5 Concept and Theories of State Succession

State succession — defined by the 1978 Vienna Convention (Succession in Respect of Treaties): "the replacement of one State by another in the responsibility for the international relations of territory" — occurring when territory changes sovereign hands: by cession (transfer), annexation, unification (merger), dismemberment (break-up), decolonization (newly independent states), separation.The theories (the doctrinal pair inherited from private law):1. Universal succession theory (the Grotian lineage, from private inheritance): the successor absorbs all rights and duties — the state's legal personality continues in the new sovereign (the 19th-century annexation doctrine);2. Continuity theory / the modern rule of non-succession for general treaties: the default is continuity of territorial obligations — treaties attaching to the territory (boundaries, local regimes) continue; political treaties lapse;3. Clean slate (tabula rasa) theory: the successor starts free of the predecessor's treaty obligations (VCSST Article 16's option for newly independent states — the decolonization compromise);4. The functional inventory: each category of succession follows its own rules — the modern method (treaties: devolution vs. renegotiation; property and archives: equitable apportionment; debts: equitable shares subject to the "odious debts" debate; nationality: option/automatic grant; membership: successor-state practice).