Diminished Responsibility

• Diminished Responsibility (DR) can lead to a conviction of manslaughter instead of murder if the individual was suffering from an abnormality of mental functioning that arose from a recognised medical condition, substantially impaired their ability to understand the nature of their conduct, form a rational judgment, or exercise self-control, and provides an explanation for their acts and omissions in killing
• Before 2009, the term "abnormality of mind" was used, but now it must arise from a "recognised medical condition"
• A recognised medical condition includes psychological and physical conditions according to established medical classification, such as psychotic conditions, post-natal depression, mental disorders, alcohol dependency syndrome, depressive illness, Asperger’s syndrome, and Battered Spouses’ Syndrome
• Severe learning difficulties may also be included, but "normal immaturity" on the part of the child should not qualify for a defence of diminished responsibility
• Evidence from expert witnesses is crucial at the trial to establish the presence of an abnormality of mental functioning
• The abnormality of mental functioning must substantially impair the individual's ability to understand the nature of their conduct, form a rational judgment, or exercise self-control
• To understand the nature of their conduct, the impairment must be beyond merely trivial, but the individual's mental functioning need not be totally impaired
• To form a rational judgment, the impairment must be substantial, for example, if the individual suffers from paranoia or schizophrenia
• To exercise self-control, the impairment must be significant, for instance, if the individual has an uncontrollable urge to commit an act despite knowing its consequences
• The abnormality of mental functioning must provide an explanation for the individual's conduct, showing a causal connection between the abnormality and the killing
• The burden of proof is on the defence to prove diminished responsibility on the balance of probabilities
• Intoxication alone cannot support a defence of diminished responsibility as the temporary effect of drink or drugs on the brain is not a recognised medical condition
• Voluntary intoxication at the time of the killing cannot be used as the basis of a defence of diminished responsibility
• Alcohol Dependency Syndrome (ADS) is a recognised medical condition that may be the cause of an abnormality of mental functioning, but not every drink consumed due to ADS can be considered involuntary
• If an individual is already suffering from an abnormality of mental functioning and has taken drugs or alcohol, the defence of diminished responsibility may be available if the abnormality substantially impaired their mental responsibility for the fatal acts