Environmental groups were cheering a Saskatchewan Court of Appeal ruling on carbon pricing that legal experts say strongly affirms the federal government's essential role in the fight against climate change.
"I cannot hide my joy," Isabelle Turcotte of the Pembina Institute, a clean energy think tank. "This is such great news for climate action in Canada."
Ian Bruce of the David Suzuki Foundation, which intervened in the case, said the 3-2 decision is a step toward a consistent national policy to reduce greenhouse gas emissions.
"It's a historic day. This decision helps pave the way for a really strong, fair and unified approach to tackling climate change across the country."
Legal scholars says that despite the two dissenting opinions, the majority ruling is a powerful endorsement of the notion that the provinces and the federal government share jurisdiction over environmental issues. Ottawa has the right to set national standards, while giving the provinces leeway to decide how to meet them.
"The federal government can assert jurisdiction over a consistent federal price for carbon and then the provinces can still do a ton of work within their own jurisdictions if they want," said Martin Olszynski of the University of Calgary.
He said the court sidestepped the issue of federal intrusion into provincial spheres by limiting the federal role to setting a minimum national standard.
That approach is consistent with how other aspects of Canadian federalism operate, said Stewart Elgie of the University of Ottawa.
"This is essentially the approach Canada has taken to health care and social programs. Provinces are free to flesh out and apply their own legislation to meet their own needs provided they meet the minimum standards.
"It recognizes that greenhouse gases, while they're an international problem, also have significant provincial and local impacts, as we're seeing with the (Ottawa) flooding right now."
Joshua Ginsburg, an Ecojustice lawyer who argued in the case, pointed out the ruling's strong language indicates the court took the urgency of the issue seriously.
"They agreed with us that climate change is an emergency," he said. "They said 'Climate change is doubtless an emergency in the sense that it presents a genuine threat to Canada.'"
Mark Jaccard, an energy economist at Simon Fraser University, said that whatever the legal arguments, climate change is an issue that has to be addressed at levels above the municipal or provincial.
"It's a global problem. You want the most senior level of government to solve it," he said.
"You need national governments around the planet to be able to contribute to a global governance effort."
All agreed that the Saskatchewan ruling isn't the end of the game. Ontario has argued a challenge before its Court of Appeal and Manitoba has done the same in Federal Court.
But Olszynski said the arguments in Ontario were similar to those used in Saskatchewan.
The issue is likely to wind up before the Supreme Court.
Until it does — months if not years down the road — environmental groups hope Friday's ruling will quicken Canada's response to climate change.
"There is no time to be wasted in fights to fight climate action," Turcotte said. "This is a call to unity and working together because we can't delay action."
— Follow Bob Weber on Twitter at @row1960
Bob Weber, The Canadian Press