The problems arises not in the easy to agree laws (murder, theft) or the easy to condemn laws (ban on homosexuality), but with the ones which are debatable on if responding with violence is justified. Many would say that violence against pot dealers isn't justified, but what about heroin dealers? What about opiate dealers? Pot dealers who sell to teens?
If it's "debatable" then it isn't justified. The only universal, objective justification for a violent response is that the other person already did the same thing, and thus cannot claim that responding in kind is wrong without simultaneously condemning their own actions. If you claim that your response is justified on subjective grounds then they can just as easily claim that their actions were justified from their subjective point of view, at which point the whole situation devolves into a case of might-makes-right and justification becomes irrelevant.
None of your "debatable" examples would be justified because the actions you are proposing a violent response to are not themselves violent. Even when the original action is violent, the response must be proportional: applying the death penalty for theft would not be justified because it isn't a response in kind.
