EDMONTON -- Allowing Ottawa's carbon tax law to stand would give the federal government a tool it could use to repeatedly chip away at provincial powers, lawyers for the Alberta government argued Monday.

“If you uphold this legislation, you're opening the door to exactly that type of thing,” Peter Gall told a panel of five Alberta Court of Appeal judges.

The federal government justifies the law under a section of the Constitution that allows Ottawa to step in over issues of “national concern.”

Gall argued such issues are rare. Greenhouse gases don't meet the test, he said, and letting the carbon tax law stand would open the door to allowing Parliament to step in whenever it wanted.

“You can call anything a national concern,” he told court.

The Constitution gives provinces adequate power to regulate greenhouse gases and Ottawa's legislation simply ties their hands, Gall said.

“It's invasive in terms of taking away policy options that would otherwise be open to the provinces.”

Alberta is the latest province to challenge the tax. Ontario and Saskatchewan lost cases in their top courts, but are appealing to the Supreme Court of Canada.

Lawyers for attorneys-general in Ontario and Saskatchewan presented arguments in support of Alberta's challenge on Monday afternoon.

Those representing New Brunswick and British Columbia are also to speak during the three-day hearing. Eight First Nations, non-governmental groups and Crown corporations have also been granted intervener status.

Ottawa argues that authorization for the tax comes under the Constitution's peace, order and good government clause. Establishing minimum national standards on greenhouse gas emissions “is a matter of national concern that only Parliament can address.”

University of Alberta law professor Eric Adams said using the nation concern argument to justify the law is a bit of a leap.

“The federal government made a gamble here that this was a case that was worth opening up that previously neglected box,” Adams said. “They've taken a bit of a risk here.”

He said he believes Alberta is unlikely to win. But if there's a dissenting judge, that could bolster the government's argument before the Supreme Court, which has already scheduled a January date for the Ontario and Saskatchewan appeals.

“If they don't win, they hope for a judgment from some judges that lends weight and credibility, and maybe a new perspective to add to the dissenting opinions that have already been rendered in Saskatchewan and Ontario,” said Adams.

Three out of five Saskatchewan appellate judges agreed with Ottawa, as did four out of five of their Ontario colleagues. Past judgments have recognized the environment as a matter of shared jurisdiction.

Alberta Premier Jason Kenney ditched a consumer carbon tax that the previous NDP government had brought in soon after his United Conservatives won the provincial election in April.

He has established a $30-a-tonne carbon tax on industrial emitters, replacing somewhat stronger measures introduced by the former NDP government. Prime Minister Justin Trudeau's Liberals have approved that tax.

The consumer carbon tax is to begin in Alberta starting Jan. 1.

Alberta Justice Minister Doug Schweitzer said in a statement Monday that Ottawa doesn't always know best.

“Even if you support a carbon tax, it doesn't mean that the federal government's carbon tax is the best or only approach for every province,” he said.

“Each province is unique, with different economies, different demographics, and different geographies. That is why our federation is structured to give provinces the right to make our own laws and regulations over businesses when it comes to issues like reducing greenhouse gas emissions.”

This report by The Canadian Press was first published Dec. 16, 2019.