The judge in the first American war crimes trial since World War II barred evidence on Monday that interrogators obtained from Osama bin Laden's driver following his capture in Afghanistan. Prosecutors are considering whether to appeal the judge's ruling - a development that could halt the trial of Salim Hamdan that began earlier Monday after years of delays and legal setbacks. "We need to evaluate ... to what extent it has an impact on our ability to fully portray his criminality in this case, but also what it might set out for future cases," said Army Col. Lawrence Morris, the tribunals' chief prosecutor. Hamdan, who was captured at a roadblock in Afghanistan in November 2001, pleaded not guilty at the start of a trial that will be closely watched as the first full test of the Pentagon's system for prosecuting alleged terrorists. He faces a maximum life sentence if convicted of conspiracy and aiding terrorism. The judge, Navy Capt. Keith Allred, said the prosecution cannot use a series of interrogations at the Bagram air base and Panshir, Afghanistan, because of the "highly coercive environments and conditions under which they were made." At Bagram, Hamdan says he was kept in isolation 24 hours a day with his hands and feet restrained, and armed soldiers prompted him to talk by kneeing him in the back. He says his captors at Panshir repeatedly tied him up, put a bag over his head and knocked him the ground. The judge did leave the door open for the prosecution to use other statements Hamdan gave elsewhere in Afghanistan and at Guantanamo. Defense lawyers asked Allred to throw out all of his interrogations, arguing he incriminated himself under the effects of alleged abuse - including sleep deprivation and solitary confinement. Michael Berrigan, the deputy chief defense counsel, described the ruling as a major blow to the tribunal system that allows hearsay and evidence obtained through coercion. "It's a very significant ruling because these prosecutions are built to make full advantage of statements obtained from detainees," he said. A jury of six officers with one alternate was selected from a pool of 13 flown in from other US bases over the weekend. Hamdan's lawyers succeeded in barring others, including one who had friends at the Pentagon at the time of the Sept. 11 attacks, and another who had been a key government witness as a student. Monday marked the first time after years of pretrial hearings and legal challenges that any prisoner reached this stage of the tribunals. The US plans to prosecute about 80 Guantanamo prisoners, including the self-proclaimed mastermind of the Sept. 11 attacks and four alleged coconspirators. Hamdan seemed to go along with the process despite earlier threats to boycott. The Yemeni with a fourth-grade education appeared to cooperate fully with his Pentagon-appointed military lawyer, whispering in his ear during the questioning of potential jurors. "Mr. Hamdan expressed great interest in this," said Charles Swift, one of his civilian attorneys. Morris said the statements obtained from Hamdan are "significant" to the government's case, and his office was evaluating whether to proceed to trial without some of them. In addition to the other interrogations, the judge said he would throw out statements whenever a government witness is unavailable to vouch for the questioners' tactics. He also withheld a ruling on a key interrogation at Guantanamo in May 2003 until defense lawyers can review roughly 600 pages of confinement records provided by the government on Sunday night. Hamdan has been held at Guantanamo since May 2002. A challenge filed by his lawyers resulted in a 2006 Supreme Court ruling striking down the original rules for the military tribunals. Congress and President Bush responded with new rules, the Military Commissions Act. Hamdan met bin Laden in Afghanistan in 1996 and began working on his farm before winning a promotion as his driver. Defense lawyers say he only kept the job for the $200-a-month salary. But prosecutors allege he was a personal driver and bodyguard of the al-Qaida leader. They say he transported weapons for the Taliban and helped bin Laden escape US retribution following the Sept. 11 attacks.