The Dawn of a New Era of Climate Action Based on Rule of Law - Understanding the ICJ Advisory Opinion

Commentary column by Senior Researcher Izumi Kubota of the Social Systems Field at the National Institute for Environmental Studies on the advisory opinion on state obligations regarding climate change published by the International Court of Justice (ICJ) on July 23, 2025. This advisory opinion is an extremely important view where the ICJ stated that "under international law, states have an obligation to take climate action" and that countries that fail in this obligation bear legal responsibility. Led by Vanuatu with joint proposals from 132 countries and participation from 96 countries and 11 international organizations, it became the largest-scale procedure in history. The ICJ determined that obligations arise not only from climate-related treaties but from all international law including customary international law, the UN Convention on the Law of the Sea, and international human rights law, confirming that the 1.5°C target is an important standard based on scientific evidence under the Paris Agreement. State obligation violations include fossil fuel production, consumption, exploration permits, and subsidy provision, with violations resulting in full compensation obligations. While advisory opinions have no legally binding force, they will significantly influence future climate litigation and international negotiations, signifying the dawn of a new era of climate action based on rule of law.