Malum in se is a concept in criminal law referring to an inherently immoral act, regardless of whether the action is criminalized. Common examples of malum in se actions include arson, murder, and rape. Malum in se offenses are usually based on common law crimes where a specific intent requirement is incorporated into the definition of the offense. Malum in se differs from malum prohibitum, which is an act that is illegal but not necessarily immoral. Malum in se acts may also be called malum per se or crime malum in se.
The concept of malum in se has also been applied in contract law, where malum in se contracts are absolutely void. In contrast, malum prohibitum contracts are only void if they fall within the area of conduct that a legislature intended to deter.
[Last updated in July of 2023 by the Wex Definitions Team]