Opposition MPs voted in favour of holding a judicial inquiry into allegations of Afghan detainee abuse, but the Conservative government is expected to ignore the non-binding motion.
The Tories voted against the bill, but it still passed by a vote of 146-129.
Prime Minister Stephen Harper has blocked efforts for an in-depth investigation into the allegations, citing security concerns.
The Military Police Complaints Commission, created by Parliament in 1998 to toughen Canada's military justice system, had to suspend its own investigation because the government would not hand over the needed documents.
Among those documents were apparent warnings from diplomat Richard Colvin, who said Afghan intelligence agents likely tortured all the detainees Canada transferred in 2006-2007.
The MPCC has since obtained the documents from Ottawa, but they are heavily censored -- some pages are completely blacked out. On Tuesday, opposition leaders questioned why the government kept information from the agency.
Liberal Leader Michael Ignatieff said the documents are "so heavily redacted as to be useless."
In the House of Commons, NDP Leader Jack Layton asked: "Does the government somehow believe the commission is working in league with the Taliban?"
Â鶹´«Ã½ obtained 180 pages of e-mails, including ones written by Colvin, that are among the documents. They were heavily censored, and what could be seen shed little light on the controversy.
But one e-mail underlined Colvin's frustration. He complained about "hyper secrecy" on the detainee issue, and orders from Ottawa to put "nothing in writing."
He said the apparent restrictions amounted to "a very troubling politicization of reporting" and effectively told diplomats, "We must lie to each other."
Alex Neve, secretary-general of Amnesty International Canada, said the MPCC has top security clearance, so censoring the documents makes little sense other than as a political move.
"There will undoubtedly be all sort of information, some of which is embarrassing to the government, others embarrassing to other governments, and it's being withheld for that reason," he said.
Transport and Infrastructure Minister John Baird insisted the government is protecting Canada's national security.
"Our number one priority is to protect the operational security of men and women in uniform," he said.
Last week, before appearing at a parliamentary committee examining the allegations, top generals read the full documents and dismissed Colvin's claims.
Retired general Rick Hillier, who was chief of the defence staff when the military moved in Kandahar in 2006, called Colvin's allegations "ludicrous."
"There was simply nothing there (in Colvin's reports) ... to warrant the intervention of the chief of defence staff," he said.
With a report by CTV's Roger Smith in Ottawa
