On May 1, 2025, the Supreme Court of Canada (the "SCC") dismissed the Government of Ontario's application for leave to appeal and the application from cross-appeal in His Majesty the King in Right of Ontario v. Sophia Mathur,1 a 2024 decision from the Court of Appeal for Ontario ("ONCA").2 Ontario and the youth plaintiffs asked the SCC to weigh in on the case, stating that Mathur raises questions of national importance about whether governments are constitutionally required to fight climate change. The SCC's decision to not grant leave to appeal in Mathur means that the ONCA's decision in Mathur and its broad interpretation of the justiciability of climate issues stands, pending the Ontario Superior Court of Justice's ("ONSC") rehearing of the case.
Our earlier analyses of the Mathur decisions explored the significant implications of this groundbreaking case. In our previous post, The Heat is On: Justiciability of Climate Claims, we discussed the original decision of the ONSC,3 highlighting the complexities plaintiffs encountered in attempting to establish standing and clear justiciability thresholds in climate-related matters. Our subsequent article, Turning Up the Heat: Ontario's Climate Case Reignites, reviewed the ONCA's judgment, acknowledging the careful but important progression toward recognizing climate change as a potentially justiciable issue.
The ONCA remitted the decision back to the ONSC for a rehearing of whether Ontario's climate change policies violate sections 7 and 15 of the Canadian Charter of Rights and Freedoms ("Charter"), instructing the ONSC to reconsider the matter using the correct analytical framework. In doing so, the ONCA noted that the Charter challenge was not an assertion of positive rights, but rather concerned the actions of the Government of Ontario in respect of obligations that it had already voluntarily assumed. As such, the central question of Charter compliance remains unresolved. Should the ONSC conclude upon rehearing that Ontario's climate policies do indeed breach the Charter, it would be an unprecedented judicial decision in Canada that inadequate governmental climate policies can constitute constitutional violations.
Moving forward, stakeholders should continue to closely monitor the Mathur rehearing and other emerging climate litigation strategies and judicial responses across Canada. The decision by the SCC to not grant leave to appeal for Mathur could lead to legislative or policy-based approaches as alternative pathways to address climate concerns, prompting both governmental and private actors to reassess their legal and regulatory frameworks in anticipation of ongoing and increasingly sophisticated climate litigation.
With the case now heading back to the ONSC for another hearing, this landmark climate litigation remains very much alive. We will provide ongoing updates and analysis as the case progresses.
Footnotes
1 Mathur v Ontario, 2024 ONCA 762, leave to appeal to SCC refused, 41596 (1 May 2025).
2 Mathur v Ontario, 2024 ONCA 762.
3 Mathur v His Majesty the King in Right of Ontario, 2023 ONSC 2316.
To view the original article click here
The content of this article is intended to provide a general guide to the subject matter. Specialist advice should be sought about your specific circumstances.
