A Quebec Superior Court judge has dismissed a challenge from Bloc Québécois candidate Nathalie Sinclair-Desgagné, who sought to annul the result of the federal election in the Montreal-area riding of Terrebonne, where she lost by a single vote to Liberal candidate Tatiana Auguste.
The decision, issued Monday by Justice Éric Dufour, rejected claims that a clerical error by an Elections Canada worker — which caused at least one Bloc voter’s ballot to be returned — constituted an “irregularity” that undermined the integrity of the election.
Sinclair-Desgagné’s petition followed revelations from a Bloc supporter, Emmanuelle Bossé, who said her special ballot was mailed back to her after the election because the return envelope had an incorrect postal code printed on it. The error prevented her vote from being counted.
During court proceedings, Elections Canada acknowledged the mistake, which stemmed from an employee who had inadvertently printed his own postal code on a batch of special ballot envelopes — an error estimated to have affected at least 40 ballots. However, Justice Dufour ruled that the mistake was “a simple human error, committed inadvertently and without any dishonest or malicious intent.”
“The error in no way affects the integrity of the Canadian electoral system, in which citizens can still have confidence,” Dufour wrote in his 27-page judgment. He added that expanding the legal definition of an “irregularity” to include administrative errors would “open the door to numerous contestations” after every close election.
Sinclair-Desgagné’s lawyer, Stéphane Chatigny, argued that the voter’s Charter rights were violated because her ballot was effectively discarded. But Marc-Étienne Vien, counsel for the Liberal MP, countered that cancelling the entire election over a single uncounted vote would be unreasonable and would disenfranchise tens of thousands of voters who had cast valid ballots.
Justice Dufour agreed, writing that even if the postal code mistake were considered an irregularity under the law, it did not prevent the affected voter from exercising her right to vote — and therefore did not meet the high threshold required to overturn election results.
The case followed one of the tightest federal races in recent memory. The April 28, 2025, general election initially saw Auguste declared the winner before a review flipped the lead to Sinclair-Desgagné. However, a judicial recount completed on May 10 confirmed Auguste’s victory by a margin of 23,352 votes to 23,351 — just one vote apart.
A spokesperson for the Bloc Québécois said the party is reviewing the ruling and has not decided whether to appeal.
The decision leaves the Liberals with 169 seats in the House of Commons, just three short of a majority, while the Bloc Québécois retains 22 seats.