When Pierre Trudeau's cabinet met to debate the inclusion of the notwithstanding clause in the Constitution nearly 40 years ago, there was a significant minority who argued that political leaders would always be tempted to use it.

But "the optimists" in the room thought it would be used rarely yet judiciously — that premiers would be constrained by their reluctance to overturn fundamental rights, according to the former prime minister's principal secretary.

"And by and large, that has occurred. Until Ford," said Tom Axworthy, who advised Trudeau during the Constitution consultations.

Now Axworthy fears that Ontario Premier Doug Ford's promise to invoke the clause — for the first time in the province — may put more pressure on other governments to use it.

"The worry is now, with Ontario announcing this, that this will embolden, if not premiers, lots of other activists on lots of other issues who don't like this [or that] particular court ruling … they'll start saying: 'Let's use the notwithstanding clause. Doug Ford did," he said.

'Legitimate concern'

It's a fear shared by constitutional expert Wayne MacKay, professor emeritus of law at Dalhousie University. In an era of of populist politicians, using the notwithstanding clause may no longer be considered politically dangerous, MacKay said.

"[It's] maybe going to be seen as a politically good thing to do — that maybe you're not going to, as traditionally viewed, lose votes by setting aside the charter," he said.

"I think it is a legitimate concern, because of the odd times in which we live in, in terms of people like Trump and others, who are able to appeal to a certain segment of the population that aren't necessarily very rights-focused."

Prime Minister Pierre Trudeau signs the proclamation giving Canada independence from Britain in 1982 by repatriating Canada's Constitution. (Ryan Remiorz/Canadian Press)

Ford announced Monday that he would take the rare step of invoking Section 33 of the Canadian Charter of Rights and Freedoms after an Ontario Superior Court judge ruled that his provincial government's legislation to cut the number of Toronto city councillors was unconstitutional.

Section 33 — known as the notwithstanding clause — allows for premiers or prime ministers to override rulings on legislation that judges have determined would violate sections of the charter for a five-year period.

Pierre Trudeau opposed the clause, but reluctantly acquiesced to its inclusion in order to get a deal on the Constitution Act of 1982, which wrested control of Canada's Constitution from Britain.

Used 15 times before

Political leaders have generally been reluctant to use the notwithstanding clause, which is viewed by many as politically toxic. It's been invoked more than 15 times, and mostly in Quebec, which included it in every piece of legislation from 1982 to 1985 as form of political protest.

"The perception is that when you invoke the notwithstanding clause, you've decided to prioritize political expediency over rights," said Vanessa MacDonnell, a constitutional law expert and associate professor at the University of Ottawa.

"That's the dominant feeling people have, which is why it really hasn't been used much. So it's exceptional that Ford has said that he intends to use it."

The convention has been that it only be used "on the most important possible issues imaginable after a very fair process of debate," said Axworthy, a distinguished fellow at the Munk School of Global Affairs and chair of Public Policy at Massey College.

Former Prime Minister Brian Mulroney spoke in Ottawa on Tuesday 2:06

Some premiers, such as Alberta's Ralph Klein, have been tempted to use the clause on social issues such as same-sex marriage, he said, but no one has carried through.

"I could not have foreseen it being imposed, in my worst nightmares, over an issue like the size of a council for Toronto," Axworthy said.

MacKay, who isn't opposed to the use of the clause, agreed that it was meant for issues such as the War Measures Act, language, or those of political and cultural significance.

"I can't imagine in the complex, lengthy constitutional negotiations that there was a single person who thought, 'Gee, maybe they'll want to change the number of city councillors. So let's have this clause just in case.'"

Fears unfounded

But Emmett Macfarlane, an associate professor of political science at the University of Waterloo, who also specializes in the charter, said the clause has already been used in ways not anticipated by its framers — including Quebec's early, pre-emptive implementation of it before challenges had come up in court.

And despite Ford's pledge to invoke the clause, Macfarlane said he expects politicians will continue to be shy about using it "precisely because of the backlash we've seen."

The topic has generated mostly "the sky is falling" media coverage, he said, meaning the average voter will likely have a negative view of its implementation.

"The dominant narrative with the notwithstanding clause is that it overrides rights — that's not going to make it popular. So I'd be surprised if we saw the floodgates open outside of Ontario," he said.

MacDonnell said there hasn't been enough time to process the public reaction to Ford's actions and whether he will take a political hit.

"I would be shocked if we saw the proliferation of the notwithstanding clause by other governments as a result of this. I think Ford's an outlier," she said.

But if Ford, as he suggested Monday, begins using the clause routinely, it could "shift the expectations a little bit and that opens the door to its use by others," MacDonnell said.