Canada’s highest court has determined that Elections Canada made a significant administrative blunder that could compromise the integrity of the electoral process by failing to rectify issues related to mail-in ballots in a riding near Montreal ahead of the federal election in 2025.
The Supreme Court of Canada annulled the election results for the Terrebonne riding in a ruling issued in February and disclosed the reasoning behind its decision on Friday.
The court stated that its order for a new election “enhances public trust in the electoral process by confirming that a federal election should not be determined by recognized and correctable official errors,” according to the ruling.
Liberal candidate Tatiana Auguste was initially declared the winner in April 2025, edging out the incumbent Bloc Québécois candidate Nathalie Sinclair-Desgagné by a single vote.
The Bloc candidate contested the election outcome and called for a byelection after a supporter indicated that she had attempted to vote by mail using a special ballot that went uncounted.
The voter, Emmanuelle Bosse, reported that her special ballot was returned to her mailbox due to an error on the postal code affixed to a label provided by Elections Canada.
A Superior Court judge dismissed Sinclair-Desgagné’s plea for a new election, but the Supreme Court overturned that decision in a divided ruling announced from the bench in February, leading to a byelection that Auguste won on April 13.
After a challenging year, the Liberals’ Tatiana Auguste will serve as the representative for the Quebec riding of Terrebonne in the House of Commons. She secured Monday’s byelection victory by over 700 votes against Nathalie Sinclair-Desgagné of the Bloc Québécois.
Justice Mahmud Jamal, writing for the majority, indicated that an employee at Elections Canada had been aware for weeks that some voters received envelopes with incorrect postal codes, yet the agency failed to take any corrective measures.
The ruling stated, “Elections Canada did not receive or count an elector’s vote because it took inadequate steps to rectify the error, even though it knew it had made a mistake and expected that affected electors would have been contacted by one of its employees.”
“Elections Canada caused the error and held the responsibility and capacity to correct it.”
The court learned that an Elections Canada employee had sent out incorrectly addressed envelopes for mail-in ballots to approximately 40 voters.
This employee recognized the mistake more than three weeks prior to election day but did not notify any supervisors. He believed the error was not causing any issues “since the Terrebonne polling station was receiving completed special ballots in the usual manner, even in envelopes with the postal code error,” according to the ruling.
Prime Minister Mark Carney’s Liberals secured the riding just outside of Montreal by around 700 votes in Monday’s byelection. Tatiana Auguste had won the riding by just one vote in April 2025, a result later annulled by the Supreme Court of Canada due to a mail-in ballot not being counted.
Justice Jamal stated that the Superior Court made a mistake by concluding that an accidental administrative error was not significant enough to be classified as a voting irregularity.
“Unintentional, honest, or good faith errors can also compromise the integrity of the electoral process if they prevent electors from exercising their voting rights,” the judge noted.
Elections Canada issued a statement indicating that it had reviewed its special ballot procedures following the election and had already implemented changes. The agency mentioned that it would thoroughly analyze the Supreme Court’s ruling before determining any further actions.
“Elections Canada continuously seeks new methods to better equip the thousands of workers who facilitate the execution of federal elections,” the agency stated in a news release.
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The ruling was a split decision, 6-3.
In dissenting opinions, Justices Andromache Karakatsanis and Sheilah Martin argued that the clerical error did not rise to a level sufficient to warrant a new election.
They cautioned that this ruling might pave the way for additional challenges.
“If this error affecting a single vote is sufficient to reopen an election result, it is difficult to determine what type of error would not reach this threshold,” they noted. “Such a low bar could jeopardize all election outcomes, eroding the stability, certainty, and finality of election results.”
Conversely, the majority asserted that the standards for overturning an election remain strict, and their decision will not “open floodgates” to challenges for every minor mistake made during an election.