ICJ concludes UK must end administration of the Chagos Archipelago “as rapidly as possible”


Re: Legal Consequences of the Separation of the Chagos Archipelago from Mauritius In 1965

The International Court of Justice has today delivered its Advisory Opinion on the legal consequences of the separation of the Chagos Archipelago from Mauritius. The Court, by a majority of 13-1, found that the UK’s claim to sovereignty over the remote Chagos Islands in the Indian Ocean is illegal.

The Chagos Archipelago was detached from Mauritius by the UK in 1965, when Mauritius was a UK colony, three years before it gained independence in 1968. The islands were turned into a new colony which the UK calls the “British Indian Ocean Territory”. All residents of the Archipelago were removed, and the largest island, Diego Garcia, was made available to the United States for a military base.

The case was submitted to the Court by the United Nations General Assembly (UNGA) in June 2017. The UNGA, in a resolution endorsed by 94 States, formally requested that the Court answer two legal questions: (1) was the decolonisation of Mauritius lawfully completed? (2) If not, what are the legal consequences?

In their advisory opinion, the Court found that the decolonization of Mauritius was not conducted in a manner consistent with the right of peoples to self-determination thus it follows that the United Kingdom’s continued administration of the Chagos Archipelago constitutes a wrongful act.

The Court concludes that the United Kingdom has an obligation to bring to an end its administration of the Chagos Archipelago as rapidly as possible, and that all Member States must co-operate with the United Nations to complete the decolonization of Mauritius.

Professor Philippe Sands QC and Alison Macdonald QC were involved in this case.