Intoxication and criminal behaviour

The common law position in Australia in relation to self‐induced intoxication and criminal responsibility is that evidence of intoxication should be taken into account when determining whether the Crown has proved beyond reasonable doubt that an accused person acted voluntarily and intentionally. In the Code jurisdictions, similar principles apply, although evidence of intoxication is generally only relevant to certain classes of offences. Although many legal commentaries on the issue of intoxication and criminal responsibility have been published in recent years, many of these have largely ignored the vast and rapidly growing scientific literature on the nature and effects of intoxication. This article describes the major effects of various psychoactive drugs, with particular emphasis on the potential effects of these drugs on criminal behaviour. The drugs are classified according to their major pharmacological properties — central nervous system depressants, central nervous system stimulants, opiates, cannabis, hallucinogens and anabolic steroids. The literature reviewed in this article suggests that the effects of intoxication on criminal behaviour may vary greatly depending on the type of drug that is taken and a number of situational factors. Therefore, it is considered inappropriate to deal with the law on intoxication and criminal responsibility with ‘blanket’ principles. Instead, each individual case of intoxication should be considered separately to determine whether the accused's behaviour was likely to be a consequence of intoxication.