The first Guantanamo war crimes trial began today with a not guilty plea from a former driver and alleged bodyguard for Osama bin Laden.
Salim Hamdan, a Yemeni, entered the plea through his lawyer at the US Navy base in Cuba.
He is the first prisoner to face a US war crimes trial since the Second World War.
Judge Keith Allred, a Navy captain, called a jury pool of American military officers into the courtroom and began reading them instructions. A minimum of five of the 13 officers must be selected for the trial.
Hamdan, a Yemeni, wore a khaki prison jump-suit to the courtroom. The flowing white robe and headdress he wore at pre-trial hearings was not cleaned in time for his trial, said Charles Swift, one of his civilian lawyers.
The trial is expected to take three to four weeks, with testimony from nearly two dozen Pentagon witnesses.
Hamdan was captured at a roadblock in Afghanistan in November 2001, with two surface-to-air missiles in the car. But his lawyers say he was merely a low-level driver and mechanic without any role in al-Qaida.
Hamdan was taken to Guantanamo in May 2002 and selected as one of the first inmates to face prosecution. His case has created repeated legal obstacles for the Pentagon including a Supreme Court ruling that struck down an earlier version of the tribunal system.
Judge Allred began the proceedings by indicating that he would not allow the government to use some of the evidence interrogators obtained from Hamdan during his detention in Afghanistan.
Defence lawyers have argued those statements were tainted by “coercive” techniques and the fact that interrogators did not advise him of a right against self-incrimination.
The US has so far charged 20 Guantanamo prisoners and military officials say they expect to prosecute about 80 in all.