In an advisory opinion issued on February 25, the International Court of Justice (ICJ) concluded that the United Kingdom violated core principles of international law by separating the Chagos Archipelago from Mauritius in the 1960s and continuing to administer the islands as a British territory. See Legal Consequences of the Separation of the Chagos Archipelago from Mauritius in 1965, Advisory Opinion, ICJ Reports 2019, para. 183. Despite the U.K’s numerous attempts to challenge the Court’s jurisdiction over the matter, the Court ultimately determined that it was competent to address the questions presented and issued its answer. See id. In its opinion, the Court made clear that the U.K’s actions with respect to this former colony run counter to what are now well-established rights of peoples to self-determination. See id. at paras. 177-178. The UN General Assembly is expected to discuss implementation of the advisory opinion, including returning the islands to Mauritius and resolving the status of the thousands of people the U.K. forcibly expelled from Chagos following its agreement with the United States to allow an American military base, and later secret CIA detention site, on the island of Diego Garcia. [Guardian; Nation]
ICJ’s Discretion to Exercise Jurisdiction
The UN General Assembly requested this advisory opinion in 2017 via Resolution 71/292. See Legal Consequences of the Separation of the Chagos Archipelago from Mauritius in 1965, para. 1. The resolution raised two questions before the Court: 1) whether the decolonization of Mauritius had been completed lawfully following its independence and the separation of the Chagos Archipelago, and 2) what the legal consequences of the U.K.’s ongoing administration of Chagos are. See id. Article 65 of the Statute of the International Court of Justice governs the Court’s jurisdiction to issue advisory opinions, limiting it to “any legal question at the request of whatever body may be authorized by or in accordance with the [UN] Charter” to make a request of this nature. See id. at para. 55. Article 96 of the UN Charter provides that the General Assembly is a competent body to request an advisory opinion, and the Court determined that the questions raised by the UN General Assembly concerned a legal question in accordance with Article 96 of the Charter and Article 65 of the Statute. See id. at paras. 56-58.
While the Court concluded that it had jurisdiction to issue an advisory opinion on the matter, the Court considered whether it should decline to exercise its jurisdiction given the complexity of the factual issues disputed, the actual relevance of the Court’s opinion in assisting the General Assembly in performing its functions, a potential violation of the principle of res judicata, and a concern that the Court would be effectively making a decision on a bilateral dispute over territorial sovereignty between States that have not consented to the ICJ’s jurisdiction. See id. at paras. 67, 69, 75, 79, 83, 85.
The Court addressed whether the questions posed relate to a dispute between the U.K. and Mauritius over territorial sovereignty, and emphasized that the questions actually relate to the decolonization of Mauritius. See id. at paras. 83, 86. Thus, the Court concluded that its opinion would not resolve the bilateral dispute regarding territorial sovereignty over the Chagos Archipelago; an opinion on that issue may have resulted in “circumventing the principle that a State is not obliged to allow its disputes to be submitted to judicial settlement without its consent.” See id. at paras. 85, 90. Rather, the Court considered that this advisory opinion would assist the General Assembly in its activities aimed at decolonizing Mauritius. See id. at paras. 86-89. Further, referencing prior findings by the Arbitral Tribunal in the Arbitration regarding the Chagos Marine Protected Area, which are binding on Mauritius and the United Kingdom, the Court clarified that the principle of res judicata itself does not preclude it from issuing an advisory opinion. See id. at para. 81. The Court also determined that whether or not an opinion would assist the General Assembly in the performance of its functions is an irrelevant consideration when exercising its discretion to respond to a request for an advisory opinion. See id. at paras. 76-78. Similarly, the Court did not consider the complexity of the disputed factual issues a satisfactory ground for declining to issue an advisory opinion given the “abundance of material [that] has been presented before it” to help it arrive at a conclusion. See id. at paras. 73-74.
Opinion of the Court
First, the Court addressed the question regarding the legality of the decolonization process in Mauritius, focusing on the applicable international law standards in place during the time period between the separation of the Chagos Archipelago from Mauritius in 1965 and 1968 when Mauritius gained its independence. See id. para. 140. However, the Court stated that while this timeframe is relevant to determining what law applies, it may still consider the evolution of law on self-determination, particularly in matters of customary international law. See id. at para. 142. Thus, in determining the scope of the right to self-determination that applies to Mauritius’ decolonization process, the Court considered that the right to self-determination has, in fact, crystalized as customary law and is therefore binding on all States. See id. at para. 148.
The Court articulated that the right to self-determination, as understood given the State practice and opinio juris at the relevant period of time, means that the peoples of non-self-governing territories are entitled to exercise “territorial integrity” over the entirety of their territory and that any detachment of part of that territory by the administering power—unless it results from the “freely expressed and genuine will of the people”—runs counter to the right to self-determination. See id. at para. 160. The Court cited the history of the U.K.’s colonial rule over Mauritius, particularly the fact that Mauritius was still under the authority of the U.K when it agreed to cede the Chagos Archipelago, to conclude both that the Chagos Archipelago was detached contrary to the will of the people, making it illegal under the relevant international law. See id. at paras. 170-174. The Court emphasized that “heightened scrutiny should be given to the issue of consent in a situation where a part of a non-self-governing territory is separated to create a new colony.” See id. at para. 172.
On the second question regarding the legal consequences of the U.K.’s continued administration of the Chagos Archipelago, the Court noted that because the decolonization itself contravened the peoples’ right to self-determination, the ongoing administration of the island is a wrongful act under international law. See id. at para. 177. The Court stated that not only is the U.K. under an obligation to end its administration of the Chagos Archipelago as quickly as possible, but that all other UN Member States have an obligation to cooperate in undertaking a legitimate and complete decolonization of Mauritius. See id. at paras. 178-182. Additionally, the UN General Assembly must ensure that the decolonization process of Mauritius is completed, determine the necessary steps for completing it, and ensure the protection of the human rights of the expelled Chagossians. See id. at paras. 179, 181.
Mauritius consists of a group of islands located approximately 2,000 km off the coast of Africa in the Indian Ocean. See id. at para. 25. Since as early as 1826, the Chagos Archipelago has been listed and described by British officials as a dependency of Mauritius. See id. at paras. 27-28. In 1965 the United Kingdom established a new colony known as the British Indian Ocean Territory that consisted of Chagos, detached from Mauritius, and other islands. See id. at para. 33. The explicit expression of the local Mauritian leadership’s desire to prevent the separation of Chagos was dismissed. See id. at paras. 99, 106.
An agreement in 1966 between the U.K. and the United States, gave the U.S. rights to establish a military base on the Chagos Archipelago and committed the U.K. to take necessary “administrative measures,” including the “resettling of any inhabitants” off the island. See id. paras. 36-37. Mauritius officially gained its independence on 12 March 1968, while the entire population of Chagos was forcibly expelled or prevented from returning to the island between 1967 and 1973. See id. at paras. 42-43. While the British government itself has since acknowledged that its removal of the inhabitants of Chagos was “shameful and wrong,” the U.S. maintains a military base on the island of Diego Garcia and the Chagossians are still prevented from returning to the Chagos Archipelago. See id. at para. 122. The Human Rights Committee has on several occasions in its review of the U.K. expressed that it is unlawful to prevent Chagossians from returning and that they must be given the option to go back. See id. at paras. 123, 126.
The Chagossians have pursued redress for decades, with mixed results until now. In 2012, the European Court of Human Rights rejected a complaint submitted by Chagos islanders concerning their removal from the islands, concluding that the islanders could no longer be considered “victims” because they accepted financial compensation in settling prior national-level litigation concerning these claims. See ECHR, Chagos Islanders v. United Kingdom, no. 35622/04, Admissibility Decision of 11 December 2002.
The ICJ is the principal judicial organ of the UN, often referred to as the “World Court.” See ICJ, The Court. The ICJ can hear legal disputes between States submitted to the Court by States that have accepted or agreed to its contentious jurisdiction, and can answer requests for advisory opinions on legal questions referred to it by UN organs and specialized agencies. See ICJ, How the Court Works.
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