Actus Reus

The physical or external element of a crime

Overview

Actus reus comprises the prohibited act, result, or circumstance, together with any required causation, and must ordinarily be voluntary. Omission can satisfy it where a legal duty exists, as with parents and lifeguards, and possession counts as an act in most systems. Concurrence with mens rea, a guilty mind accompanying the act, completes liability. The distinction matters because thoughts alone are never punishable in liberal systems, a boundary drawn long before modern neuroscience tested it. Possession offenses push the boundary, since the act is the state of holding, not any movement.