“This is just one of many areas,” a government brief said, “where it is inappropriate to compare C.S.R.T. proceedings with background principles that stem from domestic criminal law.”

Another aspect to the case in the appeals court that has caused public debate involves the government’s request that the court tighten restrictions on lawyers for the detainees. One proposal would have limited the number of visits the lawyers could make to Guantánamo, a request that the Justice Department withdrew Friday.

The practice of repeating some of the hearings is shrouded in secrecy. It first came to public attention in November, when a report by Seton Hall University Law School documented that “at least three detainees were initially found not to be enemy combatants” but were then reclassified as enemy combatants after a new hearing.

Reviewing records of 102 hearings that were obtained from the government through lawsuits, the report’s authors found that “at least one detainee, after his first and second tribunals unanimously determined him not to be an enemy combatant, had yet a third tribunal” that then classified him as an enemy combatant. About 380 men are now detained at Guantánamo.

Military officials have not said in how many cases such hearings were repeated.

A Pentagon spokesman, Lt. Cmdr. Chito Peppler of the Navy, acknowledged that some decisions had reversed earlier findings that detainees were not enemy combatants.

At the same time, Commander Peppler said, after reconsideration in Washington, some detainees benefited from tribunal hearings that were repeated and that reclassified them from enemy combatant to “no longer enemy combatant,” making them eligible for release.

Commander Peppler disputed the way the detainees’ lawyers described the repeat hearings. He said multiple hearings for a single detainee were part of the process. Under Defense Department rules, he said, the hearing process is not finished until a Pentagon official “completes final review and approval of the decisions of the tribunals.”