Found this pretty interesting.
"So, all you hyper-moral pacifist purists, if you could learn Ms. Wang's location and save her by waterboarding a captured guard, would you do it? Or is her permanent crippling and disfigurement a satisfactory consequence of your own personal interpretation of right and wrong? That's what you seem to be saying by your absolute opposition to any form of physical coercion, even if it doesn't maim or kill.
But if that's really your position, then you've entered the paradox zone. You have to explain -- to your own satisfaction -- why it is less moral to commit a lesser crime in order to prevent a larger crime than it is to enable a larger crime by refusing to commit a lesser crime. You can't allow the SWAT sniper to shoot the kidnapper who's holding a knife to your spouse's throat. You can't acquit the woman who kills her rapist in an act of self defense. You can't acquit the father who kills a child-molester in the act of sodomizing his infant daughter. In all these examples the killers are guilty of the same order of crime you're too moral to commit."
Read all about it.