The Court of Appeal held that if D realizes there is a risk that his conduct may lead to aggressive, unpredictable, and uncontrollable conduct, and he nevertheless deliberately runs the risk, this will amount to recklessness. If D is reckless in becoming an automaton, he cannot succeed with the defence if charged with a basic intent crime.

D was an insulin-dependent diabetic who had not taken insulin and had not eaten for several days. He sought to raise a defence of automatism, in that the offences with which he was charged were committed during a state of hyperglycaemia.

That was an internal cause (the diabetes itself) and not an external cause (the insulin). The correct defence was insanity.

D had paedophiliac tendencies and was charged with indecent assault on a boy aged 15. D’s defence was that he had been drugged by another, X, who had arranged to blackmail D by photographing D in a compromising situation with the boy. D stated that had he not been drugged, he would not have acted as he did, and that he had no recollection of so acting. The jury was directed that a drugged intent was still an intent. He was convicted.

Although the Court of Appeal had allowed D’s appeal because of the apparent absence of moral fault, the House of Lords held that where the prosecution proved that the mens rea was present when the actus reus occurred, the defence of involuntary intoxication could not be open to D.

D was involved in a brawl at a public house in which he assaulted the landlord, customers, and police officers. His defence was that the offences had been committed while he was suffering from the effect of alcohol and drugs.

If D is charged with a specific intent crime and did not form mens rea, he is not guilty of that crime (but liability may be reduced). Voluntary intoxication is not a defence to basic crimes (+ the Richardson and Irwin ‘gloss’; if D would have formed the mens rea when sober).

D was suffering from morbid delusions and a persecution syndrome. He fired his gun at the Prime Minister’s secretary, believing he was actually shooting the Prime Minister, because M’Naghten believed there was a plot against him.

The House of Lords stated: ‘the jury should be directed that every man is presumed to be sane ... until the contrary be proved to their satisfaction, and that to establish a defence on the ground of insanity it must be clearly proved that at the time of committing the act the party accused was labouring under such a defect of reason, from disease of the mind, as not to know the nature and quality of the act he was doing, or, if he did know it, that he did not know that he was doing what was wrong.’

D was a nurse who was charged with assaulting a patient. D, a diabetic, gave evidence that he had taken insulin as prescribed on the morning of the assault, had then drunk alcohol and eaten little food and had no recollection of the assault. He called medical evidence to the effect that he was suffering hypoglycaemia.

The Court of Appeal held that ‘disease of the mind’ within the meaning of the M’Naghten Rules was a malfunctioning of the mind caused by disease. It did not include the application to the body of some external factor, such as insulin.

D kicked V in the head and body while suffering an attack of psychomotor epilepsy. D gave evidence, which was not challenged, that he had no recollection of the incident.

The House of Lords accepted that it was regrettable that the label of insanity had to be applied to a case of epilepsy, but D had an internal disorder which impaired D’s mental faculties of reason, memory, and understanding.