When is Torture OK?

According to the The Guardian, much of the information that stopped the London airplane terrorists came from torture of an informant.

When is torture OK? In this case, hundreds to thousands of lives were apparently saved based upon information derived from torture. If the only information supporting the arrests were derived from torture, I would have to decry it. An accuser under torture is inherently unreliable, unless.... Unless the information extracted from the tortured individual is confirmed by other means.

We can have no faith in convictions based upon confessions extracted under torture. No court should condone such activity.

But when torture is necessary to save many, many innocent lives, because the tortured person is plotting death (or even knows of the plot and refuses to help), I have trouble dredging up sympathy for the villain.

What happens, though if we condone torture as a means to extract information about terrorist activities? Will we be torturing innocent people before we can determine that the information extracted was false?

I don't know. I hate the idea of torture. But worse than the torture of an evil plotter of human misery, I hate the human misery he or she would create if left untortured.