This chapter considers the UK’s assertion of sovereignty over the Chagos Archipelago in the wake of the Advisory Opinion of the International Court of Justice (ICJ) in Legal Consequences of the Separation of the Chagos Archipelago from Mauritius in 1965. It will be argued in this chapter that the UK’s assertion to sovereignty is tenuous as it rests on weak foundations which are increasingly undermined by the colonial context in which the then colony of Mauritius agreed to the detachment of the Chagos Archipelago. The UK’s sovereignty over the Chagos Archipelago is contested by Mauritius (and by the majority of countries that have given their support to the campaign to force the return of the territory). The Republic of Mauritius first challenged the UK’s sovereignty at the United Nations General Assembly (UNGA) in 1980, some twelve years after gaining its independence.1 The Court’s Advisory Opinion is a landmark in terms of how sovereignty over the Chagos Archipelago must now be approached.

The Advisory Opinion of the International Court of Justice (ICJ) on the Chagos Archipelago left a number of questions unanswered, deferring them to the ‘modalities’ of decolonisation to be addressed by the UN General Assembly (UNGA).2 Rather than speculating on those modalities, this chapter will instead address some related legal aspects which have a bearing on the future status of the Chagos Islands. After a brief inventory of significant gaps in the coverage of applicable multilateral agreements, the focus of the analysis that follows will be on issues of maritime delimitation, ocean governance and nuclear disarmament in the area.

Current threats might include in particular the proliferation of nuclear weapons and terrorism as well as international crime, policing the oceans, the antics of cybergeeks, securing energy sources, climate change, economic challenges, and the protection of allies. Singly or in groups, these problems and issues scarcely justify the maintenance of a large military force in being, and complacency is, in general, a more fitting response than agitated, and particularly militarized, alarm. Proliferation has been of little practical consequence, and alarmed efforts to prevent it have proved to be very costly and may hamper the forging of a permanent normalization in Korea. Counterterrorism policy has been driven primarily by public opinion, not by an apt analysis of the threat. Cybergeeks may be able to commit sabotage, steal intelligence, or spread propaganda, but any military disruptions are likely to be minor and call more for a small army of counter-cybergeeks than for a large military. One possible use of American military forces in the future would be to deploy them under international authority to police destructive civil wars or to depose vicious regimes. However, this would not require a large number of troops and is unlikely to become routine.

At the heart of the Chagos Advisory Opinion1 lies paragraph 172, where the International Court of Justice (ICJ) held ‘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’. Applying this new and stricter standard for consent, the Court concluded in the very same paragraph that the 1965 detachment of the Chagos Islands from Mauritius, then a colony of the UK, ‘was not based on the free and genuine expression of the will of the people concerned’. Consequently, the Court ruled that the process of decolonisation of Mauritius was not lawfully completed. The Court’s reasoning remains enigmatic; its ruling reminds one of the proverbial ‘black box’ deliberations of a grand jury. The answer the judges provided is clear: the free will of the people was disregarded and consequently the detachment of the Chagos Islands was unlawful. However, the reasons underlying the decision remain opaque.2

The separation of the Chagos Archipelago from Mauritius in 1965, and its setting aside by the UK ‘for defence purposes’,1 was the precursor to a human tragedy. The covert expulsion of the Chagossians from their homeland in the years that followed has been described as ‘unhappy – indeed, in many respects, disgraceful’ (by one of the UK’s most senior judges),2 ‘sordid’ and ‘morally indefensible’ (by a former British Foreign Secretary)3 and ‘shameful and wrong’ (by counsel for the UK in the International Court of Justice (ICJ)).4

Although the American military record since 1945 has been pretty unimpressive, some argue, first, that the United States, aided perhaps by the attention-arresting fear of nuclear weapons, was necessary to provide worldwide security and thus to order the world, and, second, that the United States was vital in constructing international institutions, conventions, and norms, advancing economic development, and expanding democracy–processes, it is contended, that in various ways have ordered the world and crucially helped to establish and maintain international peace. However, it seems more plausible that the positive developments would mostly have happened even without much American security participation, and that, for the most part, world order has developed not from the machinations of the reigning superpower but from the aversion to international war embraced after World War II especially by developed countries. In fact, if the nearly 200 states that inhabit the world order come substantially to abandon the idea that international war is a sensible method for solving problems among themselves, the notion that they live in “anarchy” becomes misleading and could encourage undesirable policy developments. “World order” is based on a general aversion to international war and does not depend on the United States.

This chapter argues that the weight of teachings in the ICJ varies between works. Some works are cited far more than others. The most-cited writers tend to men from Western countries. The judges frequently justify citations of teachings, by arguing that the teachings of high quality, that the writer is an expert, that the writer holds an official position, or that multiple writers agree. It is plausible to view this as factors that influence the weight of teachings. Explanations for why the judges distinguish between works is that they want to make their opinions authoritative, that they want to save time, and that they want to comply with the ICJ Statute Article 38(1). Finally it is argued that the variations between the weight of teachings shows that authority in international law is established through an informal, collective process.