In the 8/1/2002 memo to then Counsel to the President Alberto Gonzales signed by Jay Bybee, Bybee starts his discussion of "severe pain" (which is part of the definition of "torture" in federal law, 18 U.S.C. 2340), with a brief discussion of the "ordinary or natural meaning" of "severe pain" with reference to several dictionary definitions of "severe."  The discussion concludes with the statement that "the adjective 'severe' conveys that the pain or suffering must be of such a high level of intensity that the pain is difficult for the subject to endure."

If the memorandum had continued with a discussion of what is meant by "difficult for the subject to endure," it might have been a good memorandum.  But instead the memorandum wandered off into a kind of legal sophistry.  Let's not wander off now, but instead look at what kind of pain might be "difficult for the subject to endure."

Pain that is difficult to endure would be, in extreme cases, pain that is unendurable or unbearable.  How could we identify what pain is unendurable or unbearable?  That seems to be fairly obvious.  If the pain is so severe that it is unendurable or unbearable, then the subject will do anything, anything, to end the pain.  If someone is subjected to "severe pain," then they will say anything and agree to anything in order to stop the pain, because "severe pain" is unendurable.

So now we have a practical, objective, and functional definition of "severe pain" (and, by extension, "torture").  If the pain is so great that the subject will do anything to stop it, then the pain is "severe" and the infliction of the pain is "torture."

Assuming that this definition is correct, what are the practical consequences?

The practical consequence is that, if someone doesn't want to tell you something, and you inflict enough pain that they tell you want you want to know even though they didn't want to tell you, then you have almost certainly inflicted pain that is severe and unbearable.

If that proposition is true, then the interrogator/torturer is faced with a Catch-22.  If you inflict pain that is unbearable, so that the subject tells you what you what to know, then you have tortured.  But if you inflict pain that is bearable, and the subject can choose whether or not to tell you what you want to know, then you haven't tortured but you also haven't accomplished anything because the subject of the pain is still free to withhold information.

In other words: Heads, you torture; but Tails, you get no information.

Which is fine as far as I am concerned, because it eliminates any incentive to torture.  If the interrogator knows in advance that any pain that is coercive is torture (and a crime), while pain that is not coercive is not a crime, but also useless, then there is no incentive to apply any pain at all.

Former Vice-President Cheney has said that waterboarding and other "enhanced interrogation" techniques are "effective."  If "effective" means that the subject does what you want, then torture is "effective" because severe, unbearable, pain (i.e., "torture") will coerce someone into saying whatever you want.  In that sense, torture is "effective."  (Whether severe pain is "effective" in producing reliable information is a completely different question that is not necessarily related to the question of whether severe pain is "effective" in producing desired information.) 

Which means that Cheney has totally missed the point.  Yes, torture is "effective" because it allows the torturer to coerce the victim into saying what the torturer wants.  And it is the very effectiveness of the pain that makes it torture.  The fact that Cheney believes that waterboarding is "effective" is not evidence that waterboarding is justified, but evidence that waterboarding is torture.