AbstractIn its Chagos Advisory Opinion, the International Court of Justice (ICJ) ruled that the UK's detachment of the Chagos Archipelago from the colony of Mauritius on the eve of independence constituted a violation of customary international law (CIL). This article analyses the Court's approach to establishing the emergence and content of the right to self-determination in this frustrated case of decolonisation. It goes on to examine the argument that self-determination's peremptory character has decisive consequences in this specific context—a contention which found favour with several judges in their Separate Opinions. The article explores the extent to which the claims and counterclaims, made during the advisory proceedings, turned on countervailing readings of not only the key sources of custom but also of the principle of inter-temporal law. The final sections consider the significance of the Chagos Opinion for the Chagossians, both in relation to the Archipelago's resettlement and for their outstanding appeal in the UK courts (where the European Convention on Human Rights performs a pivotal role).
In its Chagos Advisory Opinion, the International Court of Justice (ICJ) addressed two questions posed in a request from the UN General Assembly. First, had Mauritius's decolonization been completed when it gained independence in 1968, after the excision of the Chagos Archipelago? Second, what were the legal consequences flowing from the United Kingdom's continued administration of the Archipelago? It was thought that the Court might shy away from giving an Opinion in this case as, arguably, it concerned a bilateral sovereignty dispute that the United Kingdom had not agreed to have resolved by judicial decision. However, as it turned out, the Court delivered surprisingly robust responses to the questions posed. The Opinion—and the numerous Separate Opinions that accompanied it—offer a thorough re-evaluation of the customary international law (CIL) concerning the right to self-determination in cases of decolonization.
On February 8, 2018, the U.K. Supreme Court delivered its judgment in R (Bancoult No 3) v. Secretary of State for Foreign and Commonwealth Affairs. The case concerned a challenge to the validity of a Marine Protected Area (MPA) extending 250,000 square miles around the British Indian Ocean Territory (BIOT or Chagos Archipelago). Declared in 2010, the MPA was justified on the ground of environmental protection and resulted in a ban on all commercial fishing in this zone. The appellant alleged that the MPA had been established for an improper purpose—to prevent the Chagos Islanders from resettling the Archipelago. He claimed that this was evidenced by a diplomatic cable sent from the U.S. embassy in London. It recorded a 2009 meeting in which U.S. and British officials discussed the reasons behind the MPA. The cable was subsequently leaked via the WikiLeaks website and published in two national newspapers. Accordingly, as Lady Hale rightly observed, "[t]he crucial legal issue in this case is therefore the admissibility of the cable."