The Supreme Court of Canada has voided the one-vote victory of a federal Liberal candidate in the 2025 federal election to preserve the trust in the electoral system. The court’s decision to annul the election outcome was made to prevent a federal election from being influenced by a known and correctable administrative mistake.
Tatiana Auguste, representing the Liberal party, was initially declared the winner in the Terrebonne riding in Montreal by a solitary vote over the incumbent Bloc Québécois candidate Nathalie Sinclair-Desgagné in April 2025. Following a complaint from a Bloc supporter who attempted to vote by mail using an uncounted special ballot, Sinclair-Desgagné contested the election results and called for a byelection.
Although a Superior Court judge initially dismissed Sinclair-Desgagné’s plea for a new election, the Supreme Court overturned this decision in a split verdict announced in February. Justice Mahmud Jamal, writing for the majority, highlighted that an Elections Canada staff member was aware for weeks that some voters had received envelopes with incorrect postal codes, but corrective actions were not taken by the agency.
Subsequently, Auguste secured victory once again in a byelection held in April, retaining the Terrebonne riding.
