ABSTRACT
This chapter discusses the concept of diminished responsibility as a partial defence to murder, having regard to its origins and development, and considers the legal issues. The Commission's proposals revised partial defences of diminished responsibility and provocation, and participation in a suicide pact, would reduce first degree murder to second degree murder. Depending on the breadth of the expression 'a recognized medical condition', practitioners may need to consider whether an overlap exists between the partial defence of diminished responsibility and the new partial defence of loss of self-control. The Commission reported that leading experts such as Professor Mackay advised against the introduction of a strict causation requirement. One can point to theoretical incoherence between rules relating to diminished responsibility, insanity, and unfitness to plead, but in practice imperfections are likely to be resolved by a combination of the exercise of discretion, the so-called 'benign conspiracy', judicial interpretation and guidance, and the common sense of juries and practitioners.
