The ICJ affirmed that States have binding customary obligations to prevent significant harm to the climate system and to cooperate in addressing the crisis. Rejecting arguments that climate treaties override these duties, the Court clarified that non-parties remain bound. While acknowledging law’s limits, the ICJ’s opinion provides a powerful legal foundation to guide climate negotiations, litigation, and collective action worldwide.
While there are many aspects of the Inter-American Court of Human Rights (IACtHR)’s Advisory Opinion 32/25 (AO-32/25) that are new and groundbreaking, the inclusion of a reflection on jus cogens might have surprised some observers. The legal consequences of the recognition as jus cogens of the obligation not to create irreversible damage to the climate and the global environment are profound. Treaties violating the norm are void, customary international law rules cannot exist, nor does the persistent objector rule apply.
In this blog post, we document and analyse the numerous apparent breaches of international law that have occurred within the first six weeks of the 2025 Trump administration. What began as an informal discussion at the Lauterpacht Centre for International Law has evolved into this analytical overview. We believe this documentation serves both academic purposes and potentially supports future legal proceedings. While defenders of these actions will undoubtedly offer justifications for what we identify as clear breaches of international law, our analysis aims to provide an assessment based on established international legal principles.
13. September 2025
Giovanni Capoccia
12. September 2025
Anne Peters
12. September 2025
Anne Peters