Is it justifiable to enact vengeance on another if the vengeance also serves as a justifiable punishment?

Vengence can be justifiable if it truly is equal justice. Something must be learned, a path for that must be advanced in our judicial system. If the end of Jeffry Dohmer's life was just, and he could learn nothing them we as a society must learn how to eliminate the likelyhood that others would fallow a similar path. Vengence must have meaning or else it is worthless.