Washington (CNN) -- Lawyers for a terror suspect detained at Guantanamo -- linked by authorities to the bombing of the USS Cole -- say his waterboarding and other mistreatment plus delays in his case should force the government to halt his pending military trial and possible death sentence.
The government says Abd al Rahim Hussayn Muhammad Al-Nashiri was the mastermind behind the 2000 bombing that crippled the U.S. warship and killed 17 sailors.
Al-Nashiri's lawyers have filed a brief with the military commission asking that the proceedings stop.
"By torturing Mr. Al-Nashiri and subjecting him to cruel, inhumane and degrading treatment, the United States has forfeited its right to try him and certainly to kill him," the brief said. "Through the infliction of physical and psychological abuse, the government has essentially already killed the man it seized almost 10 years ago."
Al-Nashiri's legal team is making its request to the so-called Convening Authority of the military court, retired Vice Adm. Bruce MacDonald, who has the power to decide whether cases go to trial at Guantanamo Navy Base in Cuba. The military commission was established by President George W. Bush and overhauled by President Barack Obama.
"The United States has lost its moral authority to seek the death penalty," the defense brief says. "Accordingly, you should not refer charges -- or authorize the death penalty -- against Mr. Al-Nashiri."
His lawyers say Al-Nashiri was waterboarded. Also, while he was naked and hooded, his questioners revved a power drill in his hearing and chambered a round in a handgun, they say.
"The government has admitted to waterboarding Mr. Al-Nashiri and subjecting him to verbal and physical threats to his life and threats to the safety of his family. Both set of acts constitute torture," the brief says.
CNN obtained a copy of the legal document, which was filed at the end of last week and is the latest signal that the Al-Nashiri case is moving forward, with a possible arraignment later this summer.
A military trial of Al-Nashiri is seen as a test of the law and the procedures at Guantanamo before the 9/11 defendants are prosecuted in coming months or years.
Defense lawyers have complained that they have been denied "meaningful discovery" about what information the prosecution has.
"Other than some partial medical records from Guantanamo, Mr. Al-Nashiri and his counsel have been denied discovery from the prosecution," the defense brief says. "The defense is unable to even discern what evidence supports the prosecution's allegations ... accordingly the defense cannot make any principled showing of the weaknesses in the prosecution's case."
The defense also says they are facing other difficulties in preparing for a trial, including political upheaval in Yemen where the USS Cole bombing took place and the CIA's destruction of the videotapes made of Al-Nashiri's interrogation.
"The world wonders whether the Untied States will continue to be an example of how fair trails are conducted or whether it will descend further down the path of expedient and secret justice that Military Commissions have come to represent," the defense brief says.
Government prosecutors have not yet responded to a CNN request for comment.