Defences

Contributed by Bill de Mars and Judith Fordham and current to 1 September 2005

Although the prosecution may be able to show on the evidence that the accused has committed the offence, a number of defences are available to an accused which may either reduce the offence charged to a lesser offence or which may provide a complete defence to the charge and lead to the acquittal of the accused. The general rule is that the accused must raise the defence by some evidence, and then the onus is on the prosecution to prove beyond reasonable doubt that the defence does not apply.

PROVOCATION

The defence of provocation is potentially available to any accused person charged with an offence of which assault is an element. Provocation consists of any wrongful act or insult by the complainant of such a nature as to be likely to deprive an ordinary person of the power of self-control and to induce an ordinary person to assault the complainant (s.245 Criminal Code). A lawful act cannot constitute provocation. The defence only applies if the accused person acts upon the provocation suddenly and before there is time for his or her passion to cool, and provided the force used by the accused is not disproportionate to the provocation (s.246 Criminal Code).

A defence of provocation may reduce murder to manslaughter (s.281 Criminal Code) and is an absolute defence to assault. For some offences (such as unlawful wounding) the defence is not available because assault is not an element of the offence.

SELF DEFENCE

Self defence will excuse a person charged with an offence of violence (such as murder, assault or grievous bodily harm) provided it is clear that the accused reasonably believed that the force he or she used was necessary for his or her own defence or the defence of others (ss.248, 249 Criminal Code).

Unless the accused person has reasonable grounds for believing that the assault upon them will cause death or grievous bodily harm, they are not permitted to use force intended to cause death or grievous bodily harm. However, if there is a reasonable apprehension of death or grievous bodily harm, the accused person may use any force necessary for his or her defence.

Further, where death or grievous bodily harm has been caused in response to such apprehension, the defence may not be available where the person who uses such force themselves began the assault with the intention to kill or do grievous bodily harm.

ACTING UNDER LAWFUL AUTHORITY

A person cannot be criminally responsible for acts done in execution or obedience of the law (s.31 Criminal Code).

INSANITY

It is a defence to any charge that at the time of the alleged offence, the accused was ‘insane’ within the meaning of that term as it is used in the criminal law. Broadly speaking, a person is ‘insane’ if, at the relevant time, he or she is suffering from a recognised mental disease which renders him or her incapable of knowing what he or she is doing, incapable of controlling his or her actions, or incapable of knowing that what he or she is doing is wrong (s.27 Criminal Code).

The result of a successful defence on this ground on indictable matters is that the defendant is detained in a mental hospital ‘during the Governor’s Pleasure’. Because of this serious consequence, insanity is usually raised only in the most serious cases, such as murder.

Upon the defence being successfully raised in the Magistrates Court (formerly known as the Court of Petty Sessions), a Magistrate has considerable discretion as to how he or she may deal with the person and may, if considered appropriate, release the person unconditionally (ss.20-22 Criminal Law (Mentally Impaired Defendants) Act 1996 (WA)).

INTOXICATION

The fact that a person’s mind is affected to some degree by alcohol or drugs is generally no answer to a criminal charge, but intoxication to a sufficient degree may be. It will provide a defence to a criminal charge in two situations:

• Firstly, if the intoxication is caused without intention on the part of the accused and the intoxication leads to insanity of the type described above, then it is as much a defence as insanity caused by other means;
• Secondly, where intention to cause a specific result is an element of an offence (for example, causing grievous bodily harm with intent) then intoxication, whether intentional or unintentional, may be considered for the purpose of ascertaining whether such an intention in fact existed (s.28 Criminal Code).

HONEST CLAIM OF RIGHT

This defence is sometimes available in relation to property offences (for example theft).

The defence only arises if the accused person honestly believes that he or she has a legitimate claim to the property and there is no intention to defraud (s.22 Criminal Code).

ACCIDENT

A person cannot be criminally responsible for an act or omission which occurs independently of the exercise of his or her will, or for an event which occurs by accident.

This does not mean that the prosecution must prove that the accused person intended the consequences of his or her actions (unless such an intention is a specific element of the relevant offence).

An event occurs by accident if it was neither intended nor foreseen and was unlikely as a consequence of the physical actions of the accused (s.23 Criminal Code).

MISTAKE OF FACT

Ignorance of the law does not constitute a defence to a criminal charge.

However, an honest and reasonable mistake of fact may constitute a defence. For example if, in relation to a charge of driving while disqualified, an accused person honestly and reasonably believes that he or she holds a motor driver’s licence when in fact the driver’s licence has been disqualified, the defence may be open. The defence of honest and reasonable but mistaken belief does not apply to so called ‘strict liability’ offences (s.24 Criminal Code).

EMERGENCY

There is a general rule excusing what would otherwise be criminal conduct done in circumstances of sudden or extraordinary emergency where an ordinary person possessing the ordinary power of self-control could not reasonably be expected to have acted otherwise (s.25 Criminal Code).

ALIBI

Alibi evidence is that which tends to show that the defendant was not at the place where the offence is supposed to have been committed because at the time he or she was in another place. This evidence may be given by the accused and other witnesses on the accused person’s behalf. As a general rule, notice of the alibi evidence must be given to the prosecution at least 14 days prior to the trial (s.62 Criminal Procedure Act 2004 (WA)).

INFANCY

A person under the age of 10 years is not criminally responsible for any act or omission.

Children between the ages of 10 and 14 years are not criminally responsible unless the prosecution proves that, at the time of doing the act or making the omission, the child had the capacity to know that he or she ought not do that act or make that omission (s.29 Criminal Code).

DEFENCE AGAINST HOME INVASION

Someone lawfully occupying a dwelling may use any force or do anything else that the occupant reasonably considers necessary to prevent the entry of a home invader, to cause a home invader to leave the dwelling, or to make effectual defence against violence used or threatened by such a person. They may also take such action in order to prevent or to stop a home invader from committing an offence in the dwelling (s.244 Criminal Code).

DEFENCE OF PROPERTY

In certain circumstances it is lawful for a person to use reasonable force to protect their property from a trespasser (ss.251, 252, 253 Criminal Code).