Ensuring every vote counts

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The Supreme Court of Canada says it had no choice but to annul election results in a Quebec riding to preserve confidence in the electoral process.

The decision was made earlier this year after the 2025 federal election result in the riding of Terrebonne was challenged due to a one-vote margin and an issue with a mail-in ballot. The Court’s written reasons were released on Friday.

Liberal Tatiana Auguste won by a single vote in the Montreal-area riding over incumbent Bloc Québécois candidate Nathalie Sinclair-Desgagné in April of last year. However, one voter who attempted to vote by mail complained that her ballot was returned due to an administrative error. She said that had it counted, she would have voted for Sinclair-Desgagné, which would have tied the result.

It turns out Elections Canada had improperly labelled the return envelopes with the wrong postal code. An elections worker at the returning office discovered the error three weeks before election day, but did not notify their superiors. As ballots were arriving by mail despite the error, they didn’t think they needed to take any action or notify remaining voters who had requested these special ballots. The voter who complained, however, had her ballot returned by Canada Post, stating there was no such address.

Sinclair-Desgagné challenged the result in the Quebec Superior Court, which dismissed the challenge, finding that the test for voter irregularities established in Opitz v. Wrzesnewskyj was not met. The Court said the term “irregularities” was read in the context of the terms “irregularities, fraud, or corrupt or illegal practices,” which could involve serious errors able to undermine the integrity or honesty of the electoral process, but that didn’t include inadvertent human errors without malicious intent. 

Further, the Court said the affected voter could have used the provided tracking number to ensure the ballot had been received. If it wasn’t, she could have made other arrangements to vote in advance or on election day.

Sinclair-Desgagné appealed that decision directly to the Supreme Court of Canada, as the Canada Elections Act allows. The top court found the test for annulment had been met, and nullified the election result. 

Within weeks, Prime Minister Mark Carney called a by-election in the riding and Auguste won by a much larger margin, which secured Carney’s majority in the House of Commons. 

Opening the floodgates?

In the 6-3 decision, the majority said the lower court had made errors in every step of the Opitz test. The postal code error, combined with Elections Canada’s failure to correct it over three weeks, constituted an irregularity under the Act. That affected the result because it prevented an elector from voting. And because the number of affected votes matched the margin of victory, the results were in doubt, so the judge should have annulled the result to maintain trust in the electoral process.

“The irregularity in this case—involving a serious administrative error caused by Elections Canada that it had the ability and responsibility to correct and that affected a voter’s franchise—is narrowly circumscribed and will not open floodgates to electoral challenges for every human error during a federal election,” Justice Mahmud Jamal wrote for the majority. 

“The stringency of the Opitz test ensures that the annulment of an election will remain an extremely rare occurrence.”

Jamal said the lower court was wrong to conclude that an administrative error must be intentional or made in bad faith to meet the level of seriousness required for an irregularity.

“It need not involve dishonest intent or bad faith.”

He recognized that annulling an election is serious because it can disenfranchise not only those whose votes were disqualified, but every elector in the riding. However, he said there was no choice here because the magic number test—that the affected ballots were within the margin of victory—was met.

“This recalls the crucial point discussed above: every vote counts,” Jamal said.

The dissenting judges said voters who use the special ballot process have to assume the responsibilities that come with that choice. Under the law, it’s their responsibility to ensure their ballot is received at the right place and at the right time, as errors in the process are inevitable. 

“In our view, the mistake falls well short of being an irregularity,” Justices Karakatsanis and Martin wrote in dissent, with Justice Moreau concurring. 

“The mistake was limited in scope, inadvertent in origin, and confined in its operation. The inquiry should end at the first stage of the analysis.”

They also felt that, contrary to the majority's assertions, establishing such a low threshold in the Opitz test could indeed open the floodgates to challenges of election results.

“It would be absurd if the [Canada Elections Act] could contemplate the annulment of an election based on such an error when the CEA simultaneously assigns responsibility to the elector to track and ensure the ballot is received in the event of this type of error,” Karakatsanis and Martin concluded.

The impact of a single vote

Connor Bildfell, a partner with McCarthy Tétrault LLP in Vancouver, says that, from a democratic perspective, the decision is a powerful illustration of the impact of a single vote in what was the closest election in Canadian history. From a legal perspective, it was arguably the most consequential decision on the test for annulling election results since it was set out in Opitz. And it comes as the issue of elections and the extent to which they may be set aside or questioned through various processes has been a part of recent public discourse.

“It’s very much an issue of public confidence in the electoral process. What the court says is that the bar for setting aside an election based on an irregularity is very high.”

He was struck by the divergence between the majority and the dissent on the scope of when errors can result in a potential annulment.

“It’s a very interesting debate, and it’s one where Canadians may reasonably disagree,” Bildfell says. 

“The majority is really saying that we are focused on the integrity of the election system, and the ability to exercise one’s right to vote. That’s the compass that guides the analysis. The dissent is taking a more perhaps pragmatic approach where they say it should really only be in circumstances where it’s a really serious error that meets an even higher standard.”

He also finds the divide within the Court over whether the Act places the sole responsibility for ensuring the delivery of special ballots onto the elector interesting. The majority’s approach is to focus on the significance of Elections Canada’s role in the system.

“(They’re) looking at it from a practical perspective, that even though the burden falls on the voter, voters do in many ways largely depend on Elections Canada to exercise their rights to vote, and we’re not going to say the burden is entirely on the individual,” Bildfell says.

‘A real line-drawing question’

Kyle Morrow, founder and principal lawyer at Morrow Law in Ottawa, says the majority’s reasoning on the facts is understandable, but he identifies more with the dissent’s reasoning.

“The dissent focused on the fact that Parliament has recognized that mail-in voting carries inherent risks, and has expressly shifted that responsibility onto the electorate,” Morrow says. 

“I’m not sure that the majority’s interpretation is consistent with the language of section 240 of the Canada Elections Act.”

As for what imperils election integrity, the majority focused on the individual right to vote, while the dissent was broader, emphasizing the collective electoral system itself.

“If an incorrect postal code can constitute an irregularity, where do we draw the line?” Morrow asks. 

“That’s the main point the dissent is making. There is a real line-drawing question here.”

And that question matters, as he notes there were five ridings where the margin of victory was less than 100 votes in the last election, compared to three ridings in the election before.

“These razor-thin election results are more common than many voters may think,” Morrow says.

In a statement, Elections Canada said it will review the decision and the chief electoral officer will determine what actions the agency should take.

“It is important to note that after the 45th general election, Elections Canada conducted a thorough review of the special ballot process," the agency said. 

“The recommendations that came out of this review have already been actioned. Elections Canada is also always looking at new ways to better equip the tens of thousands of workers who make the delivery of federal elections possible.”