Elements Of A Crime: Mens Rea And Actus Reus

Elements Of A Crime: Mens Rea And Actus Reus

Author- Pallav vats, Geeta Institute of Law, Panipat


Most crimes consist of two broad elements: mens rea and actus Reus. Mens rea means to have “a guilty mind.” The rationale behind the rule is that it is wrong for society to punish those who innocently cause harm. Actusreus literally means “guilty act,” and generally refers to an overt act in furtherance of a crime. Requiring an overt act as part of a crime means that society has chosen to punish only bad deeds, not bad thoughts.

 “Actus non facitreum nisi mens sit rea”, which literally means “an act does not make a person guilty unless the mind is also guilty”. If a person is guilty, they are proved to be culpable or blameworthy in both thought and action. That’s the general difference between murder and manslaughter.

You could hit and kill someone whilst driving, but if you didn’t intend to kill them, its manslaughter. If it’s proven that you jumped into your car fully intending to run down some poor victim, then you’re a murderer. However, there are complications, such as the omission to act, legal causation, intention, and recklessness.


Omission, or failure, to act generally carries no liabilities. That means a person can only be criminally liable where they have performed a positive act. For example, A walking past a drowning person B. Person B can be saved if person A holds their hand. Person A doesn’t hold their hand and person B drowns. Person A is not liable. There are six exceptions to this rule.      

  • The first of these is a duty arising from a statute. For example, the Children and Young Persons Act 1933 makes omissions culpable by people over the age of 16 failing to look after a child under 16. For example, if a child is not provided with adequate food or clothing (omission), this is the actus reus of that crime.
  • The second exemption is a duty arising from special relationships. R v Gibbins and Proctor (1918), ruled that a man and his wife were guilty of murder by failing to feed the man’s daughter. As the woman hated the daughter, this is sufficient enough to make her liable for the crime.
  • Thirdly, the assumption of care is an exception to omission to act. Although statutory law states that parents are no longer liable for their children after the age of 16, common law, particularly, R v Chattaway (1922), imposed a duty of care upon parents where their child is over 16 but continues to reside with them and is a dependent.
  • The three other exceptions include official, contractual or public duties, duty to avert danger of one’s own making and failure to provide medical treatment.

Legal causation

Causation simply links conduct to a result. Factual causation is established by conducting the “But-for” test. Legal causation is a bit trickier. The proximate cause rule can be applied. For example, you could argue that if a mechanic didn’t build a car, manslaughter wouldn’t have happened. But this is a bit of a silly argument, rather, the legally liable cause lies with the one closest to the incident. Intervening causes can also remove liability. If someone is injured by a gunshot, and then they are struck by lightning in an ambulance, you could argue the shooter is liable using the ‘but-for’ test. However, legally, the shooter wouldn’t be liable for injuries sustained through the lightning strike. It has been ruled in R v Cheshire (1991) that medical negligence amounts to a break in the chain of causation unless it was “so independent” of the defendant’s act or “so potent” in causing death.


Intending the action; foreseeing the result; desiring the result: e.g. murder. Knowledge: knowing of the falsity or wrongfulness of one’s actions or knowledge of a risk that a prohibited result is likely to occur but proceeding anyway. This also includes wilful blindness in most jurisdictions and recklessness in some others. An example would be offenses involving possession: the accused must have controlled the item and knew that it was contraband.

The intention is important because it is the mens rea requirement for serious offences, including murder. There are two types, direct intent, and oblique intent.

  • Direct intent is relatively straightforward and is linked to the defendant’s aim or purpose.
  • Oblique intent is where the defendant did not desire the consequences, but they knew they were certain to occur.


In criminal law and in the law of tort, recklessness may be defined as the state of mind where a person deliberately and unjustifiably pursues a course of action while consciously disregarding any risks flowing from such action. Recklessness is less culpable than intentional wickedness but is more blameworthy than careless behavior. Recklessness was defined in R v Cunningham (1957) as foreseeing that a particular kind of harm may be done, but going on to do it anyway. There is also a second way of detecting recklessness, as outlined in R v Caldwell (1981).

Wilful blindness:

Having a subjective awareness that a risk could exist (but not necessarily full knowledge) but proceeding without making more inquiries, e.g. a person is asked to bring a suitcase across a border: the person may not know that the suitcase contains drugs but has some suspicions (the person may think the suitcase could contain large sums of money) and, without ever asking or checking what’s inside, bringing the suitcase across the border.

Carelessness (also known as negligence):

failing to exercise due diligence to prevent the actus reus that caused the harm from occurring – rarely used in criminal law, often encountered in regulatory offenses