ACTUS REUS
We have seen that criminal offences typically contain both actus reus and mens rea elements.
In the next two lectures, we turn to look in more detail at the actus reus: the conduct element
in crimes. This will include a discussion of the role of causation in criminal law.
Reading:
Gane, Stoddart and Chalmers (4th edn), chs 2 and 4 OR
Jones and Christie (5th edn), ch 3 OR
Ferguson and McDiarmid, pp 125-139 and pp 161-173
1. What is an Actus Reus?
Although criminal law does not prohibit mere thoughts, there is otherwise a wide range of
types of actus reus. Most crimes can be placed into the following categories:
Result crimes (causing a prohibited result)
Conduct crimes (acting in a prohibited manner / in specified circumstances)
States of affairs
Omissions
It can be seen from this that, in practice, most instances of criminal liability require an act.
This is because we cannot claim that an accused has caused something or done something
unless there is some conduct that can be attributed to him/her. This raises questions about
what constitutes an act for the purposes of the criminal law.
A. Voluntariness
Criminal acts must be voluntary: they must be chosen and consciously controlled by the
accused. Correspondingly, there should be no criminal liability for involuntary conduct. In
practice, criminal law operates with an implicit presumption of voluntariness. There are a
number of ways in which an accused might attempt to deny voluntariness, which the law
treats with varying degrees of sympathy.
(i) Automatism
An action is 'automatic' when the accused exercises no conscious control over it: for example,
if he/she is sleepwalking. Automatism functions as a defence, and it overlaps considerably
with insanity and intoxication. The current rules governing the defence are set out in Ross v
HM Adv 1991 SCCR 823. These issues will be considered in detail in later lectures.
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