WASHINGTON - A federal judge on Friday appeared reluctant to give Donald H. Rumsfeld immunity from torture allegations, yet said it would be unprecedented to let the departing defense secretary face a civil trial.

"What you're asking for has never been done before," U.S. District Judge Thomas F. Hogan told lawyers for the American Civil Liberties Union.

The group is suing on behalf of nine former prisoners in Iraq and Afghanistan. The lawsuit contends the men were beaten, suspended upside down from the ceiling by chains, urinated on, shocked, sexually humiliated, burned, locked inside boxes and subjected to mock executions.

If the suit were to go forward, it could force Rumsfeld and the Pentagon to disclose what officials knew about abuses at prisons such as Abu Ghraib prison in Iraq and what was done to stop it.

Rumsfeld, who leaves the Defense Department on Dec. 18, told Pentagon employees and reporters Friday that the day he learned about abuses at Abu Ghraib was his worst day in office.

"I remember being stunned by the news of the abuse at Abu Ghraib," Rumsfeld said. "And then watching so many determined people spend so many months trying to figure out exactly how in the world something like that could have happened, and how to make it right."

Lawyers for the ACLU and Human Rights First, however, argue that Rumsfeld and top military officials disregarded warnings about the abuse and authorized the use of illegal interrogation tactics that violated the constitutional rights of prisoners.

Foreigners outside the United States are not normally afforded the same protections as U.S. citizens, and Hogan said he was wary about extending the Constitution across the globe.

Doing so, he said, might subject government officials to all sorts of political suits. Osama bin Laden could sue, Hogan said, claiming two American presidents threatened to have him murdered.

"How do you control that?" Hogan asked. "Where does it stop? Does it stop at the secretary of defense? Does it stop at the president? How does this work?"

The Justice Department argues that is exactly why government officials generally are immune from suits related to their jobs. By allowing the case to proceed, Hogan would make all future military operations subject to second-guessing by the courts, the government contends.

"We cannot have courts interfering with core military functions," Deputy Assistant Attorney General C. Frederick Beckner III said.

Hogan questioned the scope of that immunity. He said freedom from torture is a basic right accepted by the United States and all civilized nations.

"Would you take the same policy if the argument was one of genocide?" Hogan asked. "Are you saying there could be no inquiry done?"

Beckner said abuse claims should be handled by the military, which has prosecuted more than 100 such cases. In his farewell speech Friday, Rumsfeld said such prosecutions demonstrated "how our democracy deals openly and decisively with such egregious wrongdoing."

Lawyers for the civil rights groups, which have criticized the military's prosecution record, said the government is trying to operate a "rights-free" zone overseas.

"The defendants had a duty to deter and punish acts of torture and they did 180 degrees opposite of that: They encouraged and directed that torture," lawyer Paul Hoffman said.

Hogan said torture is a crime against mankind, but he did not see how the Constitution applied to foreigners held in overseas military prisons.

Hogan said he would rule quickly on whether to dismiss the case; he did not make a decision Friday.

The other officials named in the suit are: retired Lt. Gen. Ricardo S. Sanchez, former Brig. Gen. Janis L. Karpinski and Col. Thomas M. Pappas.

Karpinski, whose Army Reserve unit was in charge of the Abu Ghraib prison, was demoted last year and is the highest-ranking officer punished in the scandal. Sanchez, who commanded U.S. forces in Iraq, retired from the Army last month, calling his career a casualty of the prison scandal.

Pappas, the former top-ranking intelligence officer at Abu Ghraib, was granted immunity from prosecution in exchange for testimony about the abuse.

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