‘Rational’ Reconstruction: Diminished Responsibility and Substantially Impaired Ability to Form a Rational Judgment

This case note examines two cases, Conroy and Squelch, which were decided by the Court of Appeal in the first week of February 2017. Both cases raised a number of issues relating to the special and partial defence to murder of diminished responsibility, in particular the meaning and scope of s. 2 of the Homicide Act 1957 (‘the 1957 Act’), as amended by s 52 of the Coroners and Justice Act 2009 (‘the 2009 Act’). Section 2 (as amended) requires the accused to prove, on the balance of probabilities, that at the time of the killing the accused had an ‘abnormality of mental functioning’; arising from a ‘recognised medical condition’; which ‘substantially’ impaired the accused’s ability to understand the nature of their own conduct, form a rational judgment and/or exercise self-control; and which provided an explanation for the killing.