International Court of Justice issues advisory opinion on states’ climate obligations

What happened

On 23 July 2025 the International Court of Justice delivered its advisory opinion in Obligations of States in respect of Climate Change. The Court sat at the Peace Palace in The Hague. The opinion answers legal questions referred by the United Nations General Assembly; it does not decide a dispute between named parties.

The request asked the Court to identify the obligations of states under international law to protect the climate system and other parts of the environment from anthropogenic greenhouse-gas emissions, and to identify the legal consequences where those obligations are breached. Written and oral submissions came from a larger group of states and international organisations than in any previous proceeding of the Court.

The opinion was adopted unanimously. Judges appended separate opinions addressing aspects of reasoning they wished to state independently. The operative text is the opinion itself; summaries and press releases are not a substitute for it.

Because the proceeding is advisory, the legal force of the text depends on how states, international organisations, and later courts make use of it. The document does not, by itself, impose a new treaty, set a global emissions number, or award damages. What it does is state the Court’s view of the law on the questions asked, with citation to the instruments it examined.

Key facts

The opinion is Obligations of States in respect of Climate Change, Advisory Opinion of 23 July 2025, General List No. 187.

The request came from the United Nations General Assembly.

The Court adopted the advisory opinion unanimously. Several judges appended separate opinions.

The proceeding recorded the highest number of participating states and international organisations in the Court’s history.

An advisory opinion is not a binding judgment in a contentious case. It is an authoritative statement of the Court’s view of the law on the questions asked.

Perspectives

The Court’s opinionThe Court treated climate change as a question of existing international law rather than a new special regime. It examined the U.N. Charter, the climate treaties including the Paris Agreement, customary international law, and related human-rights and environmental instruments, and set out duties of states to protect the climate system from anthropogenic greenhouse-gas emissions.

Requesting states and supporting submissionsStates and organisations that supported the request described the opinion as a clarification of duties already undertaken, and as guidance for domestic courts, treaty bodies, and future negotiations. They emphasised participation by climate-vulnerable states.

Separate and cautious readingsSeparate opinions and later official comments stressed limits: the opinion is advisory, implementation remains with states and political organs, and specific questions of attribution, causation, and remedies in particular disputes were not settled as if they had been litigated between identified parties.

What happened

Key facts

Sources

Perspectives