To decide that some act is a crime; to pass a law stating that an act is a crime; see also decriminalize. criminal justice system. N. The government's system of law enforcement that apprehends, prosecutes, and punishes criminals, including law enforcement officers, courts, and correctional institutions. criminal law.N. The branch of law that deals with the prosecution and punishment of criminals; the body of law that determines what constitutes a crime and what constitutes suitable punishment...