A military judge has postponed the trial of Osama bin Laden’s former driver, Salim Ahmed Hamdan, saying the Supreme Court should first rule on the rights of inmates to contest their detention and to see if that ruling affects the detainees’ cases.

The Supreme Court is expected to rule by 30 June.

Hamdan was to be the first prisoner tried in the US detention facility at the Guantanamo Bay, Cuba.

In the case of five men accused of conspiring to kill thousands of people by finacing, directing and organizing the 9/11 suicide missions, who could face death penalty if convicted, the military defense lawyers said that the accused “are entitled to due process and a fair trial.”

“When the government seeks the death penalty, it must not reduce legal procedures to mere formalities.”

A US military judge has disqualified earlier this month the Pentagon’s top legal adviser, Gen. Thomas Hartmann of the Air Force Reserve, saying that he was too closely allied to the prosecution. He was supposed to provide impartial legal advice to the Pentagon appointee overseeing the Guantanamo trials but, as the former chief prosecutor of the tribunals testified last month, Hartman pushed the prosecution team to use evidence obtained through coercion, he pressured prosecutors to present certain cases because they were “sexy,” he suggested that factors others than case’s merits “were at play” and he tried to influence the professional judgement of the prosecutors.

Hamdan was scheduled to go to trial in early June but a military judge, Navy Capt. Keith Allred, delayed it until July 21. The ruling is the latest delay for the US government which is trying to prosecute Mr Hamdan, a Yemeni, for helping the al-Qaeda chief avoid capture in Afghanistan following the 11 September 2001 attacks on the US.

His lawyers ordered that a mental competency review be completed by June 13. They say that the years of detention and harsh treatment left him mentally impaired and seriously influenced his ability to assist in his defense.

Hamdan is charged with conspiracy and supporting terrorism and faces life in prison if convicted. He said he never joined al Qaeda, he denied taking part in any attacks but he acknowledged working for Bin Laden in Afghanistan for $200 (£99) a month.

Prosecutors say he was a trusted al Qaeda insider who transported weapons for the group and helped bin Laden escape U.S. forces in Afghanistan.