

There is a risk. If the ruling is presented only as an instrument of alliance politics, its wider legal authority may weaken. Its strongest value lies in UNCLOS. Philippine policy is most persuasive when it frames the decision as a defence of the Convention, not merely as a strategic position against China.

The Philippine experience shows that litigation is only one stage. After a favourable ruling, a State must preserve the legal gain through diplomacy, documentation, partnerships, and consistent public argument.

7.5 Support by third States

Third-State support has helped keep the 2016 decision active in legal and diplomatic debate. Several States and institutions have described it as final, binding between the parties, or significant for the interpretation of UNCLOS. Japan, Australia, the United States, the European Union, and G7 members have all used diplomatic language that supports key elements of the Tribunal’s reasoning (Ministry of Foreign Affairs of Japan, 2024; Australian Department of Foreign Affairs and Trade, 2024; European Union, 2024).

This support must be described accurately. It does not make third-party states to the case. It does not turn the decision into a formal precedent binding on every UNCLOS tribunal. Its value lies in consolidation. Repeated reliance helps normalize the view that maritime claims in the South China Sea must comply with UNCLOS and that broad historic-rights assertions cannot defeat treaty-based entitlements.

Diplomatic statements are most useful when they identify legal propositions rather than only political preferences. Strong statements refer to UNCLOS, finality, binding force between the parties, freedom of navigation, EEZ rights, or the rejection of excessive maritime claims. General calls for peace and stability have less interpretive value.

Naval operations and joint patrols should be analysed separately. They may signal rejection of excessive claims or support for navigational freedoms. Their legal meaning depends on what claim is being challenged, what conduct is performed, and how the State explains its action (Rothwell and Stephens, 2016).

Third-State support also has limits. Some governments endorse the ruling but avoid direct confrontation with China. Others support UNCLOS in general terms while staying cautious on particular findings. Regional States may value the legal reasoning but fear economic or military pressure. Legal agreement does not always produce operational alignment.

Even so, external support has prevented the ruling from being treated as an isolated bilateral episode. Its main propositions remain part of the wider legal debate: historic rights must fit within UNCLOS; artificial construction cannot create maritime entitlements; small features do not automatically generate vast maritime zones; and a binding decision remains legally valid even when one party rejects it.

8. Wider legal impact

8.1 Impact on UNCLOS dispute settlement

The 2016 decision strengthened UNCLOS dispute settlement in a practical way. It showed that a State cannot defeat Annex VII arbitration by refusing to appear. Non-participation may make the procedure politically harder, but it does not remove jurisdiction if the tribunal is properly constituted and the dispute falls within Part XV (UNCLOS, 1982; South China Sea Arbitration, 2016).

That point matters for smaller and middle powers. If compulsory procedures depended on the respondent State’s cooperation at every stage, they would be weakest against the States most capable of resisting legal scrutiny. Annex VII would become voluntary in practice, even though UNCLOS designed it as a compulsory mechanism subject to defined exceptions.

The case also made the tribunal’s burden heavier. Because China did not participate, the Tribunal had to test jurisdiction, facts, and law with particular care. It could not simply accept the Philippines’ account. It examined China’s public position, diplomatic statements, and legal objections, then assessed whether each submission could be decided under UNCLOS (South China Sea Arbitration, 2015; Talmon, 2022).

This strengthened the credibility of Annex VII arbitration, but it also exposed its limits. A final and binding ruling does not guarantee compliance. UNCLOS has no centralized enforcement arm. Implementation depends on reputational pressure, diplomacy, State practice, domestic policy, and the willingness of other States to treat the decision as legally significant (Klabbers, 2024).

The result is mixed but important. Part XV can produce authoritative legal findings even against a non-appearing State. It cannot by itself force a major power to change conduct at sea. That is not a reason to dismiss the system. It is a reason to understand international adjudication as one part of a wider legal and diplomatic strategy.

8.2 Impact on Article 121 doctrine

The Tribunal’s interpretation of Article 121 is now unavoidable in debates about rocks, islands, and artificial enhancement. Before 2016, international courts often dealt with small islands indirectly, especially during maritime delimitation. They sometimes reduced the effect of small features without fully deciding whether they were rocks under Article 121(3). This case forced the issue into the open (Churchill, Lowe and Sander, 2022; Tanaka, 2019).

The key contribution was the focus on natural capacity. A feature must be assessed as it naturally exists, not as it appears after military occupation, land reclamation, desalination, imported supplies, or artificial infrastructure. This prevents States from manufacturing maritime entitlements through engineering projects (South China Sea Arbitration, 2016).

The decision also gave substance to “human habitation” and “economic life of their own.” Temporary personnel, military garrisons, subsidized outposts, or externally supported installations do not prove that a feature can sustain a stable human community. Nor does economic value in nearby waters prove that the feature itself has an economy. The Tribunal rejected circular reasoning: a feature cannot generate an EEZ merely because the surrounding EEZ would be valuable (South China Sea Arbitration, 2016; Villamizar Lamus, 2020).

This interpretation remains contested. Some scholars argue that the Tribunal applied Article 121(3) too strictly, especially when assessing Itu Aba. Others view the reasoning as necessary to stop tiny or inhospitable features from projecting massive maritime zones into crowded seas. Talmon’s study shows that State reactions to the Article 121 findings have been uneven, which limits any claim that the interpretation is already settled as general law (Talmon, 2022).

The lasting impact is not that every later tribunal must copy the reasoning word for word. Its importance is methodological. It gives future decision-makers a structured way to ask the right questions: what is the feature’s natural condition, can it support a real human community, and does any economic life belong to the feature itself rather than to the surrounding maritime area?

8.3 Impact on historic-rights claims

The case narrowed the legal space for broad historic-rights claims where UNCLOS already allocates maritime zones. This point extends beyond China. Any State seeking to rely on historical usage, old maps, fishing traditions, imperial records, administrative practice, or national memory must now confront the treaty structure of UNCLOS.

The Tribunal did not erase history from the law of the sea. Historic bays, historic title, and localized traditional fishing rights may still matter in specific circumstances. The problem arises when history is used to claim resources or jurisdiction in areas that the Convention assigns to another State’s EEZ or continental shelf (South China Sea Arbitration, 2016; Symmons, 2019).

This reasoning protects the basic bargain of UNCLOS. Coastal States accepted the EEZ as a measured legal zone extending up to 200 nautical miles. Maritime powers retained navigation and overflight freedoms. If vague historical claims could cut across that arrangement, the Convention’s predictability would be seriously weakened (Klein, 2005; Churchill, Lowe and Sander, 2022).

The decision also creates a discipline of legal translation. A State cannot simply say that it has historical rights. It must identify the right claimed, the area covered, the legal source, the evidence of exclusive exercise, and the response of other States. Historic use is not enough. The claimant must show legal entitlement.

This has practical effects in semi-enclosed seas. Such areas often have long histories of shared fishing, migration, trade, and navigation. Turning one State’s historical use into exclusive maritime control would erase the plural character of regional practice. The Tribunal’s approach resists that move by distinguishing shared historical activity from exclusive legal authority.

8.4 Impact on environmental law of the sea

The environmental findings gave UNCLOS Part XII sharper legal force. The Tribunal treated coral reef destruction, giant clam harvesting, and large-scale reclamation as matters capable of producing international responsibility. Marine environmental protection was not treated as background language or diplomatic aspiration (South China Sea Arbitration, 2016).

This matters because Part XII contains broad provisions. Article 192 requires States to protect and preserve the marine environment. Article 194 requires measures to prevent, reduce, and control pollution. Article 206 requires an environmental assessment where planned activities may cause substantial pollution or significant harmful changes. The case showed how these provisions can operate together when serious ecological harm occurs (UNCLOS, 1982).

The reasoning also strengthened due diligence. A State must regulate activities under its jurisdiction or control when those activities risk serious marine harm. It may be responsible for direct construction works, but also for failure to prevent known destructive practices by vessels or nationals. Knowledge, capacity to act, and regulatory failure all matter (South China Sea Arbitration, 2016; Boyle and Redgwell, 2021).

Later law of the sea proceedings have treated this approach as significant. In climate-related advisory proceedings, Article 192 has been read as a broad obligation involving active protection and restraint from degradation. The South China Sea reasoning helped show that the general duty can be applied to modern environmental threats, including those not limited to traditional ship-source pollution (ITLOS, 2024).

The broader impact is doctrinal and practical. Environmental obligations can now be pleaded more confidently in maritime disputes involving reef destruction, seabed activity, artificial island construction, harmful fishing methods, and damage to endangered species. This gives States another legal route beyond resource entitlement and sovereignty rhetoric.

The case also links marine environmental law to evidence. Scientific assessment, expert reports, satellite imagery, ecological data, and habitat analysis become central to legal responsibility. A State alleging environmental harm must prove damage and causation. A State carrying out risky works must show assessment, prevention, and control.

8.5 Impact on regional negotiations

The ASEAN-China Code of Conduct negotiations remain politically important, but their legal value depends on their relationship with UNCLOS. A regional code may reduce incidents, improve communication, regulate encounters at sea, and create confidence-building measures. It cannot lawfully dilute rights already granted by the Convention (UNCLOS, 1982; ASEAN-China Plan of Action, 2025).

This is the central legal point. ASEAN and China may agree on procedures for restraint, notification, crisis management, resource cooperation, or incident prevention. They may not use a political instrument to validate maritime claims that contradict UNCLOS. Nor can a code deprive third States or individual ASEAN claimants of treaty rights unless those States clearly and lawfully consent within the limits of international law.

The negotiations have long faced difficult questions: geographic scope, legal status, enforcement, dispute settlement, military activities, resource cooperation, and the relationship between the future code and the 2002 Declaration on Conduct. Recent official materials still emphasize the aim of concluding an effective and substantive code in accordance with international law (ASEAN, 2026). That phrase is not cosmetic. If the final text is not anchored in UNCLOS, it risks becoming a political management tool that leaves the legal conflict intact.

The 2016 decision affects the negotiation baseline. It makes it harder to treat the nine-dash line as an acceptable ambiguity. It also makes it harder to use artificial island construction or occupation of small features as a basis for enlarged maritime claims. Any credible code must operate around the Convention’s rules on EEZ rights, navigation, environmental protection, feature status, and peaceful settlement.

A weak code could create legal risk. If it avoids UNCLOS language, ignores the decision, or treats all claims as equally plausible without legal analysis, it may normalize excessive claims. If it contains vague restraint language without enforcement, it may manage optics while incidents continue. A stronger text would preserve UNCLOS rights expressly, avoid prejudice to lawful entitlements, include operational rules for coast guard conduct, and establish procedures for incident reporting and environmental cooperation.

The code will not settle sovereignty. It is not designed to decide titles over islands or rocks. Its realistic role is narrower: reduce escalation, create behavioural rules, and prevent daily confrontations from becoming crises. Its legal success will depend on one condition above all others: it must sit under UNCLOS, not beside it.

8.6 Limits as precedent

Annex VII arbitral decisions bind the parties to the dispute. They do not create formal precedent in the way common-law judgments may bind later courts. Article 296 confirms that a decision has binding force only between the parties and only for that particular dispute (UNCLOS, 1982).

This limit matters. Vietnam, Malaysia, Brunei, Indonesia, and Taiwan are not formally bound by the 2016 decision. Future tribunals are not legally compelled to adopt every part of the reasoning. A later court could distinguish the facts, interpret Article 121 differently, or treat evidence of historic rights in another case in a different way.

Yet lack of formal precedent does not mean lack of influence. International courts and tribunals regularly refer to earlier decisions for persuasive reasoning. States cite them in pleadings. Diplomats use them in notes and public statements. Legal advisers rely on them when assessing risk. Academic commentary builds on them, criticizes them, or narrows them (Talmon, 2022; Tanaka, 2019).

The decision’s influence is strongest where its reasoning is treaty-based and fact-sensitive. Its treatment of non-appearance, Article 121, historic rights, environmental due diligence, and entitlement versus delimitation will remain important because these issues recur in many maritime disputes. Later tribunals may not be bound, but they will need to explain agreement or disagreement.

The weakest point as precedent is the State reaction. Some States have endorsed the decision strongly. Others have stayed silent, used cautious language, or rejected parts of the reasoning. That mixed practice matters, especially for the Article 121 findings. A persuasive decision can influence law, but it does not automatically create universal acceptance.

The correct assessment is measured. The 2016 ruling is not a global statute for the oceans. It is not irrelevant because China rejects it. It is a major interpretive decision under UNCLOS with binding force between the parties and persuasive authority beyond them. Its long-term impact will depend on how often States invoke it, how later tribunals treat it, and how consistently its core reasoning is applied in future maritime disputes.

Also Read

• Territorial Disputes and International Law: Principles, Cases and Resolutions

• Peaceful Settlement of International Disputes

• Fisheries Case (United Kingdom v Norway)

• Principles Of Jurisdiction In International Law

• Strait of Hormuz Tensions: Law, Security & Global Trade

• Iran's Strait of Hormuz Closure Under International Law

• Jurisdictional Gaps in Subsea Data Cables

• The Lotus Principle Explained in Contemporary International Law

9. Critiques and unresolved issues

9.1 Jurisdictional criticism

The strongest criticism of the Tribunal’s jurisdictional reasoning is not that it ignored sovereignty and delimitation. It clearly did not. The serious objection is that it may have separated maritime entitlement, maritime delimitation, and territorial sovereignty more cleanly than the facts allowed.

The Tribunal treated the Philippines’ submissions as questions about the interpretation and application of UNCLOS. That was plausible. The claims concerned historic rights, the legal status of maritime features, interference with EEZ rights, environmental harm, and navigational safety. None of those questions, in formal terms, required the Tribunal to declare who owned the Spratly Islands or Scarborough Shoal (South China Sea Arbitration, 2015; South China Sea Arbitration, 2016).

The criticism is subtler. By deciding that no Spratly feature could generate an EEZ or continental shelf, the Tribunal sharply reduced the maritime value of sovereignty over those features. It did not decide on a title, but it reduced what the title could produce. For China, and possibly for other claimants, that looked like an indirect decision with consequences for the broader territorial dispute (Talmon, 2022).

The entitlement-delimitation distinction also invites debate. The Tribunal said it was not drawing a boundary; it was only deciding what zones certain features could generate. Legally, those are different tasks. Yet entitlement findings can shape future delimitation. If a feature has no EEZ, it cannot produce an overlapping 200-nautical-mile claim. In practical effect, that narrows the field before any boundary negotiation begins.

That does not mean the Tribunal acted without jurisdiction. It means the jurisdictional reasoning is powerful but not immune to criticism. The case shows how a tribunal can stay formally within UNCLOS while producing consequences that affect the strategic value of territorial claims. This is the unavoidable tension in mixed disputes.

China’s argument was strongest where it warned against the disguised adjudication of excluded matters. Its weakness was overbreadth. If every UNCLOS claim linked to a sovereignty dispute were excluded, Part XV would be easy to neutralize. States could avoid compulsory settlement by attaching every maritime disagreement to unresolved title over rocks, reefs, or islands.

The better assessment is balanced. The Tribunal did not decide sovereignty or delimit a boundary. Its reasoning was legally defensible. Still, the case pushed Part XV close to its jurisdictional edge. Future tribunals will need the same claim-by-claim discipline, especially in disputes where entitlement findings may reshape later negotiations.

9.2 Article 121 criticism

The most controversial substantive issue remains Article 121(3). The Tribunal’s interpretation of “human habitation” and “economic life of their own” was demanding. It required more than temporary occupation, military presence, imported supplies, or externally supported economic activity. The feature had to show a natural capacity to support a stable human community or an economic life genuinely connected to the feature itself (South China Sea Arbitration, 2016).

Critics argue that this standard was too strict, especially for Itu Aba. Itu Aba has fresh water, vegetation, and a longer record of human use than many other features in the Spratly group. Some commentators contend that the Tribunal placed too much weight on the absence of an ordinary settled community and too little on historical patterns of use, available natural resources, and the possibility of small-scale economic activity (Talmon, 2022).

The counterargument is that a looser interpretation would make Article 121(3) almost useless. If a military outpost, a rotating official presence, or an externally supplied installation could prove habitation, States could manufacture EEZ-generating islands through occupation and logistics. If fishing in surrounding waters counted as the feature’s economic life, tiny rocks could project vast maritime zones because the waters around them are valuable. The Tribunal rejected that circular logic (South China Sea Arbitration, 2016; Villamizar Lamus, 2020).

Earlier ICJ and arbitral cases did not resolve the issue with the same directness. In maritime delimitation cases, courts often reduced or ignored the effect of small islands without deciding their Article 121(3) status. Jan Mayen, Qatar v Bahrain, Nicaragua v Colombia, and other delimitation disputes show a judicial preference for equitable adjustment rather than a full doctrinal test of rocks and islands (Maritime Delimitation in the Area between Greenland and Jan Mayen, 1993; Maritime Delimitation and Territorial Questions, 2001; Territorial and Maritime Dispute, 2012).

That difference matters. Earlier courts could avoid Article 121(3) because delimitation allowed flexibility. The South China Sea case did not involve boundary drawing. The Tribunal had to decide legal capacity directly. This made the reasoning more exposed and more controversial.

The Tribunal’s approach has one clear virtue: it gives Article 121(3) real work to do. The provision was designed to prevent small, incapable features from generating disproportionate maritime zones. The decision makes that limit operational. Its weakness is that it gives limited guidance on borderline cases. Future disputes involving more habitable but still remote features may test how far the reasoning can go.

9.3 Evidence and non-appearance

China’s refusal to participate created evidentiary problems. A tribunal can continue proceedings when a party is absent, but the process becomes less balanced. There is no full adversarial testing of documents, experts, witnesses, and factual assumptions. That problem is serious in a case involving historical records, hydrographic data, environmental science, and the status of remote maritime features.

The Tribunal recognized this difficulty. It did not treat non-appearance as admission. It considered China’s public statements, position papers, diplomatic communications, and official materials. It also asked the Philippines for further evidence, appointed independent experts, examined hydrographic records, and used archival materials to test factual claims (South China Sea Arbitration, 2016; Talmon, 2022).

Those steps strengthened the procedure. They showed that the Philippines was not simply handed a victory because China stayed away. The Tribunal had to satisfy itself on jurisdiction and merits. Annex VII requires that safeguard, and the Tribunal took it seriously (UNCLOS, 1982).

Still, the question remains: was that enough? On many issues, yes. The physical status of maritime features could be assessed through charts, satellite imagery, expert evidence, and historical hydrographic surveys. Environmental damage could be assessed through scientific material and observable changes to reef systems. Navigational incidents could be examined through records of vessel conduct.

Historical rights were more difficult. Claims based on long-term usage, official control, acquiescence, and regional practice are evidence-heavy. China’s absence meant the Tribunal did not receive a full Chinese evidentiary case. It relied on public materials and available historical records. That was procedurally permissible, but it leaves critics room to argue that the record was less complete than it could have been.

The problem was caused by China’s own litigation choice. A State that refuses to appear cannot later complain as if it had been denied the chance to present its evidence. Yet legitimacy is not only about formal opportunity. It is also about the perceived completeness of the record. Non-appearance allowed China to reject the result politically while avoiding detailed evidentiary testing inside the proceedings.

The lesson is practical. Tribunals dealing with absent parties must build a record that can survive external scrutiny. They need independent experts, careful questioning, transparent reasoning, and restraint in factual findings. The Tribunal largely followed that model. The remaining weakness is not procedural invalidity, but the unavoidable asymmetry created by one party’s absence.

9.4 The enforcement gap

The 2016 decision exposes a structural weakness of international adjudication. A final and binding ruling may clarify the law without producing immediate compliance. This is not unique to the South China Sea. It is a recurring feature of international law, especially where a powerful State sees high strategic costs in compliance (Klabbers, 2024).

UNCLOS does not create a centralized enforcement authority for Annex VII decisions. There is no automatic seizure, penalty, or international police mechanism. The legal effect depends on the parties’ good faith, diplomatic pressure, reputational costs, domestic implementation, and reactions by other States. That makes compliance a political process as well as a legal obligation.

The Philippines gained legal clarity but not automatic control of disputed waters. China continued to reject the ruling. Incidents involving coast guard vessels, fishing access, resupply missions, and maritime patrols continued. This gap between legal decision and operational reality is the central practical limitation of the case.

The available tools are indirect. The Philippines can issue diplomatic protests, publicize incidents, invoke the decision in international forums, build coalitions, deepen maritime cooperation, and rely on domestic law and policy to reinforce its position. Other States can support UNCLOS interpretations, reject excessive claims, conduct lawful navigation operations, and coordinate diplomatic messaging.

Countermeasures are theoretically relevant but politically and legally difficult. Any countermeasure must meet strict conditions under the law of State responsibility: prior wrongful act, proportionality, reversibility where possible, and respect for obligations that cannot be suspended (ILC, 2001). In a sensitive maritime environment, poorly designed countermeasures could escalate the dispute rather than strengthen legal compliance.

Alliance support may increase deterrence, but it also changes the political character of the dispute. Stronger defence cooperation can help protect lawful maritime activity. It can also allow China to frame the issue as strategic containment rather than treaty compliance. The legal challenge is to keep the focus on UNCLOS rather than a pure power contest.

The enforcement gap does not make the ruling meaningless. It changes what success looks like. The decision functions as a legal baseline, a diplomatic tool, and a constraint on the legitimacy of excessive claims. Its effect is cumulative, not automatic.

9.5 The sovereignty shadow

The Tribunal sidestepped the issue of sovereignty; however, sovereignty continues to heavily influence regional actions. This represents the primary unresolved tension in the case. While legal clarity regarding maritime entitlements has been achieved, it does not diminish the political significance of islands, reefs, and shoals. Countries remain concerned with ownership because it provides strategic presence, domestic symbolism, military access, administrative control, and bargaining leverage.

The decision reduced the maritime consequences of many features, especially in the Spratlys. It did not reduce their strategic importance. A rock with no EEZ may still host installations, support surveillance, influence patrol patterns, and serve as a symbol of national resolve. A low-tide elevation may lack its own maritime zones but still become operationally valuable after construction.

This is why the case did not settle the South China Sea dispute. It answered important UNCLOS questions. It did not determine who owns contested features. It did not create a regional security mechanism. It did not settle fisheries management, resource sharing, military activity, or crisis communication.

Sovereignty also shapes domestic politics. Governments may find it difficult to compromise over maritime features because concessions can be framed as territorial weakness. This is especially acute where historical narratives, national identity, and military presence are tied to the dispute. Legal arguments alone rarely overcome those pressures.

The sovereignty shadow also affects negotiations. A code of conduct can reduce risk, but it cannot settle title unless States agree to a much deeper process. Joint development can manage resource disputes, but it may be resisted if seen as prejudicing sovereignty. Fisheries cooperation can protect livelihoods, but enforcement encounters may still trigger nationalist reactions.

The lasting value of the 2016 decision is that it separates what can be legally clarified now from what remains politically unresolved. It shows that States can receive answers on maritime entitlements, historic rights, environmental duties, and conduct at sea even while sovereignty remains unsettled. That is useful, but it is not a complete settlement.

The unresolved problem is implementation under conditions of strategic rivalry. UNCLOS can discipline claims. It cannot by itself remove military competition, domestic nationalism, or the desire to control maritime space. Any durable settlement will require legal compliance, negotiated restraint, fisheries arrangements, environmental cooperation, and crisis-management mechanisms. Legal clarity is necessary. It is not sufficient.

10. Conclusion

The South China Sea Arbitration has lasting importance because it clarified the legal structure of UNCLOS in a dispute where history, geography, power, and maritime law were tightly entangled. The Tribunal did not resolve sovereignty over the Spratly Islands, Scarborough Shoal, or any other disputed feature. It also did not draw a maritime boundary. Its contribution was different: it explained how the Convention limits maritime claims, allocates entitlements, protects marine ecosystems, and regulates State conduct at sea (South China Sea Arbitration, 2016).

The first level of impact is doctrinal. The Tribunal rejected the use of broad historic-rights claims where they conflict with the EEZ and continental shelf regime created by UNCLOS. That finding matters because it protects the Convention’s central bargain. Coastal States receive resource rights in defined zones, while other States retain navigation and other lawful uses. A vague historical line cannot override that legal structure (UNCLOS, 1982; Klein, 2020).

The case also gave Article 121 practical force. It showed that a feature’s maritime effect depends on its natural capacity, not on occupation, military infrastructure, reclamation, or political importance. A rock unable to sustain human habitation or economic life of its own cannot generate an EEZ or continental shelf. That interpretation remains contested, especially in relation to Itu Aba, but it has become unavoidable in any serious discussion of islands, rocks, and small maritime features (South China Sea Arbitration, 2016; Villamizar Lamus, 2020).

The environmental findings are equally important. The Tribunal treated coral reef destruction, harmful harvesting of giant clams, and large-scale construction as legal issues under UNCLOS Part XII. This strengthened the role of due diligence, environmental assessment, and the general duty to protect and preserve the marine environment. The case made clear that disputed sovereignty does not suspend environmental obligations (Boyle and Redgwell, 2021; South China Sea Arbitration, 2016).

The second level of impact concerns dispute settlement. China’s refusal to participate did not stop the proceedings. Annex VII allowed the case to continue, while still requiring the Tribunal to satisfy itself that jurisdiction existed and that the claims were supported by fact and law. This is one of the decision’s strongest institutional messages: a State cannot defeat compulsory adjudication under UNCLOS simply by staying away (UNCLOS, 1982; Talmon, 2022).

That point strengthens smaller and middle powers. It confirms that Part XV is not merely diplomatic language. It can produce binding legal findings even in disputes involving a major power. At the same time, the case shows that jurisdictional discipline remains essential. The Tribunal’s authority depended on its ability to separate UNCLOS questions from sovereignty and delimitation issues. Without that careful separation, the decision would have been far more vulnerable.

The third level of impact is more uncomfortable. The case exposes the enforcement limits of international law. The 2016 decision is final and binding between the Philippines and China, but China continues to reject it. Legal validity has not produced full compliance. Maritime incidents, coast guard confrontations, fishing disputes, and competing narratives have continued. This does not make the ruling irrelevant. It shows that international adjudication needs diplomatic, institutional, regional, and domestic support to have a practical effect (Klabbers, 2024; Talmon, 2022).

The decision’s value now depends on use. The Philippines must continue to invoke it consistently. Other States must treat their core legal propositions as part of the UNCLOS framework, not as optional political language. ASEAN-China negotiations must remain subordinate to the Convention, not create ambiguity that weakens treaty rights. Future tribunals and legal advisers must engage with its reasoning carefully, especially on historic rights, Article 121, environmental duties, and due regard.

The balanced assessment is straightforward. The South China Sea Arbitration is legally authoritative but not self-executing. It clarified the law more than it changed behaviour. It narrowed the range of lawful maritime claims but did not eliminate strategic rivalry. It strengthened UNCLOS dispute settlement but also revealed how much international law still depends on pressure, reputation, diplomacy, and repeated legal use.

Its lasting significance lies in that tension. The case did not end the South China Sea disputes. It did something more precise and more durable: it gave States, tribunals, and legal advisers a disciplined framework for judging claims that rely on historical ambiguity, artificial construction, coercive presence, or environmental disregard. In a contested maritime region, that legal discipline remains indispensable.

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