Diminished Responsibility

• Diminished Responsibility


  • Burden of proof lies with the defendant - on the balance of probabilities
  • Two medical experts required
• Diminished Responsibility

  1. Defendant must prove they were suffering from an abnormality of mental functioning

  2. Caused by a recognised medical condition

  3. Which substantially impaired their ability to understand the nature of their conduct, form a rational judgment, or exercise self-control

  4. And this provides an explanation for the defendant's acts or omissions in doing or being party to the killing
• Abnormality of Mental Functioning (AMF)

  A state of mind so different from that of ordinary human beings that the reasonable man would term it abnormal
• The cause of the abnormality of mental functioning must be due to a recognised medical condition as listed on the World Health Organisation List</b>
• Examples of recognised medical conditions causing AMF

  • Battered spouse syndrome
  • Alcohol dependency syndrome
  • Paranoia
  • PMT
  • Post natal depression
  • Schizophrenia
  • Severe depression
• Acute voluntary intoxication and developmental immaturity in those under 18 are excluded as causes of AMF
• Impairment must be 'substantial'


  It must make a great difference to the way the person acted
• The abnormality of mental functioning must be a significant contributory factor that explains why the defendant killed the victim
• Intoxication alone is not enough to amount to diminished responsibility
• Where the defendant has a recognised medical condition and was voluntarily intoxicated, the jury can take account of both the medical condition and the intoxication
• Where the defendant has brain damage as a result of alcohol misuse, the brain damage can be included as an AMF
• In Brennan (2014) the court stressed the importance of expert medical evidence. Two medical experts must agree that the defendant is suffering from a recognized medical condition. If this can be proved than the judge must withdraw the question of murder from the jury
• Byrne (1960)


  Sexual psychopath who could not control desire to strangle women.
• Impairment must be ‘substantial’ – test set in Golds


  jury told to consider whether the person’s ability to either:

  understand the nature of his conduct

  form a rational judgement

  exercise self control

  Was substantial which means:

  Did it make a great difference to the way they acted.
• Osbourne


  O had an argument with a man.  Furious that the man had argued back he went and got a plank of wood and beat the man to death.

  He claimed DR due to his condition of severe ADHD.

  Defence failed as it was his anger issues that caused him to kill and was not linked to his AMF.
• Dowds


  The defence failed as Dowds could control his drinking and beyond his excessive drinking he did not have an abnormality of mental functioning.

  He was convicted of the murder of his wife.
• Abnormality and intoxication together

  Dietschmann (2003)

  D was suffering from mental condition linked to recent death of his aunt.  He was also intoxicated. His friend said something about the aunt which caused him to lose control and kill his friend. He claimed DR.

  The court stated that where the def. has a RMC and was voluntarily intoxicated, the jury can take account of both the RMC and the intoxication.
• Stewart (2009)

  Where def. has brain damage as a result of alcohol misuse, the brain damage can be included as an AMF.