The Supreme Court of Canada has rendered its highly anticipated decision in Sinclair-Desgagné v. Canada (Chief Electoral Officer), 2026 SCC 31. In a 6-3 majority decision, the Court has issued the reasons supporting its February 13, 2026 order setting aside the result of the federal election held on April 28, 2025 in the riding of Terrebonne. As a reminder, the election in that riding had been decided by a single vote, while a voter's mail-in ballot never reached its destination because of an error in the last three characters of the postal code appearing on the return label prepared by Elections Canada. The Court concluded that an administrative error by Elections Canada, combined with its failure to correct it in time, constituted an "irregularity" within the meaning of the Canada Elections Act, even in the absence of dishonest intent or bad faith. This decision considerably clarifies the criteria for contesting the result of a federal election.
Background
While preparing for the federal general election of April 28, 2025 in the riding of Terrebonne, an Elections Canada employee mistakenly printed the wrong postal code on the return address labels affixed to prepaid envelopes accompanying several mail-in ballots. The employee discovered the error on April 6, 2025 — more than three weeks before polling day — but did not report it to supervisors nor notify the affected voters.
The election was ultimately decided by a margin of a single vote in favour of the Liberal Party of Canada candidate, Tatiana Auguste, over the Bloc Québécois candidate, Nathalie Sinclair-Desgagné. Shortly after polling day, a voter, Ms. Emmanuelle Bossé, discovered that her mail-in ballot had been returned undelivered by Canada Post because of the erroneous postal code. Ms. Bossé stated that she had voted for Ms. Sinclair-Desgagné but her vote was never counted.
Ms. Sinclair-Desgagné filed an application contesting the election before the Superior Court of Quebec under paragraph 524(1)(b) of the Canada Elections Act, which allows an election to be contested on grounds of "irregularity, fraud, corrupt practice or illegal practice that affected the result of the election." The Superior Court dismissed the application, finding that the error, made in good faith and without dishonest intent, did not constitute an irregularity within the meaning of the Act. It further stated that, even if an irregularity had been established, it would not have exercised its discretion to annul the election.
The Supreme Court's Decision
Ms. Sinclair-Desgagné appealed the decision as of right to the Supreme Court of Canada under subsection 532(1) of the Canada Elections Act. The Court, by majority, allowed the appeal and annulled the election held in Terrebonne.
The Court reaffirms the three-step framework established in Opitz v. Wrzesnewskyj, 2012 SCC 55, and finds the outcome consistent with that decision. Applying that framework, the majority, per Justice Jamal, concluded that the trial court had erred in law at each stage of that framework.
First step — the existence of an irregularity. The majority held that an irregularity within the meaning of paragraph 524(1)(b) does not require proof of dishonest intent or bad faith. An honest, unintentional administrative error can still constitute an irregularity if it is serious enough to undermine the integrity of the electoral process by having a direct impact on a person's right to vote. In this case, the postal code error, combined with Elections Canada's failure to correct it when it had both the capacity and the responsibility to do so, constituted such an irregularity.
Second step — the effect on the result of the election. The majority found a direct causal link between the irregularity and the uncounted vote. It also specified that it was inappropriate for a court to consider a voter's actual electoral choice, given the tradition of the secret ballot. The majority further rejected the argument that sections 239(2) and 240 of the Act, which place responsibility on the elector to ensure that their ballot reaches its destination, would have the effect of exonerating Elections Canada from its own errors that it had the power to correct.
Third step — the exercise of discretion to annul the election. The majority held that discretion should be exercised in favour of annulment, since the number of affected votes (one) was exactly equal to the margin of victory (one), which cast doubt on the identity of the true winner.
The majority was careful to emphasize that this conclusion remains narrowly confined to the facts of this case and does not open the door to a proliferation of election challenges over minor or promptly corrected administrative errors.
The Dissent
Karakatsanis and Martin JJ., with Moreau J. concurring, would have dismissed the appeal. In the dissenting justices' view, the error at issue did not meet the high threshold required to constitute an irregularity: it was a minor, unintentional error of limited scope that was not capable of undermining public confidence in the electoral process. The dissenting justices emphasized that the Canada Elections Act specifically places on an elector who chooses to vote by mail-in ballot the responsibility for ensuring that their vote reaches its destination, and that this responsibility applies regardless of the source of the error. In their view, the analysis should have ended at the first step of the framework established in Opitz.
Key Takeaways
- An irregularity within the meaning of paragraph 524(1)(b) of the Canada Elections Act can arise from a serious, honest, and unintentional administrative error; dishonest intent or bad faith are not required elements.
- The determinative consideration is whether the administrative error was capable of undermining a voter's right to vote, not whether it was intentional or fraudulent.
- Provisions of the Canada Elections Act that place responsibility on the elector to ensure that their mail-in ballot reaches its destination do not relieve Elections Canada of its own responsibility where it caused an error that it had the power to correct.
- The "magic number" test remains determinative at the third step of the analysis established in Opitz: where the number of votes affected by the irregularity equals or exceeds the margin of victory, annulling the election is required.
- The scope of this decision remains limited to serious administrative errors that Elections Canada had the capacity and responsibility to correct; it should not lead to a proliferation of election challenges based on minor errors alone.
The authors of this bulletin represented a candidate of another political party who had run in this election and who supported both the application contesting the election and the appeal filed before the Supreme Court.
