An evil necromancer has been captured. He has recently enacted an elaborate ritual that on the next new moon will cause every corpse for 10,000 miles to animate. The death toll will be in the thousands or possibly tens of thousands, expecially among the common peasantry and townfolk.
The ritual can be stopped but only by some secret method known to the necromancer.
The local Paladin order opposes torture at all times and no matter the reason. They would rather see thousands die at the hands of the rising dead instead of beat the answer out of the necromancer.
When your moral code is more important than the lives of innocent people that is evil.
1) In a world with actual necromancers, there are probably also actual diviners, and torture is unnecessary and unreliable in comparison to divination magic.
2) there are also likely to be mind altering magics that would make the malfeasor confess because he now believes his actions to be wrongnor that the interrogator is his ally, e.g. Helm of Opposite Alignment and various charm spells. Torture is unnecessary and unreliable in comparison.
I could go on, but I have a RW appointment to drive to.