ICJ renders advisory opinion on decolonisation of the Chagos Archipelago

In an advisory opinion given on 25 February 2019, the International Court of Justice (ICJ), by a majority of thirteen votes to one, held that the process of decolonisation of Mauritius was not lawfully completed and that the United Kingdom consequently has an obligation to bring an end to its administration of the Chagos Archipelago as rapidly as possible.  The ICJ also considered that all Member States of the United Nations are under an obligation to co-operate in order to complete the decolonisation of Mauritius.

Pursuant to the United Nations General Assembly’s resolution No. 71/292 of 22 June 2017, the ICJ was requested to render an advisory opinion on two questions: first, whether Mauritius’ decolonisation process was “lawfully completed” when it was granted its independence in 1968; and, second, the consequences under international law arising from the continued administration by the United Kingdom of the Chagos Archipelago.  Unlike the Court’s judgments, advisory opinions are not binding and the requesting organ (here, the UN General Assembly) remains free to give effect to the opinion as it sees fit.

This request was preceded by an UNCLOS Annex VII arbitration initiated by Mauritius against the United Kingdom in April 2010.  The arbitral tribunal in that case issued a final award in March 2015, in which it concluded that it lacked jurisdiction given the sovereign character of the dispute.

The ICJ, by contrast, considered that it had jurisdiction to render an advisory opinion on the questions presented by the General Assembly and that it should exercise its discretion to do so.

Concerning the substance of the matter, the ICJ analysed whether the right to self-determination in the context of decolonisation had crystallised as a customary rule binding all States.  It determined that it had done so, and that the right was applicable during the period under consideration.  Additionally, the Court concluded that the United Kingdom’s detachment of the Chagos Archipelago from Mauritius was unlawful, as was its incorporation into a new colony, resulting in the Mauritius decolonisation process not having been lawfully completed when Mauritius gained its independence in 1968.

Consequently, the ICJ concluded that the United Kingdom’s continued administration of the Chagos Archipelago constitutes a wrongful act engaging the United Kingdom’s international responsibility and necessitating that the United Kingdom bring an end to its administration of the Chagos Archipelago as rapidly as possible.

Finally, given the erga omnes nature of the right to self-determination, the Court considered that all States are required to co-operate to ensure the completion of the decolonisation process.

The full text of the advisory opinion can be found here.

For the ICJ press release click here.