Board Thread:General Mod Discussion/@comment-26410366-20161006020829/@comment-29777393-20161006155156

The wiki page on Bandits talks about this very question:

Alignment does not affect the behavior of the bandits. They will not be attacked by most NPCs, such as High Elves and Orcs. However, if you have hired NPCs nearby, they will attack the bandits. If the bandit is provoked (that is, you decide to attack him), he will fight back with his bronze or iron dagger. They are also able to steal from NPCs.