It is not generally a defence to have been intoxicated by alcohol or drugs at the time of committing an offence. However, Part 8 of the Criminal Law Consolidation Act 1935 (SA) [ ss 267A - 269] provides an intoxication defence in limited circumstances.
This defence is based on the argument the defendant’s consciousness was (or may have been) impaired to the point of criminal irresponsibility at the time of the offence.
Intoxication is not a defence when the defendant formed an intention to commit the offence before becoming intoxicated or where the defendant became intoxicated for resolve to commit the offence. Intoxication is generally not a defence when the intoxication is self induced.
Recreational use of a drug is considered self induced use. Where intoxication arose from both recreational use and therapeutic use of drugs (or the same drug) the resulting intoxication is also considered self induced.
Evidence of intoxication can also be damaging to a defendant’s case. It can form the basis for an inference of intent or motive and can also establish criminal negligence. Whilst intoxication can be viewed as a mitigating factor at sentence, it is more often viewed as an aggravating factor, resulting in an increase in penalty when the defendant is sentenced.
This is a complicated defence and should not be used without proper legal advice and representation.