The Ontario government has escalated their carbon tax fight with an appeal to the Supreme Court — an announcement that comes less than a week after Premier Doug Ford said the fate of the federal levy would be decided at the ballot box this fall.

“In June, we were disappointed to learn that in a split decision, the Ontario Court of Appeal did not accept our position that the federal carbon tax is unconstitutional,” Ontario Environment Minister Jeff Yurek wrote in a statement released Wednesday afternoon. “Despite this decision, we remain committed to using every tool at our disposal to fight against the job-killing carbon tax.”

Ontario’s highest court decided that the Trudeau government’s carbon levy was constitutional in late June. In a 4-1 decision, the court ruled that the carbon tax fell under Ottawa’s peace, order and good government power as stipulated in the Canadian Constitution, rejecting the Ontario government’s position that such a levy infringed on provincial responsibilities. Yurek pledged then to appeal the ruling.

BACKGROUNDER: Federal carbon tax is constitutional, rules Ontario Court of Appeal

It was not immediately clear whether the Supreme Court has already agreed to hear Ontario’s case. Canada’s top court decides on which appeals it hears, and there isn’t an automatic right to escalate a case to that level. Before filing an appeal to the Supreme Court, a party must ask for leave, or permission, to do so.

However, the Premier’s office shared a full notice of appeal document with reporters on Wednesday, noting that they appealed “as of right” to the country’s top court. Ontario, per the document, is arguing that the appeal court erred in finding the carbon tax to be a “valid exercise” of the peace, order and good government power. As well, they’re arguing that the the tax doesn’t in fact comply with the Constitution.

Yurek said on Wednesday that Ontario was part of a “coalition of provinces” — Saskatchewan, Alberta, Manitoba and New Brunswick — fighting the tax, saying their approach was co-ordinated and that Ontario had intervened in Saskatchewan’s appeal of its reference to the Supreme Court, as well as Alberta’s Court of Appeal reference and Manitoba’s application for a Federal Court judicial review.

According to Andrew Buttigieg, a spokesperson for Yurek, the Ontario government has so far spend “substantially less” than the $30-million figure budgeted for a fight against the federal carbon tax during the last provincial campaign.

The escalation to the Supreme Court comes less than one week after Ford appeared to leave open the possibility of his government abandoning their carbon tax fight, depending which party won the federal election. “This carbon tax, it’s not going to be the courts that decide,” the Premier told reporters at an announcement in Etobicoke on Friday morning. “The people are going to decide when the election is held. Once the people decide, I believe in democracy, I respect democracy, we move on.”

READ MORE: Sask. Court of Appeal rules federal carbon tax is constitutional

Ford evaded giving a yes-or-no answer when asked whether he’d drop his court challenge of the carbon tax if the Liberals, or another party favouring the levy, won this fall — saying instead that he’d consult with his attorney general and his cabinet.

The decision to appeal to the Supreme Court was immediately rebuked by the provincial opposition, with NDP energy critic Peter Tabuns alleging that Ford’s government was fighting a “losing legal battle.” “We should be leading the fight against the climate crisis, not fuelling the fire and burning public money,” he said.