Since the emergence of the international climate change regime in the early 1990s, frustration with the slow pace of the negotiations has bubbled over from time to time in proposals to address climate change through international adjudication.1 I was involved in one such episode two decades ago, as part of a team of international lawyers researching the claims that small island states might bring for climate change damages. A dozen years later, the idea of climate change litigation was revived by the Pacific island state of Palau, which proposed that the United Nations General Assembly request an advisory opinion from the International Court of Justice (I.C.J.) concerning the duties of states to ensure that greenhouse gas emissions from their territory do not harm other states.2 That initiative didn’t go anywhere either, but the idea of international climate litigation continued to percolate. In September 2015, the British barrister and scholar, Philippe Sands, gave a public lecture arguing that international adjudication could play a positive role in addressing climate change, as part of a symposium supported by the British government and Supreme Court, and the United Nations Environment Programme, among others.3 A year later, the idea of seeking an I.C.J. advisory opinion on climate change was renewed by a resolution adopted at the International Union for Conservation of Nature (IUCN) 2016 World Conservation Congress in Hawaii.