---
title: "Actus Reus"
type: Legal Term
source: https://casebriefly.com/legal-terms/actus-reus
---

# Actus Reus

Actus reus ("guilty act") is the physical or external component of a crime. It requires a voluntary act or, in limited circumstances, an omission to act when there is a legal duty to do so. Involuntary acts — such as reflexes, convulsions, or conduct during unconsciousness — do not satisfy the actus reus requirement. The actus reus must coincide in time with the mens rea. An omission can constitute actus reus when there is a statutory duty, contractual duty, special relationship, or voluntary assumption of care.

## Related Terms

- mens-rea
- murder
- attempt

## Related Cases

- people-v-acosta
- commonwealth-v-malone

## Pronunciation

AK-tus REE-us

## Example

A bystander watches a stranger drown and does nothing. Unless there is a legal duty to act (such as a lifeguard's contractual duty), the bystander's inaction does not constitute actus reus.

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Source: [Actus Reus — CaseBriefly](https://casebriefly.com/legal-terms/actus-reus)