A reader writes:
In invoking Just War Theory Marc Thiessen stresses the legitimate right of self-defense to justify our actions in regards to treatment of prisoners. In doing so he is attempting to address the Just War Theory of Jus ad Bellum, that is, one can only wage war and take life for a truly just cause, usually in defense of self or innocent others. As you point out, the torture of defenseless prisoners can hardly be said to be "self-defense".
However, no matter how just or righteous the cause is, the second and equally important tenant of Just War Theory is Jus in Bello - the means with which you wage war. While these have developed over time and are subject to some varying interpretations, they have always been known to include, amongst other things, prohibitions against the targeting of civilians, the doctrine of proportionate response and of course humane treatment of prisoners.
It is impossible to wage a just war, or what we might call a morally justified use of lethal violence against others, unless both of these standards are met. One without the other is not morally defensible no matter the nature of the threat (be it Nazis or Osama Bin Laden).
Father Winters, who headed the Ethics and International Relations Department at Georgetown University when I was there, always would stress when challenged on this, that as great a gift as our temporal life is from our creator, it pales in importance when compared to our eternal soul.