Actus reus is the act—or the omission or failure to act when there is a duty to act—that comprises the physical elements of the commission of a crime. The actus reus generally must be voluntary bodily movements that constitute a crime.
In contrast, mens rea (meaning “guilty mind”) is the criminal intent element of a crime. It is the intent to commit a crime, or the knowledge that the action, or failure to act when there is a duty to act, will result in the commission of a crime.

In Wyoming, as in other jurisdictions, the concept of actus reus requires that a defendant must have engaged in a voluntary act, or an omission when there is a legal duty to act, that constitutes the physical elements of a crime. This means that the individual's actions or inactions must be deliberate and lead to the commission of a crime as defined by Wyoming statutes or case law. For a conviction, it is not enough for the act to occur; it must be accompanied by the appropriate mens rea, or 'guilty mind.' Mens rea refers to the mental state of the defendant at the time of the crime, indicating an intent to commit the crime or knowledge that one's actions or failure to act would likely result in a crime. Wyoming law requires that both actus reus and mens rea be established for most crimes, aligning with the general principles of criminal responsibility. Specific definitions and requirements for actus reus and mens rea may vary depending on the crime and are detailed in the relevant state statutes and case law.