State Succession in International Law: Rules and Legal Effects
- Edmarverson A. Santos
- 14 hours ago
- 26 min read
Introduction
State succession in international law concerns the legal consequences that arise when one State replaces another in responsibility for the international relations of a territory, the formulation adopted in Article 2(1)(b) of the 1978 Vienna Convention on Succession of States in Respect of Treaties (United Nations, 1978). Not every major political transformation amounts to succession. A revolution, coup, constitutional reorganization, or change of government does not by itself create a successor State where the same international legal personality continues. Succession arises when responsibility for the international relations of territory passes from one State to another, whether the predecessor State continues to exist or disappears as part of that process.
The occurrence of succession does not itself determine which legal relationships survive or pass to the successor. Treaties may continue, cease to apply to the affected territory, or require a successor State to establish its participation under the relevant rules. Questions of State property, archives, and public debts follow different legal frameworks. Succession may also require decisions about the acquisition, retention, or loss of nationality by affected persons, while participation in international organizations depends partly on the constituent rules and practice of each organization. Responsibility for internationally wrongful acts committed before succession presents a further and still unsettled problem.
International law has attempted to regulate these consequences without producing a single universally accepted regime. The 1978 Vienna Convention on Succession to Treaties is in force, but its limited participation means that its provisions cannot simply be treated as universally binding treaty law. The 1983 Vienna Convention on Succession of States in Respect of State Property, Archives and Debts has not entered into force (United Nations, 1983). The International Law Commission's 1999 Articles on Nationality of Natural Persons in relation to the Succession of States are non-binding codification and progressive-development materials rather than a treaty regime (International Law Commission, 1999). In 2026, the Commission also decided not to pursue further its work on succession of States in respect of State responsibility, leaving that area without a completed general codification (International Law Commission, 2026).
A central question is whether a particular transformation involves succession at all or instead leaves the same State in existence. State continuity preserves international legal personality even where territory, population, constitutional arrangements, or governmental structures change substantially. Where a State is treated as continuing, its international rights and obligations generally remain those of the same legal person, subject to particular rules affected by territorial change. Post-Cold War practice involving the Soviet Union, Yugoslavia, Czechoslovakia, and German unification demonstrates how strongly the classification between continuity and succession can shape treaty relations, organizational membership, property claims, and other legal consequences (Craven, 1998; Devaney, 2022).
The central question is not whether a successor State simply inherits everything that belonged to the predecessor. Each category of rights and obligations must be assessed according to its own legal basis, including applicable treaties, customary international law, institutional rules, judicial decisions, State practice, and agreements between the States concerned. State recognition, the criteria of statehood, and the existence of any right of secession raise related but distinct legal questions; the focus here is the law governing the consequences once a succession of States has occurred.
1. State Succession in International Law: Meaning and Scope
State succession in international law has a narrower meaning than broader political change. Article 2(1)(b) of the 1978 Vienna Convention on Succession of States in Respect of Treaties defines a succession of States as the “replacement of one State by another in the responsibility for the international relations of territory” (United Nations, 1978). The International Law Commission used the same formulation in its work on State property, archives, State debts, and nationality, giving the concept a consistent technical core across the principal codification projects (International Law Commission, 1981, 1999).
The predecessor State is the State replaced in relation to the territory concerned; the successor State is the State that replaces it. The date of succession is the date on which that replacement occurs. These terms do not imply that the predecessor must disappear. When territory is transferred, or part of a State separates while the remainder continues, the predecessor may retain its international legal personality while another State becomes responsible for the international relations of the affected territory.
A continuator or continuing State occupies a different legal position. It is treated as the same international legal person that existed before the territorial or constitutional transformation, despite changes in territory, population, governmental structure, or other circumstances. Succession and continuity must consequently be kept separate: succession raises questions about legal consequences flowing from replacement, whereas continuity begins from the persistence of the same State (Craven, 1998; Devaney, 2022).
The ILC deliberately framed the definition of succession without building inheritance into the concept. Its commentary to the 1974 draft articles explained that “succession of States” identifies the fact of replacement and leaves aside any implication that rights and obligations automatically pass to the successor (International Law Commission, 1974). Treaty relations, property, archives, State debts, nationality, organizational membership, and responsibility must each be examined under the rules applicable to that particular subject.
Changes confined to the internal political order ordinarily fall outside the concept. A revolution, coup, constitutional transformation, change of regime, or replacement of government does not by itself create a new international legal person. Nor does temporary governmental collapse necessarily extinguish a State. International law distinguishes succession of States from succession of governments because the persistence of State identity does not depend on the survival of a particular constitution, administration, or political system.
The principal codification instruments also contain an explicit legality qualification. Article 6 of the 1978 Vienna Convention, Article 3 of the 1983 Vienna Convention, and Article 3 of the ILC's 1999 nationality articles confine their respective regimes to successions occurring in conformity with international law, particularly the principles embodied in the United Nations Charter (United Nations, 1978, 1983; International Law Commission, 1999). These provisions prevent the codified succession regimes from being used to legitimate territorial acquisition achieved unlawfully. They do not, however, resolve every consequence of an unlawful territorial change, which remains subject to the wider rules of international law governing the use of force, territorial integrity, recognition, and related obligations.
2. State Succession and State Continuity
The distinction between succession and continuity determines the legal starting point for almost every later question. If the same State continues, its international legal personality persists despite political or territorial transformation. If another State replaces it in responsibility for territory, succession law becomes relevant to the allocation, continuation, or extinction of particular legal relationships.
International law does not ordinarily treat territorial reduction, constitutional reorganization, occupation, or serious governmental disruption as sufficient to terminate State identity. A State may survive major changes in population, territory, and institutions. More difficult situations arise when a State fragments and one resulting entity claims to preserve the predecessor's legal personality while others claim separate status or challenge that continuity claim (Craven, 1998; Devaney, 2022).
The dissolution of the Soviet Union illustrates one outcome. In December 1991, the Russian Federation informed the United Nations that the USSR's membership, including its permanent seat on the Security Council, was being continued by Russia. That position was accepted in United Nations practice without a new Russian application for membership. Most other former Soviet republics entered international organizations in their own capacities. Estonia, Latvia, and Lithuania occupied a distinct position: they maintained that the independence of their pre-1940 States had been restored and did not base their international status on succession to the USSR.
The breakup of Yugoslavia produced a different result. The Federal Republic of Yugoslavia, consisting of Serbia and Montenegro, claimed to continue the international legal personality of the Socialist Federal Republic of Yugoslavia. That claim was not accepted for United Nations membership. Security Council Resolution 777 considered that the former SFRY had ceased to exist and that the FRY could not automatically continue its UN membership; General Assembly Resolution 47/1 acted on that recommendation (UN Security Council, 1992; UN General Assembly, 1992). The FRY was eventually admitted to the United Nations as a new member in 2000.
Czechoslovakia and German unification demonstrate two further models. Czechoslovakia ceased to exist on 31 December 1992, and neither the Czech Republic nor Slovakia was treated generally as its sole continuator; both were subsequently admitted to the United Nations as separate States. German unification proceeded differently. The German Democratic Republic acceded to the Federal Republic of Germany in 1990, while the Federal Republic's international legal personality continued. Germany did not have to begin again as a newly created State in organizations to which the Federal Republic already belonged.
These episodes show why classification cannot be inferred merely from the scale of territorial change. The Russian Federation's continuity claim and the Federal Republic of Yugoslavia's claim arose from major State disintegration but received different treatment. Czechoslovakia ended without a single general continuator, while the Federal Republic of Germany remained the continuing State after unification. Agreements among the States concerned, institutional practice, third-State responses, and the factual and legal structure of the transformation all contribute to determining whether continuity or succession provides the appropriate framework.
3. The Main Forms of State Succession
The law of State succession uses several categories to organize different forms of territorial change. The principal ones are the transfer of part of a territory to another State, the unification of States, separation in which part of a State forms one or more new States while the predecessor survives, complete dissolution of the predecessor, and the special category of newly independent States emerging from dependent territories. The principal codification instruments do not employ an identical taxonomy in every detail, but these categories remain useful for legal analysis (United Nations, 1978; International Law Commission, 1981, 1999).
A transfer of territory involves a limited replacement of responsibility. The predecessor and successor usually both continue to exist, but the territory concerned passes into the international responsibility of another State. That change can affect the territorial application of treaties, the ownership or allocation of State property, access to archives, nationality, and other legal relationships connected with the transferred area.
Unification can take different legal forms. Several existing States may cease to exist and combine into a new State, or one State may become incorporated into another State whose international personality continues. German unification is generally analyzed through the latter model: the German Democratic Republic acceded to the Federal Republic rather than both German States disappearing and being replaced by a wholly new international legal person.
Separation and dissolution must also be distinguished. Separation occurs when part of a State becomes one or more new States while the predecessor continues. Dissolution occurs when the predecessor itself ceases to exist, and its territory becomes the territory of two or more successor States. That distinction can affect the treatment of treaties, State debts, property, international-organization membership, and other legal relations because separation leaves an existing predecessor whose legal position must be considered alongside that of the new State or States.
The 1978 Vienna Convention assigns special significance to the “newly independent State.” Article 2(1)(f) uses that term for a successor State whose territory, immediately before succession, was a dependent territory for whose international relations the predecessor State was responsible (United Nations, 1978). The category reflects the decolonization setting in which much of the modern law of State succession developed. It is not a synonym for every newly created State. A State formed by separation outside a colonial relationship does not become a “newly independent State” merely because its independence is recent.
Secession raises a related but different legal inquiry. It concerns the process by which part of an existing State seeks or achieves separate statehood. State succession concerns the legal consequences once responsibility for the territory has changed. Questions about a claimed right to secede, self-determination, recognition, and the validity of the resulting statehood cannot be answered simply by applying succession rules. Nor does the law of State succession itself establish a general right of unilateral secession.
These categories do not mechanically determine every legal consequence. Their importance lies in identifying the factual structure to which more specific rules must be applied. A former dependent territory may face a different treaty regime from a State created through non-colonial separation; dissolution raises allocation problems that do not arise in the same way where a predecessor survives. Classification narrows the legal inquiry, but it does not replace it.
4. Why State Succession Has No Single Legal Rule
No single rule determines everything that happens when State succession occurs. International law has approached the subject through separate codification projects, treaty rules, customary international law, judicial decisions, institutional practice, treaty-depositary practice, and agreements among predecessor and successor States. The degree of legal certainty differs markedly among particular questions, which helps explain why attempts to reduce succession to either automatic continuity or a universal clean slate have proved inadequate (Craven, 1998; Sarvarian, 2016; Devaney, 2022).
The 1978 Vienna Convention on Succession of States in Respect of Treaties is the principal multilateral instrument devoted to treaty succession. It entered into force on 6 November 1996 but still has limited participation; as of 2026, it has 23 parties (UN Treaty Collection, 2026a). Its treaty rules bind the States parties under the conditions governing the Convention, but limited participation means that the instrument cannot simply be applied as treaty law to every succession. Some provisions may also reflect customary international law independently of the Convention, while others remain associated with progressive development or contested practice.
The 1983 Vienna Convention on Succession of States in Respect of State Property, Archives and Debts occupies a different legal position. It has not entered into force. As of 2026, it has seven parties, while Article 50 requires fifteen instruments of ratification or accession for entry into force (United Nations, 1983; UN Treaty Collection, 2026b). Its provisions remain relevant to the history and analysis of codification, but they cannot be presented as an operative multilateral treaty regime binding States generally. Any claim that a particular rule expressed in the Convention also exists in customary international law requires independent support.
Nationality was addressed through yet another legal form. In 1999, the International Law Commission adopted the Articles on Nationality of Natural Persons in Relation to the Succession of States. The General Assembly later annexed the text to Resolution 55/153 and invited States to take its provisions into account (International Law Commission, 1999; UN General Assembly, 2000). The Articles are not a treaty. Their treatment of statelessness, habitual residence, rights of option, non-discrimination, family unity, and procedural protection must be distinguished from treaty or customary obligations that may independently bind particular States.
Judicial and institutional practice fills some of the remaining space without producing a comprehensive substitute for codification. International courts and tribunals have encountered specific succession questions rather than constructing a universal doctrine for every consequence. International organizations apply their constituent instruments and membership practices. Treaty depositaries record notifications of succession, continuity claims, and other acts by States. In many successions, negotiated agreements have dealt directly with property, archives, financial liabilities, pensions, treaty relations, and related questions that general international law did not settle completely.
The appropriate method is consequently issue-specific. Treaty succession must be examined through the relevant treaty rules and applicable customary law; organizational membership through the constituent instrument and institutional practice; property, State debts, nationality, and responsibility through their own legal sources. Agreements among the States concerned may resolve matters that would otherwise remain disputed.
This fragmentation should not be mistaken for an absence of law. Some propositions have much firmer support than others. The stability of boundaries and certain territorial regimes, for example, rests on stronger authority than several disputed rules concerning automatic treaty succession. What the law does not provide is a single doctrine under which the label “successor State” automatically determines every treaty obligation, asset, debt, nationality question, institutional position, or responsibility inherited from the predecessor.
5. What Happens to Treaties After State Succession?
Succession to treaties is the most developed branch of State succession law, yet it still reflects a tension between stability and consent. Existing treaty relationships may structure borders, trade, security arrangements, environmental cooperation, or other long-term expectations that third States have relied upon. Automatic transmission of every predecessor treaty, however, may bind a newly created State to obligations it did not itself accept. The 1978 Vienna Convention addresses that tension through different rules for different forms of succession rather than through a universal principle of either continuity or termination (United Nations, 1978).
Where part of the territory of one State becomes part of another existing State, Article 15 adopts the approach commonly described as the moving-treaty-frontiers rule. Treaties of the predecessor State generally cease to apply to the transferred territory, while treaties of the successor State generally extend to it. The latter consequence does not apply where extension would be incompatible with the treaty's object and purpose or would radically change the conditions for its operation (United Nations, 1978, art. 15). The rule concerns the territorial reach of the two States' treaty relations rather than succession by the acquiring State to the predecessor's treaties.
The Convention takes a different position toward a “newly independent State” in its technical decolonization-related meaning. Article 16 establishes the clean-slate or tabula rasa starting point: the new State is not bound to maintain a predecessor treaty merely because that treaty applied to the territory before independence. This does not require the State to reject the predecessor's treaty network. Under Article 17, it may establish participation in many multilateral treaties through notification of succession, subject to the qualifications contained in the Convention. For newly independent States, Article 24 separately provides that a bilateral treaty may continue where the new State and the other party expressly agree or their conduct establishes that they considered the treaty to remain in force (United Nations, 1978, arts 16–17, 24).
Separation and dissolution outside the colonial context receive a stronger continuity treatment under Article 34. Where part of a State separates to form one or more States, treaties in force for the predecessor generally continue in relation to the successor territory to which they previously applied, subject to agreement between the States concerned and the Convention's object-and-purpose and changed-conditions qualifications (United Nations, 1978, art. 34). That treaty rule should not be converted automatically into a universal rule of customary international law. Post-Cold War practice has not been sufficiently uniform to remove the controversy surrounding automatic succession in such cases (Devaney, 2022; Sarvarian, 2016).
The International Court of Justice did not resolve that wider customary-law question in Gabčíkovo-Nagymaros Project. Although succession to the 1977 Treaty between Hungary and Czechoslovakia formed part of the dispute, the Court did not find it necessary to determine whether Article 34 of the 1978 Convention reflected customary international law as a general rule (ICJ, 1997). The case is consequently relevant to treaty succession without providing a judicial endorsement of the Convention's entire continuity regime.
Boundary arrangements stand on firmer ground. Article 11 provides that a succession of States does not as such affect a boundary established by treaty or the rights and obligations connected with a boundary regime. Article 12 protects specified territorial regimes attached to particular territories, while expressly excluding treaty obligations concerning the establishment of foreign military bases (United Nations, 1978, arts 11–12). These provisions protect territorial stability against the proposition that a change of sovereignty or international responsibility automatically reopens an established boundary.
Human rights treaties have generated a more difficult debate. In General Comment No. 26, the Human Rights Committee took the position that rights protected under the ICCPR belong to the persons living in the territory of a State party and that, once Covenant protection has been accorded to them, it continues despite a change in government or State succession (Human Rights Committee, 1997, para. 4). This is the Committee's interpretation of the Covenant and carries significant institutional authority, but a General Comment does not itself amend the treaty or establish agreement among all States parties on a rule of customary succession law.
Other international bodies and scholars have likewise supported continuity of certain human rights and humanitarian obligations, particularly because interruption may remove legal protections from individuals for reasons beyond their control (Kamminga, 1996). State practice remains less uniform than that normative argument might suggest. Successor States have used notifications of succession, accession, confirmation of treaty commitments, and other procedures to establish their treaty positions. The better view is consequently not that every human rights treaty automatically binds every successor State, but that treaty-specific rules, institutional practice, State conduct, and any independently applicable customary obligations must be distinguished carefully (Devaney, 2022).
6. Membership in International Organizations
Succession to a treaty establishing an international organization does not automatically determine membership in the organization itself. Constituent instruments create institutional systems with their own rules on admission, representation, voting, suspension, and membership. Article 4 of the 1978 Vienna Convention recognizes this distinction expressly: its treaty-succession rules apply to constituent instruments without prejudice to rules governing the acquisition of membership or other relevant rules of the organization (United Nations, 1978, art. 4).
The distinction explains why continuity status can have immediate institutional consequences. After the dissolution of the USSR, the Russian Federation informed the UN Secretary-General on 24 December 1991 that the Soviet Union's United Nations membership, including its permanent Security Council seat, was being continued by Russia. United Nations practice gave effect to that claim without requiring Russia to submit a new application for membership (United Nations, 1991). This was an institutional acceptance of continuation in the particular circumstances, not a general rule that a successor State automatically acquires its predecessor's seat.
The Federal Republic of Yugoslavia encountered a different response. Serbia and Montenegro claimed that the FRY continued the international legal personality of the former Socialist Federal Republic of Yugoslavia. Security Council Resolution 777 stated that the FRY could not automatically continue the SFRY's United Nations membership and recommended that it apply for membership. General Assembly Resolution 47/1 acted on that recommendation and decided that the FRY should not participate in the work of the General Assembly (UN Security Council, 1992; UN General Assembly, 1992). The FRY was admitted to the United Nations in 2000 following a new application.
The contrast demonstrates the importance of institutional law without requiring the earlier continuity analysis to be repeated. Russia's continuation claim was given effect within the United Nations, whereas the FRY's claim did not preserve the former Yugoslavia's membership. Neither result can be converted into a universal rule applicable to every case of dissolution or separation.
Other organizations may reach different outcomes because their constituent instruments and admission procedures differ. Membership in a regional organization, international financial institution, specialized agency, or integration organization may depend on legal conditions not found in the UN Charter. The relevant inquiry is consequently institutional: whether the entity is treated as continuing the predecessor, what the organization's governing instrument requires, and what its competent organs and established practice permit.
7. State Property, Archives, and State Debts
Succession also requires decisions about material assets and liabilities. State property may include government buildings, diplomatic premises, movable assets, financial interests, and other property owned by the predecessor State. Archives raise related but distinct questions about public records, title documents, administrative files, and historically significant material. State debts concern financial obligations of the predecessor rather than ownership of physical assets. These subjects were codified separately in the 1983 Vienna Convention on Succession of States in Respect of State Property, Archives and Debts, which has not entered into force (United Nations, 1983).
The Convention does not prescribe one allocation rule for every form of succession. In territorial transfers, the location of immovable State property and the connection between movable property and the territory are particularly relevant. Other forms of succession, including separation and dissolution, require more elaborate allocation because several States may assert legitimate interests in assets formerly serving the predecessor as a whole. Agreement between the States concerned receives substantial weight throughout the regime, with residual rules applying where agreement is absent (United Nations, 1983).
Archives are treated separately because possession and administrative need do not always point in the same direction. A successor State may require cadastral records, civil registries, court files, tax documents, maps, or other material necessary to administer the territory even where the physical records were historically kept elsewhere. Archives may also provide evidence of territorial title, property rights, nationality, or historical events. The 1983 Convention and the ILC commentaries accordingly address transfer, preservation, access, and the provision of reproductions rather than treating archives simply as another class of movable property (United Nations, 1983; International Law Commission, 1981).
State debts pose a different problem because territorial location cannot by itself allocate a financial obligation. The 1983 Convention gives negotiated agreement priority in several forms of succession and, where agreement is absent, uses concepts of equitable allocation that may take account of the property, rights, and interests passing to the successor. Newly independent States receive separate treatment. Since the Convention is not in force, these provisions cannot be cited as generally binding treaty law; the customary status of an asserted allocation rule must be demonstrated independently (United Nations, 1983).
Actual succession settlements often rely heavily on negotiation. The former Yugoslavia offers a particularly detailed example. Bosnia and Herzegovina, Croatia, the Republic of Macedonia (now North Macedonia), Slovenia, and the Federal Republic of Yugoslavia concluded the Agreement on Succession Issues in Vienna on 29 June 2001. It entered into force on 2 June 2004. Rather than relying on a single general allocation formula, the Agreement established separate regimes for different categories of assets and liabilities.
Its annexes address movable and immovable property, diplomatic and consular properties, financial assets and liabilities, archives, pensions, other rights, interests and liabilities, and private property and acquired rights. The arrangements also created implementation and dispute-resolution mechanisms. The structure of the Agreement reflects the practical difficulty of treating an embassy abroad, an archival record, a pension liability, and State-owned land as legally equivalent succession problems.
The Yugoslav settlement is significant precisely because it was negotiated for a particular dissolution. Its detailed allocation rules bind the parties under the Agreement; they do not by themselves establish a general customary formula for every future State succession.
8. Nationality and the Prevention of Statelessness
Nationality places individuals at the center of State succession. Where a predecessor disappears, people who held its nationality need a legal relationship with one or more successor States. Where the predecessor survives after separation, persons connected with the affected territory may qualify for the nationality of the new State while retaining links to the continuing State. The central international-law concern is not simply allocation between governments but the avoidance of arbitrary loss of nationality, discrimination, and statelessness.
The International Law Commission addressed these issues in its 1999 Articles on Nationality of Natural Persons in Relation to the Succession of States. The Articles are non-binding codification and progressive-development materials, not a treaty. Their provisions provide a structured framework for identifying the interests of the predecessor State, successor States, and persons whose nationality may be affected, but each claimed binding rule still requires an independent treaty or customary-law basis where the Articles themselves are the only authority (International Law Commission, 1999).
Article 4 makes prevention of statelessness a central principle. It provides that the States concerned “shall take all appropriate measures” to prevent persons who held the predecessor State's nationality on the date of succession from becoming stateless as a result of that succession (International Law Commission, 1999, art. 4). Within the non-binding Articles, that is mandatory language. The commentary explains that the provision imposes a duty to take appropriate measures rather than an absolute guarantee that statelessness can never result.
Article 5 adds a presumption linked to habitual residence. Subject to the rest of the Articles, persons who habitually reside in the territory affected by succession are presumed to acquire the successor State's nationality on the date of succession (International Law Commission, 1999, art. 5). Habitual residence offers a strong territorial connection, but the Articles do not use it as the sole criterion in every situation.
Other forms of connection appear in the category-specific provisions governing dissolution and separation. Depending on the situation, these include an appropriate legal connection with a former constituent unit, place of birth, previous habitual residence, and other relevant ties. Such factors should not be transformed into a free-standing universal test applicable identically to every succession. Their role depends on the type of succession and the particular provisions being applied (International Law Commission, 1999, arts 22–26).
Individual choice also receives protection, although the Articles do not recognize an unlimited entitlement to choose any nationality. Article 11 requires States to give consideration to the will of persons qualified for the nationality of two or more States concerned. It also provides for a right of option where persons have an appropriate connection with a State and would otherwise become stateless. More specific rights of option appear in the provisions governing particular forms of succession (International Law Commission, 1999, art. 11).
The framework extends to family unity, habitual residents, non-discrimination, arbitrary nationality decisions, procedural safeguards, and cooperation between States. Articles 15–17 address discriminatory denial of nationality rights, arbitrary deprivation or denial, and procedures including written decisions and effective administrative or judicial review. Article 18 calls for information exchange, consultation, and negotiation where nationality problems arising from succession produce harmful effects for the persons concerned (International Law Commission, 1999).
Domestic nationality legislation remains central because nationality is ordinarily acquired, retained, and lost under national law. State competence is nevertheless exercised within applicable international-law limits. Depending on the State and the persons concerned, those limits may arise from binding obligations relating to statelessness, non-discrimination, children's nationality, or other human rights protections. The ILC Articles help organize these questions, but their non-binding status must remain separate from treaty obligations or customary rules that independently constrain national authorities.
9. Does State Responsibility Pass to a Successor State?
Succession to State responsibility remains one of the least settled parts of the law. The difficulty arises where an internationally wrongful act occurred before succession, and the responsible State later loses territory, continues in altered form, or ceases to exist. International law has not reduced these situations to a generally accepted rule under which responsibility either always remains with the predecessor or automatically passes to the successor.
This problem is distinct from succession to primary international obligations. The International Law Commission's 2001 Articles on Responsibility of States for Internationally Wrongful Acts address the secondary consequences that arise when conduct attributable to a State breaches an international obligation. They do not contain a general regime governing succession to State responsibility. A successor State may become bound by the same treaty or customary rule that bound its predecessor without that fact determining who bears responsibility for a breach committed before succession (International Law Commission, 2001).
Where the predecessor State continues to exist, the traditional starting point has been that responsibility for its own pre-succession conduct remains attached to that continuing international legal person. Territorial separation does not ordinarily extinguish claims arising from wrongful acts attributable to the predecessor. Complete dissolution presents the harder case. If the responsible State has ceased to exist, there may no longer be a continuing predecessor against which the consequences of its internationally wrongful conduct can be invoked (Devaney, 2022).
Attempts to address that problem have produced proposals rather than a settled transmission test. During the ILC's work, consideration was given to circumstances such as the connection between a wrongful act and territory passing to a successor, conduct by successor authorities, benefits associated with an earlier wrongful act, and agreements dealing with outstanding responsibility. Academic writing has examined similar considerations. Their appearance in the codification debate does not establish that international law recognizes a general multi-factor rule under which responsibility passes whenever one or more of them are present (International Law Commission, 2024).
The ILC ultimately concluded that its work could not be brought to a satisfactory general codification. At its seventy-fifth session in 2024, the Commission decided that a Working Group should prepare a report bringing the topic to an end and explaining the difficulties that would arise if work continued. Those difficulties included limited and inconsistent State practice, unresolved conceptual questions, and uncertainty about which proposed rules could be identified as existing law rather than progressive development (International Law Commission, 2024). Work on the closing report continued during the following sessions.
At its seventy-seventh session in 2026, the Commission adopted the Working Group's report and formally decided not to pursue consideration of succession of States in respect of State responsibility further (International Law Commission, 2026). That decision did not establish a rule of non-succession, automatic succession, or extinction of responsibility. It left the customary position unresolved. Questions involving pre-succession wrongful acts must consequently be approached through the ordinary law of State responsibility, the distinction between continuity and succession, relevant State practice and judicial authority, and any agreements capable of regulating the consequences between the States concerned.
10. How State Practice Fills the Gaps
State succession operates through more than codified treaty rules. Judicial decisions may settle a particular dispute, international organizations apply their own constitutional rules, depositaries record treaty notifications and continuity claims, and States negotiate arrangements tailored to the consequences of a particular territorial transformation. These materials have different legal weight, and none can be treated as a substitute for identifying the applicable source of law.
The dissolution of Yugoslavia illustrates that interaction unusually clearly. The European Community Arbitration Commission, generally known as the Badinter Commission, was established within the European Community peace process rather than by treaty or a conventional arbitration agreement between disputing States. Its opinions were consultative and non-binding, although the Commission approached the questions before it through international legal reasoning and its conclusions became influential in subsequent diplomatic and institutional practice (Craven, 1996).
Opinion No. 1 characterized the SFRY as being in the process of dissolution. Opinion No. 8 later treated that process as complete, while Opinion No. 10 regarded the Federal Republic of Yugoslavia as a new State that could not be considered the sole successor to the former SFRY. These conclusions were not international judgments carrying res judicata, and European States did not follow every Badinter opinion in every context. They nevertheless helped shape the legal framework through which the Yugoslav dissolution was understood (Craven, 1996).
United Nations practice then addressed a separate institutional consequence. Security Council Resolution 777 and General Assembly Resolution 47/1 rejected the FRY's attempt automatically to continue the former Yugoslavia's UN membership. Treaty depositary practice and notifications by the emerging States addressed their participation in individual treaties, while international litigation raised further questions concerning continuity, succession, jurisdiction, and treaty status. No single one of these processes determined all the consequences of Yugoslavia's dissolution.
The later Agreement on Succession Issues demonstrates a different function of State practice. Concluded in 2001 by the five successor States, it established detailed arrangements concerning State property, diplomatic and consular assets, financial assets and liabilities, archives, pensions, private property, acquired rights, and other interests. Rather than purporting to declare universal succession rules, the parties settled concrete allocation questions through agreement. The resulting obligations derive from that agreement and bind its parties; they do not automatically become rules applicable to unrelated future successions.
This distinction is essential when practice is invoked as evidence of customary international law. A bilateral or multilateral succession settlement may reflect compromise, political expediency, or a solution tailored to particular circumstances. It does not establish a general customary rule merely because States agreed to it. Identification of custom requires sufficiently general and representative State practice accompanied by acceptance as law, or opinio juris (International Law Commission, 2018). State practice fills many practical gaps in succession, but its legal significance depends on why States acted as they did and on the source through which a particular consequence becomes legally binding.
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Conclusion
State succession in international law does not operate through a universal doctrine of automatic inheritance. When one State replaces another in responsibility for the international relations of territory, the occurrence of succession identifies the legal event but does not determine every consequence. Treaties, organizational membership, property, archives, State debts, nationality, and responsibility must each be examined under the rules applicable to that particular legal relationship.
The first question is often whether succession has occurred at all. If the same international legal person continues despite territorial or political transformation, continuity preserves the State's existing legal position subject to rules affected by the territorial change. Where responsibility for territory genuinely passes to another State, the form of succession becomes relevant, but classification alone still does not answer what passes. Treaty law, customary international law, institutional rules, judicial decisions, State practice, and agreements between the States concerned may point to different outcomes for different consequences.
State succession is thus better understood as a series of legal questions arising from the reorganization of territorial responsibility than as the transfer of an indivisible package of rights and obligations. Some relationships continue because international law protects their stability; others depend on consent, institutional rules, negotiated allocation, or rules whose customary status remains contested. The central task is to determine, for each consequence, what continues, what passes, what ends, and what requires a separate legal settlement.
References
Agreement on Succession Issues (2001) concluded at Vienna, 29 June 2001, entered into force 2 June 2004, 2262 UNTS 251, No. 40296.
Craven, M.C.R. (1996) ‘The European Community Arbitration Commission on Yugoslavia’, British Yearbook of International Law, 66(1), pp. 333–413.
Craven, M.C.R. (1998) ‘The Problem of State Succession and the Identity of States under International Law’, European Journal of International Law, 9(1), pp. 142–162.
Devaney, J.G. (2022) ‘The law of state succession: regulating the aftermath’, in Vidmar, J., McGibbon, S. and Raible, L. (eds.) Research Handbook on Secession. Cheltenham: Edward Elgar Publishing, pp. 331–347.
Human Rights Committee (1997) General Comment No. 26 (61): General comment on issues relating to the continuity of obligations to the International Covenant on Civil and Political Rights, adopted 29 October 1997, CCPR/C/21/Rev.1/Add.8/Rev.1, 8 December 1997.
International Court of Justice (1997) Gabčíkovo-Nagymaros Project (Hungary/Slovakia), judgment, 25 September, I.C.J. Reports 1997, p. 7.
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International Law Commission (1999) ‘Draft articles on nationality of natural persons in relation to the succession of States with commentaries’, Yearbook of the International Law Commission, 1999, vol. II, Part Two, ch. IV; UN Doc. A/54/10, ch. IV.
International Law Commission (2001) ‘Draft articles on Responsibility of States for Internationally Wrongful Acts, with commentaries’, Yearbook of the International Law Commission, 2001, vol. II, Part Two; UN Doc. A/56/10.
International Law Commission (2018) ‘Draft conclusions on identification of customary international law, with commentaries’, Report of the International Law Commission, Seventieth Session, UN Doc. A/73/10, ch. V.
International Law Commission (2024) ‘Succession of States in respect of State responsibility’, Report of the International Law Commission, Seventy-fifth Session, UN Doc. A/79/10, ch. IX.
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Kamminga, M.T. (1996) ‘State Succession in Respect of Human Rights Treaties’, European Journal of International Law, 7(4), pp. 469–484.
Sarvarian, A. (2016) ‘Codifying the Law of State Succession: A Futile Endeavour?’, European Journal of International Law, 27(3), pp. 789–812.
United Nations (1991) Letter dated 24 December 1991 from the President of the Russian Federation to the Secretary-General concerning the continuation by the Russian Federation of the membership of the Union of Soviet Socialist Republics in the United Nations, 24 December. Not issued as a separate United Nations document; summarized in Official Records of the General Assembly, Forty-seventh Session, Supplement No. 2 (A/47/2), p. 277.
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United Nations Treaty Collection (2026b) Vienna Convention on Succession of States in Respect of State Property, Archives and Debts: Status of Treaties [online]. Available at: https://treaties.un.org/pages/ViewDetails.aspx?chapter=3&mtdsg_no=III-12&src=TREATY (Accessed: 22 August 2026).
Vienna Convention on Succession of States in Respect of State Property, Archives and Debts (1983) adopted 7 April 1983, opened for signature at Vienna 8 April 1983, UN Doc. A/CONF.117/14, not yet in force.
Vienna Convention on Succession of States in Respect of Treaties (1978) adopted 22 August 1978, concluded at Vienna 23 August 1978, entered into force 6 November 1996, 1946 UNTS 3, No. 33356.
