The 2019 Chagos Advisory Opinion of the International Court of Justice is a decision of profound legal and political significance. Presented with a rare opportunity to pronounce on the right to self-determination and the rules governing decolonization, the ICJ responded with remarkable directness. The contributions to this book examine the Court's reasoning, the importance of the decision for the international system, and its consequences for the situation in the Chagos Archipelago in particular. Apart from bringing the Chagossians closer to the prospect of returning to the islands from which they were covertly expelled half a century ago, the decision and its political context may be understood as part of a broader shift in North/South relations, in which formerly dominant powers like the UK must come to terms with their waning influence on the world stage, and in which voices from former colonies are increasingly shaping the institutional and normative landscape.