Editorial
Actus reusactus reus
Definition
The physical element of a criminal offence: the prohibited conduct, the circumstances in which it must occur and, where the offence requires it, the result. An omission suffices only where a duty to act exists.
In plain English: The act itself — what the defendant actually did, or failed to do when the law required them to act.
A common law definition. The term may mean something different, or nothing at all, in another legal system.