It originated in the United Kingdom and adopted by the New South Wales Government and incorporated into its Crimes Act 1900 as section 23A.
The defence of diminished responsibility came into being as an answer to the plea of insanity by the accused in a murder case. This principle gives the court the discretionary authority to reduce the liability of the accused in a murder case to manslaughter only.
Section 23A of the Crimes Act 1900 provides that if the time of the commission of the offence of murder, the person responsible is suffering from an abnormality of his mind that impaired his mental responsibility for the acts or commission will not be held liable and should not be convicted for murder.
The burden of proving the diminished responsibility is on the person raising it as a defence. He must prove that he is suffering from an abnormality of the mind arising from a condition or categories of conditions. Further, he must prove that the abnormality of his mind substantially impaired his mental responsibility in relation to the murder he committed.
Any person suffering from an abnormality of the mind because of intoxication will not qualify to raise diminished responsibility as a defence in murder. This is because such abnormality of his mind was a mere transient in nature and did not arise from a condition with permanence or endurance. The jury has the obligation to determine whether the facts satisfy the tests for the defence.
Disclaimer : This article is just a summary of the subject matter being discussed and should not be regarded as a comprehensive legal advice for you to defend yourself alone. If you are charged with criminal offences, it is recommended that you seek legal assistance from criminal lawyers.