What’s happening with the reformed diminished responsibility plea?

The reformed section 2 of the Homicide Act 1957 is markedly different from the original provision. Despite this, the ‘official line’ has been that the changes to the plea were merely ones of ‘clarification’ and ‘modernisation’. This article analyses the requirements of the new section 2 in the context of the results of an empirical study into the operation of the new plea carried out by myself and Professor Barry Mitchell. In doing so, it attempts to evaluate the changes which have taken place through an analysis of a sample of 90 cases involving the new plea. The results of the study are discussed in order to assess the validity of the ‘official line’. Is it correct, or have the new elements in section 2 resulted in unintended consequences?