voluntary manslaughter (diminished responsibility)

• Voluntary Manslaughter (Diminished Responsibility)

  A partial defence to murder where the defendant has an abnormality of mental functioning that substantially impairs their ability to understand, form a rational judgement, or exercise self-control
• Diminished Responsibility


  Section 2 of the Homicide Act 1957, as amended by section 52 of the Coroners and Justice Act 2009.

  1. An abnormality of mental functioning caused by a recognised medical condition.
  2. This abnormality substantially impaired their ability to: understand the nature of their conduct, form a rational judgement, or to exercise self-control.
  3. Therefore. this abnormality provides an explanation for the defendant's acts or omissions in being party to the killing.
• 1 Abnormality of Mental Functioning(s.2(1)(a))

  What the jury will assess is whether the defendant's abnormality of mental functioning was so different from that of ordinary human beings that the reasonable person would term it abnormal.

  However, the abnormality must come from a recognised medical condition.

  Accepted disorders include anxiety disorders, personality disorders, alcohol dependency and schizophrenia. Accepted physical conditions include epilepsy and sleep disorders.

  Case - R v Byrne - medical evidence
• 2 Substantially Impaired the defendant's ability (s.2(1)(b)

  The defendant needs to show that this abnormality substantially impaired their ability to:

  A) Understand the nature of their conduct

  B) Form a rational judgement: or

  C) To exercise self-control.
• 2 Substantially Impaired the defendant's ability (s.2(1)(b)

  A) ability to understand the nature of their conduct:

  The defendant is in a state where they do not know what they are doing.

  This also covers those with severe learning difficulties that reduce a person's mental age.

  B) ability to form a rational judgement

  The defendant is unable to use reason or logic to handle a problem

  C) ability to exercise self-control

  The defendant is unable to control any impulses, urges or desires.
• 3 Abnormality provides an explanation for the defendant's conduct (s.2(1)(c))

  The defendant must prove that the abnormality of mental functioning can explain why the defendant did the prohibited conduct.
• 3 Abnormality provides an explanation for the defendant's conduct (s.2(1)(c))
- Intoxication


  There are three possibilities to consider:

  • The defendant was intoxicated at the time of the killing and is trying to use diminished responsibility as a defence.
  • The defendant was intoxicated and has a pre-existing abnormality of mental functioning.
  • The intoxication is due to an addiction.
• 3 Abnormality provides an explanation for the defendant's conduct (s.2(1)(c))


  Intoxication on its own cannot be used to gain a defence of diminished responsibility. This is because intoxication on its own is not a recognised medical condition

  Case - R v Dowds
• 3 Abnormality provides an explanation for the defendant's conduct (s.2(1)(c))

  The defendant was intoxicated and has a pre-existing abnormality of mental functioning:

  If the defendant has a pre-existing mental disorder, intoxication will not prevent a defendant using diminished responsibility as a defence.

  Case - R v Dietschmann
• 3 Abnormality provides an explanation for the defendant's conduct (s.2(1)(c))

  The intoxication is due to an addiction:

  If the defendant has an alcohol dependence syndrome, then this can explain an abnormality of mental functioning.

  Case - R v Wood