OTTAWA — The Supreme Court of Canada has begun hearing arguments on whether to overturn the results of last spring’s federal election in the Montreal-area riding of Terrebonne.

Julius Grey, the lawyer representing defeated Bloc Québécois candidate Nathalie Sinclair-Desgagné, told the nine justices today that they must ensure the right person is sitting in the House of Commons.

Following a judicial recount, Liberal Tatiana Auguste was declared the winner by one vote in the Terrebonne riding after the April 28 general election that returned the Liberals to power with a minority government.

However, a woman in the riding later revealed that she had mailed in her vote for the Bloc, but discovered it was never counted after her special ballot was returned due to an error on the envelope’s address.

In October, a Superior Court judge rejected Sinclair-Desgagné request for a new election, saying the “human error” did not affect the integrity of the Canadian electoral system.

The justices are expected to hear arguments later in the day from Auguste’s legal team, who have said that defining a simple clerical error as an election irregularity would open a Pandora’s box of future possible contestations.

This report by The Canadian Press was first published Feb. 14, 2026.

The Canadian Press