On Wednesday 23 July the UN’s principal judicial body, the International Court of Justice (ICJ), issued its advisory opinion on the obligations of States in respect of climate change.

Read out by the President of the Court, Judge Iwasawa Yuji, the opinion declared that States have an obligation to protect the environment from greenhouse gas emissions and act with due diligence and cooperation to fulfil this obligation. This includes the obligation under the Paris Agreement on climate change to limit global warming to 1.5°C above pre-industrial levels.

The Court further ruled that if States breach these obligations, they incur legal responsibility and may be required to cease the wrongful conduct, offer guarantees of non-repetition, and make full reparation depending on the circumstances.

The reason for the ruling dates back to the September 2021 announcement by the Pacific Island State of Vanuatu that it would seek an advisory opinion from the Court on climate change. After the country lobbied other UN Member States to support this initiative in the General Assembly, on 29 March 2023, a resolution was adopted requesting an advisory opinion from the ICJ on two questions: (1) What are the obligations of States under international law to ensure the protection of the environment? and (2) What are the legal consequences for States under these obligations when they cause harm to the environment?

The UN Charter allows the General Assembly to request the ICJ to provide an advisory opinion. Even though advisory opinions are not binding, they carry significant legal and moral authority and help clarify and develop international law by defining States’ legal obligations.

An opinion piece in the Washington Post quotes Delta Merner, a lead scientist at the Union of Concerned Scientists, who said the court ruling “won’t change things overnight.” But it could ultimately “reshape the political, legal and even the moral landscape” of how to hold polluters to account.

The article also carries this quote from Ms. Merner. “We’ve been stuck in this notion that climate action is all voluntary. The ICJ reframed the climate crisis as a legal and human rights emergency.”

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