(iii) that the abnormality substantially impaired the accused's mental responsibility for the act.
4 The Crown accepted that conditions (i) and (ii) had been made out. Issue is joined on condition (iii) namely whether the abnormality of mind substantially impaired the Appellant's mental responsibility for the killing.
5 With respect to this third element the issue for this Court is whether it was open to the jury to reject the defence of diminished responsibility on the evidence before it.
6 Two psychiatrists were called in the defence case, both with varying qualifications to which I will presently refer, who gave evidence in support of the defence.
7 The Appellant accepted the statement of principle in this respect of Badgery-Parker J in R v Tumanako (1992) 64 A Crim R 149 at 160 as follows:
"Because the existence of the first and the third elements are matters for determination by the jury being matters of degree not capable of scientific measurement, and the jury is entitled to approach them in a broad commonsense way and not necessarily in accordance with the medical evidence, on neither issue is the jury, bound to accept the medical evidence if there is other material before it which in the judgment of the jury, conflicts with it and outweighs it."
8 The Appellant, accordingly, had to submit, and did submit, that there was no other material before the jury which conflicted with the medical evidence and outweighed it.
9 In his written submissions the Appellant did not focus on the fact that the existence of such material was a matter for "the judgment of the jury", as Badgery-Parker J put it. The Appellant did accept the conclusion of Badgery-Parker J at 160-161:
"On any of the three issues in the case, it is open to the jury to reach a conclusion different from that expressed by the medical experts, but only where there is other evidence displacing or throwing doubt upon it, or where the medical evidence is not unanimous."
10 The third element in the defence of diminished responsibility was considered by Hunt CJ at CL, in R v Trotter (1993) 68 A Crim R 536. His Honour said at 537-538:
"... the tribunal of fact is not bound to accept the medical evidence where there is other material before it which, in its judgment, conflicts with it and outweighs it [ Byrne [1960] 2 QB 396 at 403]. Such material includes the nature of the killing, the conduct of the accused before, at the time and after the killing and any history of mental abnormality: Walton [1978] AC 788 at 793. The tribunal is in any event entitled to consider the quality and the weight of the expert medical evidence (at 793).
The 'crucial' question in the defence of diminished responsibility is, however, whether the impairment of the accused's mental responsibility for his act was substantial: Byrne (at 403). Some impairment is not sufficient; if the abnormality of mind did not really make any great difference, even though it may have made it harder for the accused to control himself, the impairment is not substantial ... .
It was held in Byrne (at 404) that medical evidence is relevant to this question as well, but not decisive of it. The Court of Criminal Appeal pointed out (at 403-404) that the question involved matters of degree, and that it is one which is essentially for the jury. And, as the question is not merely a medical one of whether there was an impairment but also whether that impairment can 'properly' be called substantial, it was pointed out (at 404) that this is a matter upon which juries make quite legitimately differ from the medical experts. See also Lloyd [[1967] 1 QB 175 at 179]. It is often put to juries that an impairment is substantial if it is such as warrants the reduction of the crime from murder to manslaughter: Ignjatic (1993) 68 A Crim R 333 at 346-347.
Those criteria demonstrate why expert medical evidence is not really of great assistance in determining this crucial question of whether the impairment is substantial. The doctors are obviously qualified to say whether the extent of the particular impairment to the accused's perceptions, judgment and self-control is slight, moderate or extensive, or somewhere in between, but whether that impairment to the accused's mental responsibility for his actions may 'properly' be called substantial (in the sense of being such as to warrant the reduction of the crime from murder to manslaughter) is not a matter within the expertise of the medical profession. That is a task for the tribunal of fact, which must approach that task in a broad commonsense way: Byrne (at 404); Walton (at 793). It involves a value judgment by the jury representing the community (or by a judge where there is no jury), not a finding of medical fact."
11 This passage was substantially reproduced by Hunt CJ at CL with whom Grove and Allen JJ agreed in R v Ryan (1995) 90 A Crim R 191 at 195-196.
12 The Crown also referred to the judgment of this Court in Regina v Gieselmann (Supreme Court of NSW, Court of Criminal Appeal, 12 November 1996, unreported). In that case there was a substantial unanimity of professional opinion. Nevertheless, this Court held that the jury was entitled to rely on other evidence with respect to the third element of substantial impairment. (See for example at 34-36 per Sully J.)
13 The Appellant relied on the evidence given at the trial by two psychiatrists, Dr Canaris and Dr Shand. Dr Canaris was, in fact, engaged by the Crown to examine the Appellant although he was ultimately called in the defence case. As is often the case in such matters the opinions of the psychiatrists were based on a version of the events given to them by the Appellant. As is the case with all forms of expert opinion evidence, the extent to which reliance can be placed by the tribunal of fact on an expression of opinion depends on whether the factual assumptions upon which the opinion has been based are otherwise made out in the evidence. In this case in a number of respects that proved not to be so.
14 The weight which the jury was entitled to give to the opinion of Dr Canaris was affected further by two factors. First, at the commencement of his cross-examination, Dr Canaris accepted the proposition that whenever he was asked to give an opinion on matters of this character, he began with the proposition that he would want to make a finding of diminished responsibility "If I can". Secondly, in his evidence-in-chief Dr Canaris introduced his conclusion with the words:
"… the reality is this is a very difficult case - or it is not straight forward."
15 He gave evidence of the following character by way of conclusion:
"… Mr Hoss is anything but a well adjusted man. There is evidence of substantial disturbance in his functioning going as far back as his early childhood his experience of rape at a young age with a decidedly unhelpful if not grossly destructive response from his mother seems to have set the tone for his life. From what he told me he seems to have suffered from a chronic post-traumatic stress disorder PTSD is the common way that that is abbreviated, [arising] from the rape perpetrated on him at the age of 9 years. There had been periodic exacerbations of his disorders in which he has become overtly anxious, depressed, sleepless and suicidal with increasingly intrusive recollections of the rape. His depression has at time been of moderate to severe intensity and there is strong evidence that he has been strongly suicidal in the past. He claims no recollection whatsoever of the actual shooting of his wife saying that he had purchased the gun solely with the intention of killing himself if he were not allowed access to his children ... .
Taking his account entirely at face value Mr Hoss would be a serious contender for a defence of diminished responsibility. This would be on the basis of a chronic pre-existing and substantial disorder of mood with features of anxiety and depression arising in the context of a diagnosis of PTSD. ... His personality development was in all likelihood substantially flawed because of the combined impact of the sexual abuse and the chronic PTSD giving rise to a reasonable probability that his judgment at the time of the shooting was significantly impaired. We would still have a problem in defining the precise connection between his mood state and the shooting because of his claim to have no recollection whatever of his actions."
16 At trial the thrust of the Crown's cross-examination of Dr Canaris was the identification of a number of factual matters which Dr Canaris had accepted from the Appellant and which were disputed. On this appeal the Crown directed attention to two specific matters: