Litigation Note

This guide provides a series of structured 'Litigation Notes' designed to help legal practitioners integrate the findings of the International Court of Justice's (ICJ) July 23, 2025, Advisory Opinion (AO) on States' obligations regarding climate change into domestic, regional, and international court cases. The document breaks down the ICJ AO by key themes—including government framework cases, adaptation, remedies and reparations, the right to a healthy environment, corporate conduct, climate financing, speculative interventions, and regulatory rollbacks—providing specific excerpts from the opinion and illustrating their application through existing and potential litigation categories.

• The ICJ AO establishes that the 1.5°C threshold is the primary temperature goal for limiting global average temperature increase under the Paris Agreement.
• States are subject to a 'stringent' due diligence standard of care regarding climate mitigation and the prevention of significant harm to the climate system. This requires States to do their 'utmost' to ensure Nationally Determined Contributions (NDCs) reflect their 'highest possible ambition'.
• The ICJ concluded that the human right to a clean, healthy, and sustainable environment is a binding norm of international law and is essential for the enjoyment of other human rights, such as the rights to life, health, and an adequate standard of living.
• States have binding legal obligations to implement adaptation measures. Under the Paris Agreement, this includes a legally binding obligation to undertake adaptation planning actions, which are assessed against a due diligence standard requiring 'best efforts' in line with the best available science.
• The ICJ AO affirms that the failure of a State to take appropriate action to protect the climate system—specifically including fossil fuel production, consumption, the granting of exploration licenses, or the provision of subsidies—may constitute an internationally wrongful act.
• Breaches of States' climate obligations can trigger a full range of legal consequences under the law of State responsibility, including obligations of cessation, non-repetition, and full reparation (restitution, compensation, and/or satisfaction).
• The ICJ determined that obligations under climate change treaties and customary international law are 'erga omnes' (or 'erga omnes partes' for treaties), meaning they are the concern of all States and can be invoked by any State.
• The Court clarified that the plurality of contributors to climate harm does not exempt individual States from responsibility. It is scientifically possible to determine each State's total contribution to global emissions, including historical and current emissions.
• Developed country parties have a legally binding obligation under both the UNFCCC and the Paris Agreement to provide financial resources to assist developing country parties with mitigation and adaptation.
• The ICJ AO emphasizes that the duty to prevent significant harm requires addressing the source of climate change (GHG-emitting activities) rather than merely attenuating effects. Reliance on speculative technologies or offsets may be inconsistent with the principle of prevention if proven mitigation measures are available.
• The document identifies 'regulatory rollbacks'—the weakening or dismantling of environmental protections—as potential breaches of a State's international obligations, particularly when they conflict with the requirement for NDCs to show 'progression'.
• The ICJ AO establishes that IPCC reports constitute the comprehensive and authoritative restatements of the best available science on climate change, which must inform the standard of due diligence applied by States.

APA

Avila, L., Campos, M., Chowdhury, J., Dey, R., Dutta, R., Fournier, L., Alves, D. B. G., Lennon, E., Main-Klingst, L., Masiye-Moyo, N., Pfitzner, L., Reisch, N., Shetye, A., Slidders, C., Tan, F., Udell, J., & van Es, C. (2026). Litigation Note. Center for International Environmental Law. https://www.ciel.org/wp-content/uploads/2026/03/ICJ-AO_Litigation-Notes-Digest_Feb2026.pdf

Chicago

Avila, Liliana, Mariana Campos, Joie Chowdhury, Riddhi Dey, Ritwick Dutta, Louise Fournier, Danilo B. Garrido Alves, et al. Litigation Note. Center for International Environmental Law, 2026. https://www.ciel.org/wp-content/uploads/2026/03/ICJ-AO_Litigation-Notes-Digest_Feb2026.pdf.

Wikipedia

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BibTeX

@techreport{avila2026litigation, author = {Avila, Liliana and Campos, Mariana and Chowdhury, Joie and Dey, Riddhi and Dutta, Ritwick and Fournier, Louise and Alves, Danilo B. Garrido and Lennon, Erika and Main-Klingst, Lea and Masiye-Moyo, Nomasango and Pfitzner, Linn and Reisch, Nikki and Shetye, Aditi and Slidders, Charles and Tan, Floris and Udell, Joe and van Es, Catherine}, title = {{Litigation Note}}, institution = {Center for International Environmental Law}, year = {2026}, month = feb, url = {https://www.ciel.org/wp-content/uploads/2026/03/ICJ-AO_Litigation-Notes-Digest_Feb2026.pdf}, urldate = {2026-08-17}, note = {Indexed by Climate Insights Directory} }