On Friday, the Saskatchewan government officially launched its carbon tax appeal to the Supreme Court of Canada.

On May 3, the Saskatchewan Court of Appeal ruled in a 3-2 decision that the federal government's carbon tax, imposed on provinces deemed not to have sufficient plans of their own, is constitutional.

Following the decision, Premier Scott Moe promised to appeal the decision to the Supreme Court. The province had 30 days to file its notice of appeal, which it did Friday.

Saskatchewan is asking the Supreme Court two questions:

Is the Greenhouse Gas Pollution Pricing Act unconstitutional in whole or in part?

In particular, does Parliament have jurisdiction to establish minimum national standards for price stringency for greenhouse gas emissions under the national concern branch of the peace, order and good government power set out in the opening words of section 91 of the Constitution Act, 1867?

"Our government will continue to stand up for Saskatchewan people against what we believe is an unconstitutional tax on their families, communities and businesses," said Saskatchewan Attorney General Don Morgan.

The province now has a two-month window to file its factum — the statement of facts around the case — to the Supreme Court of Canada.

Morgan said he hopes the court will hear the appeal this fall.

As for what the government is spending on the appeal, "we use staff lawyers to do the legal work on it, so there's no direct out of pocket legal fees," Morgan said. "There's some filing costs and maybe some travel costs and some hotel costs."

The Ontario government also launched its own constitutional challenge, in which the Saskatchewan government was an intervenor. The Ontario Court of Appeal has not released its decision in that case.

Similar challenges are expected in Manitoba and in Alberta, where the recently elected government of Premier Jason Kenney ended that province's carbon tax this week.

Morgan said if the Ontario court rules in favour of the province and the federal government appeals, the Supreme Court would likely combine the Ontario and Saskatchewan cases into one hearing.

The federal election result could also play a role in the future of the carbon tax, he said. Federal Conservative Leader Andrew Scheer has vowed to get rid of the carbon tax if elected.

"A change in government could conceivably have the tax withdrawn. If it's a re-election of the same government, my guess is that they will double down and carry on."