The federal government's Supreme Court of Canada victory to establish a national minimum price on carbon should not be taken as a green light for Ottawa to broaden its powers over provincial jurisdictions and centralize more control, some legal and political science experts say.
"I do think the decision, overall, was crafted carefully enough to avoid a slippery slope or massive expansion of federal power," Emmett Macfarlane, an associate professor of political science at the University of Waterloo, wrote in an email to CBC News.
In a 6-3 decision, the highest court ruled the federal Liberal government's carbon pricing regime — the Greenhouse Gas Pricing Act — is constitutional, rejecting the argument by some provinces that such action was an unconstitutional foray into provincial jurisdiction.
It was also a significant ruling in that it was one of the rare times Canada's top court has allowed Ottawa to successfully flex its powers over the provinces under the Constitution's "peace, order and good government" clause, also known by the acronym POGG.
In this case, the top court found that Parliament has the jurisdiction to implement its carbon pricing act as a matter of "national concern" under POGG.
Writing for the majority, Chief Justice Richard Wagner argued that the threat of climate change "justifies the limited constitutional impact" and that it "readily passes the threshold test and warrants consideration as a possible matter of national concern."
However, Wagner also noted that "courts must approach a finding that the federal government has jurisdiction on the basis of the national concern doctrine with great caution."
Macfarlane, who also wrote Governing from the Bench: The Supreme Court of Canada and the Judicial Role, said it was difficult to see how, with this ruling, the federal government would push its authority in other policy contexts.
'Wasn't altered by the Court'
"Any attempt by the federal government to do so would still face a fairly onerous 'national concern' test under POGG or its other branch, the 'emergency' test, the latter of which wasn't altered by the court in this case," he said.
The federal government can only take action in situation when a concern has been established but provinces have failed to act, Macfarlane said.
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But Macfarlane noted the three dissenting Supreme Court justices raised a number of valid concerns, including the scope, reach, and complexity of the federal law.
In a his dissenting opinion, Justice Russell Brown wrote that the ruling would have wider implications and open the door to "federal intrusion … into all areas of provincial jurisdiction."
Gerald Baier, an associate professor of political science at the University of British Columbia, said the decision seems to strengthen the federal government's hand in some jurisdictional disputes with the provinces.
However, he noted the top court has not allowed the federal government to use the POGG clause since the late 1980s and "continues to sound a note of caution in this case as well."
"The court has had opportunities over the last [few] decades to expand federal powers under peace, order and good government and they've declined to take them every time," Baier said in a phone interview.
The last time the federal government was successful in making such a POGG argument before the Supreme Court was more than 30 years ago, in a 1988 case involving the dumping of waste in provincial marine waters.
'Controversial kind of federal power'
"It's been a very controversial kind of federal power. And the reason is that it was thought to give the government broad scope to regulate areas that would normally be within the provincial jurisdiction," said Sujit Choudhry, a lawyer and expert in constitutional law.
"And so it's been used very sparingly by the court."
In the carbon tax case, Choudhry said the court was "very alert" to the concerns of provincial jurisdiction encroachment and that its decision narrowed the scope of the assertion of federal authority just to the minimum standards of greenhouse gas pricing.
"I think that it'll be difficult, quite frankly, for anyone to come forward and argue that the national concern branch of the POGG power … can be used for something else," he said.
"The court did kind of make it clear that this was a very unusual case."
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Nathalie Chalifour, a law professor at the University of Ottawa, said while it was very significant for the court to confirm the federal Liberal government's authority to implement the Greenhouse Gas Pricing Act, it was very careful in doing so.
'Very precisely defined'
"They focus in on pricing as the means. And I think that was partly an attempt to constrain federal jurisdiction and make sure that it's very precisely defined," she said.
"They did that really to ensure that they were not overstepping provincial jurisdiction."
Baier said based on the court's history of deferring to provinces, he doesn't belive this decision is a signal that Supreme Court is trying to take Canada in a more centralized direction.
"I think the potential for peace, order good government has since 1867 been really big and the Supreme Court has never really given it the scope that the federal government would like."
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