In 2024 and 2025, three international courts issued advisory opinions on climate change: the International Tribunal for the Law of the Sea (ITLOS), the Inter-American Court of Human Rights (IACtHR), and the International Court of Justice (ICJ). Together they confirm that states’ contributions to climate change, and their action or inaction in response, can give rise to liability under several sources of international law. Scholarship on the opinions is growing quickly, but far less attention has gone to their actual and likely impacts.
On 25 March 2026, the University of Cambridge hosted an expert workshop on that question, supported by the Lauterpacht Centre for International Law and organised with the Cambridge Centre for Environment, Energy and Natural Resource Governance (C-EENRG), the LSE Grantham Institute and the European Association of Climate Law (EACL). This summary outlines the discussion’s main themes.
Key takeaways
- Legal impacts extend beyond international courts. The opinions are non-binding but carry authority and have already been cited by the European Court of Human Rights. They may shape domestic litigation, investment arbitration and the use of states’ written submissions to test the consistency of government positions. More broadly, they affirm international law’s role in addressing climate change at a time when the international legal order is under strain.
- Political impacts are real but hard to isolate. The opinions may serve as advocacy tools for civil society, particularly in Pacific Island States and the Global South, and have already supported efforts to negotiate a fossil fuel phase-out treaty. They may also encourage business and investor action, but generally their effects will vary with each country’s politics and the fragmented international geopolitical context.
- Measuring impact is methodologically challenging. Impacts are non-linear, and the opinions build on decades of prior legal developments. Suggested approaches include citation analysis (including detection of implicit citations), media analysis, surveys, process tracing, scenario planning, the Delphi Method and ethnographic methods. Researchers should guard against funder influence and bias against publishing findings of “no impact”, including silent non-absorption of the opinions.
- The way forward is interdisciplinary collaboration. Participants called for methodologically rigorous but expansive research that draws on fields such as psychology and economics, informs processes like the IPCC’s Seventh Assessment Report, gives voice to the communities that initiated the proceedings, and helps translate the courts’ climate obligations into real-world action.