Ontario’s top court has given new life to a youth-led constitutional challenge against the province’s weakened emissions target, ordering a new hearing to reconsider the case “through the correct analytical lens.”

“This decision is a game-changer,” said Stewart Elgie, a specialist in environmental and natural resources law at the University of Ottawa, told CBC. “This is the strongest decision ever in Canada about a constitutional obligation to address climate change.”

“This is an important day for climate justice,” Nader Hasan, a lawyer with Stockwoods LLP and lead counsel for the case, said at a press conference after the Court of Appeal’s ruling.

He noted that while an earlier decision of the Superior Court had dismissed the challenge on legal grounds, it accepted the evidence about the dangers of climate change. The appeals court, however, found that the trial court had made several legal errors, warranting a fresh review.

The new ruling “provided considerable guidance to the trial courts on how this charter challenge should be adjudicated,” said Hasan.

The case, Mathur v. Ontario, challenges Ontario for its 2018 Cap and Trade Cancellation Act, which replaced the province’s stronger emissions reduction targets with weaker ones below international standards. Ontario’s new target aims for a 30% reduction in greenhouse gas emissions from 2005 levels by 2030, compared to the previous goal of a 37% cut by 2030 and 80% by 2050.

In Mathur, seven Ontario youth claimed that by failing to impose effective emissions targets the Ontario government was violating their rights under two sections of the Charter of Rights and Freedoms. Section 7 says everyone has a right not to be deprived of life, liberty, and security of the person, while Section 15 provides that “every individual is equal before and under the law and has the right to the equal protection and equal benefit of the law without discrimination.”

“This case is about my future, and is about the future of my grandchildren, and really thinking forward, to what the forest and lake and what this will look like in 100 years,” Madison Dyck, one of the youth represented in the case, said at the news conference. “I continue to be hopeful that this victory puts governments across the country on notice that they can’t get away with continuing to fuel the climate crisis, and that young people will stop at nothing.”

Beze Gray, another plaintiff and a climate activist from Aamjiwnaang First Nation, near Ontario’s St. Clair River, said they have “witnessed firsthand the devastation caused by the fossil fuel industry.”

The seven youths are asking that the court order Ontario to set a science-based target consistent with Ontario’s share of the reductions necessary to align with international targets.

The application for the case had previously been ruled on by the Superior Court of Justice in April, 2023. Justice Marie-Andrée Vermette had considered the issues raised by the young people as justiciable—meaning the issues can be decided in a court—but she interpreted that their claims were centered on “positive rights,” or rights that a government needs to provide to Canadians rather than rights it cannot deprive Canadians of.

On the basis that the rights in sections 7 and 15 are not positive rights, Vermette ruled that they were not being violated, and so dismissed the case.

The new ruling found that the Superior Court was wrong to interpret the young people’s argument as a positive rights case.

“The question before the application judge was not whether Ontario’s target did not go far enough in the absence of a positive obligation to do anything,” wrote the Court of Appeals judges.

The issue is not whether Ontario is depriving the young people of their rights by not setting an effective emissions target, they added, noting that the province had assumed responsibility for reducing emissions by enacting a target. The Superior Court judge “should have considered whether, given Ontario’s positive statutory obligation to combat climate change that it had voluntarily assumed, the target was Charter compliant.”

“She erred by failing to consider the correct question,” they wrote.

“Where the state does legislate, it must do so in a constitutional manner that complies with the Charter,” the judges added.

Some of the issues raised by the young people for the new ruling had been added after the Superior Court’s decision, and the appeal judges advised that the new issues should be “properly pleaded” by amending the pleadings.

Hasan told the press conference the youth will seek to have a new hearing as soon as possible, but the timeline will be determined by how quickly the court can accommodate them.

He added that he hopes the case “will serve as a blueprint for other charter challenges, challenging government action and inaction as it relates to climate change across the country.”

“Ontario, from the very beginning, has been trying to erect legal hurdle after legal hurdle, legal technicality after legal technicality,” he said.

“One by one, the dominoes have fallen for Ontario.”