In a ruling and a set of rules for the trial, both of which were released Wednesday, the judge presiding over the case said the measures requested by prosecutors were necessary to prevent potential danger to national security by release of government secrets.
The rules include provisions that would prevent the defendants from publicly revealing details about their captivity in the CIA's clandestine network of overseas prisons before they were taken to the U.S. base in Cuba in September 2006.
The use of a 40-second delay allows a courtroom security officer to screen anything said inside the court to prevent it from being heard by spectators, who watch from behind soundproof glass or from a separate viewing area.
Lawyers for the American Civil Liberties Union and a coalition of media organizations, including The Associated Press, had argued against the 40-second delay and other aspects of the restrictions at a hearing in October, saying it would limit the public's access to one of the most significant terrorism prosecutions in U.S. history.
A lawyer for the ACLU also argued the restrictions will prevent the public from learning details about harsh conditions that the defendants endured while in CIA custody, treatment that human rights groups say amounts to torture.
The judge in the case, Army Col. James Pohl, said the use of a 40-second delay was the "least intrusive" way to protect national security while ensuring public access. In a statement, the ACLU said it would seek "further review" of his decisions.
The five prisoners are accused of orchestrating and aiding the terror attacks on Sept. 11, 2001. The men include Khalid Sheikh Mohammed, who has portrayed himself as the mastermind of the attacks. The defendants could get the death penalty if convicted in a trial that is at least a year away.