Criminal Law

Actus Reus

/ˈæktəs ˈreɪəs/

Definition

Actus reus (Latin: 'guilty act') is the physical element of a crime — the wrongful act, omission, or state of affairs that constitutes the conduct element of a criminal offence. Together with mens rea (the mental element), actus reus forms the foundation of criminal liability in common law jurisdictions.

Key elements

1A voluntary act (or omission where there is a legal duty to act)
2Causation (the act must have caused the prohibited result)
3Contemporaneity (act and mental state must coincide in time)
4Absence of a legal defence (automatism, involuntary act)

How this applies across jurisdictions

India

BNS 2023 s.8 defines 'act' to include illegal omissions. Involuntary acts do not constitute actus reus. The requirement of a voluntary act is implicit throughout the BNS.

UK

English law requires actus reus to be a voluntary act. Omissions can constitute actus reus only where there is a prior legal duty (statutory, contractual, family relationship, or assumed duty — R v Miller [1983]).

USA

MPC § 2.01 requires a voluntary act. Possession, status offences, and omissions where there is a legal duty to act are also recognised.

Frequently asked questions

Can an omission constitute actus reus?

Yes, but only where the defendant had a legal duty to act. Such duties arise from statute, contract, special relationship (e.g., parent-child), voluntary assumption of responsibility, or creating a dangerous situation.

What is the difference between actus reus and mens rea?

Actus reus is the physical or external element of the crime (what was done). Mens rea is the mental element (the state of mind). Both must usually be proved for criminal conviction.

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