A U.S. military judge has delayed the trial of Omar Khadr, the Canadian detainee held at Guantanamo Bay, until late January.

Omar Khadr is shown here at 15, not long before he was captured by U.S. forces in July 2002. (Canadian Press)

The new trial date set by Col. Patrick Parrish, the judge overseeing the case, is Jan. 26.

Khadr, 22, has been held at the U.S. naval base 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.

Earlier in the week, Khadr's lawyer asked that the trial be postponed, arguing the young man wouldn't get a fair trial without a proper psychological assessment. The trial had been slated to go before a military commission at the U.S. naval base on Nov. 10.

The assessment is imperative to Khadr's defence as it will determine his ability to comprehend his legal rights, as well as his recollection of the events in questions, his lawyers said this week.

In particular, the assessment could qualify the admissibility of statements Khadr made to his captors while under duress, according to documents that have shown he was sleep-deprived and held in stressful positions. His lawyers have argued the treatment was tantamount to torture.

The delay also means Khadr's case won't be heard until days after the next U.S. president takes office.

Members of Khadr's family said Friday that could play in his favour.

"It's a good thing," Khadr's sister Zaynab, 29, said from Parliament Hill, where she's subsisting on juice and water for three weeks in an attempt to compel Prime Minister Stephen Harper to repatriate her younger sibling. "The Bush administration is not going to be able to use Omar to justify their detention centre."

Both Democratic candidate Barack Obama and Republican John McCain have vowed to shut down Guantanamo.

"I'm hoping [the delay] will give the Canadian people and government more time to do the right thing and bring him home," she said.

Khadr is the only Westerner held at the controversial American prison, widely decried as illegal by critics and human-rights activists.

Lawyers for Khadr have filed a lawsuit in Federal Court to try to compel the Canadian government to repatriate him, arguing Canada is obliged under international law to ensure Khadr's rehabilitation since he was a child at the time of the alleged crime.

Harper has consistently rejected appeals to have Khadr brought back to Canada, saying the U.S. proceedings should continue as planned.

With files from the Canadian Press