A criminal act is an action done by someone that is against the laws of the country or region he or she is within. This action typically consists of the two basic aspects of a crime, which are typically referred to as mens rea and actus reus. Mens rea, or “guilty mind,” refers to the thought of a crime, usually involving the planning or decision to commit a crime, while actus reus, or “guilty action,” refers to the actual commission of the crime. A criminal act is typically considered to be an action that violates a law, regardless of whether the law is malum in se or malum prohibitum.
Often simply referred to as a “crime,” a criminal act generally consists of two distinct aspects of the act that must be present for it to be considered a crime. The first aspect is often called mens rea, or “guilty mind.” This refers to the process of planning or considering a crime, and it can consist of anything from months or years of planning that go into an elaborate criminal act to a few seconds of anger before an impulsive act. The basic idea is that a person must have the thought to commit a crime, which is why someone who kills another person out of self-defense is often not considered guilty of a crime.
Actus reus, or “guilty action,” refers to the second aspect of a criminal act, which is the actual process of committing the crime. Even if someone is not successful in the act, there are still often criminal charges involved with the attempt. In many countries the “guilty action” is important since it indicates what can be made illegal; in the US, for example, drug addiction has generally not been made illegal since it is a pattern of behavior and not an action.
The “guilty action” of a criminal act typically consists of one of three types of “action.” Commission of an act refers to the process of actively attempting to do something, such as trying to harm someone or stealing someone’s property. Omission, with regard to criminal acts, refers to inaction during a crime, such as the act of witnessing a crime but making no effort to help or notify authorities. Possession of an illegal substance is also considered a type of guilty action, since the act of acquiring and possessing that substance can constitute actus reus.
Once the “guilty mind” and “guilty action” have been established, then an action is considered a criminal act as long as it violates a law. Laws referred to as malum in se govern those actions most people would generally agree are wrong, such as murder, rape, and theft. While laws that are malum prohibitum deal with actions that are illegal to ensure a more orderly society, but not on any intrinsic moral grounds, such as many traffic laws or laws regulating the rights of convicted criminals.