Everyone is getting all exercised about the "ticking bomb" scenario, apparently because some commentators (seemingly including NPR's Diane Rehm) believe that it is an unanswerable argument in favor of torture.
Let's leave aside for the moment the extreme implausibility of the situation. We've learned that a nuclear device is planted in an American city, set to explode at some unknown time. Furthermore, we've captured a terrorist who we know for sure knows where the bomb is and when it will go off. All of this begs the question: how did we learn all this yet fail to learn the exact location of the bomb? How do we know that the terrorist knows, but not what he knows? All of this is fanciful in the extreme.
But let's go further. If you were an al-Qaeda cell planning this attack, don't you think that you would:
a) set up all kinds of blind alleys for investigators to follow and get bogged down in;
b) make damn sure that all of your operatives with critical knowledge were well away from the scene, say, in the mountains of northwest Pakistan, before the event was imminent?
Lastly, and simplest of all: the argument that even a saint would engage in torture under these circumstances is completely irrelevant to the question of whether or not torture should be legal. Our policy should be very simple, along the lines suggested by John McCain: torture is illegal, period. If in some extreme circumstance operatives of the US government find it necessary to torture someone in their custody, they will do so knowing that they risk prosecution.
The option of clemency is always there if it is the only way to serve the larger interests of justice.