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 Oklahoma, 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 element of a crime. This means that for a person to be found guilty of a crime, it must be shown that they actually performed an action that is considered criminal, or failed to act when they were legally required to do so. For instance, if someone has a duty to care for a child and fails to provide food, resulting in harm to the child, that omission could be considered actus reus. On the other hand, mens rea refers to the mental state of the defendant at the time of the crime. Oklahoma law recognizes various levels of mens rea, from intentional acts to reckless or negligent behavior. To secure a conviction, the prosecution typically must prove that the defendant had the requisite mens rea to commit the crime in question. This means showing that the defendant had the intention to commit a crime or was aware that their actions would likely result in a criminal outcome. Both actus reus and mens rea are critical components of most crimes, and a defendant must generally possess both for a crime to have been committed under Oklahoma law.