GUANTANAMO BAY NAVAL BASE, Cuba - The first war-crimes trial of the Obama administration is slated to start this week as Canada's Omar Khadr fights a desperate battle to stave off a possible life behind bars.

Just 15 when taken into custody for the crimes of which he stands accused, the now 23-year-old Khadr finds himself in the cross-hairs of the American War on Terror.

The start of the trial itself with the seating of a jury comprising military officers may still be days away.

The court first must consider several pretrial motions filed by an emaciated defence, now comprising only Pentagon-appointed lawyer Lt. Col. Jon Jackson. Khadr fired his American civilian advocates.

Among those motions -- 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 infer guilt.

Another motion calls for three-for-one sentencing credit if he's convicted due to "illegal punishment" in custody.

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

The prosecution insists Khadr, now 23, was always properly treated during eight years in custody.

Duelling experts could testify as to Khadr's mental health.

Captured in July, 2002 in Afghanistan, Khadr was found horrifically wounded in the rubble of a bombed-out compound following 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 it 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, are in need of 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 of a 30-year sentence.

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

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 enacted last year in response to the high-court ruling has yet to be properly tested by the U.S. courts.