R v Burgess  2 WLR 1206
Acquittal by virtue of insanity where accused committed crime whilst sleep-walking
The appellant (B) was charged with wounding with intent to do grievous bodily harm. His defence was that during the event he was sleep walking and suffering from non-insane automatism. However, the judge ruled that on the medical evidence available the only defence available was insanity. The jury found B not-guilty by reason of insanity.
On appeal, B argued that automatism should not be considered insanity. The Crown argued that B suffered from an abnormal state of mind and it was irrelevant how it arose. The Court accepted that there was a failure in B’s mind which caused him to act as he did. The key issue was therefore whether that failure was a disease of the mind or, rather, a defect or failure of the mind not due to disease.
B’s appeal was dismissed. The Court found that the failure in B’s mind was due to an abnormality which manifested itself in violence and might recur. This amounted to a disease of the mind and the trial judge’s application of insanity as a defence was therefore correct. In particular, the Court noted the absence of obvious external factors (such as, for instance, concussion) which could have caused the failure in B’s mind. The Court adopted the reasoning of the Supreme Court of Canada in Rabey v the Queen  2 S.C.R. 513 and found that any malfunctioning of the mind which has its source in some condition or weakness internal to the accused may be a ‘disease of the mind’ and, accordingly, a finding of insanity may follow.