Saskatchewan's opposition to a federally imposed carbon tax has reached the courts.

On Wednesday, the government submitted a reference case to the Saskatchewan Court of Appeal to see if the federal carbon tax is unconstitutional.

The government is asking the province's highest court to answer a question:

"The Greenhouse Gas Pollution Pricing Act was introduced into Parliament on March 28, 2018 as Part 5 of Bill C-74. If enacted, will this Act be unconstitutional in whole or in part?"

The province said it believes carbon emissions fall under provincial and not federal jurisdiction.

"We believe that this is in our constitutional jurisdiction," countered federal Natural Resources Minister Jim Carr on Wednesday.

"This is going to be an effort that is expensive and, worse, risky," Saskatchewan NDP Leader Ryan Meili said of the court action.

He said the provincial government's tax-free climate change strategy, released last December, is a thinly sketched alternative to the federal government's own plan.

Meili added there's a "very great likelihood" the federal government will impose its own plan on the province before the court action is resolved.

"We're very likely to have by the end of this year a plan that's been designed by Trudeau and the Liberals in Ottawa rather than something that's designed with the best interest of Saskatchewan," he said.

A spokesperson for the premier's office said the reference case was launched using internal staff of the government.

Saskatchewan NDP Leader Ryan Meili says the province's case has little legal merit. (CBC)

Part of Saskatchewan's argument is that a federal carbon pricing plan would treat each province differently and thus go against federalism.

"It's certainly, I think, a novel argument," said Eric Adams, an associate law professor at the University of Alberta. "But we're in a novel area of the law generally. There are not clear precedents obviously in place, given that this is really the first major foray into carbon pricing by the federal government."

University of Alberta associate professor Eric Adams thinks it's unlikely the Saskatchewan government will convince the courts of its case. (CBC)

Adams thinks it's unlikely Saskatchewan will convince the court, however.

"There's no section of the Constitution that says all provinces must be treated exactly the same by every piece of legislation," he said.

Premier ran on anti-carbon pricing campaign

Last fall, the province of Manitoba sought a legal opinion to see if it would win a court challenge against the carbon tax. After receiving the opinion, it decided to sign the federal framework.

"We do not believe the federal government has the constitutional right to impose the Trudeau carbon tax on Saskatchewan against the wishes of the government and people of Saskatchewan," Premier Scott Moe said.

When Moe won the party leadership in January, he promised to fight the carbon tax.

"Justin Trudeau, if you are wondering how far I will go, just watch me," Moe said during his victory speech.

On Wednesday, Moe defended his government's plan.

"We have a made-in-Saskatchewan plan to reduce emissions and fight climate change, and that plan does not include a job-killing carbon tax on Saskatchewan families."

Could win, minister says

Former premier Brad Wall long resisted a carbon tax in Saskatchewan and threatened legal action back in 2016.

In March, Meili called the fight against carbon pricing "pointless" and asked what the legal costs would be of taking on Ottawa in court.

Saskatchewan Justice Minister Don Morgan said the province's constitutional lawyers believe it could win a court challenge.

"We do not believe the federal government has the right to impose a tax on one province but not others just because they don't like our climate change plan," Morgan said.

Environment ministers disagree

Last December the province released its plan — Prairie Resilience: A Made-in-Saskatchewan Climate Change Strategy.

In March, federal Environment Minister Catherine McKenna and her Saskatchewan counterpart Dustin Duncan exchanged letters.

Duncan said the federal carbon tax would result in "carbon leakage, lost jobs and human vulnerability."

McKenna countered by saying she could not accept the province's position.

On Wednesday, McKenna called Saskatchewan's legal move "disappointing," but said she was confident the federal government has the legal authority to impose a carbon tax.

"It's a question of fairness. We want to have a price on pollution across the country and every province has an opportunity to design a system that makes sense for them," she said.

McKenna has previously said Saskatchewan would be forced into the federal carbon plan if it doesn't come up with one that fits Ottawa's mandate.

The federal plan sets a starting price at $10 per tonne of carbon dioxide emissions this year, escalating to $50 per tonne in 2022. The money collected by the tax would go back to the province.

On Wednesday, Duncan said Saskatchewan "is the solution, not the problem."

"Our plan to reduce emissions from the electricity sector by 40 per cent and methane emissions from the oil and gas sector by 40 to 45 per cent by 2030 shows we are serious about tackling climate change."

Duncan also pointed to the agriculture industry sequestering "nearly 12 million tonnes of CO2 annually" and a carbon capture system at Boundary Dam 3.

Saskatchewan may lose $62 million from the Low Carbon Economy Fund by not signing on to the federal framework.

Duncan has said the province should still receive the full amount. He said the province stands to lose $4 billion over five years through a carbon tax.