‘Irresistible impulse’: historicizing a judicial innovation in Australian insanity jurisprudence

Abstract

In twentieth-century Australian criminal law a distinctive departure from the M’Naghten Rules developed as a critique of the discourse of reasoning and verdicts applying in the relevant English trials from the 1880s. The English verdict of ‘guilty but insane’ was criticized by the leading jurists as contradictory. In a sequence of influential judgments, the jurist Owen Dixon articulated an approach to the insanity defence that made room for a medico-legal discourse which broadened the possible referents of what it meant to ‘know’ the legality of an act, and also acknowledged the complex behavioural factors that might determine an act of homicide. This paper explores the shaping and significance of this departure and its comparative judicial, medical and social contexts. A concluding discussion considers whether the more flexible interpretation of the insanity defence implied by the direction of Dixon’s decisions made as much of a difference to frequency of use of the defence as the contemporaneous decline and eventual abolition of capital punishment.