The chief of the Guantánamo war court has approved the use of a time delay on public viewing of the Sept. 11 death-penalty trial as well as a censor in his court to make sure nobody divulges details of a now defunct CIA interrogation program, citing national security interests.

The American Civil Liberties Union challenged the 40-second delay, arguing that the Pentagon had transformed the courtroom at Camp Justice in Cuba into a “censorship chamber” for the coming death penalty trials. The rules effectively prevent the public from learning anything about what the CIA did with the alleged terrorists before their 2006 transfer to Guantánamo for trial.

Spectators who watch the proceedings at the war court sit in a soundproof room, watching the trial live but hearing the audio 40 seconds later. If a court security officer functioning as a censor deems what is being said is a national security secret, the sound is obscured by white noise.

Army Col. James L. Pohl, the judge, wrote in his five-page decision that he is “acutely aware” that he has “twin responsibilities of insuring the transparency of the proceeding while at the same instance preserving the interests of national security.”

But, he wrote, “the brief delay is the least intrusive and least disruptive method of meeting both responsibilities.”

The delay lets a security officer who sits near the judge push a button to muffle any details that the trials might divulge of the captives’ years of captivity in the CIA’s now closed secret overseas prison network — who captured them, interrogated them, where and using which Bush-era “enhanced interrogation techniques.” All the men say they were tortured by the CIA — which has admitted to waterboarding the alleged mastermind 183 times — to extract confessions and other information in the program that the Obama administration has since banned.

The censor has done this twice this year, both times to stop the public from hearing defense lawyers, and both times in error.

The chief prosecutor, Army Brig. Gen. Mark Martins, has said only voluntary confessions will be admissible at the trial of five men accused of orchestrating, financing and training the 19 hijackers who killed nearly 3,000 people on Sept. 11, 2001.

Charged are alleged mastermind Khalid Sheik Mohammed, 47, who told a Guantánamo panel after his transfer from CIA custody that he devised the Sept. 11 attacks “from A to Z” and four alleged conspirators. They are Yemenis Ramzi bin al Shibh, 40, and Walid bin Attash, 34, described as Mohammed’s deputies; and two men accused of helping arrange the hijackers’ travel and United States finances, Saudi Mustafa al Hawsawi, 44, and Pakistani Ammar al Baluchi, 35.

All are charged with war crimes to be heard by a jury of military officers, which can also order their execution.

The judge explained the security arrangements in a ruling and accompanying 20-page “protective order” ruling, which he also signed Dec. 6. Both were made public on a Defense Department website Tuesday evening after the Pentagon gave the intelligence agencies an opportunity to scrub them of information the public shouldn’t see.

In this instance, they were released unredacted.

The protective order itself spells out that anything about their CIA custody is classified, including “their observations and experiences,” meaning the accused can’t say what happened to them at the so-called “dark sites” in open court.