Define: Mens Rea

UK Accounting Glossary

Definition: Mens Rea


Full Definition of Mens Rea

The State of Mind of the Person Committing the Crime

In Britain and other common law jurisdictions, there is a saying that, “an act does not make a person guilty unless the mind be also guilty.” In other words, simply doing something will not, in

general, make a person a criminal unless their intent was to do, or cause, a criminal act. It is this intention which often establishes mens rea (literally the ‘guilty mind’) and turns the act into a crime.

In criminal law, mens rea – the guilty mind – is usually one of the necessary elements of a crime.
Mens rea, the ‘fault element’ of a crime, attempts to ensure that only those who are morally culpable will be punished by the criminal courts.

The standard common law test of criminal liability is usually expressed in terms of Edward Coke’s statement ‘actus non facit reum nisi mens sit rea’ which means that ‘the act does not make a person guilty unless their mind is also guilty. There must be an actus reus accompanied by some level of mens rea to constitute the crime with which the defendant is charged.

There are four possible states of mind recognised by British law:


A range of words are used to express intention in the various criminal laws. For the offence of murder for example, the required level of mens rea is ‘malice aforethought’ which is interpreted as ‘intention to kill or cause grievous bodily harm’.

Effectively, a defendant intends a certain consequence if he foresees that it will occur if the given series of acts or, in some cases, omissions, continue and he desires that it will happen.

Intention can, therefore, be either direct, where the defendant intends a particular consequence of their act, or oblique, where the defendant foresees the certainty of a consequence of their act even if it is not their main objective.


Recklessness demonstrates less culpability than intention but more than negligence.

The modern definition of recklessness comes from R v Cunningham [1957] and states that recklessness involves foreseeing the kind of harm that occurred and going ahead anyway. Cunningham recklessness is a subjective test since the jury need to decide what the defendant was thinking.

In R v Caldwell [1982] Lord Diplock decided that Cunningham recklessness was too narrow for the Criminal Damage Act 1971. He widened it to also include the case where the defendant commits an act which creates a risk which is obvious to the ordinary person but not to the defendant. The definition of Caldwell recklessness has two limbs:

  • The defendant does an act which creates a risk and he has recognised that there was some risk. This subjective test is known as the advertent limb.
  • The defendant does an act which creates a risk which is obvious to other people but is not obvious to the defendant. This objective test is known as the inadvertent limb.


The test for negligence in British law is an objective one, the jury must decide if the defendant has gone below the standards to be expected of the reasonable person. To do this, the defendant must have failed to exercise such care, skill or foresight as a reasonable person in the same situation would exercise. The characteristics of the particular defendant are not taken into account when considering negligence.

Transferred Malice

Transferred malice occurs when the intention to harm one individual inadvertently causes a second person to be hurt instead. Under British law, the individual causing the harm will be seen as having intended the harm caused through the transferred malice doctrine and so will be liable for their actions.

Does Mens Rea Require Motive?

Although in the majority of cases, mens rea will require a person to intend to commit a certain action, there are exceptions to the rule. It is sometimes possible to commit a crime without intending to do so at all, or even while intending to commit a different crime. Under section 47 of the Offences Against the Person Act 1861, a person in England & Wales can be found guilty even if they were ‘reckless’ as to the effect of their actions. Someone is ‘reckless’ under English law if, following the ruling in the case of Metropolitan Police Commissioner v. Caldwell [1982], they are aware of the risks associated with an action but they choose to undertake that action nevertheless.

Desire as an Aspect of Mens Rea

Intention may be a secondary matter and still form part of the mens rea of a crime. For the crime of causing grievous bodily harm with intent, contrary to section 18 of the Offences Against the Person Act 1861, a person must desire a certain outcome different to that which they set out to achieve through the guilty act itself; what is known as ‘ulterior intent’. In other words, the motive for the crime must separate to the intent to commit the crime itself. There are two forms of ulterior intent’ possible in a section 18 offence: intent to cause grievous bodily harm; and intent to resist or prevent an arrest. The motive for such a crime could, therefore, be to escape from the police, but the mens rea of the crime is intending (or being simply reckless about) causing grievous bodily harm while wishing to evade arrest.

Mens Rea and Negligence

Some crimes require no motive or intent whatsoever, but mens rea will still exist. In the case of crimes of negligence, it is not necessary to demonstrate that a person intended or even thought about the consequences of their actions in order to secure a conviction. The crime on manslaughter, for example, may be committed through the unintentional killing of another person. In the case referred to in Ford v Primrose (1824), a husband was accused of killing his wife through administering the wrong medicine; the implication in the Ford case being that her death had been the result of a mistake on his part. In such cases, the mens rea for the crime is simply being negligent while committing the act in question.

Is Mens Rea Always Required?

There is one part of the criminal law where mens rea is not required at all. In strict liability crimes, the only requirement for conviction is that a person can be proved to have committed an act, or a failure to act; the motive or intention of the defendant being ignored unless it forms part of their defence. Road traffic crimes, such as speeding or failure to display a tax disc, rely heavily on strict liability laws to ensure swift application of justice.

What is the Effect of Mens Rea?

Mens rea is a necessary part of the majority of crimes and indeed the idea of ‘no crime without a guilty mind’ is one of the foundations of the common law legal system. It is the ‘fault element’ of the majority of crimes and its continued use ensures that no-one can be punished unless they are proved in court to be at fault for the crime in question.

The limiting of strict liability laws to situations where it is not only infeasible to require negligence or malice aforethought, or where it would often be impossible to establish such, helps strengthen the law by minimising the chance of convicting for a pure accident or unintended transgression and thus maintaining the principle of punishment only where guilt is truly evident.


  • Herring, J. (2008) Criminal Law: Text, Cases and Materials (Oxford: OUP)
  • Elliott, K. & Quinn, F. (2008) Criminal Law (Longman)
  • Allen, M. (2007) Textbook on Criminal Law (Oxford: OUP)


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Definition Sources

Definitions for Mens Rea 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: 4th March 2020.