ABSTRACT
Section 52(1) of the Coroners and Justice Act 2009 replaced the definition of 'diminished responsibility' as originally enacted in section 2(1) of the Homicide Act 1957 (HA 1957), and it added subsections (1), (1A) and (1B) to that Act. The revised section 2 of the HA 1957 introduced major structural changes to the partial defence of diminished responsibility that go beyond mere 'clarification of the way in which that defence works'. The Law Commission pointed out that immaturity and the effect of traumatic events, other than those involving injury, were not included within the range of aetiologies specified in old section 2(1) HA. The omission had been the subject of strong criticism by leading psychiatrists and psychologists Revised section 2(1)(a) ensures that the defence of diminished responsibility is founded on a 'recognised medical condition'. Section 2(1A)(a) HA 1957 is confined to the defendant's understanding of his own conduct and not that of the victim.
