Ontario’s top court will release its ruling on the constitutionality of the federal carbon tax on Friday.
The Court of Appeal heard arguments over four days in April, after the Progressive Conservative government challenged the levy.
Ontario says the tax undermines co-operative federalism by allowing Ottawa to step into areas of provincial authority.
Other provinces have launched similar challenges, and Saskatchewan is appealing to the Supreme Court of Canada after losing its court challenge last month.
Saskatchewan’s Court of Appeal found that establishing minimum national standards for a price on greenhouse gas emissions falls under federal jurisdiction.
Premier Doug Ford has said that if carbon tax opponents lose in the courts, they will win at the ballot box in October _ federal Conservative Leader Andrew Scheer has promised he’d scrap it.