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Actus Non Facit Reum Nisi Mens Sit Reais often quoted at the very beginning of almost every criminal law manual around the world. This maxim was written by Sir Edward Coke in the 16th century and is said to contain the essence of criminal law. A simple translation of the maxim reads that an act cannot be considered to make someone guilty, without them also having a guilty mind to commit such an act. This has become the legal standard of evaluating guilt of an offender, wherein both elements must be satisfied for him to be guilty. Hence, the basic elements of a crime consist of both a physical as well as a mental aspect. The physical element of a crime is called the ‘actus reus’ or the ‘guilty act’ and the mental element is called the ‘men rea’ or the ‘guilty mind’.


Actus Reus

The Actus reus or the guilty act has been defined by Glanville Williams as a “technical term including all the external circumstances and consequences specified in the rule of law as constituting the forbidden situation.” According to him, a crime consists of external and internal elements, of which, the act becomes a sum of all external aspects. He further elaborates,

“Reus must be taken as indicating that the situation specified in the actus reus as on that, given any necessary mental element, is forbidden by law. In other words, actus reus includes the whole definition of the crime with the exception of the mental element

Actus reus is further divided into acts and omissions. While an act is a positive definition of an actus reus, an omission is the negative definition. An act forms a part of the actus reus when an action is done which is against the prescribed law of the land, while an omission takes the form of an absent-action, which an individual was legally and morally expected to do, but did not. The actus reus of a crime includes the conduct and the consequences arising due to this wrongful conduct.

Norrie describes unlawful omissions as a “conduct where a person fails to act where it would be normal to do so, identified as a failure to act in conformity with an expected or required norm.” For example, suppose X is a firefighter on duty who witnesses a young 7 year old child Y running towards his burning house to save his toys from the fire. X knowing full-well that he could have saved Y from the fire makes no efforts to stop Y. Y enters the burning house and dies. Here, even though Y died due to his own action of running into a burning house, X would be liable as he could have saved Y, if not for his wilful omission to act.


The principle of causation dictates that a crime must be the direct result of an offender’s action. Lord Hoffman highlights the legal importance of the principle of causation “Questions of causation often arise for the purpose of attributing responsibility to someone.” However, there is an ambiguity as to what constitutes a ‘cause’ for the occurrence of a crime. Hart and Honore highlighted the difference between causes and mere conditions of a crime, as having two contrasts. These were “an abnormal feature of a situation”, i.e., something out of the ordinary which becomes a key feature of the crime, or a “deliberate human action”

Some established legal principles of an act becoming a cause are proximity, last voluntary act, and the causal chain, and other circumstances such as intervention by a third party, etcetera. The proximity principle holds that the act in question must be the most efficient cause of the final effect. The last voluntary act principle primarily affixes the ‘causal responsibility’ on that person whose last active intervention resulted in the final effect.

Every causation contains a causal chain, which is a series of events that eventually leads to the commission of the offence. This causal chain is broken when any third party intervenes, and the pre-existing last voluntary act is then replaced by the intervention which ultimately becomes the last voluntary act in a crime. For example, if A voluntarily gave B poisoned sweets to cause his death after 6 hours, but B is stabbed to death by a burglar C before then, criminal law shall affix causal responsibility on C. Even though A would have caused B’s death eventually, C’s intervention negates his act and breaks the causal chain. Thus ultimately making C guilty of murder.

Mens Rea

The mens rea or ‘mental element’ is attributed to the commission of every crime. It is often said that no act is a crime which lacks the involvement of a guilty conscience, except in the case of strict liability offences where no mens rea is required for an act to become a crime. Bishop highlighted the necessity of the mental element in a crime, “There can be no crime, large or small, without an evil mind… the essence of an offense is the wrongful intent, without which it cannot exist.”

Criminal law holds that every person has their individual autonomy, this principle dictates that a man is responsible for the consequences of his actions when he voluntarily and intentionally performs them. Ashworth has highlighted the importance of including mens rea as an element of a crime,

“The essence of the principle of mens rea is that criminal liability should be imposed only on persons who are sufficiently aware of what they are doing, and of the consequences it may have, that they can fairly be said to have chosen the behavior and its consequences.”

There are specific terms associated with mens rea, these include intention, desire, motive, knowledge, foresight, negligence and recklessness. Intention denotes an active thought process, wherein an act is done to bring about a specific result. Desire is an impulse of wanting something. The difference between desire and intention lies in the actual commission of an act, while a desire merely denotes the wanting of it, while an intention is a thought which compels one to act. The motive is an eventual objective with which a person commits a crime, it is not to be confused with intention. A person may kill someone motivated by patriotism towards his country.

Even though his motive might seem amiable to some people, his intention to kill makes him a murderer. Hence, a motive is never material to an offence. Foresight denotes an anticipatory outcome expected to occur as a result of a certain act. Having knowledge means being aware of the possibility of an outcome occurring. The key difference between foresight/knowledge and intention is the fact that “Knowledge or Foresight is at the best material which entitles or compels a jury to draw the necessary inference as to intention.” Recklessness is similar to knowledge but differs in degree. Negligence denotes absence of due diligence and care. This reflects on the lack of awareness or ignorance on the part of the offender.

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