actus non facit reum nisi mens sit rea
~   Voluntary activity does not make one a criminal unless one's mind is guilty.
Mens rea - 'the guilty mind'
In most offences, one's mens rea must be proven as well as the act which caused the offence (actus reus
). The mens rea must coincide
with the actus reus, that is, the action and the intent must occur contemporaneously.
Principles of criminal law in New South Wales state that mens rea can be proven if one of the following is present:
(a) intent (basic or specific)
When one foresees the certainty of injury
. Intention for say, murder
can exist without there being a
specific desire to kill. If A burns down a building and kills a watchman, B, even though he had no quarrel with B, intention exists because he foresaw B's death as certain.
Some offences can be committed only if there is a specific intention present, eg. attempted murder
(the intention to kill), larceny
or attempted larceny (the intention to deprive permanently of property).
of activity likely to cause harm does not occur, the perpetrator
is said to have acted with recklessness. The likelihood of harm must be that which would be apparent to a reasonable person
(c) gross negligence
Acting without the care, skill and foresight of a reasonable person
liability for inactivity (inertia rea)
In the case of homicide
, inertia rea might exist if (1) Q is in a special relationship
with D, or is responsible for a previous act of commission towards him, and (2) knowing he is helpless, does not do what is reasonable to help him.
Offences which do not requre mens rea to be proven. For example, most traffic offences are strict liability offences. Attempting to stow
away on a train, no matter your intention, would also be an offence.