Why should the state, as opposed to private citizensm be the one who brings criminals chargers and administers punishments?
Why should we have a criminal law in the first place? Why not just have the civil law, why not just have the civil law, and allow those who have been wronged to bring legal suits against those who have harmed them?
The state's ultimate purpose is to aid our escape from the state of nature. The actions that pose the greatest danger to society are prohibited by the criminal law.