Near the end of the fall sitting of Parliament, Tom Mulcair had a little bee in his bonnet over the lost, then found, emails of Ben Perrin, the prime minister's former legal counsel at the centre of the Duffy-Wright affair.

During question period in the Commons Dec. 3, Mulcair pummelled Harper's stand-in, Industry Minister James Moore, with questions about transparency.

After a bit of back and forth, Moore offered that "the Privy Council Office has taken responsibility for the mistake that it made in not handing over the information to the RCMP."

To which Mulcair replied, "apparently the only person who has not assumed responsibility is the person who is responsible. The Privy Council Office is the ministry of the prime minister and ministerial responsibility should apply first and foremost to the prime minister."

Well, not so much. And here's why the Leader of the Official Opposition should remember that when Parliament resumes sitting Monday.

Somewhere between the first Conservative election victory and the last election, the rules on ministerial responsibility changed without any fanfare or public discussion.

The 2007 guide for ministers, written by the PCO, explained ministerial responsibility this way: "Ministers are individually responsible to Parliament and the prime minister for their own actions and those of their department, including the actions of all officials under their management and direction, whether or not the Ministers had prior knowledge."

By 2011, there had been a shift in thinking.

"Ministerial accountability to Parliament does not mean that a minister is presumed to have knowledge of every matter that occurs within his or her department or portfolio, nor that the minister is necessarily required to accept blame for every matter," wrote PCO in an updated version of the pamphlet.

This includes Nigel Wright

And the new rules didn't just apply to bureaucrats but to the minister's political staff as well. They are the partisans who handle everything from answering media inquiries to advising them on policy.

Nigel Wright is the prime minister's former chief of staff. He cut a $90,000 cheque for Senator Mike Duffy last year. He no longer works for the prime minister because of that. (THE CANADIAN PRESS/Adrian Wyld) They are people like Nigel Wright, the prime minister's former chief of staff, who cut a $90,000 cheque to Senator Mike Duffy last year. According to the new rules, those people are now responsible for their screw-ups.

"This shift in the guidelines puts them in a more precarious position. Because if the minister isn't responsible for their actions — at least in terms of explaining them — then the minister has this incredible 'get out jail free' card to just blame staff," said David McLaughlin, who served as chief of staff for former prime minister Brian Mulroney and Finance Minister Jim Flaherty.

But there is something even more fundamental about the change in ministerial responsibility, according to Lori Turnbull, a self-described political nerd with a job to match her interests. She teaches political science at Dalhousie University in Halifax.

"In a parliamentary system, it's the way that a government is held to account in the House of Commons," she explained.

"That's how Canadians know what's going on in government, what's going on in departments, what's going on with spending, policies, programs. It's because the ministers have to be in the House to answer questions. That's what ministerial responsibility is in a practical sense."

For McLaughlin, that is the most important thing about holding cabinet members to account: we know where they live. They live in the House of Commons. Political staff, on the other hand, don't really have a fixed address like their bosses.

"This movement away from that principle in the guideline is fudging that accountability linkage," said McLaughlin.

The switch is making it harder to hold the minister and government responsible for their actions, he argued.

"They can simply say, well, it was a political staffer. I'm not accountable for that. I'm not responsible for that."

PCO: language plainer

In an email to CBC News, the PCO's chief spokesman disagreed with that assessment.

"Ministers are required to attend to all matters in Parliament concerning their portfolio organizations, including answering questions. As stated in the 2011 edition, ministers must also take appropriate corrective action to address any problems that may arise within their portfolio organizations, which includes problems arising from the actions of officials," wrote Raymond Rivet, the PCO's director of communications.

In essence, cabinet members don't have to take the blame but they do have to clean up the mess. And this, wrote Rivet, is nothing new.

"There has been no shift in the concept of ministerial accountability; there has always been a distinction between actions deemed blameworthy and the idea that ministers must answer questions in Parliament," argued Rivet. All that has changed is the language.

It's a lot plainer, he explained.

Stockwell Day is a former minister of Public Safety, International Trade and president of the Treasury Board. He doesn't think ministers should have to take responsibility for everything that happens in their offices or departments. (CANADIAN PRESS/Sean Kilpatrick) Stockwell Day says he couldn't agree more.

"A minister cannot be held responsible for the actions of every employee in her ministry," the former Conservative minister of Public Safety, International Trade and Treasury Board president said in an email to the CBC.

He even offered up an example of how he interpreted the concept of ministerial responsibility: the obnoxious drunk in the office.

"The minister cannot be held responsible [for this]. However she must require that a thorough assessment of the situation be done, including an undertaking on behalf of anybody who may have been hurt and whether there is a counselling plan and/or legal consequences in place for the offender."

Narrowing of accountability

McLaughlin calls this explanation a narrowing of accountability. He said it's obvious that not every offence demands a ministerial hanging despite what the opposition and the media often demand.

But he thinks the original principle is critical.

"Accountability means accepting responsibility (a) for the action, and (b) for the correction. PCO/PMO guidelines suggest only the latter responsibility."

Turnbull put an even sharper point on it than that.

While these guidelines are written down, they are just guidelines, she said. The idea of ministerial responsibility is a convention. It is an unwritten constitutional rule.

"It's easier to ignore an unwritten convention than it is to ignore a written part of the constitution," she pointed out.

"It becomes a test of what the government can get away with if they want to start playing with conventions. And that's a huge problem," she added.

"These guidelines do not gel with the rest of our system."