Background issues: In terms of the background to the Bill, some of the paper's main findings are as follows:

• the Bill would repeal existing section 23A of the Crimes Act 1900 and the defence of diminished responsibility. In its place the Bill proposes: a new defence of substantial impairment by abnormality of mind; and a procedural requirement that an accused person must disclose before the trial starts that he or she intends to rely on the defence;
• to a substantial extent the Bill is based on the report of the NSW Law Reform Commission on Partial Defences to Murder: Diminished Responsibility;
• the partial defence of diminished responsibility was introduced in NSW in 1974, at a time when there was still a mandatory life sentence for murder. The defence served the purpose of avoiding a murder conviction by permitting a lesser punishment where the accused was mentally impaired but not insane (page 5);
• under the defence of insanity or mental illness, the person's responsibility for his or her actions is nil, which in NSW results in that person's detention in prison or hospital as a forensic patient. Under the defence of diminished responsibility, on the other hand, a degree of mental responsibility remains, thus serving only to reduce culpability from murder to manslaughter (page 7);
• under section 32 of the Criminal Procedure Act 1986 an accused person standing trial for an indictable offence may elect to have the charge of murder tried by judge alone. In Chayna (1993) 66 A Crim R 178 Gleeson CJ referred to a tendency for the legal representatives of accused persons who wish to raise a case of diminished responsibility to prefer a trial without a jury'. In 1995 the DPP issued guidelines for Crown Prosecutors as to the granting of consent to an accused to be tried by judge alone. Statistical figures for the post-1993 period are not available (pages 10-11);
• the Bill has been introduced at a time when it is felt in some quarters that the judiciary is failing to reflect the standards and values of the community in its sentencing decisions. Responding to this, a key feature of the Bill is that it places increased emphasis on the moral assessment by the jury as to whether the evidence warrants the reduction from murder to manslaughter';

• The concept of mental responsibility' is removed. The new defence requires the accused to show that his or her capacity to understand events, to judge whether his or her actions were right or wrong or to control himself or herself, was substantially impaired by an abnormality of mind.
• The current defence refers to an abnormality of mind that arises from a condition of arrested or retarded development of mind or any inherent causes or that is induced by disease or injury. The new defence instead requires the accused to prove that his or her abnormality of mind arises from an underlying condition. In the way that term is defined this will require the accused to prove that the abnormality of mind arose from a pre-existing mental or physiological condition, other than a condition of a transitory kind'.
• The new defence is satisfied only if the impairment suffered by the defendant was so substantial as to warrant liability for murder being reduced to manslaughter.

  Defence disclosure: Further, in order to improve prosecution preparation and trial efficiency, the Diminished Responsibility Bill will require:

• A person accused of murder to notify the prosecution before the trial that he or she intends to raise a defence of substantial impairment, as well as to provide the prosecution with particulars of the evidence to be given by witnesses in support of the defence.
• The main issue here is the extent to which these disclosure requirements would infringe the principle that accused person has a right to silence and is generally entitled to reserve his or defence until the prosecution has presented its case.
• Some questions raised by the proposed defence disclosure provisions include: whether there is in fact a need for legislation requiring pre-trial disclosure of evidence of substantial impairment; in what circumstances will the trial judge exercise the discretion to admit evidence of substantial impairment even though notice has not been given; whether excluding evidence of substantial impairment because the defence has not disclosed it before trial is an appropriate penalty for the failure to disclose; whether the accused's right to silence should be further compromised by allowing the court to order a psychiatric or medical assessment of the accused; and at what point in time before the trial should the defence particulars be notified to the prosecution.