Intoxication can be taken into account in determining whether an accused person facing a murder charge had the specific intention necessary to cause about the specific outcome necessary for the crime, namely, to cause really serious injury or permanent, or serious disfigurement or intended to kill, or realised the possibility of causing death but did the act anyway. This applies regardless of whether or not the intoxication was self-induced.
Certain offences in New South Wales are 'specific intent' offences, which mean they are offences of which an intention to cause a specific result is an element of the crime required to be proven beyond reasonable doubt by the prosecution in order to prove the crime. Failure to prove this will result in an acquittal ('not guilty' verdict). A murder charge is a specific intent offence in New South Wales.
When a person is intoxicated from drugs and/or alcohol to an extent that their capability of intending to cause a specific result from an act is put into question for a specific intent offence (ie murder), that person could be acquitted from the criminal charge unless the prosecution can prove (beyond reasonable doubt) that the person had the specific intent necessary. For this reason, intoxication is not technically a defence, but is commonly called one superficially.
Examples of 'specific intent' offences include murder, wounding or grievous bodily harm with intent, being armed with intent to commit an offence, money laundering, threaten to destroy or damage property. Each of these offences require as an essential element to be proven that the accused person intended to cause a specific result from the alleged offending act.
SPECIFIC INTENT OFFENCE OF MURDER
To prove murder, the prosecution needs to prove beyond reasonable doubt that the act was voluntary causing death; and that the accused person either intended to cause really serious injury or permanent, or serious disfigurement or intended to kill, or realised the probability that the act would cause death but did the act anyway, or the death was caused during the time the accused person was committing a crime punishable with up to 25-years jail or more. This is defined in section 18 Crimes Act 1900 (NSW).
Murder is a specific intent offence because an essential element required to be proven is the intention to cause either of the above mentioned specific results. Section 428B Crimes Act also specifically outlines murder, amongst other offences, as an 'offence of specific intent'.
IS INTOXICATION A DEFENCE TO MURDER AND MANSLAUGHTER?
Intoxication defence for murder charges? Being intoxicated at the time of the act of causing the death is relevant and can be taken into account in determining whether he or she had the intention to cause the specific result necessary for a murder charge. Intoxication can also be taken into account when considering whether the accused person realised the probability that the act would cause death but did the act anyway (R v Grant (2002) 55 NSWLR 80). This is regardless of whether or not it is self-induced intoxication. This is also reflected in section 428C Crimes Act.
Exceptions to this: However, intoxication will not be allowed to be taken into account even for a specific intent offence of murder if the accused person resolved before becoming intoxicated to do commit the offending conduct, or he or she became intoxicated in order to strengthen their resolve to commit the offending conduct.
Intoxication defence for manslaughter charges? If a person facing a murder charge on trial is acquitted because of intoxication, then any evidence of intoxication can only be taken into account in determining whether he or she had the mental element of the offence of manslaughter if the intoxication was not self-induced. If the intoxication was self-induced, then intoxication cannot be taking into consideration for a manslaughter charge. This is expressly outlined in section 428D and 428E Crimes Act.
The criminal law also says that a person will not be criminally responsible for an involuntary act resulting in a crime. Lord Denning in the case of Bratty v Attorney-General for Northern Ireland  AC 286 said that no act is punishable if it is done involuntarily referred to as the law on 'automatism'. Automatism means an act committed by a person who is not conscious of what he or she is doing, such as an act done whilst suffering from concussion or sleepwalking.
Is Automatism from Intoxication a Defence for Murder and Manslaughter?
Self-induced intoxication cannot be taken into account in determining whether an accused person's act was voluntary. But, an accused person will not be held criminally responsible for a crime, including murder or manslaughter, if the offending act resulted from intoxication that was not self-induced. This is outlined in section 428G Crimes Act.
If automatism defence is raised as a reasonable possibility on the evidence in a trial of murder, then the prosecution is required to prove beyond reasonable doubt that the act was voluntary in order for the offence to be proven. Failure by the prosecution to prove this to such a standard of proof will result in an acquittal of the charge.
What is self-induced intoxication?
Self-induced intoxication is defined as any intoxication except if it is involuntary, or results from fraud, extraordinary emergency, accidents, reasonable mistake, duress, force, or a result from the administration of a drug for which a prescription is required in accordance with the prescription of a medical practitioner, nurse practitioner, midwife practitioner or dentist, or of a drug for which no prescription is required administered for the purpose, and in accordance with the dosage level recommend in the manufacturer's instructions.
What is Intoxication?
Intoxication is defined as intoxication because of the influence of drugs or alcohol or any other substance.