Canadian Omar Khadr is accused of killing a U.S. soldier with a grenade during a battle in Afghanistan in 2002. (Janet Hamlin/Pool/CBC)

Federal lawyers filed an appeal in Ottawa Tuesday of a court ruling that ordered the government to seek Omar Khadr's return to Canada from Guantanamo Bay.

Federal Court Judge James O'Reilly ruled in April that the government's refusal to demand repatriation of Khadr offends fundamental justice. The government must ask the United States "as soon as practical" to send Khadr, 22, home, O'Reilly said.

An American military commission is considering the charges against Khadr, but the hearings are on hold pending a review of his case.

On Tuesday, government lawyer Doreen Mueller argued that although the Canadian Charter of Rights and Freedoms applies to the Toronto-born Khadr, it has not been breached in his case.

Canada has gone out of its way to help Khadr, she said, noting letters the government sent to the U.S. advocating on Khadr's behalf and that Canadian officials had visited him several times since his imprisonment.

"If there is an obligation … surely all this Canada has done since 2002 satisfies this obligation," she said.

The Federal Court judges grilled Mueller over the perceived harm in asking the U.S. to send Khadr home. "Canada doesn't want to ask for this because Canada doesn't want to get a yes answer," Judge Karen Sharlow said.

Court dictating foreign affairs: lawyer

Interfering in the matter would be tantamount to the courts dictating Canada's foreign affairs, Mueller said.

Moreover, the prospect of the U.S. abandoning its court case against Khadr and returning him to Canada was the "most remote of all possibilities," she said. "That's one one-millionth of possible outcomes."

Outside court, Navy Lt.-Cmdr. William Kuebler — who was recently fired and then reinstated as Khadr's U.S. military lawyer — disagreed with Mueller, saying the U.S. would honour a request for Khadr's repatriation.

"I think in light of the stated policy of the Obama administration to whittle down the population of Guantanamo Bay and repatriate as many detainees as possible, that it's just absurd to think that if a request from Canada came in tomorrow that the Obama administration would not leap to take advantage of that."

Opposition parties demand repatriation

Opposition parties have demanded Khadr be brought home and tried in Canada, if necessary, in light of the court decision.

In an interview with Fox News this month, however, Prime Minister Stephen Harper said Canada won't be taking any Guantanamo Bay detainees until the U.S. decides what it will do in the case of a Canadian being held there. Harper did not mention Khadr by name.

Khadr has been held at the U.S. military prison in Cuba since his capture in Afghanistan following a bloody firefight near the Pakistani border in 2002. He is accused of tossing a hand grenade that killed a U.S. medic during the battle.

While Khadr's plight has garnered him sympathy, his family has been referred to as the "first family of terrorism."

His father was an alleged al-Qaeda militant and financier who was killed by Pakistani forces in 2003. A brother, Abdullah Khadr, is being held in Canada on a U.S. extradition warrant, accused of supplying weapons to al-Qaeda.

Another brother, Karim, was wounded and left a paraplegic in the gunfight that killed his father. He returned to Canada in 2004 for medical treatment and lives in Toronto.

With files from The Canadian Press