Of course there is, according to this thread, you are good if you want to kill killers, but killers are bad, nkay?
Killers are not necessary bad.
Churchill killed 1000 french soldiers, he was a good guy and britain was lucky to have a leader like him who had the gut to take the responsibility. (thank god, there werent many seneca s in Britain at that time.)
I'm not claiming it's a perfect world. I am a big boy and know that the randomness and craziness of the world will always ensure instability, but if we can all be a bit more peaceful and not be ruled by mindless bloodlust, it will be a little more acceptable.
Calling for murder in the name of the law is no better than murdering. Same mentality. Murder is acceptable to both, therefore both are equally "good" or "bad" depending on which side of the fence you position yourself.