Conservative MP Brad Trost is not backing down from his legal battle against the Conservative Party of Canada.

His lawyer is filing a motion to appeal a previous decision which confirmed that Trost's leadership campaign has to pay a $50,000 fine, and added $22,000 to cover the party's legal costs.

Trost has threatened in the past to take his battle "all the way" to the Supreme Court.

The Conservative Party determined that Trost's leadership campaign leaked a copy of the party's membership list to a firearms rights group. It levied the $50,000 fine against Trost's campaign — but Trost has insisted no one from his team was responsible.

Trost's campaign wanted the courts to launch a judicial review of the party's decision. The courts said no. In a decision released in May, the Ontario Superior Court said it couldn't launch a judicial review of Trost's case because the dispute involved a private organization.

Trost and his lawyers say they believe that was the wrong call. Today, they're serving notice of a motion to appeal. In a copy of the motion provided to CBC News, Trost's lawyers argue the court needs to clarify the legal framework on judicial reviews of decisions by political parties.

The 'broader question'

This case has now become something much bigger than one MP's dispute with his party, said Trost's leadership campaign manager Joseph Ben-Ami.

"There's a broader question at stake here right now," he said, suggesting a ruling will make clear whether when internal party decisions subject to the Elections Act should be eligible for judicial review.

Trost is covering his legal costs through donations, Ben-Ami said. He said the dispute could "very easily" wind up before the Supreme Court.

"We have no desire to be in this fight with the Conservative Party. Zero desire," said Ben-Ami. But there are issues of principle at play because, he said, the party has not followed its own rules.

"We feel this was pushed on us and, unfortunately, at some point in time you have to take a stand."

A spokesperson for the Conservative Party said the party hadn't yet received notice of the motion to appeal.

"It's unfortunate Conservative Party members and donors may have to endure more unnecessary legal costs on a matter the courts have already decided on. We believe the divisional court ruled appropriately in this case," said party spokesman Cory Hann.

Regardless of the result, Trost won't be representing the Conservatives in the next election. The MP for Saskatoon-University is one of a handful of incumbent Conservative MPs who had to fight to run again for the party in the 2019 election. Trost lost the nomination battle to provincial politician Corey Tochor.

While Trost initially suggested elements within the party were trying to oust him, he ultimately blamed the loss on himself, saying he was "too complacent" during the nomination race.