Torture is an impermissible evil. Except under two circumstances. The first is the ticking time bomb. An innocent’s life is at stake. The bad guy you have captured possesses information that could save this life. Even John McCain, the most admirable and estimable torture opponent, says openly that in such circumstances, “You do what you have to do.” And then take the responsibility.

Some people, however, believe you never torture. Ever. They are akin to conscientious objectors, who will never fight in any war under any circumstances, and for whom we correctly show respect by exempting from war duty. But we would never make one of them Centcom commander. It is similarly imprudent to have a person who would abjure torture in all circumstances making national security decisions upon which depends the protection of 300 million countrymen.

The second exception to the no-torture rule is the extraction of information from a high-value enemy in possession of high-value information likely to save lives. This case lacks the black-and-white clarity of the ticking time bomb scenario. We know less about the length of the fuse or the nature of the next attack. But we do know the danger is great. We know we must act but have no idea where or how – and we can’t know that until we have information. Catch-22.

Under those circumstances, you do what you have to do. And that includes waterboarding.

Did it work? The current evidence is fairly compelling. George Tenet said that the “enhanced interrogation” program alone yielded more information than everything gotten from “the FBI, the Central Intelligence Agency and the National Security Agency put together.”

Michael Hayden, CIA director after waterboarding had been discontinued, writes (with former Attorney General Michael Mukasey) that “as late as 2006 … fully half of the government’s knowledge about the structure and activities of al-Qaida came from those interrogations.” Even Dennis Blair, Obama’s director of national intelligence, concurs that these interrogations yielded “high value information.” So much for the lazy, mindless assertion that torture never works.

Asserts Blair’s predecessor, Mike McConnell, “We have people walking around in this country that are alive today because this process happened.”

Of course, the morality of torture hinges on whether at the time the information was important enough, the danger great enough and our blindness about the enemy’s plans severe enough to justify an exception to the moral injunction.

Judging by Nancy Pelosi and other members of Congress who were informed at the time, the answer seems to be yes. In December 2007, after a Washington Post report that she had knowledge of these procedures and did not object, she admitted that she’d been “briefed on interrogation techniques the administration was considering using in the future.”

Today Pelosi protests “we were not – I repeat – were not told that waterboarding or any other of these other enhanced interrogation methods were used.” She imagines that this distinction between past and present, Clintonian in its parsing, is exonerating.

On the contrary. It is self-indicting. If you are told about torture that has already occurred, you might justify silence on the grounds that what’s done is done and you are simply being used in a post-facto exercise to cover the CIA’s rear end. The time to protest torture, if you really are as outraged as you now pretend to be, is when the CIA tells you what it is planning to do “in the future.”

But Pelosi did nothing.

On the contrary, notes Porter Goss, then chairman of the House Intelligence Committee: The members briefed on these techniques did not just refrain from objecting; “on a bipartisan basis, we asked if the CIA needed more support from Congress to carry out its mission against al-Qaida.”

More support, mind you. It is one thing to have disagreed at the time and said so. It is utterly contemptible, however, to have been silent then and to rise now “on a bright, sunny, safe day in April 2009” (the words are Blair’s) to excoriate those who kept us safe these harrowing last eight years.