act
In a legal context, an act refers generally to the exercise of will expressed through conduct, or a formal expression of law. The term is used in both criminal law and legislative contexts.
In criminal law, an act refers to a voluntary movement or expression that forms part of the actus reus, the physical element of a crime. To qualify as an act, the conduct must be voluntary. While most crimes require proof of an affirmative act, a failure to perform a legal duty, known as an omission, can also satisfy the actus reus requirement when the law imposes a duty to act.
In legislation, an act refers to a formal body of law enacted by a legislature. Acts are often collections of provisions addressing a single subject, such as the Clean Water Act or the Civil Rights Act. At the moment of passage by the legislature and approval by the executive, a bill becomes an act. Proposed laws may also be referred to as acts during the drafting and legislative process.
[Last reviewed in August of 2025 by the Wex Definitions Team]
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