International Court of Justice Issues Landmark Climate Ruling
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On July 23, 2025, the International Court of Justice (ICJ) ruled that nation states have a duty to protect the environment from excess greenhouse gas (GHG) emissions, and that failing to prevent environmental harms could lead to financial repercussions.
The ICJ ruling follows a similar decision from the inter-American Court of Human Rights (IACHR) earlier in July.
In its unanimous landmark decision, the ICJ clarified that “a clean, healthy and sustainable environment is a precondition for exercising many human rights,” such as the right to life, health and an adequate standard of living. States are obliged to guarantee the enjoyment of such rights.
Granting fossil fuel exploration licences and the provision of fossil fuel subsidies “may constitute an international wrongful act” in the eyes of ICJ, and offending states may be compelled to pay reparations – for the restoration of infrastructure, for example – to those states harmed by their actions. Where damage is irreparable, the ICJ ruled, financial compensation may also be ordered.
As an advisory opinion the decision is not legally binding. However, it is likely to be regarded as persuasive jurisprudence.
Advisory opinions are often cited by national courts, the UN, and other adjudicative bodies, for their interpretive authority, guiding the development of both international and domestic legal decision-making. In Mathur v. Ontario, for example, the Ontario Court of Appeal acknowledged that international climate law may inform how Canadian courts interpret the interplay between climate change and the Canadian Charter of Rights and Freedoms.
The Mathur decision explored whether Ontario’s GHG targets violated ss. 7 and 15 of the Charter with reference to Canada’s climate commitments, and the scientific consensuses established under the Framework Convention on Climate Change (“UNFCCC”) and the Paris Agreement. Similarly, in La Rose v. Canada, the Federal Court of Appeal held that Canada’s Paris Agreement commitments - which were ratified by Parliament - are objective standards against which Charter claims may be assessed.
The ICJ’s ruling consolidates various international legal frameworks to establish a benchmark for assessing environmental action under international law. Just as the Paris Agreement and even the Dutch Urgenda case have informed the manner and context in which Canadian courts adjudicate climate-related lawsuits, this latest non-binding ruling by the ICJ may be expected to play a role in prospective, binding decisions by Canadian courts.
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