Minister of Justice Rob Nicholson said Tuesday the government wants assurances that evidence gathered by Canadian agents during interviews with Khadr in 2003 and 2004 would not be used against him by U.S. authorities. (Sean Kilpatrick/Canadian Press)

The Harper government showed bias and bad faith and acted in a "perverse" manner by not requesting the return of Omar Khadr from the U.S. military prison in Guantanamo Bay, Cuba, his lawyers say in court documents filed Wednesday.

The emergency motion was filed in the Federal Court by Khadr's lawyers after Justice Minister Rob Nicholson asked the United States not to use evidence gathered from Khadr by Canadian officials in any American legal proceeding.

Nicholson's request was the government's response to a Supreme Court of Canada ruling last month that the Canadian government violated Khadr's constitutional guarantees under the Charter of Rights by questioning him in U.S. custody. But the high court justices did not order the government to seek Khadr's repatriation, and the government has already said it will not do so.

In Wednesday's court application, Khadr's lawyers renewed their constitutional objections and took the government to task for ignoring requests to consult them before sending Tuesday's diplomatic note to Washington.

"The Conservative government's policy and decisions with respect to the applicant are patently unreasonable and perverse, and were formulated in bad faith," said the filing.

It added that Ottawa's "sudden and automatic decision without regard for the basic principles of fairness would raise a reasonable apprehension of bias in the mind of an informed and objective observer."

Khadr, 23, has been imprisoned at Guantanamo Bay, Cuba, since he was arrested in Afghanistan at age 15, accused of throwing a grenade that killed a U.S. soldier. He is scheduled to be tried in July by a U.S. military court on charges of murder, conspiracy and support of terrorism.

This latest legal manoeuvre in the Khadr saga came as opposition parties slammed the government Wednesday for asking the United States to withhold any Canadian-gathered evidence against Khadr instead of seeking his return to Canada.

NDP Leader Jack Layton called the diplomatic note sent by Ottawa to Washington "a slap in the face" to the Supreme Court of Canada. He also blasted the timing of the Conservative government's decision, which came in a news release Tuesday evening, minutes before the puck was to drop in the debut match of the Canadian Olympic men's hockey team.

Layton joined Liberal Leader Michael Ignatieff in criticizing the government for failing to tell Washington that Khadr was a child soldier at the time of his arrest in 2002 after a firefight in Afghanistan, in which a U.S. army medic was killed.

'They did the absolute minimum'

Ignatieff said the diplomatic note Canada sent Tuesday should have specified that Khadr was a child soldier at his arrest. The Liberal leader acknowledged most Canadians do not sympathize with Khadr's plight, but said his citizenship rights should be protected by the government.

"They did the absolute minimum," said Ignatieff. "We think this is a test case in the indivisibility of Canadian citizenship. Many Canadians, including myself, take a very serious view of the accusations against Mr. Khadr. But he's a Canadian citizen. And you don't pick and choose here. You defend them all. Otherwise, no one's citizenship is worth very much. That's the key issue."

The British Columbia Civil Liberties Association sent Prime Minister Stephen Harper a letter Wednesday demanding Khadr's return.

The evidence Nicholson wants kept out of the trial includes seven hours of videotaped interrogations of the then-teenaged Khadr by a Canadian Security Intelligence Service officer. The video shows Khadr sobbing, moaning and dropping his head into his palms. He asks for protection from his American captors.