What Are the Essential Elements of a Crime?

Under U.S. criminal law, to convict someone of a crime certain elements of a crime must be proven beyond a reasonable doubt. A crime is generally defined as a misdemeanour or a felony. A misdemeanour is less serious than a felony and is punishable by a fine or a jail term of up to a year. Felonies are more serious crimes that are punishable from one year to life in prison, or in some states, by the death penalty.

If you have been charged with a crime it is advisable to seek legal help from an experienced criminal law firm such as these criminal lawyers in Melbourne. The four essential elements that must be present include a criminal act (actus reus), criminal intent (mens rea), the concurrence of both these elements, and causation. This article will examine each of these elements in more detail.

What Are the Essential Elements of a Crime?

Criminal Act (Actus Reus)

 Actus reus, meaning “guilty act”, refers to an unlawful act or omission that constitutes a crime as required by law. The thought of committing a criminal act is not sufficient to satisfy the actus reus requirement. However, certain acts such as conspiracy to commit murder can still comprise an actus reus without any physical crime being committed.

A criminal act must be performed voluntarily, meaning the defendant must control their actions. For this reason, involuntary crimes such as those committed while being asleep or unconscious, or those committed under hypnosis or during a seizure do not qualify as actus reus. An unlawful omission or lack of action can also be considered a criminal act and refers to situations where someone was under a legal duty to act.

Criminal Intent (Mens Rea)

Mens rea, or “guilty mind,” refers to the mental state of the defendant when they committed the crime. To secure a conviction, it must be proven that the defendant had the intention or knowledge of wrongdoing. There must be an intent to commit the unlawful act, however, this does not need to be malicious intent.

The level of mens rea required to be proven can differ between crimes. The more serious the crime, the greater the level of criminal intent that must be proved. There are four different levels of mens rea recognized under the Model Penal Code:

  • Intent: This is the purposeful desire to commit a criminal act
  • Knowledge: A person acts knowingly if they are aware their conduct will result in certain consequences.
  • Recklessness: A person acts recklessly if they are aware of the substantial risks associated with their actions.
  • Negligence: A person acts negligently when they should have been aware of the substantial risks that would result from their actions.


Concurrence refers to the occurrence of both actus rea and mens rea when the crime took place. There must be a coinciding between the guilty act and the guilty state of mind for this element to be present.


 Causation refers to the connection between the defendant’s conduct and whether this contributed sufficiently to produce the end result. To justify criminal liability, there must be a relationship of cause and effect between the defendant’s conduct and the injury, harm or loss which typically ensues.

In order to successfully secure a conviction for a crime, the prosecution must be able to prove the four elements mentioned above apply to the facts.