Experts on Canada’s parliamentary system say Andrew Scheer should know better than to erroneously contend that whoever wins the most seats on Monday gets to form the government.

The Conservative leader was, after all, Speaker of the House of Commons for almost five years and, as such, should be well aware that the only rule that matters is who can command the confidence of the majority of MPs — whether they be all from one party, or from a multitude of partisan affiliations.

“It lowers him in my esteem and maybe the esteem of other people because I’m sure he knows he’s wrong,” said political science professor Peter Russell, who helped advise Gov. Gen. Michaelle Jean in 2008, when she had to navigate an attempt by three opposition parties to form a coalition to replace Stephen Harper‘s minority Conservative government.

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Scheer has maintained throughout the week, and repeated Thursday, that “modern convention in Canadian politics” dictates that “a prime minister who enters into an election and comes out of that election with fewer seats than another party resigns.”

Max Cameron, director of the Centre for the Study of Democratic Institutions at the University of British Columbia, called Scheer’s assertion “nonsense, complete nonsense.”

“There is no such convention. He’s pulled that out of his hat,” said Cameron, who prior to the 2015 federal election penned a paper, endorsed by 10 leading political science experts, setting out the unwritten rules or conventions that traditionally apply when no party wins a clear majority.

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“Who gets to govern is who gets to command the confidence of the House. Period. That’s the fundamental convention.”

As a former Speaker, Cameron added, Scheer “should be steeped in parliamentary tradition and shouldn’t play partisan games with our country’s conventions.”

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Harper similarly claimed during the 2015 campaign, when it looked like no party would win a majority, that the one with the most seats would get to govern.

But even the Conservatives’ 2015 national campaign chair now disputes that claim. Guy Giorno, Harper’s former chief of staff, said in a paper for his law firm this week that Liberal Leader Justin Trudeau would remain the prime minister “regardless of the election result, until he resigns, dies or is dismissed.”

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Should no party win a majority on Monday, Trudeau is entitled to remain prime minister and test whether he can win a confidence vote in the Commons — the first of which would be on a speech from the throne opening a new session of Parliament. That is true even if the Conservatives win more seats.

That’s precisely the scenario that played out last fall in New Brunswick, when incumbent premier Brian Gallant’s Liberals captured one less seat than Blaine Higgs’ Conservatives. Gallant nevertheless decided to hang on and test whether he could command the confidence of the legislature.

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He could not, as it turned out. The Conservatives joined forces with three People’s Alliance members of the legislature to defeat Gallant’s throne speech. Higgs became premier and continues to preside over a Conservative minority government.

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Should he find himself in a similar situation after Monday, Trudeau would have good reason to expect a more favourable outcome than Gallant. The NDP, Greens and Bloc Quebecois are far more likely to support a Liberal minority than they are a Conservative one.

NDP Leader Jagmeet Singh has categorically ruled out propping up a Scheer government. While Green Leader Elizabeth May hasn’t entirely slammed the door and Bloc Quebecois Leader Yves-Francois Blanchet has indicated his MPs would decide issue-by-issue whether to support any minority government, both are more ideologically aligned with the Liberals and are adamantly opposed to Scheer’s signature policies of scrapping the Liberal carbon tax and creating a cross-country energy corridor.

Should the Conservatives emerge with substantially more seats than the Liberals but still short of a majority, Russell said Trudeau might be wise to resign and let Scheer try to gain the confidence of the House. If Scheer couldn’t win a confidence vote — a plausible scenario given his apparent lack of opposition dance partners — it would fall to Gov. Gen. Julie Payette to either call another election (highly unlikely) or invite Trudeau to give it a try.

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That route might lend more legitimacy in the eyes of Canadians to a weak Liberal minority but, Russell emphasized, it would be purely “a political calculation,” not a path required by convention.

Paul Martin resigned immediately in 2006 after the Liberals fell 21 seats behind Harper’s Conservatives, who were themselves 31 seats short of a majority. But that was a political decision, Russell said — likely based on the knowledge that a Liberal minority would have little opposition support and that his leadership of the Liberal party was in trouble.

“I think he did the right thing. But I don’t think it sets a precedent.”

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Indeed, in 1925, Mackenzie King’s Liberals won 15 fewer seats than Arthur Meighen’s Conservatives but continued with a minority government propped up by the Progressives for six months.

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In any event, winning the most seats is no guarantee a minority government will survive. Just ask Christy Clark, whose Liberals won 43 seats in the 2017 British Columbia election, just one shy of a majority and two more than John Horgan’s New Democrats. Three Green members joined the NDP in defeating Clark’s throne speech and installing an NDP minority government.

Or ask Frank Miller, whose Conservatives won the most seats in Ontario’s 1985 election, only to be supplanted a month later by David Peterson’s Liberals, who struck a deal to govern with the support of Bob Rae’s New Democrats for two years.

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Scheer has spent the dying days of the campaign issuing dire warnings about the consequences of a Liberal-NDP coalition, accusing Trudeau of being willing to pay any price to cling to power.

But there is no reason to suppose a coalition, with New Democrats being offered seats at the Liberal cabinet table, would be necessary. Indeed, Canada has never seen a formal federal coalition government.

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There has been the odd coalition provincially, most recently in Saskatchewan in 1999. More commonly, however, minority governments have survived with the informal support of one or more opposition parties on an issue-by-issue basis or with formal agreements with an opposition party to support the government for a certain period of time.

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Scheer appears to be trying to revive the anger that greeted the ill-fated 2008 attempt by the Liberals and NDP to forge a coalition government to replace Harper’s second minority. Harper successfully portrayed “the coalition of losers” as an undemocratic coup, turning public opinion against the idea.

In fact, coalitions are perfectly legitimate in the parliamentary system. The 2008 attempt was a particularly shaky construct that would have made Stephane Dion, who had already resigned as Liberal leader, prime minister for a few months before his successor was chosen, and which would have required the support of the separatist Bloc Quebecois to prop it up.

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In the end, Harper prorogued Parliament to avoid a confidence vote. By the time it resumed, the Liberals had gotten cold feet and the coalition fizzled.