The party was able to force the chamber to hold an impromptu debate on the report from the special House committee that looked into the issue earlier this year.
The Conservative-controlled committee ultimately chose not to recommend a full inquiry, but both the New Democrats and the Liberals submitted minority reports in support of a national public commission of inquiry.
New Democrat MP Romeo Saganash led off the debate with an emotional — and deeply personal — plea for a federal investigation.
Saganash told the Commons about his own family's painful experience of not knowing what happened to his missing brother until they were finally able to see where he was buried, decades later. He said learning the truth offered his family closure, and that's what the families of missing women need too.
The NDP has promised to hold an inquiry should it form government after the next election. So far, the Harper government has not been willing to call an inquiry. However, it is open to a compromise proposal originating from the provincial premiers meeting last month to create a national roundtable to tackle the issue.
After just over an hour, the debate was suspended to allow the House to move on to private members' business. The remaining time must be scheduled within the next 10 sitting days, after which MPs will be able to vote on whether to adopt the report.
Tactics in the House
So, how exactly did the New Democrats manage to manoeuvre the Commons into hosting an impromptu hour-long debate on their chosen topic?
As is ultimately always the case in the House of Commons, it came down to the numbers — and specifically, an NDP gamble that the government simply wouldn't be able to muster a sufficient contingent of Conservative MPs to override the combined opposition forces in a rare Friday vote.
Shortly after question period wrapped up, New Democrat MP Yvon Godin segued from introduction of a private member's bill to propose that the House move to the next stage of routine proceedings — in this case, first reading of Senate public bills.
It was an ironic choice for a party long opposed to the very existence of the Upper House — but an effective one, strategically, as it could have served as a test to see just how many Conservative MPs the government could get to the House on short notice.
The answer: not enough, which is why the Conservatives ended up voting in favour of the NDP motion, and didn't take the usual steps to shut down the concurrence debate before the allotted time ran out.