Canada Supreme Court overturns one-vote election win in Quebec

Canada's top court has nullified the result of an election in Quebec that was won by a single vote, leaving the seat vacant until a by-election is called.

The closely contested federal election last April in the electoral district, or riding, of Terrebonne, was initially declared for the Bloc Québécois, but a later recount found the Liberal party had won the seat by one vote.

The ruling means 25-year-old Tatiana Auguste, who won against Bloc member Nathalie Sinclair-Desgagné and has been sitting in parliament since, is no longer an MP.

It further complicates the arithmetic for Prime Minister Mark Carney. His Liberals now sit three seats short of a majority in Canada's House of Commons.

The court ruled that the seat will now be vacant until a by-election is called, in which the two candidates will face off once again.

Sinclair-Desgagné called for a do-over last year after Canadian media reported a Bloc voter's mail-in ballot was returned because of a misprint in a postal code on the return envelope.

Auguste's team argued that classifying a clerical error as an election irregularity did not set a good precedent - and in October a lower court agreed, ruling that the misprint amounted to "human error" and was not grounds to overturn the election.

But Canada's Supreme Court disagreed on Friday, nullifying the election result.

Last year, it looked like Carney's Liberals were closing in on a majority.

But that now seems increasingly out of reach, as Terrebonne is a highly-contested district.

Before Auguste's brief tenure, it had been held by the Bloc for decades.