ICJ Issues Advisory Opinion on States' Legal Obligations Regarding Climate Change
The International Court of Justice ("ICJ") stated that States have legal obligations to regulate emissions and may be held internationally responsible for climate inaction—including the failure to effectively regulate greenhouse gas emissions.
On July 23, 2025, the ICJ issued an Advisory Opinion on States' obligations with respect to climate change. The ICJ received statements from more than 90 States and ultimately concluded that all States are subject to certain obligations. It rejected the key arguments advanced by certain States.
Key Findings
- States that fail to prevent significant harm to the environment—by not exercising due diligence or failing to use all means at their disposal—may be held internationally responsible.
- "Failure of a State to take appropriate action to protect the climate system from GHG emissions … may constitute an internationally wrongful act which is attributable to that State."
- States must exercise "stringent" due diligence when preparing/implementing Nationally Determined Contributions ("NDCs") (i.e., each State's undertaking under the Paris Agreement to reduce emissions). NDCs must be ambitious, progressive, and effectively implemented domestically—and are not subject to States' unlimited discretion.
- Injured States can seek cessation of wrongful conduct or omissions, assurances of nonrepetition, and/or reparations.
- States' obligations arise not only from climate treaties, including the Paris Agreement, but also from customary international law (e.g., duty to prevent transboundary harm and duty to cooperate) and international human rights law. The ICJ makes a direct link between a State's climate obligations and international human rights law.
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