Actus Reus

Actus reus is a term of art in criminal law. Literally the Latin phrase means bad act. The technical, legal use of the phrase denotes one of the elements that must be proven by the prosecution before anyone can be liable to criminal punishment. The actus reus element is the act made criminal by some statute or other valid source of criminal law. Thus, a defendant is said to have committed the actus reus of some offense if he has done some act that is an instance of the type of action prohibited by the offense in question. Murder statutes, for example, typically prohibit the "killing of a human being"; the actus reus of murder is satisfied by any act that is an instance of the type of act so described—that is, any act that is a killing of a human being.