Criminal Law and Procedure

Actus reus is the physical or external component of a crime — a voluntary act (or a qualifying omission) that produces the prohibited result. Without a voluntary act, criminal liability generally cannot attach.

An omission can be the actus reus only where the defendant has a legal duty to act, the defendant knows of the facts giving rise to the duty, and it is reasonably possible to perform the duty. Duties arise from statute, contract, status relationship, voluntary assumption of care, or creation of the peril.

Specific intent crimes require proof that the defendant intended to bring about a specific result beyond the act itself; general intent crimes require only an intent to perform the prohibited act. Specific intent matters because certain defenses (e.g., voluntary intoxication, unreasonable mistake) apply only to specific intent crimes.

The common specific intent crimes include first-degree premeditated murder, assault (attempted battery), larceny, embezzlement, false pretenses, robbery, burglary, forgery, solicitation, conspiracy, and attempt. Each requires a particular intent beyond the underlying act.

Malice means acting with reckless disregard of an obvious or high risk that a particular harmful result will occur. Common-law murder and arson are malice crimes; malice does not require ill will or premeditation, only the intentional or reckless creation of the prohibited risk.

A strict liability crime requires no mens rea as to at least one material element — liability attaches from the act alone. These are typically regulatory or public-welfare offenses (e.g., statutory rape, selling alcohol to minors). Mistake-of-fact is not a defense to strict liability crimes.