Explanatory Note 

The World Map of State Succession (1800–Present) is the first global visual representation of the general positions of states and entities with respect to succession to the international rights and obligations of their predecessors. The Map illustrates how successor entities have approached questions of continuity, succession, or non-succession in international law following territorial and sovereignty change.

The Map includes entities that are widely treated as states in international legal practice, including partially recognised states, where sufficient practice exists to assess their approach to succession. The Map does not seek to resolve questions of statehood or recognition; rather, it reflects observable positions taken by entities that participate, to varying degrees, in international legal relations.

The temporal scope of the Map begins in 1800. A state’s or entity’s position is generally assessed at the initial moment of succession, based on contemporaneous declarations and practice. Where relevant, this assessment is supplemented by subsequent state practice in the years following succession, especially where later conduct clarifies, or modifies earlier positions. 

Sources and Data Collection

The information underlying the Map was gathered from open-access sources and verified through a combination of primary and secondary materials, including:

• bilateral and multilateral treaties;
• declarations of independence and other foundational instruments;
• domestic legislation and constitutional provisions;
• international and domestic judicial and arbitral decisions;
• official statements and practice within international organisations; and
• scholarly publications by recognised experts in the field of international law, including the law of state succession.

Given the inherent complexity of state succession and the uneven availability of authoritative materials, some classifications may reflect evolving practice. Where practice is unclear or contested, the Map aims to present the most defensible interpretation based on the totality of available evidence.

Within its institutional and resource limitations, the State Succession Index team has sought to provide a good-faith visualisation of one of the most complex and controversial branches of international law: the law of state succession. 

Basis of Classification 

Classifications on the Map are based on express declarations and observable state practice either in favour of, or against, succession to the international rights and obligations of predecessor states. Importantly, the Map reflects positions as articulated by states and entities themselves. It does not purport to determine the legally “correct” outcome under international law, nor does it prejudge disputes concerning the legal effects of succession. 

These categories are descriptive, not normative, and are based on express declarations and observable practice.

Continuator

A State and entity that claims and is generally treated as preserving the international legal personality of a predecessor, including its international rights and obligations. For the purposes of this Map, entities that existed as states by 1800 and have preserved their statehood without interruption to the present are also treated as continuators. This position is typically reflected in constitutional or institutional continuity, treaty practice, and recognition by other states and international organisations.

Full Succession

A state or an entity that accepts succession to the vast majority of the predecessor’s international rights and obligations, while not claiming identity with the predecessor. This position is commonly reflected in treaty notifications, accession to memberships, and continuity of international commitments.

Partial Succession

A state or an entity that accepts succession to certain international rights and obligations, while renegotiating or rejecting others. This selective approach is often evident in differentiated treaty practice, sector-specific declarations, or conditional acceptance of obligations. 

Clean Slate

A state or an entity that silently rejects succession to the predecessor’s international rights and obligations, except where succession is required under customary international law. 

Denied Succession 

A state or an entity for which available practice indicates an express denial and rejection of succession of international rights and obligation of its predecessor.

Disclaimer

Boundary lines depicted on the Map are for illustrative purposes only and do not imply recognition of borders in disputed or contested areas.

The categories shown on the Map do not affect the applicability of customary international law, including obligations that arise independently of succession declarations. In particular:

• classifications indicating declined or limited succession do not extend to customary international law rules that apply irrespective of consent; and
• they do not affect obligations relating to boundaries, including boundary treaties, which are governed by separate and well-established norms of international law.

Methodological Note 

The objective of the Map is to provide a comparative and visual overview of how states and entities have approached succession to international rights and obligations across different historical periods and geopolitical contexts, including succession to treaties, state debt, international responsibility, among others.

Each unit of analysis is a state or an entity that has undergone a relevant succession event (e.g. dissolution, secession, unification, absorption, annexation, or cession of territory). Succession events are identified based on widely accepted historical and legal accounts, including major geopolitical changes recognised in international practice.

For each state or entity, available evidence is assessed cumulatively. No single source is determinative; classifications reflect the overall balance of practice and declarations. Entities are assigned to succession categories based mainly on their self-expressed position and conduct.

The Map is a living project, open to academic debate and ongoing revision. It is periodically reviewed and updated to reflect newly available sources, developments in state practice, and feedback from practitioners and scholars, as well as the reassessment of existing classifications in light of further evidence.