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R v Hennessy - 1989

346 words (1 pages) Case Summary

28th Oct 2021 Case Summary Reference this In-house law team

Jurisdiction / Tag(s): UK Law

Legal Case Summary

R v Hennessy [1989] 1 WLR 297

Diabetes and defences – automatism or insanity in hyperglycaemic cases


The appellant (a diabetic) was apprehended while driving a stolen car. He later collapsed at the police station it became apparent that he was having a diabetic episode and that he had not taken his insulin for several days, at least in part because of emotional turmoil due to being left by his wife. Evidence was given that hyperglycaemia (which is what was afflicting the defendant) resulted in drowsiness and possibly degradation of one’s ability to understand what is happening around them, as well as of their physical and mental abilities. Further, emotional states such as anxiety and depression can exacerbate the effect. He was charged with both theft (contrary to the Theft Act 1968 c.60, s.1) and driving while disqualified (contrary to the Road Traffic Act 1988 c.52, s.103). The appellant did not recall taking the car and at trial relied on the defence of automatism. The trial judge ruled that automatism does not apply to his condition and that he should have relied on a plea of insanity instead. The appellant was convicted.


On appeal against the conviction, the issue was whether the automatism defence had been available to the appellant or whether insanity is the correct defence for diabetics suffering a hyperglycaemic episode.


The trial judge had correctly assessed that insanity is the correct defence to apply to a hyperglycaemic episode, since this is caused by the underlying condition of diabetes and can properly be described as a disease of the mind. Further, automatism refers to situations where the defendant’s actions are involuntary. R v Quick [1973] QB 910 distinguished.

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