Imagine that U.S. forces capture Osama bin Laden or a high-level lieutenant in Pakistan next month and hand him over to the CIA, amid intelligence reports that a massive new Qaeda attack on America may be imminent.

Should it be illegal for CIA interrogators to try to scare the man into talking by yelling at him? By threatening to slap him? By pretending to be from Egypt’s brutal intelligence service? What about turning up the air conditioner to make him uncomfortably cold? Or denying him hot food until he talks, while giving him all the cold food he can eat?

These methods would all apparently be illegal under a rider that the House-Senate conference committee added to the annual intelligence authorization bill. It would bar the CIA from using any interrogation practice not authorized in the Army field manual’s rules for military interrogators. This would mean prohibiting almost all forms of coercive interrogation, including many potentially effective techniques that come nowhere near torture and are now clearly legal.

We’ve come a long way since September 2002, when Nancy Pelosi, then a House Intelligence Committee member and now the speaker, listened without a peep of protest while being briefed about the CIA’s use of waterboarding and other harsh interrogation methods on Qaeda leaders.

Now almost all Democrats (and some Republicans) denounce waterboarding as illegal torture. They are probably right — although you can bet that after the next 9/11 they will backtrack faster than you can say "unprincipled."

The mostly Democratic sponsors of the proposed legislation unpersuasively suggest that it is necessary to prevent torture. They also hide behind the fantasy that coercion never leads to good information. But there is substantial (if anecdotal) evidence that in some cases, at least, coercive interrogation methods far short of torture may well extract information that could save lives.

In a 2004 book titled The Interrogators, for example, co-author Chris Mackey, who conducted Army interrogations in Afghanistan, condemned torture but detailed how "the harsher the methods we used — though they never contravened the [Geneva] Conventions, let alone crossed over into torture — the better the information we got and the sooner we got it."

To be sure, the Bush administration has shown that it cannot be trusted to respect the current legal prohibitions on torture and near-torture. And it is past time for Congress to adopt more-specific restrictions. It is also understandable that many in Congress — now in an uproar over the CIA’s destruction of videotapes of earlier torturous interrogations — are tempted to prevent evasion of the law by simply banning coercion.

But it would be irresponsible in the extreme for Congress to do this. And Bush is right to threaten a veto.

It does make a great deal of sense to prohibit military interrogators from using even those coercive methods that are clearly allowed by criminal and international law. But it makes little sense to impose the same restrictions on the CIA.

The military holds tens of thousands of prisoners in occupied Iraq and in Afghanistan. Most are small-fry with little or no useful information. Most also qualify for the kid-glove treatment required by the Geneva Conventions for citizens of occupied countries as well as for uniformed POWs. In addition, low-ranking personnel, who have much less professional training and supervision than CIA interrogators, are often the ones who conduct military interrogations. This helps explain the catastrophic breakdown of discipline exposed by the Abu Ghraib torture photos.

These are among the reasons why the military has traditionally imposed elaborate restraints on its interrogators and why, after intense internal debate, Pentagon General Counsel William Haynes approved amendments to the Army field manual in September 2006 that made these restraints more exacting than ever before.

The CIA, on the other hand, has a small cadre of highly trained professional interrogators operating far from combat zones and under close supervision. These attributes provide some insurance against the admittedly grave danger that individual interrogators will get carried away and, for example, freeze a detainee nearly to death when they had been authorized only to keep him uncomfortably cold during a two-hour session.

That’s why the CIA gets custody of only the relatively small number of terrorist leaders, none of them POWs, who seem most likely to have potentially lifesaving information. Since 9/11, for example, the CIA has used "enhanced" interrogation techniques on only about 30 detainees.

The expectation that the CIA would handle tough interrogations of high-value captives informed both the Detainee Treatment Act of 2005 and the Military Commissions Act of 2006, in which Congress codified the Army field manual’s restrictions on military interrogations while imposing much looser, and vaguer, restrictions on the CIA.

The current push to subject the CIA to the same restraints as the military may reflect congressional unawareness of just how restrictive the new Army field manual is. It not only prohibits practices that violate international or criminal law, such as waterboarding, mock executions, inducing hypothermia, electric shock, and burns. It also prohibits any technique other than those on a list of 19 that allows various forms of trickery but excludes threats, intimidation, an unfriendly poke in the chest, and much more.

Consider Section 8-35. The heading, "Emotional Fear-Up Approach," sounds ominous. But the section specifies that an interrogator "must be extremely careful that he does not threaten or coerce" a detainee or "act as if he is out of control or set himself up as the object or focal point of the [detainee’s] fear."

If Congress binds the CIA to provisions such as this, it will not only be prohibiting a light slap in a Qaeda leader’s face; it will also be prohibiting a threat to slap him. This, even though threats clearly fall outside the legal definition of torture, with the exception of threats specifically intended to cause fear of "imminent" death and "prolonged" mental harm.

Does Congress really want to make it unlawful for the CIA to threaten to slap Osama bin Laden (if he is captured) in the face? Or to put him through the indignity of being served MREs until he cooperates?

This is not to say that the CIA should be free to subject all its detainees to any and all interrogation methods short of torture, and of the "humiliating and degrading treatment" prohibited by Common Article 3 of the Geneva Conventions. But the CIA should be able to come a lot closer to that line than the military.

So instead of binding the CIA to the Army field manual, Congress should require it to make public its own list of permitted and prohibited interrogation techniques, perhaps with a classified appendix to avoid giving terrorists a road map for resisting. Congress should then codify the CIA manual as law, with any changes that Congress may consider necessary.

This CIA manual should allow yelling, threats, and other intimidation techniques that clearly do not rise to the level of torture or violate Geneva’s Common Article 3.

Leading experts on the laws of war have also suggested persuasively that Congress should make a special provision for emergencies, allowing the president to authorize specified interrogation techniques for specified detainees that may violate Geneva — but not the torture ban. To ensure political accountability, the president should be required to give the Intelligence committees a written finding detailing both his justifications and the authorized techniques.

What about the hypothetical "ticking bomb" scenario, or other dire circumstances in which illegal torture appears to be the only chance of averting catastrophe? Consider former CIA interrogator John Kiriakou’s astonishing account in interviews aired by ABC News on December 10 and published in the next day’s Washington Post.

Captured Qaeda lieutenant Abu Zubaydah successfully resisted various high-pressure interrogation tactics for weeks in 2002. Then the CIA waterboarded him. He broke after about 35 seconds, and soon was sharing information that, Kiriakou claimed, may have disrupted dozens of attacks and saved many lives.

But as Kiriakou added, the waterboarding also probably amounted to torture. So unless we choose to disregard Kiriakou’s account, we have five choices in cases such as this: 1) We should evade the law by pretending that this was not torture, as Bush has done; 2) We should make torture legal in such cases; 3) We should imprison the interrogators (or the superiors who gave them orders) for crimes, on the ground that they should have stood by and waited for the possibly preventable mass-murder attacks that they expected; 4) We should imprison them for crimes even if we think they did the right thing; 5) The president should pardon them.

I would choose Option 5. But the question now before Congress is much, much easier: Should it be illegal for CIA interrogators even to threaten the likes of Zubaydah with waterboarding, or with any unpleasantness at all?