The Prime Minister’s decision to put a “moratorium” on appointing Senators ahead of an election call could change the way the upper chamber functions — and if left too long, could potentially plunge Canada into a constitutional crisis.

Constitutional law experts said Stephen Harper’s vow to intentionally leave the seats empty could lead to problems with the chamber’s committee work, raises questions over what the Governor General and Supreme Court might do and could actually boost the case of any province that wants to take the issue to court.

Last Friday, Harper announced a moratorium on Senate appointments in Regina. “The government is not going to take any actions going forward that would do anything to further entrench that unelected, unaccountable Senate,” Harper said.

Emmett Macfarlane, a political science professor at University of Waterloo, says within two to three years, the Senate is going to start having serious trouble filling its committees – and therefore, in fulfilling its role of sober second thought.

“Once we’re talking about that, you’re talking about a change to the essential functioning of the Senate,” he said.

Further down the line, if the non-appointments continue, the situation could get much worse.

In a Supreme Court ruling last year, the court stated that Harper can’t abolish the Senate by ending appointments indefinitely.

Out of 105 total Senate seats, 22 are now vacant. With the current retirement schedule – and that’s not accounting for Senators who would leave or retire early – the Senate numbers would fall to almost half by 2020.

The Northwest Territories would be the first to have no Senate representation in late 2018. Manitoba would be down to two out of six Senators in early 2017, and Nova Scotia will be down to half by late 2017.

NDP Leader Tom Mulcair has pledged he won’t appoint Senators until he’s done negotiating with the Provinces on Senate abolition. Liberal Leader Justin Trudeau, meanwhile, kicked Senators out of the Liberal caucus and is promising an independent advisory board to nominate non-partisan Canadians to the Senate.

“I don’t really see an obvious case that the election is going to resolve this,” said Macfarlane.

Vancouver lawyer Aniz Alani currently has a case going to the Federal Court asking to compel the Prime Minister to fill the vacancies, although he’s now suggested he’ll drop it if Harper sends a reference question to the Supreme Court.

“I think we’re going to see Mr. Alani’s challenge in court, and perhaps make its way through the courts all the way up to the Supreme Court before we actually know what’s going to happen here,” said Macfarlane.

But Rob Walsh, former House of Commons Law Clerk, says some of these problems could potentially be dealt with internally. Committees only technically only need three Senators, including one opposition member, and legislation isn’t constitutionally required to pass through committee. That work could just come to an end.

He sees an issue far down the road with meeting the required 15-senator quorum as a “technical” constitutional problem, but adds it could actually be interpreted as an internal matter for the Senate to deal with.

“The courts would probably not rule invalid legislation that had been adopted by the House or Senate when it lacked the required constitutional quorum,” he told iPolitics.

But Walsh views the refusal to recommend appointments as “contemptuous of the Constitution” and as something that “invites constitutional disorder.”

Section 32 of the Constitution Act states that “when a vacancy happens in the Senate by resignation, death, or otherwise, the Governor General shall by summons to a fit and qualified person fill the vacancy.”

“Legally, in my view,” Walsh said, in an “extreme” situation of lack of Senators “the Governor General can and should make appointments unilaterally if this is necessary to enable the Senate to function constitutionally. The Prime Minister’s failure to recommend candidates cannot be allowed to cause the Governor General to violate his constitutional duty.”

Macfarlane says the Governor General likely won’t act until after a court ruling, and potentially, if the problem is still there, could dismiss the Prime Minister and call an election, although says that’s an unlikely hypothetical.

Carissima Mathen, a law professor at University of Ottawa, says it’s unlikely the Prime Minister wouldn’t act following a court ruling on the matter, but says Harper’s comments on the moratorium to appoint Senators raise interesting questions over the provinces’ constitutional entitlements to Senators.

She says his statement of refusal to make appointments would make it harder to argue in court against provinces upset over losing regional representation through empty Senate seats – especially once they hit a threshold of fewer than half their allotted Senators.

“The Senate doesn’t just have a legislative function. It has a constitutional function in representing a federal constitutional bargain,” she said.

That sort of case would be easiest to make by provinces because part five of the Constitution Act doesn’t deal with the Territories.

But the first step would be for a province to issue a declaration about the constitutional framework.

Mathen thinks a constitutional crisis over all this is unlikely.

“It’s hard to believe [the Prime Minister] would take us to that brink.”