Paladin and rogue in the same group - what's allowed and what's not?

[Kelb_Panthera]

No, it doesn't. Killing an [EVIL] outsider is a non-evil act. All the time. Every time.

Nitpick: That's only okay because of the [evil] subtype tag, not just because the fiend has an evil alignment; and is, in fact, a good act because it reduces the amount of evil in the plane the fiend is on. Being evil and being made of evil are two subtly different things.

Unfortunately killing in D&D is morally subjective. There are always circumstances that swing it one way or the other.