The surge of Democratic opposition to President Bush’s nomination of former Judge Michael Mukasey to be attorney general says a lot about certain Democrats, especially after the initial bipartisan applause for a superbly qualified man who has clearly repudiated Bush’s previous claims of near-dictatorial powers.

It is especially telling that the main congressional objection to Mukasey has been his unwillingness to declare illegal an interrogation technique that Congress itself has assiduously and repeatedly declined to declare illegal.

The technique, called "waterboarding," involves simulated drowning. Congress could seek to explicitly ban it, along with other highly coercive techniques. It has not done so, because it does not want to take the blame for any future terrorist attacks that might have been prevented by highly coercive interrogation.

The attacks on Mukasey are an exquisite example of Congress’s penchant for avoiding accountability by leaving the law unclear and then trashing the executive for whichever interpretation it adopts whenever something goes wrong.

Some factual context:

• Our government has not used waterboarding since 2005, according to news reports, and seems unlikely to use it again soon, if ever.

• Before suspending the practice in 2005, the CIA reportedly waterboarded three (and perhaps only three) people, all of them Qaeda terrorists deemed highly likely to have potentially lifesaving information.

• The Bush Justice Department has repeatedly found at least some forms of waterboarding to be legal under the narrow but vague 1994 and 2005 laws defining, respectively, the crime of "torture," and "cruel, inhuman, or degrading" treatment.

Mukasey has called waterboarding, as described in media accounts, "repugnant to me." But he has properly refused to issue a definitive statement that it is always illegal. Part of the reason is that Mukasey has not been briefed on details of exactly what CIA interrogators have done and whether it went on for, say, 10 hours, 10 minutes, or 10 seconds. And part of the reason, in my view, is that waterboarding is illegal in almost all — but not necessarily all — cases.

The senators who insist that Mukasey answer hypothetical questions about waterboarding are thus demanding that, without knowing exactly what CIA interrogators did, the nominee risk appearing to retroactively brand these career officials as war criminals, even though they acted in good-faith reliance on the authoritative Justice Department legal opinions that were then in place. Not to mention that he risk providing pretexts for morally preening European prosecutors to snatch U.S. officials and former officials traveling abroad.

I hope and believe that Mukasey will issue a legal opinion soon after being confirmed (as he should be) effectively banning waterboarding in almost all circumstances as "cruel, inhuman, or degrading" treatment. But if Congress wants to make it a crime to ever use waterboarding, or face-slapping, or other specified interrogation techniques, then Congress should stop ducking accountability and adopt new legislation, as Sen. Joseph Biden, D-Del., has now proposed, after full and open debate.

I look forward to hearing Sen. Hillary Rodham Clinton, D-N.Y., Sen. Barack Obama, D-Ill., and others who oppose Mukasey’s nomination because of this issue explain why the undoubted moral and diplomatic benefits of a blanket criminal prohibition of waterboarding would outweigh the possible costs, which might be zero but just might be thousands of lives.

But, one might reasonably ask, isn’t torture by CIA interrogators already a crime? And isn’t waterboarding a form of torture? The answer to the first question is yes, under a 1994 criminal law implementing the U.N. Convention Against Torture and Other Cruel, Inhuman, or Degrading Treatment or Punishment. The answer to the second question is more debatable.

Of course, being strapped to a board with a cloth over one’s face and enough water running over one’s nose and mouth to create the sensation of drowning sounds horrible and has been deemed illegal in various contexts by past administrations. But not every interrogation practice that sounds horrible or has been deemed illegal in some contexts clearly meets, in all contexts, the vague but narrow definitions embedded in the 1994 ban on "torture," or in the December 2005 McCain amendment’s ban on "cruel, inhuman, or degrading treatment or punishment."

The 1994 law defines torture as including only practices "specifically intended" to inflict "severe physical … pain or suffering" and certain other practices that cause "prolonged mental harm" (emphasis added). Under this definition, deliberately inflicting pain that is not quite "severe," or mental harm that is not quite "prolonged," is no crime.

To be sure, the 1994 definition is not so narrow as to justify the claim that only the pain associated with "death, organ failure, or serious impairment of body functions" would qualify as "severe," as the Bush Justice Department asserted in an infamous, now-repudiated August 1, 2002, memo. But the definition is certainly narrow enough to leave room for doubt whether it would be torture to waterboard a high-level terrorist for, say, 15 seconds. Indeed, U.S. military and intelligence agencies have reportedly waterboarded their own people as part of their training on how to resist interrogation.

Nor is it clear that all forms of waterboarding violate the McCain amendment’s provision specifying that the ban on CIA use of "cruel, inhuman, or degrading" treatment (called "CID") extends worldwide. The amendment, passed amid much discussion of waterboarding, limited military interrogators to the list of relatively mild, traditionally approved interrogation methods in the new Army Field Manual, which prohibits all physical coercion.

But Congress quite deliberately chose not to limit the CIA to those methods, and thus tacitly gave the CIA approval to use unspecified forms of physical coercion. Moreover, Congress defined CID as limited to forms of coercion that would violate certain provisions of the Constitution, which the Supreme Court has held to prohibit only practices that "shock the conscience." The case law suggests that whether various interrogation practices shock the conscience depends on the importance and urgency of the information likely to be obtained and "exact analysis of [the specific] circumstances."

Waterboarding and some other highly coercive techniques would shock my conscience if used routinely or frequently on terrorism suspects. That’s why I believe that, once confirmed, Mukasey will issue a legal opinion effectively banning waterboarding as CID in almost all circumstances.

But should Mukasey rule that waterboarding is always illegal? Even in the cases of those very few, if any, detainees who seem highly likely to have potentially lifesaving information? And even if it were done under rules requiring high-level, case-specific approval and prompt disclosure to the Intelligence committees? I don’t think so.

Human-rights activists and some experts claim that all highly coercive interrogation techniques shock the conscience because they are virtually useless in eliciting valuable information. But other, perhaps better-informed, experts are quite convinced that coercive interrogation has saved lives. Former CIA Director George Tenet, for one, told CBS’s 60 Minutes in April that what Bush calls "enhanced" interrogation "is worth more than [what] the FBI, the Central Intelligence Agency, and the National Security Agency, put together, have been able to tell us" about terrorists’ plans.

Mukasey’s unwillingness to declare waterboarding illegal also reflects a proper sensitivity to some little-noticed cautions in The Terror Presidency, the justly celebrated book by former Bush Justice Department official Jack Goldsmith. The author has won praise from Democrats for his devastating repudiation of Bush administration excesses in the war against terrorism. But Goldsmith is no less devastating in rejecting the when-in-doubt-it’s-illegal approach of human-rights groups and a growing number of Democrats.

Before September 11, 2001, Goldsmith asserts, "intelligence officers spooked by cautious lawyers failed to take actions that might have prevented the 9/11 attacks." And since 9/11, CIA interrogators, their superiors, and their legal advisers have been "exposed to a buzz saw of contradictory commands: [You must] stay within the confines of the law, even when the law is maddeningly vague, or you will be investigated and severely punished; but [you must also] be proactive and aggressive and imaginative, push the law to its limit, [and] prevent another attack at all costs, or you will also be investigated and punished."

Clinton typifies this congressional penchant for having it both ways. She said last month that torture "cannot be American policy." But almost everybody says that, including Bush. And Clinton left plenty of wiggle room for extreme cases. Indeed, last year she said that the president might properly "depart from standard international practices" by approving rough interrogation of "a detainee with knowledge of an imminent threat to millions of Americans."

Clinton has not ruled out waterboarding as illegal in such a case. Nor has she said she would rule out waterboarding if only thousands, or hundreds, or dozens of American lives were at risk. So she opposes Mukasey for failing to take a categorical legal position that she herself has never taken — and, I’d wager, never will.