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 Florida, 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 the individual's actions or inactions must be deliberate and lead to the commission of a crime for them to be held criminally responsible. For instance, if someone fails to pay taxes when legally required, that omission could be considered an actus reus. On the other hand, mens rea refers to the mental state of the defendant at the time of the crime. Florida law recognizes various levels of mens rea, including intent, knowledge, recklessness, and negligence, depending on the crime. To be found guilty of most offenses, a prosecutor must typically prove that the defendant had the requisite mens rea to commit the crime in question. For example, in a theft case, the prosecution must show that the defendant intentionally took property with the knowledge that it belonged to someone else.