A Brief Introduction to Criminal Law - Actus Reus & Mens Rea

The first part of this article looked at the definition, aims and origins of criminal law, in particular in comparison with civil law. The second part however outlines what constitutes a crime in a little more detail.

There are two legal concepts which are particularly key to the understanding and administration of criminal law and these are Actus Reus and Mens Rea.

Actus Reus, which is Latin for the ‘guilty act’ represents the idea of the act of a crime and therefore can be considered to be anything that an individual does, or doesn’t do, or even threatens to do, that can be said to have caused a crime. There has to be clear link between the ‘act’ and the crime (the consequence) and this brings into play ideas such as causality and proximity in determining whether the accused was actually responsible for the crime.

Mens Rea, translates from Latin as the ‘guilty mind’ and represents the intention to commit a crime or take a course of action which risks a criminal act occurring (i.e., recklessness). This is a concept that is distinct from that of motive where the accused my have had a potential reason which could have grown into an intention to commit a crime (but doesn’t necessarily) and must be present at the point in time when a crime is committed to be relevant to the outcome and severity of a case. The presence and manifestation of mens rea can influence the classification of a crime when the actus reus is the same as another and the most salient example of this is manslaughter versus murder. If an individual committed an act which resulted in death they could be convicted with murder if they intended to take that life, or the lesser charge of manslaughter if they intended to take a risk that they could or should have realised could lead to death even if they didn’t intend to take the life.

What’s more, intent to commit a crime is not specific to a victim. In a process known as transferred malice, someone who kills their victim whilst intending to kill another individual will still be convicted of murder due to their original intent to kill.

The definition of what constitutes a crime is defined by the presence of both of these concepts; an otherwise criminal consequence that results from events where no-one was intending to commit a crime, or was being reckless, broadly speaking, will be accidental. Having said that, there are however a limited number of offences that don’t require mens rea, where the legislation determines that the intention of the offender is not relevant, and these are termed strict liability offences. Strict liability offences are more common in civil law but are still found in criminal law where they often involve motoring offences. As an example, the mens rea of someone who is speeding is not relevant to their prosecution, instead simply the actus reus of speeding is sufficient for a conviction.

All areas of law can be complicated, convoluted and hold profound consequences, so anyone looking for further advice on criminal or civil law proceedings should seek professional advice from qualified criminal law solicitors or, for example, motor law solicitors specialists respectively.

© Stuart Mitchell 2012