Prime Minister Justin Trudeau’s carbon tax has never been more vulnerable. It’s time for Ontario Premier Doug Ford to step up to the plate and take the federal government to court – again.

Ford, along with his colleagues in Alberta and Saskatchewan, took Trudeau to court several years ago after he rolled out the federal carbon tax. The Ontario government argued the constitution leaves environmental policy in the hands of the provinces.

The case went all the way to the Supreme Court, which ruled the Trudeau government could impose a carbon tax on unwilling provinces for the sake of having a consistent Canada-wide approach to addressing an important policy priority.

New Brunswick Premier Blaine Higgs astutely pointed out that with its carbon tax carve-outs, the Trudeau government torpedoed the legal rationale the Supreme Court used to allow Ottawa to impose a federal carbon tax in the first place.

In 2021, the Supreme Court majority opinion reasoned that the Trudeau government could impose a federal carbon tax because climate change is a national problem that requires a national response.

Regulating greenhouse gas emissions would normally be a provincial responsibility, but Chief Justice Wagner reasoned the threat of climate change was pressing enough to allow the federal government to use a special constitutional clause to regulate the issue at the national level.

“This matter is critical to our response to an existential threat to human life in Canada and around the world,” Wagner wrote. “As a result, it readily passes the threshold test and warrants consideration as a…matter of national concern.”

Think for a moment about Wagner’s majority opinion.

Wagner suggested climate change is so pressing an issue it warrants federal intervention in an area that would normally be provincial jurisdiction. Climate change, according to Wagner, is an existential threat that can only be effectively addressed with a consistent set of standards at the federal level.

Fast forward to last fall.

After political pressure from his Atlantic caucus, Trudeau announced a three-year carbon tax exemption for furnace oil. That exemption predominantly benefits Atlantic Canadians: up to 40 per cent of Prince Edward Islanders use furnace oil to heat their homes, while just two per cent of Ontarians do.

Furnace oil is a dirtier form of home heating compared to natural gas, and yet Canadians who heat their homes with natural gas are still stuck paying a carbon tax. The average Ontario household will pay a carbon tax home heating bill of $381 this winter.

Wagner allowed the carbon tax to stay in place because the feds argued a national response with a consistent set of standards was needed to tackle the existential threat of climate change.

But with the Trudeau government creating a loophole so Canadians with a dirtier form of home heating can avoid paying the carbon tax, it undermined its case that a consistent set of national standards is needed to deal with climate change.

Trudeau’s furnace oil exemption proves the federal carbon tax is, and always has been, about politics and control. It’s not about addressing an “existential threat.”

What does all of this mean? Higgs is right when he says the legal basis on which the Supreme Court allowed the feds to impose the federal carbon tax is now on shaky ground.

This is an opportunity Ford must seize upon.

Ontario taxpayers can’t afford the carbon tax. It costs drivers $15 to fill up a minivan, $381 to heat the average home in the winter, and it’s costing the Ontario economy $4.1 billion this year alone.

It’s time for Ford to go back to court and use Trudeau’s own actions to help kill the carbon tax.