Uti Possidetis Iuris in the Twenty-First Century: Consensual or Customary?

Abstract

The doctrine of uti possidetis iuris provides that, in the succession of States arising from secession or disintegration, territorial title is delimited between successors according to internal borders at the time of succession. Although it is commonly accepted that the concept originated in the nineteenth-century successions in the Spanish Americas and was generally adopted by the twentieth-century decolonization successors in Africa, international law scholars have been divided on whether the doctrine has thereafter evolved into a universal rule of customary international law that presumptively binds successors but is rebuttable by common agreement. This article argues that the ‘presumption’ of binding application is not supported by precedent and is inconsistent with the principle of consent. Rather, the law of State succession is neutral on the delimitation of successors’ frontiers: uti possidetis iuris is one of several methods of territorial delimitation that may be adopted by their common consent.