The Chagos Advisory Opinion is in many ways a bold judgment. For one, the International Court of Justice (ICJ) agreed to give advice to the UN General Assembly (UNGA) against the wishes of three permanent members of the UN Security Council, in circumstances in which it could have dodged the bullet with a reasonable degree of plausibility.1 It declined the invitation to characterise the request as one concerning a bilateral territorial dispute between Mauritius and the UK, and sided, instead, with the several states who viewed decolonisation as a multilateral issue in which the UN retains a legitimate interest. The Opinion, moreover, comprises a scrupulous retelling of the political process leading to the excision of the Chagos Archipelago from Mauritius in the 1960s, and provides a cutting answer to the UNGA’s questions: the process of decolonisation of Mauritius has not yet been completed, and the UK is under an obligation to bring its administration of Chagos to an end.