Wayfinders for Climate Change Action: The ICJ, ITLOS, and IACtHR Advisory Opinions on Climate Change

Abstract Three international courts – the International Court of Justice (ICJ), the International Tribunal for the Law of the Sea (ITLOS), and the Inter-American Court of Human Rights (IACtHR) – have recently issued landmark advisory opinions regarding States’ responsibility to address climate change. The opinions show a high level of convergence, albeit with some notable differences. In essence, they find that, under various sources, international law imposes stringent yet differentiated mitigation obligations on States to address climate change, both individually and collectively. The courts aligned on the core tenets of the due diligence standard to meet these obligations, including on the objective to limit global warming to 1.5 °C and the need to rely on science, precaution, and differentiation. While the ICJ found a duty to regulate the emissions of private actors, the IACtHR went further in defining specific actions that States must take to regulate such actors. The opinions will likely affect future domestic and international regulation and litigation.