In the criminal law of the UK, diminished responsibility is a partial defence, which can lessen the charges of murder to manslaughter. If the defendant was suffering from an abnormality of mental functioning while killing someone, then his liability would be reduced. This defence is mentioned in Section 2 of the Homicide Act of 1957, which was amended later on as the Coroners and Justice Act of 2009. This article will carry on a critical analysis of the diminished responsibility defence, its application, and the challenges in its application.
Definition and legal criteria
The defence of diminished responsibility can be taken by a defendant when at the time of killing someone, he had an abnormality of mental functioning due to some medical condition. This condition must substantially impair the ability of the defendant to understand the nature of his conduct, make a rational judgment, and maintain the self-control. It is also necessary that an explanation is provided by the abnormality regarding the actions of the defendant. If this defence is proven, then the defendant will be convicted of manslaughter instead of murder, which has a lesser sentence. The major aim of this legal framework is to ensure that when homicide is committed by an individual due to the influence of a mental illness, then he is not given a harsh punishment like those who have murdered with the full mental capacity.
Doctrine of diminished responsibility
The doctrine of diminished responsibility is based on the belief that when a person is suffering from a mental illness or abnormality, then he should not be made accountable for a crime as like a sound person when a condition has affected his judgment or ability to control his actions. A relevant precedent is R v. Byron [2000] 2 Cr App R 56, in which the defence of diminished responsibility was successful because, due to the compulsive sexual desire of the defendant, he committed the murder, which was linked to his psychiatric disorder. Furthermore, an important element in the defence is the abnormality of mental functioning, which may occur due to a number of factors such as schizophrenia, severe depression, or PTSD. For example, in R v. Reynolds [1988] 2 All ER 951, the diminished responsibility was pleaded successfully when a murder was committed by the defendant because of his severe depression.
Evidences in diminished responsibility
In the application of the diminished responsibility defence, there is a heavy reliance on expert medical testimony. The role of psychiatrists and psychologists is critical when there is a need to establish whether the defendant was suffering from a condition due to which his mental functioning was impaired. In R v. Kemp [1957] 1 QB 399, the mental state of the defendant was impaired due to the tuberculosis and the plea of diminished responsibility succeeded. Moreover, the role of expert evidence is also undeniable in these cases.
Insanity defence V diminished responsibility
In both the insanity defence and diminished responsibility, mental illness is relevant, but they are different in some ways. Regarding the insanity defence, the defendant must show that he did not know the nature of his actions due to his mental condition. On the other side, in the diminished responsibility, the substantial impairment of mental functioning is necessary, not the lack of understanding. This difference was highlighted in R v. Tandy [1989] 1 WLR 350, in which the court considered the voluntary intoxication of the defendant enough to accept the defence of diminished responsibility, as it was linked to a medical condition. In this precedent, it is proved that there is a deep connection between the defence of  diminished responsibility and mental illness, but it is not related to voluntary intoxication.
Criticism & challenges
In the criminal justice system, the defence of diminished responsibility is uphold as a fair approach to justice, but a number of challenges are linked to its application. One of the issues is the subjective nature of the abnormality of mental functioning. It is observed that to qualify something as a substantial impairment based on medical conditioning and interpretation of expert testimony is difficult and it led to variations. A relevant case law is R v. Brown [1993] 2 All ER 75 in which, due to the differences in psychiatric reports, it was difficult for the court to decide about the fulfilment of the criteria of diminished responsibility. In addition, due to the requirement of medical expert evidence, it is difficult to create a difference between involuntary actions and actions which are based on mental illness, leading to complications in the legal analysis.
Conclusion
To sum up the discussion, the diminished responsibility defence is useful for the purpose of ensuring that individuals who have mental illness are treated in a fair manner in homicide cases. It has provided a flexible way to deal with the convictions of murder, but its application is complex because of its subjective medical interpretations and dependence on expert testimony. With the passage of time, the legal standards are evolving, that is why it is difficult to create a fair balance between justice and mental health considerations.
