The Supreme Court of Canada begins hearing appeals in three cases on Sept. 22 to determine whether Ottawa’s national carbon price is constitutional. Appellate courts in Saskatchewan and Ontario had previously upheld the law, but the Alberta Court of Appeal had ruled that it was unconstitutional and intruded on provincial powers.

Contrary to what critics of the federal carbon-pricing legislation say, neither the provinces’ authority to act on climate change nor the balance of the Canadian federation is in jeopardy.

But what is at stake is Canada’s ability to contribute to global climate action under the 2015 Paris Agreement. The agreement aims to limit global warming to 1.5 C above the pre-industrial norm, a goal increasingly on the public’s mind as wildfire smoke blows across the country.

In 2016, Ottawa obtained provincial and territorial consensus on a coordinated national approach in the Vancouver Declaration on Clean Growth and Climate Change. The Vancouver Declaration begat the Pan-Canadian Framework on Clean Growth and Climate Change, a detailed action plan agreed to by all except Saskatchewan.

In 2018, Ottawa enacted the Greenhouse Gas Pollution Pricing Act to implement the Pan-Canadian Framework. The act operates as a backstop — a national safety net — with two parts. The first imposes a charge on a broad range of greenhouse gas emitting fuels. The second establishes an “output-based performance system” that requires industrial facilities to pay for the emissions that exceed an annual limit.