Once we conclude that it is acceptable to torture some detainees in some situations, I think there will be only the briefest of pauses before we conclude that we must torture all detainees in every situation. Here's why. 

With regard to torture, we have been told that only detainees possessing certain information have been or will be tortured, and then only as an enhanced technique, after ordinary interrogation methods do not succeed. 

But how is it determined whether a detainee has torture-worthy information? Was he named by another detainee? Condemned by an enemy or rival?

And how is it determined when a not-tortured detainee has divulged all the information he has? 

If an interrogator is not getting results, then torture must follow. How can an interrogator tell the difference between a detainee that has torture-worthy information but is just holding out, and a detainee who has no useful information, without torturing him? If we are allowed to torture, then we must eventually torture every detainee to be sure we have exhausted his knowledge. And if we are going to torture him anyway, then why bother with preliminaries?

Even a detainee who spills his guts immediately must be tortured, because he might just be trying to put one over on the interrogator by pretending to be cooperative.

If we don't know which detainees have torture-worthy information, we must torture all of them.

And if it is acceptable to torture detainees, what distinction can be made for ordinary criminal defendants or suspects? How long would Scooter Libby have withstood waterboarding before he gave up Dick Cheney? How long would Cheney have held out before he admitted that he ordered Scooter to blow Valerie Plame's cover?

Torture must be an all-or-nothing proposition. Either every one of the detainees must be tortured, or none. I don't see how it can be otherwise.