Summary by Grace Lowes
Climate Justice in the Courts: Insights from Mathur v. Ontario
Last week, Osgoode Hall Law School hosted Julia Croome and Fraser Thompson of EcoJustice for a discussion about Mathur v. Ontario, a groundbreaking climate litigation case brought forward by seven youth plaintiffs. Hosted by the Jack & Mae Nathanson Centre on Transnational Human Rights, Crime, and Security and the JD-Master of Environmental Science program, the event explored how this case challenges the Ontario government’s weakened climate targets and its broader implications for accountability in Canada.
The case centers on climate change’s unique burdens on young people and future generations. The plaintiffs argue that today’s insufficient policies will disproportionately harm these groups.
A New Kind of Climate Lawsuit
Mathur v. Ontario was launched in response to Ontario’s 2018 decision to weaken its greenhouse gas emissions targets by repealing earlier commitments. EcoJustice, representing the plaintiffs, argued that this rollback violated the Charter of Rights and Freedoms, specifically Sections 7 (right to life and security) and 15 (right to equality). The plaintiffs sought a declaration that Ontario’s targets were unconstitutional and a remedy requiring the government to set science-based emissions reduction targets.
Fraser Thompson explained that the case was motivated by three key factors: the escalating climate crisis, Canada’s repeated failure to meet emissions targets, and the emerging role of courts as agents of accountability. Drawing inspiration from international cases like the Netherlands’ Urgenda decision, the legal team framed Mathur as an opportunity to compel government action through Canada’s constitutional framework.
Julia Croome highlighted the importance of the evidentiary record, which relied on authoritative climate science from the Intergovernmental Panel on Climate Change (IPCC) and expert testimony linking Ontario’s actions to increased physical, mental, and social harms. This evidence set a precedent for demonstrating the tangible impacts of climate change in Canadian courts and strengthened the connection between government policies and constitutional rights.
The case achieved a legal milestone as the first in Ontario to find that a climate lawsuit is justiciable under the Charter, recognizing that climate-related harms can be adjudicated. However, the Superior Court dismissed the case in 2023, viewing the Charter claims as requiring recognition of positive rights, a stance Canadian courts have traditionally resisted. In 2024, the Ontario Court of Appeal overturned this decision, reframing the case as addressing negative rights and sending it back to the lower courts, creating a path forward. The Supreme Court of Canada may now weigh in, as the judgment has been appealed, leaving the final outcome uncertain.
Legal Innovation: Societal Preservation and Indigenous Law
Mathur is also notable for advancing innovative legal arguments. Interveners, such as Friends of the Earth and the Grand Council of Treaty #3, framed the principle of societal preservation as both an unwritten constitutional principle and a principle of fundamental justice rooted in Anishinaabe law. This framing highlights the necessity of protecting society from long-term harms and integrating Indigenous legal traditions into Canada’s constitutional framework.
Professor Dayna Scott reflected on these arguments, noting how Mathur brings together constitutional law, Indigenous legal traditions, and environmental justice. She also cautioned against relying on voluntary government commitments to address climate change, warning that political rollbacks and resistance to frameworks like the Paris Agreement could undermine progress.
Looking to the Supreme Court
Before Mathur v. Ontario is returned to the lower court, attention turns to the Supreme Court of Canada which may entertain an appeal from the Court of Appeal judgment. The plaintiffs hope the Court will issue a ruling on remedies. Such a decision could compel the Ontario government to implement science-based emissions targets, creating a roadmap for meaningful climate accountability across Canada.
The Mathur v. Ontario seminar underscored the power of youth-led advocacy and the legal system’s role in addressing the climate crisis. With youth plaintiffs at its center, the case reminds us of what’s at stake for future generations. As the Supreme Court considers its next steps, Mathur is a powerful example of how law can drive meaningful change in the fight against climate inaction.
