Drug Induced Psychoses and Legal Insanity

• In Event: Global Perspectives on How the Law Works: Drug Policy and Wrongful Convictions

Abstract

The insanity defense holds that individuals without the capacity to reason about their action should not be held criminally responsible. The defect must arise from a ‘disease of mind’ having internal causes. So how does the law deal with externally caused defects of reason such as drug-induced psychoses, given that it depends on whether voluntary intoxication caused acute psychosis and ensuing insanity directly linked to the intoxication; triggered or exacerbated an existing psychotic illness; or triggered a psychotic illness that was fixed and permanent due to chronic substance abuse but is independent of acute intoxication: a case of ‘settled insanity’. The latter two conditions satisfy the criteria of the defense. But can cognitive impairments arising from mental disorders be distinguished from those arising from substance abuse disorders? This study discusses an Australian case to illuminate the nuanced operations of the defense because a verdict of ‘not guilty because of mental impairment’ was reached even though the defendant had no prior history of mental illness and had consumed methamphetamine prior to his killings. Evaluators should consider the predominant rather than precise cause of insanity when both voluntary intoxication and mental illness are pertinent issues for the purposes of the defense.

Author

• Meron Wondemaghen, University of Southampton