"The circumstances surrounding the confession of Mohammed, whom law-enforcement
officials refer to as K.S.M., were perplexing. He had no lawyer. After his
capture in Pakistan, in March of 2003, the Central Intelligence Agency had
detained him in undisclosed locations for more than two years; last fall, he was
transferred to military custody in Guantánamo Bay, Cuba. There were no named
witnesses to his initial confession, and no solid information about what form of
interrogation might have prodded him to talk, although reports had been
published, in the Times and elsewhere, suggesting that C.I.A. officers had
tortured him. At a hearing held at Guantánamo, Mohammed said that his testimony
was freely given, but he also indicated that he had been abused by the C.I.A.
(The Pentagon had classified as “top secret” a statement he had written
detailing the alleged mistreatment.) And although Mohammed said that there were
photographs confirming his guilt, U.S. authorities had found none. Instead, they
had a copy of the video that had been released on the Internet, which showed the
killer’s arms but offered no other clues to his identity. "
That is the problem with secret trials, they have been abused in the past, the power has been abused and people don't trust it. If you want to assure the American people that you are being honest, working to protect them, and doing your best to discover truth - you need a witness. It doesn't need to be an open trial, there are clear understandable reasons why that would not work. However a trial needs to be done in such a way that the accused is proven to be guilty beyond a reasonable doubt. When all the evidence is a secret, and all the interrogations are done in secret, there is only doubt.