The Pentagon is holding military commission sessions this week for two detainees: a young Canadian going on trial for the slaying of a U.S. soldier in Afghanistan and an aide to Osama bin Laden who is to be sentenced after pleading guilty in a deal with prosecutors.
The tribunal system that ground to a halt after Mr. Obama took office is coming alive with lawyers, human-rights observers and more than 30 journalists who are at the U.S. Navy base in southeastern Cuba to attend Monday's proceedings in two courtrooms.
Mr. Obama has introduced some changes designed to extend more legal protections to detainees, but the tribunals' long-term future remains cloudy as the president struggles to fulfill a pledge to close the prison altogether.
The trial for Omar Khadr, the Toronto-born son of an alleged al Qaeda financier, is expected to begin Tuesday following pretrial hearings.
It is to be the first trial under Mr. Obama and only the third at Guantanamo, where the system that former President George W. Bush established for prosecuting terror suspects after the 9/11 attack has faced repeated legal setbacks and challenges.
Khadr is accused of lobbing a grenade that killed U.S. Army Sgt. 1st Class Christopher Speer of Albuquerque, New Mexico, during a 2002 firefight in Afghanistan. He faces a maximum life sentence if convicted of charges including murder, conspiracy and spying.
His lawyers deny he threw the grenade and argue that Khadr, the last Westerner at Guantanamo, deserves leniency because he was only 15 when he was captured. They contend the prosecution rests on confessions extracted following abuse that included sleep deprivation and threats of rape.
"President Obama has decided to write the next sad, pathetic chapter in the book of military commissions and unfortunately the president is starting the military commissions with the case of a child solder," Army Lt. Col. Jon Jackson, Khadr's attorney, said at a news conference Sunday.
Khadr said in a May letter to one of his Canadian lawyers, Dennis Edney, that he was resigned to a harsh sentence from a system that he called unfair.
"It might work if the world sees the U.S. sentencing a child to life in prison, it might show the world how unfair and sham (sic) this process is," Khadr wrote.
A spokesman for the military commissions prosecutors, Navy Capt. David Iglesias, said the defendant's age may be considered at sentencing if Khadr is convicted but has no legal bearing on his prosecution.
"What you look to is did he know what he was doing," Iglesias said. "We'll let the evidence speak for itself."
The U.S. Supreme Court last week rejected a last-ditch request to halt the trial on grounds the system is unconstitutional.
In the other case, a military panel will begin deliberations as early as Monday on a sentence for Ibrahim Ahmed Mahmoud al-Qosi, a Sudanese detainee who pleaded guilty last month to one count each of conspiracy and providing material support for terrorism.
Al-Qosi was accused of acting as accountant, paymaster, supply chief and cook for al Qaeda during the 1990s when the terrorist network was centered in Sudan and Afghanistan. He allegedly worked later as a bodyguard for bin Laden.
The 50-year-old from Sudan faced a potential life sentence if convicted at trial. Terms of the plea deal, including any limits on his sentence, have not been disclosed. Iglesias said it may remain sealed even after the case is resolved.
Both detainees have been held at Guantanamo since 2002.