Published: Wed, 07 Mar 2018
CASES ON INSANITY
1. DISEASE OF THE MIND
R v Kemp  1 QB 399.
The defendant during a blackout, attacked his wife with a hammer causing her
grievous bodily harm. The medical evidence showed that he suffered from
arterial-sclerosis, a condition which restricted the flow of blood to the brain.
This caused a temporary lapse of consciousness. Devlin J ruled that for the
purposes of the defence of insanity, no distinction was to be drawn between
diseases of the mind, and diseases of the body affecting the operation of the
mind. Also, it was irrelevant whether the condition of mind was curable or
incurable, transitory or permanent. The jury returned a verdict of guilty but
insane. Devlin J said:
‘The law is not concerned with the brain but with the mind, in the sense that
“mind” is ordinarily used, the mental faculties of reason, memory and
Bratty v A-G for N. Ireland  AC 386.
The defendant killed a girl during a mental blackout said to be due to
psychomotor epilepsy, a disease of the nervous system, which might have
prevented him from knowing the nature and quality of his act. The trial judge
directed the jury on the defence of insanity ruling that the defence of
automatism was not available to the defendant. The jury rejected the defence of
insanity and the defendant was convicted. This was held not to be a
misdirection. Lord Denning stated obiter:
“The major mental diseases, which doctors call psychosis, such as
schizophrenia, are clearly diseases of the mind… It seems to me that any
mental disorder which has manifested itself in violence and is prone to recur is
a disease of the mind. At any rate it is the sort of disease for which a person
should be detained in hospital rather than be given an unqualified
R v Sullivan  AC 156.
The defendant kicked and injured a man during a minor epileptic fit. The
trial judge ruled that he was prepared to direct the jury on the defence of
insanity, but not that of automatism. The House of Lords held that epilepsy was
a disease of the mind because the defendant’s mental faculties were impaired to
the extent of causing a defect of reason. It was irrelevant that this was an
organic disease which was only intermittent. It would also be irrelevant if it
were only temporary. Lord Diplock stated:
‘The purpose of the legislation relating to the defence of insanity, ever
since its origin in 1800, has been to protect society against the recurrence of
the dangerous conduct. The duration of a temporary suspension of the mental
faculties of reason, memory and understanding, particularly if, as in the
appellant’s case, it is recurrent, cannot on any rational ground be relevant to
the application by the Courts of the McNaghten Rules, though it may be relevant
to the course adopted by the Secretary of State, to whom the responsibility for
how the defendant is to be dealt with passes after the return of the special
verdict of “not guilty by reason of insanity”.’
R v Hennessy  1 WLR 287.
The defendant was charged with taking a motor car without authority and
driving while disqualified. He claimed that he was suffering from
hyper-glycaemia (high blood sugar level caused by diabetes) at the time because
he had not taken any insulin to stabilise his metabolism, nor eaten properly for
days, and as a result was acting unconsciously. He pleaded automatism but the
trial judge indicated that he would only be prepared to direct the jury on the
defence of insanity.
The Court of Appeal, in confirming the correctness of the trial judge’s
ruling, held that the defendant’s loss of awareness had not resulted from the
operation of external factors upon his body, such as the injection of insulin
(as in R v Quick ), but instead had resulted from an inherent physical
defect, ie diabetes. The hyper-glycaemia suffered by diabetics, which was not
corrected by insulin, was to be regarded as a disease of the body which affected
the mind for the purposes of the M’Naghten Rules.
R v Burgess  2 WLR 1206.
The defendant visited a woman to watch a video in her flat. During the course
of the evening she fell asleep on the sofa. She was awoken by the defendant
smashing a bottle over her head. Before she could stop him he had picked up the
video recorder and brought it down on her head causing cuts and bruises. At his
trial the defendant adduced expert medical evidence to the effect that he had
been sleep-walking at the time of the attack and that the defence of automatism
should be put before the jury. The trial judge ruled that the only defence the
evidence revealed was that of insanity, and the jury in due course found him not
guilty by reason of insanity.
The Court of Appeal dismissed the defendant’s appeal. Lord Lane CJ considered
this ‘disease of the mind’ to be due to an “internal” cause. The
ordinary stresses and disappointments of life which are the common lot of
mankind do not constitute an external cause constituting an explanation for a
malfunctioning of the mind. He then went on to say:
“We accept that sleep is a normal condition, but the evidence in the
instant case indicates that sleepwalking, and particularly violence in sleep, is
Consequently, on the evidence the judge was right to conclude that this was
an abnormality or disorder, albeit transitory, due to an internal factor, which
had manifested itself in violence and which might recur.
R v Bingham  Crim LR 43.
The defendant was a diabetic who was charged with theft, and claimed that he
was hypo-glycaemic at the time of the offences. His conviction was quashed by
the Court of Appeal because the trial judge did not correctly distinguish
between hypo- and hyper-glycaemia.
Note: Hypo-glycaemia = Low blood sugar level due to an excess of insulin (an
external factor). Hyper-glycaemia = High blood sugar level caused by the
diabetes (an internal disorder).
2. DEFECT OF REASON
R v Clarke  1 All ER 219.
The defendant, a diabetic, was charged with theft of items in a supermarket.
Her defence was that she had no intent to steal. There was evidence that she had
behaved absent-mindedly in the home. She said that she must have put the items
in her bag in a moment of absent-mindedness. Her doctor and a consultant
psychiatrist testified that she was suffering from depression, which the
consultant accepted to be a minor mental illness which could produce
The trial judge was convinced that the defence was in truth a defence of
insanity. However, the Court of Appeal held that the M’Naghten Rules do not
apply to those who retain the power of reasoning but who in moments of confusion
or absent-mindedness fail to use their powers to the full.
R v Windle  2 QB 826.
The defendant had killed his wife by administering an overdose of aspirins to
her. Medical evidence showed that although he was suffering from a mental
illness he knew that he was committing a crime; hence his remark to the police,
at the time of arrest, “I suppose they will hang me for this”. The
trial judge refused to allow the defence of insanity to go to the jury on the
ground that he had known his actions were unlawful. This decision was upheld on
3. INSANE DELUSIONS
R v Bell  Crim LR 685.
The defendant had been charged with reckless driving, having used a van to
smash through the entrance gates of a Butlins’ holiday camp. When interviewed he
told the police: “It was like a secret society in there, I wanted to do my
bit against it”. The defendant contended that he had not driven recklessly
because, although he knew there was a risk of his causing criminal damage, he
felt that he was able to cope with it because he was being instructed to act by
God. Following the rejection of his submission of “no case” on this
basis, he changed his plea to one of guilty.
The Court of Appeal held, dismissing the appeal that as the defendant had
been aware of his actions he could not have been in a state of automatism, and
the fact that he believed himself to be driven by God could not provide an
excuse, but merely an explanation for what he had done. In other words he could
not rely on the defence of insanity either because the evidence was that he had
known what he was doing, or had known that what he was doing was illegal.
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