You post reminds me of a discussion I had with my students regarding the theory of "just war".

One of my students disagreed with the need for a "just war" by claiming that she was "anti-war". I informed her that no sane person is "pro-war", that is "wants to see war". The premise of just war is that it should be avoided unless no other alternative to self defense is available and practical.

All people should be against war. However, war is sometimes the "necessary evil" needed to stop a greater evil.

For more info, I recommend that people read C.S. Lewis' essay, "Why I am not a Pacifist." His theory is that pacifism cannot stop absolute evil (think Hitler in Lewis' era). Perhaps the same applies when dealing with sociopathic and psychopathic criminals.