• Ram had killed his wife and son. There was no apparent reason or motive for the double murder
and there was no attempt on his part to conceal his crime. Subsequent to his arrest he was
ordered to undergo a psychiatric examination at the mental hospital. After two months the doctor
came up with a report that Ram was fit to stand trial. The report revealed that Ram was a
habitual drug taker and glue inhaler. These unhealthy habits of his had affected his brain and had
caused him to suffer some kind of mental disease, so much so that he was incapable of knowing
the nature of his act or its criminality. In one of the sessions with the doctor, Ram said that his
mind was blank at the time of the incident and he was not conscious of what he did. He
continued to explain that of late he was not being himself. This was due to the financial and
matrimonial problems he was facing.
• Discuss whether Ram can successfully raise any of the general defences in chapter 4 of the Penal
HELP LLB 104 2
• Refer to S 84 of the Penal Code.
• S 84 drew its inspiration from the English McNagthen Rules on legal insanity, based on the case
of McNagthen (1843).
• However, there are significant differences between the defence of unsoundness of mind and the
defence of insanity as laid down in McNagthen.
HELP LLB 104 3
• Daniel McNagthen was charged with the murder of
Edward Drummond, the private secretary of Sir
Robert Peel who was then Prime Minister of
England. McNagthen was suffering from delusions
of persecution/torture that Sir Robert Peel had
• He had intended to kill Sir Robert Peel but shot and
killed Drummond instead, mistaking him for the
• He was acquitted on the ground of insanity.
HELP LLB 104 4
•To establish a defence on the ground of insanity,
it must be clearly proved that, at the time of
the committing of the act, the party accused
was labouring under such a defect of reason,
from disease of 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 he
was doing what was wrong.
HELP LLB 104 5
John a/l Nyumbei v Public Prosecutor
 2 MLJ 206
• This section exempts a person found to be insane of
any criminal responsibility if it is found that he is
'incapable of knowing the nature of the act, or that
he is doing what is either wrong or contrary to law'
(see commentary in Ratanlal and Dirajlal's Law of
Crimes, (25th Ed), at p 280).
HELP LLB 104 6
• The learned authors there further commented that a person 'is not
protected if he knew that what he was doing was wrong, even
though he did not know that it was contrary to law, and also, if he
knew what he was doing was contrary to law even though he did not
know that it was wrong.
• Thus, under s 84 of the Penal Code , criminality has to be
determined according to that legal test and not merely by the
mental state of an accused person according to the medical test.
• There is a distinction between the notion of a legal insanity and
• Not every form of insanity exempts a person from criminal
• Only legal insanity provides that exemption under s 84 of the Penal
• The specie of insanity addressed by s 84 is the one that
impairs/damages the cognitive/mental faculties/abilities of a
• Its nature and extent must be that to make the offender incapable
of knowing the nature of his act, or that he is doing is wrong or
contrary to law.
• The criminality of an act therefore must be determined by this test
laid down in s 84 as distinguished from the medical test.
Elements of the defence
HELP LLB 104 10
At the time of doing it
By reason of
unsoundness of mind
Incapable of knowing
The nature of the act
Or that he is doing
what is either wrong
or contrary to
1. At the time of doing it
HELP LLB 104 11
The crucial time that the accused is said to be suffering from
unsoundness of mind, whether temporary or permanent, is the time
of the commission of the offence.
It is irrelevant if he was suffering from the alleged condition before
or after the act.
The accused has to suffered from unsoundness of mind which
impaired their capacity to know the nature of their conduct or to
know that it was either wrong or contrary to law.
Public Prosecutor v Muhammad Suhaimi Abdul Aziz  1 CLJ
• Ariffin Zakaria JCA (as he then was) said
• “It is settled law that the defence of insanity under s
84 is concerned with the accused's legal
responsibility at the time of the alleged offence and
not with whether he was medically insane at that
HELP LLB 104 12
• The question whether a person was suffering from
unsoundness of mind at a certain time is a question
of fact for the court to be decided in the light of the
clinical evidence, if any.
• PP v Han John Han, held that there was nothing in
principle to prevent a court from making a finding of
unsoundness of mind without any clinical evidence.
• A person may be legally insane whether or not the
mental malfunction was of continuing nature. S 84
requires only that the cognitive incapacity was
present at the time of the act.
HELP LLB 104 13
Walton v The Queen  1 All ER 542
• Privy Council, at p 546, said:
• These cases make clear that on an issue of
diminished responsibility the jury are entitled and
indeed bound to consider not only the medical
evidence but the evidence on the whole facts and
circumstances of the case.
• These include the nature of the killing, the conduct
of the accused before, at the time of and after it and
any history of mental abnormality.
HELP LLB 104 14
• It being recognised that the jury on occasion may properly refuse to
accept medical evidence, it follows that they must be entitled to
consider the quality and weight of that evidence.
• As was pointed out by Lord Parker CJ in R v Byrne, what the jury are
essentially seeking to ascertain is whether at the time of the killing
the accused was suffering from a state of mind bordering on but not
amounting to insanity.
• That task is to be approached in a broad common sense way.
2. By reason of unsoundness of mind
What is the differences between unsoundness of mind and
disease of mind?
To what extend they overlap?
S 84 is wider than the term disease of mind under McNagthen
Under the McNagthen rules, the disease of the mind must give
rise to the defect of reason or an impairment of the mind.
HELP LLB 104 16
• Devlin J held that legal insanity within the Mcnagthen rules means
malfunctioning of the mind-the mental faculty of reasoning,
memory and understanding-caused by disease.
• S 84 not only include disease of the mind but could also include
mental deficiency not resulting from disease of mind.
• As in the insanity, unsoundness of mind also is a legal and not
medical concept, though the two may overlap.
• Legally, concern with the question whether the accused’s
responsibility for his actions, whereas the doctor is concerned
with the medical treatment of the patient suffering from medical
HELP LLB 104 18
• However, what may be considered by lawyers as unsoundness of
mind may not be considered medical insanity.
• E.g.: a person who grossly defective in intelligence or suffers from
psychomotor epilepsy may fall within the scope of unsoundness of
mind though he may not be medically insane.
• But medical and legal concept of insanity may overlap like
schizophrenia, paranoia or lunacy.
HELP LLB 104 19
• Delusions, hallucinations and illusions may all occur as symptoms of
• A delusion is when a man believes that he has lost all his money and is
suffering from a fatal illness, despite production of a concrete evidence
that he is still solvent and he has not demonstrate any physical disease.
• Hallucination is when a person hears voices or sees visions which no
else can hear or see which in fact the projection of his own fantasy.
• Illusion is when a person mistaken or a nurse or physician to be his
mother or father, or for devil come to take him away.
HELP LLB 104 20
The accused was suffering from schizoprenia was under a delusion
and hallucination when he killed the deceased.
The accused killed his son under a delusion that he was instructed to
do by someone in paradise. It was clear that he did not know the
nature of the act.
Jusoh v PP
•The A ran amok for no apparent reason and slashed
his sister-in-law (inflicting 12 injuries) and her 2
children to death.
•He then killed a man who was a complete stranger to
him and inflicted severe injuries on 2 young men who
led the villagers secure him.
•A medical officer who was with the A two hours after
his arrest described him “in a daze” and
“overwhelmed with woe”.
•He then was convicted under S 302 and appealed.
HELP LLB 104 22
• The court allowed the appeal o the ground that there
were 4 killings in circumstances of very great
atrocity for which there was no motive at all, in short
that the facts were such that an ordinary man might
well be prompted to say, “this is a work of a
• Besides, based on medical expert evidence who had
had the A under observation for about 3 months was
that at the time of the killing, the accused was
suffering from mania.
HELP LLB 104 23
• English law recognised 2 species of automatism, non-insane and
• Insane automatism come within the Mc Nagthen Rules.
• One of the main facts which English law has taken into
consideration in determining whether automatism is non-insane
or insane is whether the automatism was caused by internal
(insane) or external (non-insane) factor.
HELP LLB 104 24
• Violence, drugs, the administration of anesthetics causing a
malfunctioning of the mind are considered as external factors.
• English law also include concussion, all reflex actions of external
origin, sonambulism, hynotism and hypoglycemia as non-insane
HELP LLB 104 25
•A devoted husband of previous good character made an entirely motiveless and
irrational violent attack upon his wife with a hammer. He was charged with causing
grievous bodily harm. He suffered from hardening of the arteries which lead to a
congestion of blood in the brain. This caused a temporary lack of consciousness, so
that he was not conscious that he picked up the hammer or that he was striking his
wife with it. He sought to raise the defence of automatism.
The hardening of the arteries was a " disease of the mind " within the M'Naghten
Rules and therefore he could not rely on the defence of automatism.
• Devlin J:-
"It does not matter for the purposes of law, whether the defect of
reason is due to a degeneration of the brain or to some other form of
mental derangement. That may be a matter of importance
medically, but it is of no importance to the law, which merely has to
consider the state of mind in which the accused is, not how he got
R v Sullivan
•The appellant kicked a man. At the time of the attack he was suffering
from epilepsy. The trial judge ruled that on the evidence the appropriate
defence was insanity not automatism. The appellant appealed.
The appeal was dismissed. The trial judge was correct in only allowing
insanity to be put for the jury's consideration.
•"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"
The A, who had attacked the deceased with Kassi without any motive
and under the influence of a fit of ‘major’ epilepsy, was held entitled
to the defence of unsoundness of mind under S 84.
Nga Ant Bwe
• The accused murdered his mother and wounded his step-father in a
fit of epilepsy without any apparent cause.
• After the murder he hid in a ravine.
• Medical evidence, showed that he was subject to epileptic fits.
• The court held that he was entitled to the defence of insanity under
•A sleepwalker who stabbed his friend 20 times was acquitted on
the ground of non-insane automatism.
•Sleepwalking / somnambulism could be regarded as non-insane
automatism under the English law.
•But Indian Court accept somnambulism as part of S 84 as decided
in the case of Re Papathi Ammal
HELP LLB 104 32
• Mental deficiency like idiocy, imbecility and feeble-mindedness
could be regarded as unsoundness of mind unlike hypnotism.
• Idiocy mean an IQ of zero or near to it; he has no useful speech or
understanding of speech, he can seldom feed himself, seldom has
the wit or physical capacity to perform a crime.
• Imbecility is a lesser degree of severe intellectual sub normality.
The IQ is below 50.
• Feeble mindedness or morons or the subnormal. The upper limit
for the IQ of the subnormal is variously stated; some put it at 65,
others as high as 80.
HELP LLB 104 33
Irresistible impulse – where a person may know the nature of an act, may even
know that it is wrong and yet perform it under an impulse that is almost or
It is an offence on the ground of the difficulty or impossibility of distinguishing
between an impulse which proves irresistible because of insanity and one
which is irresistible because of ordinary motives of greed, jealousy or revenge.
•Irresistible impulse per se is no defence under s 84.
•A person who is suffering from irresistible impulse per se may be in full
possession of his cognitive faculties but he is unable to control his will power.
HELP LLB 104 34
Kader Nasyer Shah
• The same position was held in this case. The A was charged with the
murder of a boy.
• His plea was that he “was mad when he strangled the boy”.
• Although the A had been suffering from mental derangement due to
some occasions but after the commission of the offence, he tried to
conceal the corpse and he hid himself in a jungle.
• It showed that at the time he killed the child, was, having the
knowledge that the nature of the act.
•The D killed a boy without any motive other than he wanted to be hanged. It was held
that despite the morbid state of mind he knew what he was doing was wrong and
hence was not entitle to the defence of insanity.
•Evidence of irresistible impulse may be symptomatic of a particular disease of mind.
•Therefore, irresistible impulse is not regarded as unsoundness of mind under
Malaysian and Indian law. It is the same under English law.
HELP LLB 104 36
• Since the introduction of diminished responsibility into the
criminal law in Singapore and England, irresistible impulse could
be mitigating circumstance reducing liability for murder to one
for culpable homicide not amounting to murder.
• But no such provision in Malaysia.
HELP LLB 104 37
3. Incapable of knowing
nature of the act
E.g: A kills B under an insane delusion
that he is breaking a jar or the madman
who cut a woman’s throat under the idea
that he was cutting a loaf of bread – he
has no mens rea
Placing a baby on fire thinking that the
baby was a log of wood.
The accused does not know the surface
features of the act, that is the activity
involves in breaking, cutting or burning
a human being, let alone the harmful
consequence to the victim.
HELP LLB 104 38
Lee Ah Chye
•Interpret s 84, “In other words, there must be a certain state of mind-
incapacity of knowing the nature of the act or incapacity of knowing
it is wrong-but in every case that must exist by reason of
unsoundness of mind.
• Under Mc Naghten Rules the phrase is ‘nature and quality of his
act”; this means the nature and quality of the act and not its moral
or legal aspects.
• A lack of motive in committing the crime may be material evidence
in support of the defence.
R v Kemp
• The cause of motiveless attack by a devoted husband was because of
the accused’s arteriosclerosis.
• In this circumstances, the accused had suffered a state of insane
automatism, by its very nature, comprised an in capacity to know
the nature of his act of assault on his wife.
4. That he is doing what is either wrong or
contrary to law
• Even if the accused knows the nature of the act, i.e. that he is killing
somebody, he can claim the defence under s 84 if, at the time of
doing it, by reason of unsoundness of mind he does not know that
the act is either wrong or contrary to law.
The word wrong cannot be taken to mean
contrary to the law. The word wrong means
But it is unclear whether moral wrong
should be viewed objectively (standard
adopted by reasonable men) or subjectively
(moral standard of the accused).
HELP LLB 104 43
• The phrase is disjunctive in formula. This
mean that only one conditions need to be
satisfied for an acquittal.
• On a conjunctive approach, the accused
must satisfy both the requirements that
he did not know that the act was morally
wrong and that it was contrary to law.
HELP LLB 104 44
Geron Ali v Emperor
• [Conjuctive view]
• The A was convicted of murder and he appealed.
• In this case, the A was a disciple of Khoaz Ali (Pir) who used to be
known as holy man in the village of the A.
• He had a mistress, Tayeba (Pirani). The A called these two as father
and mother and very loyal to them.
• However, the Pir has become unpopular due to his irregular
relationship with Tayeba.
• The A complained about the attitude of the villagers to both of
them. Then the Pir told him “Take the head of those who dissuade
(discourage) you and come to your doors”.
• The Pir also gave him a dao (sword). In the evening, the Pir gave
something for the A to swallow which he did.
• At this time the Pirani said to the A that he would go to the heaven if
he offered a human head in sacrifice.
• The A armed himself with a dao and severed the head of the one
• He carried the head to his house. He saw his daughter aged 3 and he
cut off her head also.
• Taking these 2 heads he approached the Pir and Pirani and said,
“Father, you asked me for one human head, I present you with two.”
He then surrendered the heads to the Pir.
• Court allowed the appeal on the ground that the A knew the nature
of his act but he did not know that he was doing was contrary to law
and he did not know what he was doing was wrong.
• The court applied conjunctive approach in the sense that it stated
that the A will no be protected if he knew what he was doing was
contrary to law even though he did not know that what he was doing
• The evidence showed that he considered that he was doing a
meritorious act which qualified him for heaven.
• His conduct also established that he did not know what he was
doing was contrary to law because he killed these person without
any effort at concealment and he did not try to escape after doing
Ashiruddin Ahmed v King
• [Disjunctive view]
• The A was convicted for murder of his 5 year old son.
• He dreamt that he had been directed by someone in paradise to
sacrifice his son by killing him as his previous sacrifices had been
• Court had set aside the conviction held that
1. the nature of the act was clearly know to the accused;
2. he knew that the act was contrary to law; but
3. whether the A knew that the act was wrong.
• The court of the opinion that the A was incapable of knowing that
his act of causing death to his son by cutting his throat was wrong.
R v Windle
• The appellant killed his wife. She was suicidal and he administered
an aspirin overdose. Medical evidence supported the view that he
was suffering from a mental condition at the time of the crime. On
arrest he said to the police, "I suppose they will hang me for this".
The trial judge refused to allow the defence of insanity to be put
before the jury as he had demonstrated that he realised that what he
was doing was unlawful.
The appeal was dismissed. The trial judge was correct to refuse the
defence of insanity. Wrong, for the purposes of the M'Naghten rules,
meant unlawful. It did not matter that he thought his actions were
not morally wrong.
• If defence of unsoundness of mind successfully pleaded by the
accused, he will be kept in safe custody of mental hospital.
• Its differs from other defence under Chapter IV.
• Procedure – s342 – 352 of the CPC
• S 348 of the CPC – to be kept in safe custody in place and manner
as the Court thinks fit.
HELP LLB 104 53