“Diabetic hyperglycaemia constitutes insanity defence, not automatism, being an internal bodily malfunction.”
Hennessy, a diabetic, failed to take his insulin and medication due to stress and anxiety. He took a car without consent and drove while in a hyperglycaemic state. He claimed automatism, arguing he was not conscious of his actions due to his diabetic condition.
Whether hyperglycaemia caused by diabetes should be classified as insane automatism (insanity defence) or non-insane automatism, and how to distinguish between internal and external causes of automatism.
The Court of Appeal held that diabetes constitutes a disease of the mind and hyperglycaemia caused by diabetes is insane automatism, requiring the insanity defence rather than automatism.
This case clarifies the application of the internal/external factor test to medical conditions and demonstrates how the law categorises diabetic conditions within the automatism/insanity framework. It highlights ongoing tensions between legal categories and medical realities in mental health defences.
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OSCOLA Citation
R v Hennessy [1989] 1 WLR 287
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