Psychiatric evidence in Diminished Responsibility

Diminished Responsibility is a statutory partial defence to the charge of murder in the Homicide Act 1957 which has been amended by the Coroners and Justice Act 2009. In R v Brennan, the Court of Appeal described the new criteria as relating ‘entirely to psychiatric matters’. This article will explore to what extent such a conclusion is warranted. The statutory wording of the 2009 Act will be analysed and the role of expert psychiatric evidence will be considered. It will conclude that the new Diminished Responsibility is not a purely psychiatric matter. This is because of the moral dimensions inherent in the defence, the ambiguity in the statutory wording and the fundamental problems of psychiatry usurping the function of the jury in relation to the ultimate issue. This results in inconsistent application and role confusion in relation to the defence and asks psychiatric evidence questions it cannot answer