“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,” says our constitution.

The word “shall” is an imperative, creating a clear legal obligation.

Public cynicism about the Senate is widespread, thanks in part to the antics of some of the senators Stephen Harper appointed. I almost admire the political audacity of the prime minister’s unilateral moratorium on filling Senate seats. It’s something to watch Harper exploit national disgust with disgraced senators, many his hand-picked nominees, to circumvent the Constitution. More disturbing is the way many Canadians are cheering him.

Allowing any prime minister to do an end run around the Constitution is a bad plan and a bad political precedent. We elect prime ministers to defend the Constitution, not ignore bits they find inconvenient.

Peter Meekison, a retired political scientist who was Alberta’s deputy minister of intergovernmental affairs under Peter Lougheed, represented Alberta at the constitutional bargaining table. He doesn’t just study the Constitution; he helped write it. He’s not impressed with Harper’s moratorium.

“I think it’s a flagrant violation of the Constitution,” he says. “You can’t just wait for years and years for the Senate to atrophy. It’s a joke. No, it’s not even a joke.”

Now that the Supreme Court has said abolishing the Senate would require unanimous provincial consent, he says, the rules are clear.

“You can’t just let the Senate die out via attrition. If you want to abolish it, fine, but you have to have the support of the provinces and of Parliament.”

Under the Constitution, no bill can pass without Senate assent. If there aren’t enough senators in the chamber to pass bills, or if certain provinces are not properly represented, Meekison argues, bills can’t become law. Prince Edward Island has four Senate seats. One is empty. Another is held by Mike Duffy, who is on trial and may not be in the Senate much longer. Another P.E.I. senator is nearing mandatory retirement.

What happens, he wonders, when P.E.I. has only one senator instead of four? Would it be valid for the Senate to pass laws without the legally required provincial representation?

Meekison compares Harper’s move to Pierre Trudeau’s hated National Energy Policy as an attack on provincial rights. Just as Alberta fought the NEP, provinces should be prepared to fight this.

Meantime, he says, the Constitution gives the Governor General the power to appoint senators. But, he concedes, such an extreme response would be unlikely.

For Eric Adams, a professor of constitutional law at the University of Alberta, the issue is less clear-cut.