Uti Possidetis Juris

Uti possidetis juris (Latin: "as you possess under law") holds that when a state emerges from decolonization or the dissolution of a larger sovereign, its borders are presumed to follow the pre-existing internal administrative lines of the predecessor. The doctrine is designed to freeze territorial disputes at independence and discourage wars of conquest or irredentist claims among successor states.

The principle originated in 19th-century Spanish America, where the newly independent republics agreed to adopt the boundaries of the former Spanish colonial audiencias and capitanías generales as of 1810 (or 1821, depending on the region). It was later transplanted to post-colonial Africa. In 1964, the Organization of African Unity adopted the Cairo Declaration (AHG/Res. 16(I)), in which member states pledged to respect the borders existing at the time of their independence.

The doctrine received its most influential modern articulation in the International Court of Justice's 1986 judgment in the Frontier Dispute (Burkina Faso / Mali) case. The Chamber characterized uti possidetis juris as a "general principle" whose purpose is "to prevent the independence and stability of new States being endangered by fratricidal struggles." The Court applied it again in cases including El Salvador/Honduras (1992) and Benin/Niger (2005).

The principle was also invoked, more controversially, by the Badinter Arbitration Committee during the dissolution of Yugoslavia in 1991–1992, which concluded that the internal republican boundaries of the SFRY should become international frontiers absent agreement otherwise.

Critics argue that uti possidetis juris entrenches arbitrary colonial lines, splits ethnic groups, and can fuel rather than resolve conflict. Defenders counter that any alternative rule would invite endless revisionist claims. The doctrine does not bar boundary adjustments by mutual consent, and it operates as a rebuttable presumption rather than an absolute rule.