OTTAWA - The Harper government says it trusts that the U.S. will voluntarily comply with a diplomatic request to exclude Canadian-gathered evidence in any trial of Omar Khadr.

Justice Minister Rob Nicholson said Tuesday that he's satisfied a diplomatic note sent to the Americans is remedy enough for a recent Supreme Court of Canada ruling.

That ruling confirmed that Canadian officials violated Khadr's constitutional rights by questioning him in American custody in 2003 and 2004. However, the court left it up to the government whether to ask the U.S. to return Khadr to Canada -- something the Conservatives have steadfastly refused to do over four years in power.

"We have confidence in the Obama administration and their handling of these matters," Nicholson said. "But I think it was incumbent upon me to make the opinion and the statement that certain evidence improperly obtained as set out by the Supreme Court of Canada, shouldn't be used."

It was his first public comment on the matter since he issued a brief written reply last week to the Jan. 29 landmark ruling. In that reply, Nicholson said he sent a diplomatic note to the U.S. asking military prosecutors to refrain from using information gathered by the Canadian Security Intelligence Service.

The response has been criticized by the NDP as an attempt to whitewash any wrongdoing by Canadian spies in the Khadr matter.

Toronto-born Khadr, 23, has been in U.S. custody at Guantanamo Bay, Cuba, for allegedly throwing a grenade that killed a U.S. soldier in Afghanistan more than seven years ago.

Nicholson said he was not expecting any American reply to the diplomatic note, saying U.S. military prosecutors are free to do what ever they want.

"It's an American prosecution," he said.

Khadr's lawyers have filed an application in Federal Court asking for a review of the government's decision not to seek Khadr's return in response to the Supreme Court. Their application accuses the government of acting in "bad faith" and in a "perverse" manner in drafting their response.

Khadr lawyer Nathan Whitling said Tuesday that he was pleased the government at least took the step to seek assurances that statements Khadr gave to CSIS ought to be excluded.

"But what about the hundreds of other statements being relied upon by the prosecution that were obtained under worse circumstances?," he asked.

"What about the fact that Omar was a child soldier? What about the fact that he's been denied a trial within a reasonable time? And what about his right to return to Canada? I could go on and on, but the point is that the minister failed to even consider these other concerns."

Khadr is the last Western national to be held at the U.S. military prison on the tip of Cuba that has been criticized by courts and human rights groups around the world.

Seven hours of videotaped CSIS interrogation shows Khadr moaning and sobbing and asking for protection from his American captors.

Records show Khadr was subjected to a sleep deprivation technique known as the "frequent flyer program" that saw him transferred from cell to cell to break his resistance to interrogation.

Though ruling that Khadr's guarantees were breached under the Charter of Rights, the Supreme Court said it would not be appropriate to give an order to the government, instead leaving it Ottawa to respond "in light of current information, its responsibility for foreign affairs, and in conformity with the Charter."

While not urging the government to do so, the high court said bringing Khadr home "could potentially vindicate those rights."