Actus reus is the action (or inaction, in the case of criminal negligence and similar crimes which are sometimes called acts of omission) which, in combination with the mens rea ("guilty mind"), produces criminal liability in common law based criminal law jurisdictions such as the United States, Canada and the United Kingdom. According to criminal jurisprudence, there must be a concurrence of both actus reus and mens rea for a crime to have been committed.
The phrase derives from a quotation from Edward Coke actus non facit reum nisi mens sit rea,1 which roughly translated means "an act does not make someone a criminal unless (their) mind is guilty."
See also
References
1 Coke's Institutes, Part III (1797 edition) chapter 1, folio 10.
