Diminished Responsibility Criminal Law
Diminished responsibility was set out in the Homicide Act (1957). It was amended by the new law, s52
Coroners and Justice Act (2009).
DIMINISHED RESPONIBILITY:
This defence recognises that it is less culpable to kill when the mind is disturbed than it is kill when
the mind is operating normally
The essence of this defence is that some form of transient disruption to the defendant’s mental state
has rendered them less blameworthy than would otherwise be the case.
It is a special defence to murder – only available as a defence to murder only
Partial defence – reduces murder conviction to manslaughter
Judge has a full discretion on sentencing
15% of cases receive life sentences for manslaughter
About 50 successful uses of this defence
Old Law:
Created by s2(1) Homicide Act 1957
The old law said defence available if D:
o suffering from “such abnormality of mind (whether arising from a condition of arrested or
retarded development of mind or inherent cause or induced by disease or injury) as
o substantially impaired his mental responsibility for his acts and omissions in doing or being
party to the killing”.
Burden of Proof:
̶ Burden is on the Defence under s.2(2) (Ali 2001)
̶ Requires the defendant to prove on a balance of probabilities – Dunbar (1958).
̶ D will need to introduce expert evidence to support Dr (Bunch 2013)
̶ Trial judge has no power to raise the issue of DR if the D does not do so (R v Campbell 1987 84 Cr App
R 255)
̶ Must be clear evidence some expert evidence is not enough: some exert evidence is not
enough // prosecution may also have expert evidence to show there was no DR
̶ Old law – “abnormality of mind” – changed it to “abnormality of mental functioning” - to make it
easier for medical experts as the term abnormality of mind has no basis in psychiatry. Byrne - The
court said that the defence covered the mind’s activities in all its aspects (not just the brain) and the
ability to control one’s physical acts.
Pleading guilty to manslaughter on grounds of DR:
Pleas of guilty on the grounds of DR should only be accepted where there was ‘clear evidence’ of mental
imbalance.
The plea was refused in the following cases:
, Diminished Responsibility Criminal Law
-Din (1962): stabbed man who he thought was having an affair with his wife
- R. v Stefan Ivan Kiszko (1979): Killed 11-year-old by stabbing her. W’d over body.
-Walton (1978): Gave ride to gf and mum, but because of his behaviour, both women got out and hailed a
diff car. He approached the car and fired, killing one of the passengers. Argued DR but there was no
expert medical evidence given.
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DR v Insanity – do not confuse:
-DR (abnormality of mental functioning) v Insanity (disease of the mind)
-Insanity is very narrow in scope- defendant did not know what he was doing or that he did not know that
it was wrong
-DR encompasses all aspects of the mind’s activities and not just the defendant’s brain. DR does not
require a def to be insane or partially insane. DR is much wider than insanity
-Thus, a defendant may plead DR even though: he appreciated what he was doing in killing the victim,
and knew that it was wrong
- Insanity – special verdict “not guilty by reason of insanity”. Acquittal inevitably leads to committal to a
mental institution for an indeterminate length of time
V
- Diminished Responsibility –Statistics reveal that 50% of those convicted for manslaughter due to DR
receive hospital orders under s37 Mental Health Act 1983. Of the remainder sentences tend to range
from probation and suspended sentences to various terms of imprisonment.
-Prior to s.2(1) Homicide Act 1957 coming into force, there was only one option – pleading insanity
-This was a full defence, which led to acquittal, but with the verdict, “not guilty by reason of insanity”
-Ppl did not want to rely on this, because they had to stay indefinitely in a mental institution, and they
there was stigma attached to the label of being ‘insane’ makes it difficult to find a job, for example.
New Law: s.52 Coroners and Justice Act (2009):
A person who kills or is a party to the killing of another is not to be convicted of murder if D was suffering
from an abnormality of mental functioning which:
a) Arose from a recognised medical condition
b) Substantially impaired D’s ability to do one or more of the things mentioned in
subsection (1A)
c) Provides an explanation for D’s acts and omissions in doing or being a party to the killing.
(1A) Those things are:
Diminished responsibility was set out in the Homicide Act (1957). It was amended by the new law, s52
Coroners and Justice Act (2009).
DIMINISHED RESPONIBILITY:
This defence recognises that it is less culpable to kill when the mind is disturbed than it is kill when
the mind is operating normally
The essence of this defence is that some form of transient disruption to the defendant’s mental state
has rendered them less blameworthy than would otherwise be the case.
It is a special defence to murder – only available as a defence to murder only
Partial defence – reduces murder conviction to manslaughter
Judge has a full discretion on sentencing
15% of cases receive life sentences for manslaughter
About 50 successful uses of this defence
Old Law:
Created by s2(1) Homicide Act 1957
The old law said defence available if D:
o suffering from “such abnormality of mind (whether arising from a condition of arrested or
retarded development of mind or inherent cause or induced by disease or injury) as
o substantially impaired his mental responsibility for his acts and omissions in doing or being
party to the killing”.
Burden of Proof:
̶ Burden is on the Defence under s.2(2) (Ali 2001)
̶ Requires the defendant to prove on a balance of probabilities – Dunbar (1958).
̶ D will need to introduce expert evidence to support Dr (Bunch 2013)
̶ Trial judge has no power to raise the issue of DR if the D does not do so (R v Campbell 1987 84 Cr App
R 255)
̶ Must be clear evidence some expert evidence is not enough: some exert evidence is not
enough // prosecution may also have expert evidence to show there was no DR
̶ Old law – “abnormality of mind” – changed it to “abnormality of mental functioning” - to make it
easier for medical experts as the term abnormality of mind has no basis in psychiatry. Byrne - The
court said that the defence covered the mind’s activities in all its aspects (not just the brain) and the
ability to control one’s physical acts.
Pleading guilty to manslaughter on grounds of DR:
Pleas of guilty on the grounds of DR should only be accepted where there was ‘clear evidence’ of mental
imbalance.
The plea was refused in the following cases:
, Diminished Responsibility Criminal Law
-Din (1962): stabbed man who he thought was having an affair with his wife
- R. v Stefan Ivan Kiszko (1979): Killed 11-year-old by stabbing her. W’d over body.
-Walton (1978): Gave ride to gf and mum, but because of his behaviour, both women got out and hailed a
diff car. He approached the car and fired, killing one of the passengers. Argued DR but there was no
expert medical evidence given.
--------------------------------------------------------------------------------------------------------------------------------------------
DR v Insanity – do not confuse:
-DR (abnormality of mental functioning) v Insanity (disease of the mind)
-Insanity is very narrow in scope- defendant did not know what he was doing or that he did not know that
it was wrong
-DR encompasses all aspects of the mind’s activities and not just the defendant’s brain. DR does not
require a def to be insane or partially insane. DR is much wider than insanity
-Thus, a defendant may plead DR even though: he appreciated what he was doing in killing the victim,
and knew that it was wrong
- Insanity – special verdict “not guilty by reason of insanity”. Acquittal inevitably leads to committal to a
mental institution for an indeterminate length of time
V
- Diminished Responsibility –Statistics reveal that 50% of those convicted for manslaughter due to DR
receive hospital orders under s37 Mental Health Act 1983. Of the remainder sentences tend to range
from probation and suspended sentences to various terms of imprisonment.
-Prior to s.2(1) Homicide Act 1957 coming into force, there was only one option – pleading insanity
-This was a full defence, which led to acquittal, but with the verdict, “not guilty by reason of insanity”
-Ppl did not want to rely on this, because they had to stay indefinitely in a mental institution, and they
there was stigma attached to the label of being ‘insane’ makes it difficult to find a job, for example.
New Law: s.52 Coroners and Justice Act (2009):
A person who kills or is a party to the killing of another is not to be convicted of murder if D was suffering
from an abnormality of mental functioning which:
a) Arose from a recognised medical condition
b) Substantially impaired D’s ability to do one or more of the things mentioned in
subsection (1A)
c) Provides an explanation for D’s acts and omissions in doing or being a party to the killing.
(1A) Those things are:
