A-
Level
Law:
Crimi
nal
Law
(01)
Topic 6:
General Defences
1)Insanity &
Automatism
Name:
Teacher:
, Insanity
The rules on insanity are based on the M’Naghten Rules (1843):
M’Naghten (1843)
The D shot and killed the secretary of the UK Prime Minister. He believed that the
Prime Minister was conspiring against him but shot his secretary by mistake. The court
acquitted the D “by reason of insanity” and he was placed in a mental institution for the
rest of his life. The case caused public uproar and the HofL developed the test for
insanity in this case.
The courts set the test for establishing insanity:
1. The D suffers a defect of reason
2. This results from a disease of the mind
This causes the D not to know the nature and quality of his actions or
that it was wrong.
“In all cases every
man is presumed to
be sane and to
possess a sufficient
degree of reason to
be responsible for
his crimes”
For the defence of insanity to be established, the House of Lords gave the following
definition showing what a D must prove at the time of committing the act if the
defence of insanity is to be successful:
The defendant must be “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 what he was
doing was wrong”
, The burden of proof is on the defendant who must prove insanity on the
balance of probabilities.
1) Defect of
reason
The D’s powers of reasoning must be impaired. If the D is capable of reasoning but
has failed to use those powers, then this is not a defect of reason. This was decided in
Clarke (1972) where it was held that the defect of reason must be more than absent-
mindedness or confusion:
Clarke (1972)
The D was a 58 year old woman who absent mindedly
put a jar of mincemeat into her bag whilst shopping in a
super market. She claimed that she had no recollection
of this. Medical evidence stated that she was suffering
from depression and diabetes.
Insanity failed as the D wasn’t deprived of the powers
of reason. A defect of reason must be more than
confusion or absentmindedness.
2) Disease of the
mind
The defect of reason must be due to a disease of the mind. This is a legal term, not a
medical term for the purposes of the defence of insanity. The disease can be a mental
disease or a physical disease which affects the mind.
Kemp (1956)
The D violently attacked his wife with a hammer. He was of previously good
character but suffered from arteriosclerosis which caused his arteries to
harden and restricted the blood flow to his brain. This caused a temporary
loss of consciousness meaning that he wasn’t aware that he had picked up
the hammer or had attacked his wife with it.
The D was not guilty by reason of insanity as a disease of the mind must be
temporary or permanent, curable or incurable.
Sullivan (1984)
The D kicked his elderly neighbour in the head and body
whilst suffering from an epileptic seizure. The judge ruled
Level
Law:
Crimi
nal
Law
(01)
Topic 6:
General Defences
1)Insanity &
Automatism
Name:
Teacher:
, Insanity
The rules on insanity are based on the M’Naghten Rules (1843):
M’Naghten (1843)
The D shot and killed the secretary of the UK Prime Minister. He believed that the
Prime Minister was conspiring against him but shot his secretary by mistake. The court
acquitted the D “by reason of insanity” and he was placed in a mental institution for the
rest of his life. The case caused public uproar and the HofL developed the test for
insanity in this case.
The courts set the test for establishing insanity:
1. The D suffers a defect of reason
2. This results from a disease of the mind
This causes the D not to know the nature and quality of his actions or
that it was wrong.
“In all cases every
man is presumed to
be sane and to
possess a sufficient
degree of reason to
be responsible for
his crimes”
For the defence of insanity to be established, the House of Lords gave the following
definition showing what a D must prove at the time of committing the act if the
defence of insanity is to be successful:
The defendant must be “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 what he was
doing was wrong”
, The burden of proof is on the defendant who must prove insanity on the
balance of probabilities.
1) Defect of
reason
The D’s powers of reasoning must be impaired. If the D is capable of reasoning but
has failed to use those powers, then this is not a defect of reason. This was decided in
Clarke (1972) where it was held that the defect of reason must be more than absent-
mindedness or confusion:
Clarke (1972)
The D was a 58 year old woman who absent mindedly
put a jar of mincemeat into her bag whilst shopping in a
super market. She claimed that she had no recollection
of this. Medical evidence stated that she was suffering
from depression and diabetes.
Insanity failed as the D wasn’t deprived of the powers
of reason. A defect of reason must be more than
confusion or absentmindedness.
2) Disease of the
mind
The defect of reason must be due to a disease of the mind. This is a legal term, not a
medical term for the purposes of the defence of insanity. The disease can be a mental
disease or a physical disease which affects the mind.
Kemp (1956)
The D violently attacked his wife with a hammer. He was of previously good
character but suffered from arteriosclerosis which caused his arteries to
harden and restricted the blood flow to his brain. This caused a temporary
loss of consciousness meaning that he wasn’t aware that he had picked up
the hammer or had attacked his wife with it.
The D was not guilty by reason of insanity as a disease of the mind must be
temporary or permanent, curable or incurable.
Sullivan (1984)
The D kicked his elderly neighbour in the head and body
whilst suffering from an epileptic seizure. The judge ruled
