A military judge rejected a request Wednesday by lawyers for a Guantanamo detainee to talk to the alleged mastermind of the Sept. 11 attacks, thwarting their attempt to show the defendant was a minor al-Qaida figure. Civilian defense attorney Harry Schneider told reporters he had hoped that Khalid Sheikh Mohammed and the two other high-value detainees held at this isolated US military base could establish that their client Salim Ahmed Hamdan, a former driver for Osama bin Laden, was not a hardcore terrorist. The effort came the same day that the Supreme Court debated - for the third time since 2004 - the rights of foreign terrorism suspects held at Guantanamo Bay. The hearing at Guantanamo was held in a converted airport control tower and was delayed more than an hour because of technical problems. Schneider told the court that the three alleged top terrorists could clear up the role played in al-Qaida by Hamdan. "People who were actively involved unquestionably are in a much better position than me or you or anyone else in this room ... to say what Mr. Hamdan was," Schneider said. In denying the request, the judge, Navy Capt. Keith Allred, said more time would be needed to overcome the "security obstacles" posed by meeting with men accused of some of the world's most notorious terrorist attacks. Hamdan's lawyers wanted to show he does not meet the definition of an unlawful enemy combatant and is therefore not eligible to be prosecuted by a military tribunal. Allred did not make a ruling on that issue but could do so as early as Thursday, when the hearing continues. John Murphy, a civilian prosecutor from the Department of Justice, dismissed the defense's attempt to interview the high-value detainees as a fishing expedition. "You need a showing that it is relevant and necessary. Mere hoped-for evidence gathering is not enough," Murphy told the judge. The judge, however, did allow the defense to immediately interview another detainee, Abdu al-Sharqawi, an alleged al-Qaida operative known as "Riyadh the facilitator," who is not considered high-value. Allred said the defense could also speak with a prisoner who was captured with Hamdan in Afghanistan, but the man's lawyer has said he will refuse to testify without a grant of immunity from prosecution from the military authority overseeing the tribunals. Hamdan, who is from Yemen, has been charged with conspiracy and supporting terrorism and faces up to life in prison if convicted. He came to court in a flowing white robe and a grey-checkered sports coat, and smiled when technical difficulties with a translation system delayed the proceedings. Hamdan has been in custody nearly six years and was first charged more than three years ago. But his prosecution has been delayed by legal challenges, including one he filed that went to the Supreme Court and resulted in the striking-down last year of the original rules for military tribunals. Congress and President responded with the Military Commissions Act, which stripped all detainees of the right to challenge their detention in a civilian court - the focus of Wednesday's Supreme Court hearing. Air Force Brig. Gen. Thomas Hartmann, the legal adviser to the military tribunal system, said the timing of the hearings in Guantanamo and Washington was coincidental. The US holds about 305 prisoners on suspicion of terrorism or links to al-Qaida and the Taliban at Guantanamo and plans to prosecute at least 80, including the alleged architect of the Sept. 11 attacks. So far, only three detainees have been formally charged and one, Australian David Hicks, was convicted in a plea bargain and sent home. Hamdan's defense team argues that he should be considered an enemy prisoner of war who would be entitled to the same rights as a captured U.S. service member and a court martial - a legal system that critics of the government's tribunal system say has more legal protections for defendants.