“Physical disease affecting brain constitutes insanity if it impairs mental faculties and reasoning.”
Kemp suffered from arteriosclerosis (hardening of the arteries) which affected the blood supply to his brain. During a moment of impaired consciousness caused by this condition, he attacked his wife with a hammer. He was charged with causing grievous bodily harm.
Whether a physical disease like arteriosclerosis that affects the brain and mental functioning can constitute a 'disease of the mind' under the M'Naghten Rules for the insanity defence.
Devlin J held that arteriosclerosis affecting the brain constituted a disease of the mind, as the law is concerned with the mind's functioning rather than the physical nature of the disease causing the impairment.
This case established an important precedent that physical diseases can ground the insanity defence if they affect mental functioning. It laid groundwork for the broad interpretation of 'disease of the mind' later confirmed in Sullivan and remains relevant for understanding how physical conditions intersect with mental incapacity defences.
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OSCOLA Citation
R v Kemp [1957] 1 QB 399
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