Quebec's sovereigntist movement is holding up the results of the British referendum to leave the European Union as evidence that a 50-per-cent-plus-one vote should be considered legitimate in Ottawa's eyes.

In Thursday's referendum, 52 per cent of voters in the United Kingdom backed the so-called Brexit option, kick-starting the process of exiting the EU.

Prime Minister Justin Trudeau, speaking in Quebec City as part of Friday's Fête Nationale celebrations, said Canada would "respect the choice of the British people."

That comment was seized upon by contenders in the Parti Québécois's leadership race, who saw an opportunity to address a long-running point of friction with the federal government: what margin of victory is required for Quebec to leave Canada.

Alexandre Cloutier, front-runner in the PQ leadership race, cheekily suggested Trudeau had changed his opinion on what constitutes a clear majority.

"A people is always master of its destiny," Cloutier tweeted in response to tweet by Trudeau. "I salute your respect for democracy. Only one valid rule: 50% + 1."

Un peuple est toujours maître de sa destinée. Je salue votre respect de la démocratie. Seule règle valable: 50% + 1 <a href="https://t.co/87JgY1R91G">https://t.co/87JgY1R91G</a> —@alexcloutier

What is a clear majority anyway?

Since the passing of Stéphane Dion's Clarity Act, which mandates a clear question and "clear majority" in any Quebec referendum, much ink has been spilled on defining what a "clear majority" actually means.

Sovereigntists, and the federal NDP, maintain that a simple majority in a referendum would be enough to begin the process of separating from Canada.

Jean-François Lisée says Trudeau set a precedent for any future Quebec referendum in recognizing the Brexit results. (Canadian Press)

The federal Liberals have long maintained that "clear majority" entails a higher threshold, though are unclear about where exactly the bar is set.

These differences were a source of friction in the last federal election campaign, when NDP Leader Tom Mulcair tried to get Trudeau to commit to a specific number during the first debate. Trudeau refused.

Sovereigntists are interpreting Trudeau's willingness to accept the validity of the British results, despite fewer than 55 per cent supporting Brexit, as an important precedent.

"In the next referendum in Scotland, in the next step towards independence in Catalonia and in our next collective decision in Quebec, we will be in exactly the same scenario," Jean-François Lisée, one of Cloutier's rivals for the PQ's leadership, said in a Facebook post.

A sign of sovereignty

Other contenders in the leadership race focused less on the significance of the slim margin of victory than on the expression of British sovereignty.

"We really had, yesterday, a great democratic exercise and a clear [statement] of sovereignty, which shows that sovereignty issues are very relevant in the world today," said Véronique Hivon, a former provincial cabinet minister also running for the PQ leadership.

She pointed out that Scottish voters overwhelmingly supported staying in the EU. The pro-indepedence party there has already raised the possibility of holding another referendum on separating from the rest of the U.K.

For Hivon, this division in attitudes between Scotland and England about the merits of EU membership was a further sign of the importance of distinct regions acquiring more power.

"Different nations can only achieve their ambitions at their fullest when they have their own sovereignty," Hivon said.