The governing Conservatives have used their majority muscle to shut down an investigation into an alleged breach of privilege that saw two New Democrat MPs barred from the Commons, albeit briefly, by the RCMP.

The move came after House of Commons Speaker Andrew Scheer sided with NDP MPs Nathan Cullen and Craig Scott, who had both lodged formal complaints in recent weeks over their respective run-ins with the Mounties.

In a ruling handed down Tuesday, Scheer concluded there were sufficient grounds to allow Scott to put forward a motion to have the House affairs committee look into the larger issue of access on the Hill.

But after two hours of debate, the Conservatives quashed the motion by a 145-117 vote.

"I wasn't expecting this at all," Cullen told CBC News. "I'm more angry than I am confused — this is such a terrible precedent."

In Cullen's case, which took place on April 30, he and several Commons colleagues were heading back to the House for a vote when the parliamentary shuttle bus that was ferrying them back to Centre Block was stopped by the RCMP just outside the east doors.

While the delay was relatively short — just over 74 seconds, according to the RCMP — it very nearly resulted in the whole busload of MPs missing the vote, a scenario that might have had significant consequences in a minority government setting.

"I've never heard of a government, or any party, overriding the Speaker and saying that MPs being able to vote is not important," Cullen said.

"I just don't know of anything else more important. That's why the place exists."

Just days after Cullen's near miss, Scott was forced to cool his heels outside Centre Block while a delegation of visiting dignitaries was escorted inside the building. That prompted him to file a complaint of his own.

Speaker sides with MPs

The two incidents, the Speaker told the House on Tuesday, "have served as a clear reminder that members not only require but are entitled to access to the parliamentary precinct at all times, without interference" — a right he noted was "uncontested."

And while he acknowledged the reality of the post-Oct. 22 security environment, he agreed the NDP MPs' experiences "have certainly seemed to highlight" concerns that were already being raised over the potential conflict between parliamentary privilege and policing the precinct.

"I recently had occasion to discuss this challenge with [RCMP] Commissioner [Bob] Paulson, who agrees that all protective personnel need to know the community they serve," he told his colleagues.

"They need to be sensitive and responsive to the community they serve, and they need to be familiar with the expectations of the community they serve. This includes having the primary function of this place top of mind as they go about performing their duties."

Still, Scheer stressed MPs also "need to be mindful" that increased security "does require adjustments."

'Some slippage' expected: Tory MP

During debate, nearly all opposition members to speak voiced their support for a thorough review.

Nova Scotia MP Gerald Keddy, who was the only Conservative to take part in the debate, felt differently.

In a brief intervention, he stressed the need to find a "balance" between privilege and security.

"I expect there will be some slippage and some mistakes made along the way," he admitted.

"But that is why we as parliamentarians need to involve ourselves in this ongoing process, because it is, quite frankly, a new world we live in since October."

'Fundamental to our democracy'

In March, the House passed a motion to put the RCMP in charge of policing the parliamentary precinct. Previously, each chamber had its own independent security force, although there were already plans underway to merge the two units before the attacks of last fall.

The recently tabled budget implementation bill will make that change official.

The Liberals voted to support the plan but New Democrats opposed the move, which they warned could result in a blurring of the lines between the legislative and executive branches of government, as the RCMP ultimately reports to Public Safety Minister Steven Blaney.

It's unlikely this latest development will assuage those fears.

"The executive can not [have] control over the legislature, and deny opposition members the right to vote through their security force," Cullen pointed out to CBC News.

"That's the whole point. That's why you separate the powers ... it's absolutely fundamental to our democracy."

In response to a query from CBC News, RCMP spokeswoman Brigitte Mineault said the force was aware the issue had come up in the House.

"The RCMP continually strives to respect the privilege of access of parliamentarians while ensuring their safety and that of other people who visit or work on Parliament Hill," she said.

"The RCMP will continue to work with parliamentarians and security partners on Parliament Hill to strike that right balance."