So the president has asked you to do something that he claims is crucial to the national security of the United States. He assures you that the action is legal. Can you go ahead and do it, secure in the knowledge that a presidential imprimatur will keep you from getting dragged into court sometime in the future?

Probably not, no. At the very least, run the scenario by an outside lawyer.

That's the lesson a careful observer might draw from a pair of controversies swirling through Washington in recent weeks. The question of potential liability for past actions is central to the Bush administration's push to grant immunity to telecommunications firms that aided the National Security Agency's warrantless wiretap program. It also threaded through Attorney General Michael Mukasey's hedged judgment as to the legality of waterboarding.

Overall, the issue has worried many administration officials for years, according to Jack Goldsmith, who headed the Justice Department's Office of Legal Counsel from 2003 to 2004.

On one hand, these officials face unrelenting pressure to prevent more terrorist attacks on the United States. On the other, they are supposed to stay within the lines of US law, including privacy and civil rights statutes.

"That some court or judge or prosecutor or investigator down the road would interpret these criminal laws differently than the administration did and hold them criminally liable was a central, prevalent concern in the administration," Mr. Goldsmith, now a professor at Harvard Law School, told a Senate Judiciary Committee hearing Oct. 2.

The question of legal immunity for telecommunications companies that helped the government eavesdrop on Americans without court orders is likely to be a hot topic in the Senate this week. The Senate Judiciary Committee is scheduled to decide if it wants to include such retroactive protection in the new electronic surveillance legislation, which is wending its way through Congress.

Telecoms face lawsuits

Telecommunications companies face more than 30 lawsuits alleging that the firms violated customers' rights by cooperating with the government's surveillance effort. Immunity, if granted by lawmakers, would make such suits moot.

The Bush administration says it will veto the surveillance bill if the immunity provision is not included. It's only fair, supporters say, to protect an industry that answered a presidential call after 9/11.

"If the local fire company asked for your help putting out a neighbor's blaze, you would not force the firefighters to justify their request. You would just help, right? That's what the phone companies did when the Bush administration asked them in secret for help with wiretaps to target Al Qaeda communications into and out of the country," wrote Lee Hamilton, a former House member and cochairman of the National Commission on Terrorist Attacks Upon the United States, also known as the 9/11 Commission, in an opinion piece on the subject.

Critics say immunity simply would provide an incentive for corporations to break the law in the future, by giving them the impression that they might count on obtaining an after-the-fact free pass.

Immunity would let the administration, as well as telecom firms, off the hook, according to Senate Judiciary panel chairman Patrick Leahy (D) of Vermont.

"Immunity is designed to shield this administration from any accountability for conducting surveillance outside the law," said Senator Leahy in an Oct. 31 statement. "It could make it impossible for Americans whose privacy has been violated illegally to seek meaningful redress."

Meanwhile, by refusing during his Senate confirmation hearings to directly equate waterboarding with illegal torture, Mr. Mukasey may have been trying to lessen the possibility that any Central Intelligence Agency interrogators who used the harsh technique against terror suspects will face criminal prosecution or civil lawsuits in the future.

Such interrogators may have been depending on the past assurances of higher-ups that their conduct was within the bounds of US and international law. If Mukasey had contradicted those assurances, it might have been tantamount to admitting that the US had engaged in war crimes, say legal experts.

In a written response to Senate questions, Mukasey said he would not want to make any "uninformed statement" that might place professional interrogators in the field "in personal legal jeopardy."

Future liability for interrogators?

It's conceivable that interrogators might eventually have to face civil litigation filed by detainees, says Carl Tobias, a law professor at the University of Richmond. But any criminal case would have to be brought by the administration itself – an unlikely proposition, at best.

That calculus might change under a Democratic president. But even a Democratic administration would be unlikely to single out a low-level official, says Mr. Tobias. "The greater concern would be that someone in the White House who authorized waterboarding might be subject to some sort of investigation."

In waterboarding, the one being interrogated is strapped to an inclined bench. Cloth is placed over his mouth, and water is poured onto it, to the point where the liquid overcomes the gag reflex and begins to fill the throat and lungs. The Bush administration has never publicly confirmed use of the technique. According to news reports, the CIA in recent years has employed it three times – most successfully in the case of Khalid Sheikh Mohammad, a high-ranking Al Qaeda official captured in Pakistan in 2003.

The fact that immunity is such a live issue also points out the pitfalls of relying on presidential assurances of legality for potentially problematic activities, say legal experts.

The immunity debate shows that the Bush administration "is in partial retreat" from its past assertions that the Constitution grants presidents broad wartime powers that can't be fettered by statute, says Daniel Marcus, former general counsel of the 9/11 Commission.

In his book "The Terror Presidency," Goldsmith describes an administration in which officials knew they were pushing legal limits, and were preoccupied with concern about their own legal futures.

Goldsmith predicts that the US will see cycles, with the CIA and other agencies periodically pulling back for fear of retroactive discipline – until terrorists attack again, and US security personnel are pressured anew to go up to the legal edge.