Canadian defendant Omar Khadr, shown in this photo of a courtroom sketch, sits during a U.S. military commission hearing in 2009.

The trial of Toronto-born Omar Khadr by a U.S. military commission is scheduled to begin this week in Guantanamo Bay, Cuba.

Khadr, the son of a purported al-Qaeda financier, is accused of throwing a hand grenade when he was 15 that killed an American soldier in Afghanistan after an assault by U.S. forces on a compound he was in.

The start of the trial itself, with the seating of a jury of eight military officers, is still days away.

The court must first consider several pretrial motions filed by the defence, now consisting only of Pentagon-appointed lawyer Lt.-Col. Jon Jackson. The 23-year-old Khadr fired his American civilian advocates.

Among the motions that could be heard as early as Monday — all bluntly opposed by the prosecution — is one calling for lower-key security in the courtroom.

Conspicuous security, the defence argues, could indicate to jurors that Khadr is dangerous and hence suggest guilt.

Another motion cites alleged "illegal punishment" in custody and calls for three-for-one sentencing credit if Khadr is convicted.

And Jackson will be making a final pitch to have incriminating evidence deemed inadmissible on the grounds it was obtained by torture or other abuse.

The prosecution insists Khadr has always been properly treated during his eight years in custody.

Duelling experts could testify about Khadr's mental health.

Captured in 2002

Captured in July 2002 in Afghanistan, Khadr was found severely wounded in the rubble of a bombed-out compound after a four-hour assault by U.S. forces.

The prosecution maintains he threw a hand grenade that killed U.S. special forces Sgt. Chris Speer.

For that, Khadr is charged with murder in violation of the rules of war.

He also faces charges of attempted murder, conspiracy, supporting terrorism and spying.

Critics have dubbed this the first war-crimes prosecution of a child soldier in modern times.

United Nations organizations and international human rights groups have warned the case sets an unwelcome precedent. 

Child soldiers, they argue, need special protection and rehabilitation.

Last month, Khadr denounced the process as a "sham." He said he had rejected a plea agreement that would have seen him serve five more years as part of a 30-year sentence.

Calls for repatriation refused

While the case has not attracted widespread public scrutiny in the U.S., it has aroused political and legal passions in Canada.

The Conservative government of Prime Minister Stephen Harper has steadfastly refused calls from the opposition and legal groups to press for Khadr's repatriation.

The government has also, according to a recent Federal Court decision, defied Canada's Supreme Court by refusing to do something meaningful to make amends for breaching his charter rights when Canadian security agents interviewed him in Guantanamo Bay.

The trial comes 19 months after incoming U.S. President Barack Obama promised to close the notorious prison at Guantanamo, the naval base on leased Cuban territory, and end the much maligned military commission process.

Unlike criminal and civil trials, a unanimous verdict by the military commission is not required and evidence obtained by coercion is admissible. Military commissions require only a two-thirds majority for rulings.

On Friday, the U.S. Supreme Court, which had ruled a previous version of the military commissions illegal, refused an emergency stay of Khadr's trial requested by the defence.

In line with many legal experts, Khadr's defence maintained the new version of the Military Commission Act that came into effect last year in response to the high court ruling has yet to be properly tested by the U.S. courts.