I really don't understand all the back and forth about whether or not torture works. That is not a defense, that is not an excuse, that cannot offset that it is morally reprehensible and, oh yea, illegal!
Ignoring that torture generally does not work, efficacy is not an effective argument. If it were, then the genocide in Rawanda could be easily defended as a very effective method of population control to deal with the overcrowding in that country. Physical castration could be an effective way to prevent rapists from repeat offense. In fact, giving people life sentences for any crime would be an effective way to guarantee no recidivism. On the less criminal front, I could build a speed bump on the road outside my house to slow down the drivers who go by too fast, as that would be quite effective.
We have laws for a reason. No one gets to shirk them at their will because something that is illegal happens to be effective. Of course, in the case of torture, it isn't effective either.