A lot of Democrats, editorialists, and others have said not only that waterboarding is torture (as Sen. John McCain has) but also that the CIA’s use of that practice on three Qaeda leaders in 2002 and 2003 obviously violated a 1994 law making torture a crime. From that premise, some have said or implied that:

• The administration lawyers who have come to the opposite conclusion — now including Attorney General Michael Mukasey, as well as those who approved the use of waterboarding in advance — were acting in bad faith.

• These lawyers (or at least some of them) should be subject to professional discipline both by the Justice Department’s Office of Professional Responsibility, which is investigating the matter, and by state disciplinary authorities with power to disbar unethical lawyers.

Some have also called for criminal prosecution of the CIA interrogators who used harsh techniques, including waterboarding, and/or of the higher-level officials who approved the techniques, in reliance on Justice Department legal opinions.

It’s hard to see where the logic of the more passionate critics stops, short of suggesting what few have so far said overtly: that President Bush, former CIA Director George Tenet, and other top officials and former officials should be prosecuted as war criminals, presumably by the next administration.

This is a dangerous line of argument based on a flawed legal premise.

It is dangerous because the last thing this bitterly divided country needs is years — indeed, decades — of recriminations over whether the Bush administration’s war on terrorism has been a criminal enterprise whose leaders belong in prison. We should focus on amending the law to prevent future abuse of waterboarding and other repugnant techniques, not on hounding those responsible for past interrogations of questionable legality.

The flawed legal premise is the view that waterboarding — pouring water over a bound prisoner’s nose and mouth to induce a desperate sensation of drowning — was so obviously illegal torture that those responsible for the practice should be held legally accountable.

I have previously suggested that waterboarding was probably torture. But I am less confident of that opinion now than I was then. It can at the very least be plausibly argued (as detailed below) that if waterboarding is limited in duration and carefully controlled, it does not meet the 1994 law’s narrow definition of torture.

If I’m right about that, then it would be quite wrong, as Mukasey has said, to prosecute any of those involved. Not only were they trying to save innocent lives by gaining vital intelligence, they were also acting in reliance on the Justice Department’s advice that waterboarding was legal.

It would also be wrong, in my view, to subject the lawyers who gave that advice to professional discipline or disbarment, as critics — including my friend Harvey Silverglate, a distinguished Boston civil-liberties lawyer — have suggested, absent evidence not only of excessive zeal but also of deliberate dishonesty.

To be sure, the Justice Department’s original, now-infamous August 1, 2002, "torture memo," which maintained that the president had illimitable power to authorize even the most egregious forms of torture, was so widely, and properly, denounced as extreme and indefensible that the administration declared it inoperative soon after it leaked in June 2004.

But the authors of that memo were far from alone in concluding that waterboarding was legal. A substantial number of other, more respected lawyers in the Justice Department, in the CIA, and on the National Security Council also endorsed that conclusion, as did the December 2004 memo that superseded the original torture memo’s interpretation of the 1994 law. The later memo, written by acting Assistant Attorney General Daniel Levin, was welcomed fairly extensively as a sound legal analysis. At the time, few objected to Levin’s crucial footnote endorsing the legality of the coercive interrogation techniques (without identifying them) that the CIA had previously used. News reports had identified waterboarding as one of those techniques. The White House and the CIA reportedly insisted that Levin add the crucial footnote. He agreed after he had himself subjected to waterboarding as part of his research.

Meanwhile, several members of the congressional Intelligence committees, including Democratic Reps. Nancy Pelosi, now the House Speaker, and Jane Harman, raised no legal objection when they were briefed on the CIA’s use of harsh techniques, including waterboarding. (Harman did raise a policy objection.)

How could so many lawyers and other officials fail to appreciate the commonsense view — embraced in decades and centuries past by authorities in the U.S. and elsewhere — that simulated drowning is torture? Because interpreting a criminal law requires close attention to exactly what it says, not what it should say.

The 1994 law’s extraordinarily narrow definition of "torture" is critical to understanding why a reasonable lawyer could declare waterboarding personally "repugnant," as did Mukasey during his confirmation hearing, while at the same time believing that if it is short in duration and carefully controlled, it is not necessarily "torture."

The 1994 law, which Congress adopted to enforce a United Nations convention, defined torture as an act "specifically intended to inflict severe physical or mental pain or suffering" on a prisoner.

Does waterboarding inflict severe physical pain or suffering? That depends on the inherently elastic meaning of "severe." Waterboarding is clearly more severe than (say) a single face slap. But it is clearly less severe than (say) yanking out a prisoner’s fingernails. The fact that the military has long waterboarded its own soldiers in training to teach interrogation-resistance techniques cuts against the idea that it inflicts severe physical suffering.

I also suspect that many a lawyer’s interpretation of "severe" might turn on how close in time his decision was to a terrorist mass murder that he fears could soon be repeated. Just as gravity bends light, the need to prevent a catastrophe bends judgment on such subjective questions. And it should.

Waterboarding surely inflicts "severe mental pain or suffering," as most people understand those terms. But Congress further narrowed the usual meaning of "severe" in this context to include only "the prolonged mental harm caused by or resulting from … the threat of imminent death" or mind-altering substances.

This definition probably does not include waterboarding, for two reasons. First, a hardened terrorist such as Khalid Shaikh Mohammed was presumably aware that his interrogators wanted to get him to talk, not kill him. Second, while a dozen near-death waterboarding sessions in the space of a day might cause "prolonged mental harm," the CIA’s waterboarding of the three Qaeda leaders was reportedly quite limited in duration. Nor was prolonged mental harm what the interrogators "specifically intended."

Am I resorting to minute legalisms to bless repugnant conduct? No. I am interpreting a criminal law whose drafters deliberately defined torture very narrowly. The point is that we should not prosecute (or disbar) people for relying on the law as it is written — especially when their underlying motivations were to obtain intelligence that might save innocent lives.

Looking to the future, the question is whether Congress should clearly specify that waterboarding and similarly brutal interrogation techniques are crimes. My answer is yes, subject to the special presidential waiver for emergencies outlined in my December 15, 2007, column.

Currently the law in this area is a mess: The 1994 statute’s definition of torture is too vague, as illustrated above. So is the McCain amendment to the December 2005 Detainee Treatment Act; when read together with the relevant case law, it prohibits only interrogation techniques that "shock the conscience." And it includes no criminal penalties. The interrogation provisions of the Military Commissions Act of 2006 do provide criminal penalties but are also quite vague.

Congress lurched to the opposite extreme by adopting a rider to the pending intelligence authorization bill (again, without criminal penalties) that would bar the CIA from using any interrogation technique not authorized in the Army field manual’s rules for military interrogators. The media have suggested — and most members of Congress may mistakenly assume — that this would ban only waterboarding and other extreme techniques. But in fact, as explained in my December 15 column, it would also ban any and all techniques that "threaten or coerce" prisoners in any way, such as angry shouting or bluffing to scare a prisoner into thinking that he might be physically abused.

President Bush has vowed to use his veto to block this provision. And it appears that the interrogation rules will remain a mess until the next administration, which should push Congress to clarify the rules.

More important than the details is that new legislation come as close as possible to embodying a national consensus on what the rules should be. To that end, the presidential candidates should move beyond rhetorical posturing about torture and specify what (if any) legislation they will propose if elected.