Capital punishment for murder. You take a life, yours is gone. On top of justice, you don’t stick the taxpayer with lifelong care of a murderer.
One problem with that idea is that even murder convictions are not even close to 100% accurate, so you'd end up killing lots of innocent people.
It’s fine to take that approach, you’re just a complete pacifist at that point who won’t defend his women and children. I thinks it’s why pacifism is a fairly rare quality.