Criminal law is the body of law that relates to crime. It proscribes conduct perceived as threatening, harmful, or otherwise endangering to the property, health, safety, and moral welfare of people inclusive of one's self.Criminal law deals with behavior that is or can be construed as an offense against the public, society, or the state—even if the immediate victim is an individual. Examples are murder, assault, theft,and drunken driving.he part of the legal system which relates to punishing people who have committed a criminal act: Investigation of breaches of the criminal law is generally the responsibility of the police. Compare. civil law.