Lawyers for five Guantanamo Bay prisoners charged with plotting the September 11, 2001, attacks have asked US President Barack Obama to declassify the CIA programme that subjected the defendants to interrogation techniques that have been described as torture.
In a letter made public on Friday, the lawyers asked the president to release potentially mitigating information that could spare the defendants from execution if they are convicted on charges of hijacking, violent campaign and murdering nearly 3,000 people.
The CIA's Rendition, Detention and Interrogation programme, or RDI programme, was authorised by President George W. Bush's administration after the September 11 attacks.
It allowed captives suspected of links to al-Qaeda to be seized, transferred without judicial review to secret overseas prisons and subjected to "enhanced interrogation techniques" such as sleep deprivation, extreme temperatures and a simulated drowning method called waterboarding.
"The existing classification restrictions surrounding the RDI programme only facilitate further concealment of war crimes committed by agents of our government," the lawyers wrote to Obama.
Military officials have said much of the information is classified by the government because it could threaten national security if it's released publicly.
The defence lawyers say the evidence would show that the US violated the international Convention Against Torture, which President Ronald Reagan signed in 1988 and the US Senate ratified in 1994.
The secrecy restrictions violate the universal prohibition against silencing victims of torture, their letter said.
"These self-serving restrictions also prohibit us from faithfully discharging duties and defending these men in a manner consistent with our most cherished values," it said.
A White House spokeswoman confirmed receipt of the letter, but did not comment on the declassification request, instead noting that the CIA was cooperating with a report on the RDI programme by the Senate Select Committee on Intelligence.
"The president has made clear that the programme that is the subject of the committee's work is inconsistent with our values as a nation," she said.
The defence lawyers repeated their requests for the classified information this week during a pretrial hearing in the war crimes tribunal at the Guantanamo Bay US Naval Base in Cuba.
On Friday, defence lawyers and prosecutors debated whether the government should return laptops that were issued to the defendants during a Bush-era prosecution attempt and later seized.
They also debated whether the defence teams had enough Arabic translators and whether the defendants could be photographed to document injuries that allegedly occurred while they were in US custody.
The letter to Obama was signed by 14 military and civilian defence lawyers representing the prisoners.
The defendants include Khalid Sheikh Mohammed, the confessed mastermind of the September 11 plot, who was waterboarded 183 times while in CIA custody.
"Quite simply, the classification of the RDI programme is suppressing evidence, suppressing the truth and ultimately will suppress any real justice," the lawyer's letter said.
Obama banned further use of waterboarding and other "enhanced interrogation techniques" shortly after taking office in 2009, calling them "torture".
Navy Commander Walter Ruiz, one of the defence lawyers who signed the letter, said the lawyers appealed to Obama because "the court does not have the authority to declassify these documents".
The president does have the authority, he said. Army Brigadier General Mark Martins, the chief prosecutor in the case, declined to comment on the defense team's letter to Obama during a news conference after the hearing.
But he said issues of torture could arise during the trial. "The totality of the circumstances does include looking at prior treatment," Martins said.