Actus Reus

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Definition: Actus Reus

Actus Reus

Quick Summary of Actus Reus

blameworthy act – it is used to denote the event on which a criminal offence is based.

Video Guide For Actus Reus

What is the dictionary definition of Actus Reus?

Dictionary Definition

“Wrongful act.” Used to denote the event on which a criminal offense is based.

Latin for a “guilty act.” The actus reus is the act which, in combination with a certain mental state, such as intent or recklessness, constitutes a crime. For example, the crime of theft requires physically taking something (the actus reus) coupled with the intent to permanently deprive the owner of the object (the mental state, or mens rea).

Full Definition of Actus Reus

The terms actus reus and mens rea derived from Edward Coke’s statement that ‘actus non facit reum nisi mens sit rea’. Simply put, that an act does not make a person guilty unless their mind also makes them guilty. Hence, the general test at British law is one that requires proof of fault, culpability or blameworthiness in both behaviour and mind.

Actus reus comprises all the elements of the statutory or common law definition of a crime save those to do with the defendant’s state of mind.

Unlawful Conduct

In reality, actus reus consists of more than just an act. It also consists of whatever circumstances and consequences are required for the offence in question – in other words, all the elements of the offence except those relating to the mental state of the defendant.

Crimes can be divided into two categories:

  • First, there are conduct crimes, where the actus reus is the prohibited conduct itself. For example, the actus reus of the offence of dangerous driving is simply ‘driving a mechanically propelled vehicle on a road or other public place’ (s2 Road Traffic Act 1988). No harm or consequence of the dangerous driving needs to be established in order for the defendant to be guilty.
  • Secondly, there are result crimes, where the actus reus of the offence requires proof that the conduct caused a prohibited consequence or result. For example, the actus reus of criminal damage is that property belonging to another must have been damaged or destroyed ( s1(1) Criminal Damage Act 1971).

Voluntary Conduct

It is further required that actus reus must be voluntary, although ‘involuntary’ is defined narrowly and would normally only apply to situations where the defendant is not in control of their own body.

One example where a defendant’s conduct is not voluntary is in instances of automatism. Automatism is where the defendant performs a physical act but is unaware of what he is doing, or is not in control of his actions, due to some external factor.

Also, a defendant may have responded to something with a spontaneous reflex over which they had no control, as was the case in Hill v Baxter [1958] where the defendant was stung by a swarm of bees while driving and lost control of the car.

State Of Affairs Crimes

State of affairs crimes cannot be discussed in terms of voluntary acts. Such crimes are defined not in the sense of the defendant doing a positive act but consist instead, for example, of the defendant ‘being found’, ‘being in possession’ or ‘being in charge’. In cases involving this kind of crime, all that needs to be proved is the existence of the factual circumstances that constitute the crime.


The general rule of British law is that there can be no liability for failure to act so a defendant cannot be punished for not doing something. However, the exception to this is if the defendant had a duty to act and broke that duty. There are only limited circumstances in which the defendant has a duty to act, for example, the Children and Young Persons Act 1933 creates an offence of wilfully neglecting a child.

In many cases, the Actus Reus will be an explicit act (theft, assault, etc). In others, it will be a prohibited state of affairs (e.g., having an offensive weapon in a public place). In some cases, the actus can be an omission to act (see: Omission), but usually only when the accused had a legal duty to act. Sometimes the actus may not be the event itself, but the effect it has on the victim (e.g., in rape), or the circumstances that surround it (e.g., bigamous marriage).

It is fundamental that the Actus Reus be a voluntary act; if a defendant could not have acted any other way then not only is he not liable, then the Actus Reus is deemed not have occurred. Of course, there will be the `actus’ part — the action — but it will not be `reus’. In offences of Strict Liability, this is important, because in those offences the prosecution has no duty to show a Mens Rea; thus an offence cannot be defended on the basis that there was no intention to comment the offence, but it can be defended on the basis that no offence was committed.

This defence will only be available if the defendant truly had no choice; for example, he was physically pushed by someone else. A defendant who makes a choice between two equally dreadful alternatives (`help us rob this bank or we’ll shoot your wife’) is not acting involuntarily in this sense, but he may have a General defence of Duress.

In order to be guilty of a crime two things must be proved

  • The defendant carried out the criminal act – the ‘Actus reus’ (The guilty act)
  • The defendant had a guilty state of mind – the ‘Mens Rea’ (The guilty mind)


Mike is very angry with Jim. Mike goes to Jim’s house with the intention of attacking him with a baseball bat. However, Jim isn’t in. Although Mike has the Mens Rea for the crime (the guilty mind) he doesn’t actually carry out the Actus Reus (the guilty act). Mike, therefore, cannot be guilty of an offence under the OAPA 1981, but may be convicted for the attempted offence, provided he has done acts that are more than merely preparatory.

The Actus Reus of a crime usually involves doing something.

The general rule is that an omission to act will not constitute the Actus Reus of a crime.

However, there are (as you have just discovered) situations where an omission to act may amount to the Actus Reus of a crime.


To establish Actus Reus it is necessary to show;

  • The defendant’s conduct was the factual cause of the harm
  • The defendant’s conduct was in law the cause of the harm
  • There was no intervening act which broke the chain of causation

Cite Term

To help you cite our definitions in your bibliography, here is the proper citation layout for the three major formatting styles, with all of the relevant information filled in.

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Modern Language Association (MLA):
Actus Reus. Payroll & Accounting Heaven Ltd.
August 08, 2022
Chicago Manual of Style (CMS):
Actus Reus. Payroll & Accounting Heaven Ltd. (accessed: August 08, 2022).
American Psychological Association (APA):
Actus Reus. Retrieved August 08, 2022
, from website:

Definition Sources

Definitions for Actus Reus are sourced/syndicated and enhanced from:

  • A Dictionary of Economics (Oxford Quick Reference)
  • Oxford Dictionary Of Accounting
  • Oxford Dictionary Of Business & Management

This glossary post was last updated: 26th November, 2021 | 0 Views.