Intoxication from alcohol or drugs may be a condition that prevents the Crown from proving that the accused had the fault element required for a particular offence (see chapter 5). Some extreme forms of intoxication may even result in involuntary conduct which, as discussed in chapter 3, is increasingly seen as inconsistent with proof of the prohibited act. Nevertheless, the intoxication defence has been influenced by policy considerations beyond those that relate to the fault element or the prohibited act of the particular offence. For these reasons, it will be examined here in a separate chapter.
Intoxication was historically considered an aggravating factor to a crime because it "was occasioned by [the accused’s] own act and folly, and he might have avoided it."1In the nineteenth century, as greater emphasis was placed on subjective mens rea, courts became more concerned about the relevance of intoxication as a possible defence. The object was not to determine whether the accused was intoxicated, but whether intoxication, combined with any other factors, prevented the formation of the fault element required for the particular offence. At the same time, however, courts never completely abandoned the older idea that an intoxicated offender was not morally innocent, and they placed restrictions on the availability of the intoxication defence. Intoxication was admissible and could raise a reasonable doubt to the mental element for specific intent offences, which required an ulterior objective beyond
the immediate act. It was not, however, admissible when the accused was charged with general intent offences, which required proof only of an intent to perform the immediate act. In practice, this meant that intoxication could be a defence to more serious crimes such as murder and robbery, but not to less serious offences such as manslaughter and assault.
The distinction between general and...