Diminished responsibility is one of three special defences contained in the Homicide Act 1957 which exist solely for the offence of murder. Where the defence of diminished responsibility is successfully pleaded, it has the effect of reducing a murder conviction to manslaughter. The three special defences of diminished responsibility, provocation and suicide pact differ from general defences in that they do not apply to all crimes and also the effect is to reduce criminal liability rather than to absolve the defendant from liability completely.
Diminished responsibility is set out in s.2 of the Homicide Act 1957. There are three requirements of the defence of diminished responsibility which must be established by the defendant:
1. Abnormality of the mind
2. The abnormality must be caused by arrested or retarded development of the mind or any inherent causes or induced by disease or injury.
3. The abnormality must substantially impair the defendant's mental responsibility.
1. Abnormality of the mind
The question of whether the defendant is suffering from an abnormality of the mind is for the jury to decide after hearing medical evidence. The jury are not bound to follow medical opinion it is ultimately their decision as to whether the defence should succeed. A notorious example of the jury ignoring medical opinion was present in the trial of Peter Sutcliffe (the Yorkshire ripper) where the medical opinion was unanimous that the defendant was a paranoid schizophrenic, yet the jury refused to allow him the defence. It is assessed by reference to what a reasonable man would regard as abnormal. It has a wide meaning and encompasses the ability to exercise will power and control.
In each case the defendant must demonstrate that the characteristic was excessive when compared to that experienced by a reasonable person.
2. The abnormality must be caused by arrested or retarded development of the mind or any inherent causes or induced by disease or injury.
S.2 requires the abnormality to be caused by an arrested or retarded development of the mind or any inherent causes or induced by disease of injury. This has been interpreted by the courts as meaning that the abnormality must be caused by an inside source and that outside factors causing the abnormality such as alcohol or drugs can not be taken into account unless the abnormality was as a result of the disease of alcoholism or drug addiction or long term damage caused by the intake of such intoxicants:
If the defendant did not raise the defence of diminished responsibility at trial, the appeal courts are reluctant to admit fresh evidence relating to diminished responsibility:
"Ordinarily, of course, any available defences should be advanced at trial. Accordingly, if medical evidence is available to support a plea of diminished responsibility, it should be adduced at the trial. It cannot be too strongly emphasised that this court would require much persuasion to allow such a defence to be raised for the first time here if the option had been exercised at the trial not to pursue it. Otherwise, as must be clear, defendants might be encouraged to run one defence at trial in the belief that if it fails, this court would allow a different defence to be raised and give the defendant, in effect, two opportunities to run different defences. Nothing could be further from the truth. Likewise, if there is no evidence to support diminished responsibility at the time of the trial, this court would view any wholly retrospective medical evidence obtained long after the trial with considerable scepticism."
Get the film Provoked based on the case of Ahluwalia:
In deciding whether to admit fresh evidence the court must have regard to S. 23 of the Criminal Appeal 1968 which provides:
"(1) For purposes of this Part of this Act the Court of Appeal may, if they think it necessary or expedient in the interests of justice --
(c) receive any evidence which was not adduced in the proceedings from which the appeal lies.
(2) The Court of Appeal shall, in considering whether to receive any evidence, have regard in particular to --
(a) whether the evidence appears to the Court to be capable of belief;
(b) whether it appears to the Court that the evidence may afford any ground for allowing the appeal;
(c) whether the evidence would have been admissible in the proceedings from which the appeal lies on an issue which is the subject of the appeal; and
(d) whether there is a reasonable explanation for the failure to adduce the evidence in those proceedings."
The court is particularly reluctant to allow fresh evidence if the decision not to raise the defence of diminished responsibility was made for tactical reasons as oppose to reasons relating to the capacity to instruct the defence:
The Coroners and Justice Bill is currently before Parliament. Clause 46 seeks to modify the defence of diminished responsibility:
46 Persons suffering from diminished responsibility (England and Wales)
(1) In section 2 of the Homicide Act 1957 (c. 11) (persons suffering from diminished responsibility), for subsection (1) substitute—
“(1) A person (“D”) 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), and
(c) provides an explanation for D’s acts and omissions in doing or being a party to the killing.
(1A) Those things are—
(a) to understand the nature of D’s conduct;
(b) to form a rational judgment;
(c) to exercise self-control.
(1B) For the purposes of subsection (1)(c), an abnormality of mental functioning provides an explanation for D’s conduct if it causes, or is a significant contributory factor in causing, D to carry out that conduct.”
(2) In section 6 of the Criminal Procedure (Insanity) Act 1964 (c. 84) (evidence by prosecution of insanity or diminished responsibility), in paragraph (b) for “mind” substitute “mental functioning”.
