The Supreme Court of Canada has overturned the federal election result in Quebec’s Terrebonne riding, a Montreal-area constituency, from the April 28, 2025, vote. This decision vacates the seat held by Liberal MP Tatiana Auguste, who secured victory by a single vote over Bloc Québécois candidate Nathalie Sinclair-Desgagné following a judicial recount.
Election Background and Close Contest
In the tightly contested race, initial results led to a recount that confirmed Auguste’s narrow triumph. The riding’s outcome drew immediate scrutiny due to its razor-thin margin, prompting legal challenges from Sinclair-Desgagné’s team.
The Ballot Irregularity at the Center
A key factor emerged from a voter’s experience with a special mail-in ballot. One elector reported mailing her ballot on time in support of Sinclair-Desgagné, but it was returned uncounted marked “Moved or unknown – return to sender.” Officials later attributed the issue to a postal code error on the envelope by the returning officer.
Court Proceedings
Quebec Superior Court initially dismissed the contestation in October 2025, ruling that the incident constituted a human error without compromising the electoral system’s integrity. Sinclair-Desgagné appealed to the Supreme Court, arguing the error qualified as an irregularity under the Canada Elections Act that affected the result.
Auguste’s legal representatives countered that classifying such a clerical mistake as an irregularity could invite endless future disputes.
Supreme Court Decision and Next Steps
The Supreme Court granted the appeal, annulling the election outcome and requiring a byelection. Federal authorities must call the new vote within six months. Julius Grey, counsel for Sinclair-Desgagné, emphasized the need to “ensure the right person is sitting in the House of Commons.”
This ruling underscores the judiciary’s role in safeguarding electoral fairness in Canada’s parliamentary democracy.
