The federal carbon tax could set precedent that will erode provincial powers and should be ruled unconstitutional, lawyers for the Alberta government argued in court Monday.

"Prime Minister Trudeau’s carbon tax effectively amends the Constitution by expanding the power of the federal government to dictate policy in areas the Constitution says is to be regulated by the provinces, like the regulation of companies and activities that produce greenhouse gases," said Doug Schweitzer, Alberta's minister of justice and solicitor general, in a media release.

A hearing about the constitutionality of the tax is before a five-judge panel this week at the Alberta Court of Appeal in Edmonton. Alberta's is the third provincial government to challenge the carbon tax in the legal system, after Ontario and Saskatchewan lost cases at their top provincial courts. Both have appealed to the Supreme Court of Canada.

Meanwhile, the justice ministers of Ontario, New Brunswick, Saskatchewan and British Columbia are all set to appear during the three days of hearings this week.

The carbon tax is set to take effect on Jan. 1. The federal government, through its Pan-Canadian Framework on Clean Growth and Climate Change, requires that carbon pricing across Canada begin at $10 per tonne in 2019 and increase incrementally to $50 per tonne in 2022. Provinces were given the freedom to develop their own plans for carbon pricing or to be subject to a mandatory federal carbon tax, often called the "carbon backstop."

Speaking in court, federal lawyers cited the peace, order and good government clause — section 91 of the Constitution Act — in support of the carbon-tax legislation, arguing that climate change is a matter of national concern that can only effectively be addressed at the federal level.

Peter Gall, a lawyer representing Alberta, told the court that this was a dangerous argument. "You can call anything a national concern," he said, arguing that federal legislation on the issue is in fact "invasive in terms of taking away policy options that would otherwise be open to the provinces.”

"The federal scheme might fit nicely [in other provinces], but it doesn't fit nicely here," added Gall. "Regardless of what you think about the merits of its policy, the constitutionality of this legislation does not turn on the precise impact today on any particular industry, it turns on whether the federal government has the power to dictate, to impose this type of scheme."

Earlier this year, Alberta's United Conservative government passed its own plan to put a $30-per-tonne tax on greenhouse-gas emissions from large industrial emitters, including oilsands companies. The province's environment minister Jason Nixon has said Alberta believes the policy will meet the federal government's requirements for carbon pricing.

However, while federal environment minister Jonathan Wilkinson has said the Alberta plan will meet requirements for large emitters, consumers in the province may still be subject to the backstop through purchases of gas, propane and natural gas.

"We are committed to reducing emissions here in Alberta, but in a way that strikes the best balance for our province between environmental concerns and economic activity," said Schweitzer. "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. It is up to us to decide what works for us; it’s not the business of Ottawa to tell us what is best for us."

Later in the week, several First Nations groups, non-governmental groups and Crown corporations will speak before the court as intervenors. One of those groups, the David Suzuki Foundation, said Alberta's industrial-emitters tax isn't robust enough to tackle climate change.

“There’s no more time for political stunts or delay; we are in the midst of a climate emergency that threatens our children’s future and our rights to life, liberty and freedom,” said Suzuki Foundation science and policy director Ian Bruce in a media release. “Since the Alberta government is doing nowhere near enough to help solve the crisis, we’re forced to go to court.”

Bruce said a national carbon-pricing scheme is needed to effectively address climate change.

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