Cannabis-induced psychosis, where the psychosis is always preceded by drug use and ceases when drug use ceases, is a temporary disorder of an otherwise healthy mind caused by external factors and does not constitute a 'disease of the mind' for the purposes of the mental impairment defence under the Crimes (Mental Impairment and Unfitness to be Tried) Act 1997 (Vic). The term 'mental impairment' in the Act is synonymous with 'disease of the mind' as used in the M'Naghten Rules and does not represent a broader concept.
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