Jurors can consider a former child combatant's age in deciding whether he intended to commit a war crime in Afghanistan when he was 15, a US military judge has told jury candidates in Guantanamo Bay.
The prosecution of al-Qaeda suspect Omar Khadr began with jury selection yesterday, making the United States the first nation since World War Two to try someone in a military tribunal for acts allegedly committed as a minor.
Khadr is accused of killing a US soldier with a grenade during a firefight at a suspected al-Qaeda compound and making roadside bombs to target US troops in Afghanistan in 2002.
The defence contends the Canadian national was conscripted by his father, an al-Qaeda financier who took his family to Afghanistan and apprenticed Omar to a group of bomb-makers who engaged US troops in combat three weeks later.
"He was made to go there with no other choices," Mr Khadr's defence attorney, Army Lieutenant Colonel Jon Jackson, told journalists at the Guantanamo Bay naval base.
The United Nations has said the trial is of dubious legality and could set a dangerous precedent for child soldiers worldwide.
"Juvenile justice standards are clear - children should not be tried before military tribunals," said Radhika Coomaraswamy, the UN special envoy for children in armed conflict.
The military officers in the jury pool indicated they saw no problem with trying Khadr, who is now 23.
"Does anyone believe that juveniles should not be prosecuted for violent offences?" Prosecutor Jeff Groharing asked them. "Does anyone feel the accused should be held to a different standard because he was 15 years old at the time of the alleged offences?"
None said they held those beliefs.
But the judge interrupted Mr Groharing and said that in order to prove its case, the prosecution must show Mr Khadr had intent to commit a crime and that jurors could consider his age in deciding that.
"It's certainly something you may consider in deciding whether the government has proved its case beyond a reasonable doubt," said the judge, Army Colonel Patrick Parrish.
It may be difficult for jurors to view Mr Khadr's actions as those of a child because he is now a tall, broad-shouldered and bushy-bearded man who has spent eight years locked up with adult prisoners at Guantanamo.
Mr Khadr wore an ill-fitting gray suit, white shirt and salmon-colored tie rather than the loose white tunic and trousers he has worn in four-and-a-half years of pretrial hearings. He stood and smiled at the jury candidates when his lawyer introduced him.
His is the first contested trial under the administration of President Barack Obama, who missed his January deadline for shutting down the Guantanamo detention camp and had been expected to scrap the tribunals he had condemned as a presidential candidate.
"Instead President Obama has decided to write the next sad, pathetic chapter in the book of military commissions," Jackson told journalists. "So forever Obama's military commissions will be remembered for starting with a case against a child soldier."
At least five US military officers will be chosen as jurors and three-fourths of them must agree in order to convict Khadr. The judge ordered their names kept secret and barred the courtroom sketch artist from drawing their faces.
They will hear testimony from several fellow soldiers who were at the battle where US Army sergeant 1st Class Christopher Speer was fatally wounded by a grenade and where Khadr himself was blinded in one eye and shot twice through the back.
In another Guantanamo courtroom, the sentencing of Osama bin Laden's former cook was stalled while the Pentagon tried to work out a glitch that jeopardises his plea agreement.
Sudanese prisoner Ibrahim al Qosi pleaded guilty last month to conspiring with al-Qaeda and providing material support for terrorism. His plea deal requires that any sentence served at Guantanamo be spent in Camp Four, where detainees live in groups under fewer restrictions than in the other camps. But military rules forbid housing convicted criminals with other detainees.