In the Asylum Case (Colombia v Perú), judgement 20 November 1950 (General List No. 7 (1949–1950)), the International Court of Justice (ICJ) recognised that Article 38 of the Statute of the International Court of Justice encompassed local custom as well as general custom, in much the same way as it encompasses bilateral and multilateral treaties.[1]. The Court also clarified that for custom to be definitively proven, it must be continuously and uniformly executed.
The Colombian Ambassador in Lima, Perú allowed Víctor Raúl Haya de la Torre, head of the American People's Revolutionary Alliance sanctuary after his faction lost a one day civil war in Peru on 3 October 1948. The Colombian government granted him asylum, but the Peruvian government refused to grant him safe passage out of Peru.
Colombia maintained that according to the Conventions in force - the Bolivian Agreement of 1911 on Extradition, the Havana Convention of 1928 on Asylum, the Montevideo Convention of 1933 on Political Asylum - and according to American International Law, they were entitled to decide if asylum should be granted and their unilateral decision on this was binding on Perú.[2]
Both submissions of Colombia were rejected by the Court. It was not found that the custom of Asylum was uniformly or continuously executed sufficiently to demonstrate that the custom was of a generally-applicable character.