Criminal Defences

When a person is charged with criminal offence and pleads not guilty, the prosecution must try to prove to a court beyond reasonable doubt that the accused is guilty of the offence. The accused is entitled to run a legal or factual defence. A legal defence is a defence that is based on an argument that there were circumstances that rendered their actions lawful. An example of this is an assault committed in self-defence. A factual defence is based on contesting the facts alleged by the prosecution – for example, by producing an alibi. 

For most offences under Commonwealth law, available defences are set out in the Criminal Code 1995 (Cth). For Victorian offences, the defences may be set out in legislation, or they may exist as part of the common law. Common law defences are those that are described in past court decisions.

There are also time limits for the police to lay some types of charges. If a charge is laid out of time, the accused has a complete defence.

Self-defence

If a person is charged with a violent offence such as assault, manslaughter or murder, they may be able to run the defence of self-defence. This can be argued where the person believed on reasonable grounds that it was necessary to do what they did to defend themself, another person or their property.

The belief that the actions were necessary in self-defence must have been held at the time that the acts occurred and must have been based on reasonable grounds. The response must also have been proportionate to the threat that the accused believed they were facing. The defence of self-defence can succeed even if the accused was mistaken in their belief.

The defence of Duress

Duress can be relied on when a person carried out an act under serious threats to themselves or to another person. It will succeed only if committing the offence was the only way that the harm could have been avoided.

The defence of duress cannot be relied on where the threat is made by or on behalf of a person that the accused is voluntarily associating with to carry out some other violent conduct.

Duress only applies in the case of murder if the threat is to kill or to cause a really serious injury.

Sudden or extraordinary emergency

The defence of sudden or extraordinary emergency applies when a person committed an offence in circumstances where it was only reasonable way to deal with an emergency situation, even though it was illegal. An example of this is speeding to get a seriously injured person to hospital.

The defence of Mental impairment

There is a specific defence in the Crimes (Mental Impairment and Unfitness to be Tried) Act 1997 which may be relied on where a person was suffering from a mental impairment at the time of an offence. The defence of mental impairment must be proven on the balance of probabilities (i.e.. that it is more likely than not to be true).

To be mentally impaired a person must have been suffering from some real form of mental disease, disorder or disturbance that had the effect that they either did not know what they were doing, or they did not know it was wrong.

Mental impairment may be transitory or permanent and may be capable of treatment or not.

Claim of Right

The defence of claim of right can be argued in relation to offences regarding property. It can be used if a person had an honestly held belief about their ownership of or entitlement to the property allegedly stolen. The claim must be a legal right, not just a moral right. If an accused raises a claim of right, it is up to the defence to prove it existed.

Honest and Reasonable Mistake

The defence of honest and reasonable mistake of fact can only be relied on for strict liability offences. These are cases where the prosecution does not have to prove that the accused intended something to happen, only that it did happen. In such a case, it is a defence if, at the time of the offence, they were mistaken about or unaware of certain facts about something and, if the facts were as they believed them to be, they would not have been guilty of an offence. It does not apply if a person is mistaken about what the law says. If a defendant raises this defence it is up to the defence to prove the mistake was made.

Intoxication

Intoxication is not a defence in itself. Rather, it is a fact that may be taken into consideration when assessing whether the accused had the required mental state for the offence to be made out. This is only relevant to offences that involve a specific intent.

The offence of stealing, for example, requires the accused to have intended to permanently deprive the owner of the property stolen. If the accused was too intoxicated to have formed such an intention, their intoxication will be relevant in determining this element of the offence.

Consent

When a person is charged with a sexual offence where the victim is an adult, consent will usually be a valid criminal defence. Consensual sexual activity between adults is not an offence (with the exception of the offence of incest).

The Crimes Act 1958 defines consent as free agreement. It sets out 7 circumstances where a person does not freely agree to an act, such as where the person was unconscious, heavily intoxicated, or was subjected to threats of violence.

If a person accused with a sexual offence such as rape or indecent assault can convince the court that the victim consented to the sexual activity, they will be found not guilty.