Terrebonne one-vote win: postal code error on envelope unreported for three weeks

Nathalie Sinclair-Desgagné filed a challenge to the federal election result in the riding of Terrebonne, in Montreal’s north suburbs, in Superior Court. 

The incumbent lost by a single vote determined through judicial recount to current Liberal MP Tatiana Auguste after a see-saw battle.

The legal action came after a local woman, Emmanuelle Bossé, said she mailed in her ballot in early April using an addressed envelope provided by Elections Canada, but it was returned to her as undeliverable. She said she was voting for the Bloc Québécois.

The Canadian Press viewed the sworn statement filed in the case, first reported Thursday by La Presse.

Around April 6, 2025, a supervisor for the riding discovered an error on a special ballot, noting that while the address was correct, the postal code on the return ballot was his own and not that of the returning officer.

The employee noted he committed the error and immediately printed new, correct labels. He applied these to the voting kits still in reserve and destroyed all the incorrect ones that he could recover.

But he estimates a minimum of 40 envelopes had already gone out with the wrong code, and possibly more.

The employee said he didn’t deem it necessary to inform the returning officer because they were routinely receiving returned ballots despite the error. And his previous experience in the role suggested to him the rate of return was on par with previous elections. 

Sinclair-Desgagné is arguing “an irregularity had prevented an elector from voting by special ballot, which had affected the results of the election.”

In a separate sworn statement, the returning officer for Terrebonne said he was officially informed of the error only on May 12, 2025, after a visit from a reporter from Noovo, a French TV station.

According to the court documents, 116 requests for special ballots were made and 19 were not returned by the deadline. Five ballots were returned after the deadline and were therefore not counted.

According to the documents, the special ballot rate of return was just under 72 per cent, less than the national average of 78 per cent.

Danielle Duquette, the administrator of special voting rules for Elections Canada, said in a sworn statement that based on the available facts, she is unable to speculate whether the postal code error was the cause for some ballots not being received on time.

“My team and I have not detected any widespread anomalies regarding voting by special mail ballot in the constituency,” she said.

On Thursday, chief electoral officer Stéphane Perrault, testifying about the 45th general election, declined to go into specifics on Terrebonne given the ongoing legal case.

But he did say in general terms, if there is an error that prevents a voter from exercising their right to vote, that should go up the chain to those in charge, Perrault said.

Special ballots have been available since 2021 and it’s up to voters to ensure their ballots are returned on time, which can also be done in person or using a third-party in addition to by mail.

In mid-September, Elections Canada announced it was launching an investigation into problems with special ballots in the last federal election.

The case will be heard by a judge later this month. According to the clerk’s office three days have been set aside beginning Oct. 20 in St-Jérôme, north of Montreal.

This report by The Canadian Press was first published Oct. 2, 2025.

— with files from Alessia Passafiume in Ottawa.