1 I joined in the orders made on 11 June because, in my opinion, the appellant had made out his first ground of appeal, namely:

The trial of the applicant miscarried as a result of the Crown's refusal to call Dr Swieca as a witness.

2 The circumstances pertinent to this ground are set out in the reasons for judgment of Neave and Harper JJA which I have had the advantage of reading in draft.

3 In the events which occurred, I consider that the Crown was obliged to call Dr Swieca notwithstanding that he was an expert witness rather than a witness of fact. I further consider that, in the events which occurred, the Crown's refusal to call Dr Swieca occasioned an unfair trial. Upon the second point it is important to understand that the question is not whether the conviction was unsafe or unsatisfactory in the sense of M v The Queen.[1] Rather, the question is whether the defect in the proceedings deprived the appellant of a chance which was fairly open to him of being acquitted. Emphasising the different nature of the enquiries, the appellant did not raise a ground that his conviction was unsafe or unsatisfactory.

4 I go back to the proposition that, in the events which occurred, the Crown ought to have called Dr Swieca. I accept, as counsel for the Crown submitted, that there is a difference between a failure to call a witness as to the facts and failure to call an expert witness. But the difference should not be overstated, and there is no general rule which frees the Crown of the obligation of calling an expert witness. So much is apparent from Velevski v The Queen,[2] where a majority in the High Court concluded that the Crown had failed in its duty to call witnesses despite the potential witnesses being experts, despite no proofs of evidence having been obtained from them, and despite their names not being on the presentment.[3]

5 The circumstances of the present case are that the informant, having been apprised that the appellant was an alleged sleep-walker, and inferring from the appellant's record of interview - in which the appellant said that he had no recollection of the incident out of which the charge arose - that this might be of relevance to the commission of the alleged offence, somehow obtained Dr Swieca's name as being a doctor who was an expert in sleep disorders. It was not in debate, it is convenient to say, that the doctor had such expertise.

6 The informant obtained a preliminary report, dated 7 March 2007, from the doctor. It was to the effect that sleep walking is a true phenomenon, that a person may engage in different behaviours whilst sleep walking, and that it was possible that the appellant had acted in the course of what is technically called a parasomnia. As to whether the appellant was a sleep walker, the doctor indicated the desirability of a consultation and the availability and desirability of tests.

7 At the instigation of the Office of Public Prosecutions, the informant then sought and obtained a report from Professor Patrick Mullen, a well known forensic psychiatrist. The professor was provided with a copy of Dr Swieca's report. He likewise accepted that sleep walking is a true phenomenon. He commented upon the kinds of acts which a sleep walker may perform. He accepted that the appellant's conduct could have occurred in the course of sleepwalking. But he expressed a degree of scepticism.

8 Dr Swieca's name was not on the list of witnesses to be called by the Crown at the committal hearing. But that was not the end of it. There were preliminary hearings in the County Court after the appellant had been committed. Appellant's counsel told us, and counsel for the Crown did not demur, that it was indicated to the appellant's legal representatives that Professor Mullen would be assisted if the consultation and tests mentioned by Dr Swieca were carried out. At that stage, it appears, a cooperative approach was being taken by the legal representatives for the prosecution and the appellant, with a view of obtaining relevant information and more complete opinions.

9 Consistently with this situation, at a directions hearing on 20 November 2008, counsel then instructed for the Crown informed the Court that Dr Swieca was regarded as a Crown witness, and that she wanted Professor Mullen to consider the results of testing when the doctor had undertaken it. The proposed trial date was put back so that the testing could be done.

10 In fact, the appellant and his parents were interviewed by Dr Swieca, the appellant underwent the proposed tests on 26 November, and the doctor further reported on 28 November. His report was made available to the Crown, and was referred to Professor Mullen for comment. The professor did comment, by report dated 28 May 2009 (the trial having earlier been marked 'not reached').

11 Looking at the situation immediately before the trial began, both Dr Swieca and Professor Mullen accepted that the appellant was, or was probably, a sleep walker. Each of them continued to express an opinion as to what a sleep walker may do in the course of a sleep walking episode. In that connection, they agreed that the more complex is the activity undertaken by a person claiming to have acted during such an episode, the less likely it is that the conduct had in fact taken place during that episode. They did, however, express shades of opinion as to the range of activities which a sleepwalker may undertake. Further, Dr Swieca referred to the circumstance that there was a stranger (the complainant) in the house on the particular occasion - which he said 'may have been a stimulus for confusional arousal'; and he drew attention to the potential relevance of the appellant's apparent perplexity after being 'tapped on the head' by the complainant after she became aware of the assault.

12 In all, despite the matters just mentioned, there was on the face of it little difference in the opinions of Dr Swieca and Professor Mullen. Neither of them asserted, as a matter of probability, that the appellant had engaged in the impugned conduct in the course of a sleep walking episode. But neither of them excluded that possibility. It is to be remembered, of course, that only Dr Swieca had consulted with the appellant; and that it was Dr Swieca that had conducted the tests.

13 A new prosecutor was briefed on the trial. He declined to call Dr Swieca as a Crown witness. Counsel for the appellant unsuccessfully sought a direction, or at least an intimation, from the judge that the Crown should do so. The prosecutor advanced a number of reasons why he had decided not to call the witness. He first submitted that doctor had never been a Crown witness, and had been engaged by the appellant's side. He secondly asserted that there would be no prejudice or unfairness to the appellant if the defence was obliged to call the witness. He thirdly contended that the interests of justice required that he be able to cross-examine the doctor, which he submitted, citing R v Richardson,[4] was a relevant consideration. He referred to R v Fitchett[5] as a case in which this Court had not obliged the Crown to call an expert witness whom it had engaged. As to the suggestion that the Crown had changed its tune, he said that since he had been in the matter - apparently two months - his position on behalf of the Crown had been made clear.

14 It is unnecessary to set out his Honour's ruling. It is, however, at least desirable to express my opinion that the reasons advanced by the prosecutor for not calling Dr Swieca were quite unsatisfactory. First, Fitchett was a case in which the accused was seeking to establish mental impairment at the time of the alleged offence. She carried the burden of establishing that circumstance. This Court stated that -

the Crown did not have to accept the opinion of [an expert witness whom it had engaged] and his evidence did not relate to any element of the offence charged that had to be established beyond reasonable doubt or defence which the prosecution was required to exclude according to that standard. No issue of non-disclosure arose or practical forensic difficulty presented to the applicant because it was left to the defence to call him.[6]

15 Second, by no means was it correct to describe the situation as one in which it was not unfair for the Crown not to call the doctor. The unfairness was demonstrated by what occurred when Dr Swieca was called by the appellant. Further, assuming that the Crown was to call an expert, it is at least strange that it was not the only doctor who had consulted with the appellant, and who had conducted relevant tests.

16 Third, there was no revealed justification for the Crown's expressed desire to cross-examine Dr Swieca. There was, as I have said, little difference between his opinion and the opinion of Professor Mullen. On several occasions, in the course of argument, the learned judge suggested that if the Crown called Dr Swieca he would be asked a series of 'Dorothy Dixers' in cross-examination. This assumed a divergence in the opinion of the two expert witnesses which objectively did not exist. But, as will be seen, when the doctor gave evidence and was cross-examined, an attempt was made by the prosecutor to suggest that there was a real divergence of opinion.

17 Even if there had been a significant difference in the opinions of Dr Swieca and Professor Mullen, I in my opinion it does not follow that the Crown was able to pick and choose which witness it called, leaving it to the accused to take up the challenge of calling the other witness. That does not seem to me to accord with the Crown's obligation of fairly adducing relevant evidence, or with the onus of proof resting on the Crown. No doubt a criminal trial is an adversary proceeding, but that does not mean that it should become a tennis match in which the Crown is able, in effect, to put on the other side of the net a witness whose opinion it has obtained, whose expertise and impartiality are not in issue, but whom it is disinclined to call.[7]

18 At the trial, Professor Mullen gave evidence in which he explained the nature of sleep walking and in which he described the kinds of actions which sleep walkers typically behave. He described them as doing -

The kind of things they might commonly do when awoken or during the day but they do it in a clumsy and ill directed way because they're not fully conscious.

What you very rarely hear accounts of, at least outside of the law courts, is of complex activities over a period of time where people carry through what is clearly a series of collected, intentional, actions.

19 The witness, however, did not exclude a sleep walker engaging in complex behaviour. He said that -

In the usual run of things you do not see complex actions carried out during sleep walking. Occasionally, and this is particularly in the Court, people report - or there are reports of really highly complex actions, which lead to crimes where the person is held to be sleep walking.

20 The sequence of events in the present case was put to the witness. He described it as being -

On the face of it, a series of quite complex actions ...

There's no way of saying that that is impossible in a state of sleep walking.

He gave evidence also that the conduct described by the prosecutor 'could be' consistent with sleep walking.

21 In cross-examination, there was no appreciable change in the gist of the witness's evidence.

22 Dr Swieca was called by the appellant. It will be perfectly clear from what I have already said that the prosecutor's forensic plan was to put the appellant into the position of calling the doctor if the appellant wanted the advantage of a shade of opinion which was slightly more favourable than that advanced by Professor Mullen.

23 Dr Swieca described in evidence the way in which he had been brought into the matter and the opinion which he had initially offered. He described aspects of the circumstances as reported to him which in his opinion were consistent with the appellant's impugned conduct having occurred during an episode of sleep walking.

24 The doctor then described his interview with the appellant, with the appellant's parents, and the tests which he had conducted. In answer to a question by the trial judge the witness stated that the appellant -

Absolutely has all the classic predispositions to sleep walking.

25 Dr Swieca's evidence in chief differed from the evidence in chief given by Professor Mullen only to the extent which I have identified at [11] above. The doctor did, of course, identify the appellant as a likely sleepwalker. But that was not controversial. When cross-examined, Professor Mullen had not taken issue with the doctor's conclusion.

26 Pausing for a moment, counsel for the appellant accepted that if the doctor had not been cross-examined, it could not have been said with any force that an unfair trial had eventuated by reason of the Crown refusing to call the witness.

27 Then came the cross-examination. I need not refer to all of it.

Anything from minor movement to a long string of semi-purposeful events, up to and including cooking a meal.

29 It was put to the witness that the authors of the 'Diagnostic and Statistical Manual of Mental Disorders' (DSM 4) stated that most behaviours during sleep walking episodes are routine and of low complexity. The witness agreed. So far so good.

In fact I suggest to you that incidences (sic) of violence during sleep walking are extremely rare?---You would be incorrect. So there's evidence in the medical literature that up to 2% of adults have had at least one episodes of sleep related violence during their lives.

Yes?---In my clinical practice I see sleep related violence as a frequent presentation. Admittedly that's in a referral sleep medicine practice.

Have you given evidence in criminal proceedings in this State previously in relation to sleep walking?---No, never.

Have you given evidence in any other jurisdiction about sleep walking related violence?---No

Do you know ... Professor Mullen?---Of him, yes. Yes, only of him. Yes.

And you would accept that as a psychiatrist, he's a person of eminent standing within Victoria?---Yes.

He said in his evidence, that parasomnias and sleep walking is a parasomnia isn't it?---Correct.

Generally parasomnias do not cause harm, it's extremely rare that harm is caused to others, do you accept that opinion?---Not even in the least. Yes, that would be an area that I'd strongly disagree with the Professor.

32 There are five points to be made about the cross-examination to which I have referred in the two preceding paragraphs.

33 First, there was no evidentiary foundation for the prosecutor's suggestion that incidences (sic) of violence during sleep walking are extremely rare.

34 Second, there was no attempt by the prosecutor to define violence. Assuming that the digital penetration which occurred in this case could be defined as violence, it remains the fact that the prosecutor made no attempt to so define it. In the circumstances, the cross-examination was not shown to have anything to do with this case.

35 Third, the consequence of this cross-examination was to set up an apparent conflict between evidence which had not been given and the witness's evidence, and to do so in respect of an irrelevant issue.

36 Fourth, the cross-examination to establish Professor Mullen's credit was objectionable.

37 Fifth, Professor Mullen did not give evidence that it is extremely rare that harm is caused to others by a sleep walker.

38 It is next necessary to refer to the prosecutor's final address. This is part of what he said with respect to the evidence of Dr Swieca -

Now, Dr Swieca was called by the defence. Can I say this? There is no [property] in witnesses. The defence are quite entitled to call up an expert witness and they've done so in this case, and that's appropriate, they're entitled to put their case to you, their defence to you. You know that, initially, what happened here was that the informant, Mr Beard, asked Dr Swieca for an opinion. He received a letter back from him.

Then it appears from the evidence that the accused's solicitors, effectively, picked up the ball and ran with it. They then came back to Dr Swieca, they subjected their client to sleep studies and interview with Dr Swieca and, effectively, engaged him as an expert; and he's been called by the defence.

If he's called by the defence, that gives me the opportunity to cross-examine him. So just as you heard Professor Mullen cross-examine or tested by my learned friend, and you had the benefit of cross-examination there, you had, hopefully, it was of some benefit, some cross-examination of Dr Swieca.

Can I just tell you this? If I called a witness, I actually can't cross-examine them. Surely, you have gathered that by now. So if the other party calls a witness, the rules are, because it's an adversary system, the other barrister gets an opportunity to question them, in a different way from when you call your own witness.

39 I pause to make two observations. First, the prosecutor's description of the circumstances which he claimed resulted in the defence engaging Dr Swieca as an expert was a misrepresentation of what had actually occurred. Second, the prosecutor's observation about the ability to cross-examine a witness called by the other side emphasises, to my mind, the fact that the Crown's refusal to call Dr Swieca was a (misplaced) forensic decision.

40 The cross-examiner then went through aspects of Dr Swieca's evidence with a view to showing that the doctor had not committed to a conclusion that the appellant had been sleep walking at the critical time. That was unremarkable because the doctor had neither said so in his examination in chief nor in cross-examination.

He takes a particular view of it; you don't have to accept that for one moment. He disagrees with the proposition that instances of sleep-related violence are extremely rare. Remember, I put to him in cross-examination, I said: I put to you that the position is that when people are sleepwalking, you don't see instances of violence. He disagreed with that. He said: one to two percent of adults have had, at least, one episode of sleep-related violence in their lives. One to two percent of adults have, at least, one episode of sleep-related violence in their lives.

Well, that's a very high percentage; it's an awful lot of adults who have, apparently, according to him, experienced sleep-related violence in their lives. Now, we don't know what type of violence he's referring to there, whether it's just someone waking up and slapping their partner; or is he talking about something far more complex, like the scenario that we have here?

Can I say this to you? It can't be that common - that is, sleep-related violence - because, as you would well know, violence tends to occasion the interest of the police, which tends to occasion or bring about criminal charges. No doubt about that. Yet, this sleep expert has never given evidence in any criminal proceedings in Victoria, or elsewhere; never given evidence in any criminal proceedings in relation to sleepwalking in Victoria or any other jurisdiction. So it can't be too common.

Perhaps if he's right, if it is common that sleepwalkers engage in violence, then some of those who come into the city at night and engage in violence, and engage in punch-ons with each other in Queen Street or King Street, were actually just sleepwalking. Got out of their bed in the middle of the night and found their way into the city, engaged in a violent confrontation, then just found their way back home, popped into their warm bed again, not remembering what they've done.

Now, clearly, with that proposition, ladies and gentlemen, I'm seeking to say to you: it's a rather absurd proposition to say that sleep-related violence is a common phenomenon; and, as I say, it's so common that Dr Swieca has never given evidence about it in any criminal proceeding.

42 The prosecutor then compared this evidence with the evidence of Professor Mullen 'a man experienced in the criminal justice system, given his speciality, 40 years ...'. The import of the address was that there was a gulf between the evidence of Professor Mullen and that given by Dr Swieca, and that the Professor's opinion ought be applied to the facts, this yielding a finding of guilt.

43 There were a series of non sequiturs in the prosecutor's treatment of the evidence given by Dr Swieca concerning the rarity or otherwise of the violence committed by sleep walkers. The potential effect of this part of the address, apart from belittling Dr Swieca, was to create a situation in which the jury was being invited to choose between applying to the facts of the case the opinions of two expert witnesses whose opinions in fact were not greatly different, but which had been presented as being very different by cross-examination founded in one instance upon an irrelevance and in another instance upon evidence not given by Professor Mullen. Further, Dr Swieca's expertise was impliedly compared unfavourably with the expertise of Professor Mullen - a comparison which was founded upon a false premise. An unacceptable risk was created, in my opinion, of the jury rejecting what was portrayed as being unreliable evidence given by Dr Swieca, treating the appellant's defence as being thereby tarnished, and considering the other evidence in the case from a standpoint which was influenced by those considerations.

44 Trial counsel for the appellant had not objected to the irrelevant cross-examination of Dr Swieca, or the cross-examination founded upon a wrong view of the evidence given by Professor Mullen. But he did seek a direction from the learned trial judge with respect to parts of the prosecutor's address. They included -

... the invitation for the jury to infer that this was rare, because otherwise the doctor would have gone to court more often

The comparison with street violence in Queen Street in that they could all be sleepwalking.

45 This application was made immediately after the prosecutor's address. The judge rejected it. With respect to the street violence aspect, the judge told counsel that -

If you can't deal with that, then you're not worth your fee.

46 His Honour also said, with respect to the matters raised, that there was -

Counsel make their submissions. Live by the sword, die by the sword; and you have got to make a judgment whether it's worth attacking, and if it is, attack it.

47 Counsel for the appellant addressed the expert evidence. He did so by focussing upon the extent to which, in his submission, the experts actually agreed, and by applying what they had said to the circumstances revealed by the evidence.

48 In his charge, the judge said nothing, when speaking about the cross-

examination of Dr Swieca, about the parts of the cross-examination to which I have referred. With respect to that part of the prosecutor's final address which focused on the evidence of Dr Swieca, his Honour said only that the prosecutor -

criticised to some extent Dr Swieca's evidence, you will remember that.

49 In the event, in my opinion, some cross-examination which was irrelevant, some cross-examination which was founded at best upon a misunderstanding of Professor Mullen's evidence, the cross-examination being objectionably built upon in final address, was left unremarked. To my mind, the potential for that material to distract the jury from its task, in the ways and with the effect which I outlined at [42], was thereby enhanced.

50 Concerning ground 1, I should add only that I respectfully agree with what Neave and Harper JJA have written in that connection - specifically, their analysis of the evidence given by the two expert witnesses.

51 Their Honours have also dealt with, and rejected, the two other grounds pressed by the appellant. I agree with the conclusion reached in each instance.

52 On 11 June 2010, the Court ordered that the appellant's application for leave to appeal against conviction be granted, and that the appeal be treated as instituted and heard instanter and allowed. The Court also ordered that the conviction sustained by the appellant in the Court below be quashed, that the sentence passed thereon be set aside, and that a new trial be had. At the same time, the Court announced that it would publish its reasons for making those orders as soon as possible. Our reasons for agreeing in them are set out below.

53 The appellant has a history of sleepwalking and unconscious behaviours. That, at least, was the evidence of Dr John Swieca, a medical practitioner specialising

in sleep disorders who, having been called by the appellant, gave evidence at the appellant's trial for rape.

54 The only real issue at the trial was whether the appellant was sleepwalking when, as he accepts, he inserted his finger into the complainant's vagina while she lay asleep in a bedroom near his. Dr Swieca was one of two experts who were called as witnesses to assist the jury to decide this question. The other, a prosecution witness, was Emeritus Professor Paul Mullen. Both gave evidence of great importance. Both accepted that medical science recognised a condition known to it as parasomnia, but more commonly called sleepwalking. In addition, each accepted, as did the Crown itself, that the appellant had a history of sleepwalking, and therefore suffered from parasomnia. Indeed, after an examination conducted by him, Dr Swieca formed the opinion, which again the Crown did not dispute, that the appellant 'absolutely had all the classic predispositions to sleepwalking.' And when Professor Mullen was asked by the prosecutor whether he was aware of that examination, and whether he agreed with the conclusions Dr Swieca had drawn from it, the witness responded that he 'accepted Dr Swieca's opinion in total.'

55 Consistently with this, and although each expert covered slightly different territory, there was a very high proportion of middle ground, and no clear point of conflict, between them.

56 The appellant nevertheless complains, as his first ground of appeal against conviction, that 'the trial ... miscarried as a result of the Crown's refusal to call Dr Swieca as a witness.' The nub of the complaint is that, the prosecutor having declined to call the doctor, put to him a proposition in cross-examination that had no basis in fact. This in itself was bad enough. The appellant submits that it was made worse when the answer to that illegitimate question became the focus of an extravagant attack on Dr Swieca's expertise, and therefore on his credibility. Although (or so the argument runs) the attack was without justification, it may have done great harm to his standing in the eyes of the jury. In the result, the jury may have discounted important evidence; evidence which was given by Dr Swieca, which was not challenged by Professor Mullen, and which was favourable to the appellant.

57 In these circumstances, the gravamen of the appellant's complaint is that the prosecutor's cross-examination was improper, and that his final address to the jury compounded that impropriety. The complaint is thus not confined to one that the Crown failed in its duty to call Dr Swieca. Nevertheless, it was only because the doctor was called by the appellant, and not by the Crown, that the prosecutor was enabled to cross-examine him and make the final address which he did, with - as the appellant contends - the consequence that a fair trial was not had. It therefore remains relevant, in examining the first ground of appeal, to consider the duty of the Crown in the calling of witnesses for the prosecution.

58 It is trite law that those who appear as advocates in litigation before courts or tribunals have a dual responsibility. They have a duty to their client or clients. They also have another, and higher, duty: to the court or tribunal before which they appear. For those who act for the Crown in criminal proceedings, that higher duty embraces a duty to act with the fairness which is essential if they are to put, as they must, the interests of justice, rather than the conviction of the accused, above all else.

59 It is important for the proper administration of justice that this consideration inform every decision about those to be called to give evidence for the Crown. As was said by Deane J in Whitehorn v The Queen:[8]

Under the adversarial system which operates in a criminal trial in this country, it is for the Crown and not the judge to determine what witnesses are called by the Crown. That is not to say that the Crown is entitled to adopt the approach that it will call only those witnesses whose evidence will assist in obtaining a conviction. Prosecuting counsel in a criminal trial represents the State. The accused, the court and the community are entitled to expect that, in performing his function of presenting the case against an accused, he will act with fairness and detachment and always with the objectives of establishing the whole truth in accordance with the procedures and standards which the law requires to be observed and of helping to ensure that the accused's trial is a fair one. The consequence of a failure to observe the standards of fairness to be expected of the Crown may be insignificant in the context of an overall trial. Where that is so, departure from those standards, however regrettable, will not warrant the interference of an appellate court with a conviction. On occasion however, the consequences of such a failure may so affect or permeate a trial as to warrant the conclusion that the accused has actually been denied his fundamental right to a fair trial. As a general proposition, that will, of itself, mean that there has been a serious miscarriage of justice with the consequence that any conviction of the accused should be quashed and, where appropriate, a new trial ordered. If there be exceptions to that general proposition, they do not presently occur to me.

The observance of traditional considerations of fairness requires that prosecuting counsel refrain from deciding whether to call a material witness by reference to tactical considerations. Whether or not their names appear on the back of the indictment or information, all witnesses whose testimony is necessary for the presentation of the whole picture, to the extent that it can be presented by admissible and available evidence, should be called by the Crown unless valid reason exists for refraining from calling a particular witness or witnesses, such as that the interests of justice would be prejudiced rather than served by the calling of an unduly large number of witnesses to establish a particular point. All available witnesses whose names appear on the back of the indictment or information or who were called by the Crown to give evidence on any committal proceedings which preceded the trial should be called to give evidence, or, where the circumstances justify the Crown in refraining from leading evidence from such a witness, either be sworn by the Crown to enable cross-examination by the accused or, at the least, be made available to be called by the accused. Among the considerations which may justify the Crown in refraining from leading evidence from a particular witness is that the evidence which he or she would give is plainly untruthful or unreliable. If the Crown proposes to refrain from calling as a witness a person whose name appears on the back of the indictment or information or who it would otherwise be expected to call as a matter of course, it should communicate that fact to the accused or his lawyer a reasonable time before the commencement of the trial. If the accused seeks to be told why the Crown is refraining from calling such a witness, fairness to the accused would ordinarily require that the Crown communicate the reason or reasons.

60 In the same case, Dawson J stated that all available witnesses should be called whose evidence is necessary to unfold the narrative and give a complete account of the events upon which the prosecution is based. His Honour excluded from this proposition witnesses whose evidence the prosecutor judges to be unreliable, untrustworthy or otherwise incapable of belief. His Honour also agreed with Deane J in excepting from the general rule witnesses whose evidence would be unnecessarily repetitious.

61 In our opinion, the calling of Dr Swieca by the Crown was necessary for the presentation in this proceeding of the whole picture. He was appropriately qualified, having practised for 17 years before the appellant's trial as a specialist in disorders that adversely affect sleep. His evidence was admissible. He was also available. Moreover, his first point of contact with this prosecution came not through the appellant but through the informant who, because of the suggestion that the appellant might be a sleepwalker, thought that Dr Swieca's expertise might assist the authorities in their investigation into the complainant's allegations. Dr Swieca agreed to review the police brief of evidence, with a view to assessing whether the events as there depicted could (as he put it from the witness box) 'possibly have been related to sleepwalking'.

62 Having conducted the review, Dr Swieca prepared a preliminary report for the informant. It is dated 7 March 2007. In it, he said that sleepwalking was a recognised sleep disorder, and that the incident in question was possibly a consequence of a sleepwalking episode. He formed this opinion on the basis of the evidence then available to him. It was to the effect that the appellant had a history of suffering from the condition, that the impugned conduct was brief, that there was no evidence of premeditation, that the victim as a stranger in the house may have been a stimulus for what the witness described as 'confusional arousal', that the appellant was - on being confronted by the complainant in her bedroom - perplexed, made no attempt to disguise himself or what he was doing, and stated that he had no memory of the event. Moreover, the event occurred within a period of sleep during which the sufferer is most likely to be affected by his or her sleep disorder.

63 Dr Swieca summarised this portion of his evidence in chief by saying:

So yes, my opinion based on that related to the possibility that this would be the sort of clinical patient I might see with somnambulism, with sleepwalking.

64 This opinion should have been led from Dr Swieca by the Crown. But the prosecution had further reason to conclude that it had a duty to call him. On examination of the appellant, he found what is known as an oropharynx, or 'crowded airway' and damage to the appellant's nasal septum. These, he said, were 'findings that predispose a patient to obstructive sleep apnoea.' Other 'unusual symptoms' suggested that the appellant may, in addition to his oropharynx and nasal septum, also suffer from another sleep disorder, known as narcolepsy.

65 According to Dr Swieca, his findings indicated that the appellant's sleep should be medically monitored. He therefore recommended 'an overnight sleep study followed by a test called a multiple sleep latency test, a series of daytime naps where the patient is monitored to look for disorders such as narcolepsy and related conditions.'

66 These studies were undertaken at the Mercy Private Hospital on 26 November 2008. If Dr Swieca is to be believed, the results were significant. They revealed that the appellant suffered from what Dr Swieca described as 'micro arousals from sleep, brief periods awake - almost typically around three seconds in duration - [which were] frequent enough to cause very fragmented, light and typically non-restorative sleep.' Indeed, as Dr Swieca said in his evidence in chief, approximately 54% of the appellant's non-dreaming sleep was associated with repeated arousal from sleep. The normal range, he said, was less than 35%, but even lower in someone as young as the appellant. It was on these findings that Dr Swieca based the conclusion to which we referred earlier in this judgment: that the appellant 'absolutely has all the classic predispositions to sleepwalking.'

67 The Crown knew, or was in a position to know, all this before the trial. It was, accordingly, incumbent upon the Crown to call Dr Swieca as its witness. The question is whether its failure to do so deprived the appellant of a chance which was fairly open to him of being acquitted. It is necessary, in order to answer that question, to examine the evidence, and the conduct of the trial. We turn first to the evidence.

68 The appellant's involvement with the complainant was brief. They met for the first and only time on 4 July 2006. It was her birthday. She had been invited to stay that night at a house owned by the appellant's parents, who for work-related reasons were then dividing their time between Wycheproof and their Melbourne home, in which the appellant resided with his sister, his brother, and his brother's girlfriend, Rachel. The invitation had been issued by Rachel, with whom the complainant had become acquainted because the two worked in close proximity to each other at Victoria Gardens in Richmond.

69 At about 6 pm on 4 July, the appellant's brother, the complainant and Rachel travelled by public transport from Richmond to Box Hill. They were there met by the appellant. The complainant and Rachel both say that the appellant was introduced to her, but merely as 'Gary'; he maintains that no introduction took place at all, and that he never knew her name.

70 From Box Hill, the appellant drove the other three to his parents' home. Thereafter, Rachel and the complainant spent the evening, until about 11.30 pm, in a caravan parked at the rear of the property, while the two brothers played video games. The complainant then left the caravan, because she was to sleep in Rachel's bedroom in the house while Rachel spent the balance of the night in the caravan with the appellant's brother.

71 When the complainant entered the lounge room of the house, she found the appellant on the couch watching television. It seems that neither had consumed any alcohol in the course of the evening, although the appellant confessed to the police that he had smoked marijuana.

72 Shortly after her arrival in the lounge room, the complainant left to have a shower. She returned afterwards in a clean set of clothes, and asked to share some pizza that the appellant was then making. He obliged, and the two watched television until about 1 am. They did not talk, and sat on separate couches or chairs.

73 There is a difference in the accounts of the two about who retired first. But this is not a matter of particular relevance. There is no dispute about the fact that the complainant went to go to sleep in the bedroom allocated to her, and that she was wearing a pair of black pants with two buttons on the side and a zip. The buttons were fastened and the zip was closed.

74 The complainant then fell asleep. She awakened some time later to feel a finger turning inside her vagina. The buttons and the zip on her pants were undone. According to her evidence, she froze. She then pushed herself slightly off the bed. As she did so, the finger was removed, a hand was placed on the bed, and she saw the appellant leaning across while at the same time (as she put it in her evidence) 'almost cowering ... and shaking, violently shaking.' Barely conscious herself, she tapped him on the head. He initially made no move to escape, but (according to the complainant) 'was almost like he was trying to hide in the bed'. Now more fully awake, she smacked him across the face before running out of the room and over the backyard to the caravan, where she aroused Rachel and the appellant's brother. She told them what had happened. As she later recounted the episode in her evidence, this included her swearing at the appellant, and he saying to her in the hallway: 'Was I in your room?'

75 In the meantime, the appellant put on some shoes and walked to a nearby park. He remained there for a few minutes before returning to the house. By this time Rachel had contacted the police. When they arrived, the complainant left with them.

76 The appellant was interviewed shortly after 7 pm on 5 July. His account of the evening did not much differ from that of the complainant. He agreed that he was watching television when he was joined at about midnight by her. He agreed that she had showered, and that she accepted some pizza from him before joining him in front of the television set - but on a different couch or armchair. He confirmed that, after about half an hour during which there was no conversation between them, she went to the bedroom allocated to her and he went to his. As he told the police, he lay awake for about 15 minutes and then, because he could not get to sleep, re-entered the lounge room. He subsequently fell asleep upon a couch.

77 According to the appellant, his next memory is of awakening after being (as he described it to the police) 'tapped on the head'. He was on his knees in the bedroom occupied by the complainant, with his arms spread across the bed. He was wearing his tracksuit pants and a t-shirt. She stood up, swore at him when he asked her what happened, and went out of the bedroom. When later approached by his brother, the appellant replied that he did not know what had happened.

78 Given that this was the substance of the relevant evidence as given to the jury, it is not surprising that the only issue in the trial was whether the sexual assault, admittedly committed by the appellant in the early morning of 5 July 2006, was a conscious and voluntary act. That, of course, was an element in the crime, and therefore something which the Crown had to prove. His defence was that he was sleepwalking. It was for the Crown to establish beyond reasonable doubt, if it could, that he was not.

79 We pause here to observe that, even without expert assistance, the jury may have found some aspects of this evidence to be of significance. Both the appellant and the complainant spoke of her tapping him on the head. He told the police that it was at that point that he awoke. She described his reaction to her tapping his head as remaining mute and putting his head down as if trying to hide, while shaking uncontrollably, and making no attempt to escape. This is, the jury might have thought, a somewhat bizarre reaction if the person involved is fully conscious and has just committed an unforgivable, brazen and particularly demeaning sexual assault. And if, as he accepts, she was asleep when he interfered with her, he must have known, had he been fully conscious, that he could not plead consent or any other defence to it.

80 In this context, it was open to the jury to place some importance on Dr Swieca's evidence that he diagnosed the appellant as a possible sleepwalker in part because of his description of the scene immediately after the complainant tapped him on the head, and in part because he asserted that he had no memory of anything that happened after he went to sleep on the couch.

81 We have already referred to the fact that Professor Mullen was called as part of the prosecution case. He has impressive professional credentials. These were unchallenged. Early in the professor's career he ran a sleep laboratory, and since he became a forensic psychiatrist he has, as he said in his evidence, 'taken a particular interest in the relationship between disorders of sleep and behaviours which can lead to criminal prosecution.' Among his many distinctions, he was formerly Professor of Forensic Psychiatry at Monash University and Medical Director of Forensicare, the Victorian forensic mental health service.

82 Professor Mullen described sleepwalking as 'a disorder of sleep which involves someone coming to partial wakefulness during the phase of sleep which is known as deep sleep, or slow wave sleep'. He continued:

So sleepwalking is really something that isn't all that complicated at all. It's a matter of being in a state of disordered consciousness which sits somewhere between being asleep and being awake, and in that state you can carry out actions.

83 Sleepwalking is usually 'directed', to adopt the professor's word, by the carrying out of the kind of actions that people would commonly carry out, particularly in the morning. He added:

What you very rarely hear accounts of, at least outside of the law courts, is of complex activities over a period of time where people carry through what is clearly a series of connected, intentional, actions.

84 Professor Mullen was asked about the possible degree of complexity of actions in which a sleepwalker might engage while sleepwalking. He replied that the answer was not straightforward. While complex actions are not generally carried out during sleepwalking, occasionally -

... there are reports of really highly complex actions, which led to crimes where the person is held to be sleepwalking. All I can say is that one's level of scepticism about whether this is compatible with sleepwalking, should increase the more complex the action is and the more it appears to require a direction or intention. So that I can't say that any action is excluded. All I would say is that ... the closer it comes to the complex actions of someone who is carrying out a plan of action, the more cautious one should be about attributing that to a sleepwalking state.

85 A little later in his evidence-in-chief, Professor Mullen said:

And I think the final thing is that it's absolutely necessary for an action to be automatic; for it not to be motivated by the desires and wishes of an individual. So that you would typically look for activities and actions - certainly in a legal context - where there is no plausible explanation for why the person did it. The classic examples are automatic behaviour which have been raised in the courts in the past often involve acts of violence directed against people ... [with] whom the person who acted violently had no quarrel; had no motivation for doing these things.

86 Given the complainant's evidence that immediately after she 'tapped [the appellant] on the face with my right hand ... he was shaking uncontrollably' it is perhaps significant that, at another point in his evidence-in-chief, Professor Mullen spoke about the very disorientating and distressing reaction which sleepwalkers have when they are suddenly awakened. He added:

You are a long way away or distance from where you were and you don't know what has happened in the interim. Typically, people just act in a very confused and worried manner.

87 In cross-examination, Professor Mullen did not directly comment upon the likelihood of an assault by a sleepwalker upon another person. He did, however, say that:

The events that lead to harm to others almost always involved the presence at or near the sleepwalker of something which can harm someone. So one of the famous cases is of the man whose job was sharpening knives, and had knives by the side of his bed. It appeared that he was carrying one of the knives when someone tried to wake him from his sleepwalking and in his confusion he lashed out with a knife.

... experience in this area ... [is] that sleepwalking has involved the sleepwalker engaging in uncharacteristically risky, threatening or violent behaviour.

Asked whether 'On a particular occasion, sleepwalking was or was not occurring?' Professor Mullen answered:

I can definitely exclude almost nothing in this world, I'm afraid.

88 It will be remembered that, as recorded in paragraph [53] above, Professor Mullen was aware that Dr Swieca had taken a history from the appellant, had interviewed his parents, and had studied the results of the appellant's tests for sleep disorders. On this basis, Professor Mullen said that, with that knowledge, he 'accepted Dr Swieca's opinion in total'.

89 Our examination of the evidence given by Professor Mullen demonstrates, as it seems to us, two things. First, that what he said to the jury was by no means wholly adverse to the appellant. Secondly, he endorsed without qualification the conclusions to which Dr Swieca had come following the overnight sleep study and multiple sleep latency test. In this, as in the evidence generally, the opinion of each expert complemented that of the other. But in respects which we have already noted, Dr Swieca went a little further than Professor Mullen. Having referred to what he described as the 'impulsive' nature of the appellant's assault on the complainant, and the absence of evidence of either motivation or premeditation, Dr Swieca said that the presence of the complainant, a stranger in the house, 'may have been a stimulus for confusional arousal'. It was also in the history given to him, Dr Swieca said, that the appellant:

... was perplexed and ... that there was no apparent attempt to cover up actions [and] ... there was stated amnesia for the event ... The timing of the alleged incident with respect to the time of onset of the stated sleep would be consistent with the timing that many of these parasomnias or sleepwalking-like events occur.

Reinforcing his comment about 'confusional arousal' Dr Swieca said that 'sometimes a change in the environment - whether it is in the physical environment or other people within the home - can trigger a sleepwalking episode in otherwise predisposed individuals'.

90 When Dr Swieca completed his examination in chief, the appellant, it seems had before the jury all the expert evidence he needed to support the proposition that he was a sleepwalker. One aspect of the prosecution case tended, however - at least on initial examination - to tell with particular force in its favour. The violence inflicted upon the complainant by the appellant involved his undertaking a series of somewhat complicated tasks. He got out of bed. He may have dressed himself, because immediately after the incident he was wearing his day clothes. He entered her bedroom, positioning himself in a particular way, and then - taking advantage of that positioning - he unbuttoned the complainant's pants and unzipped them before committing his assault.

91 On this vital point, the evidence of Professor Mullen was slightly more favourable to the Crown than that of Dr Swieca. Both accepted that the possibility that sleepwalkers could, while sleepwalking, do what the appellant did. But the professor stressed that a sleepwalker cannot have complex intentions, that dressing oneself while sleepwalking is one thing, while undressing someone else is another, and that the more complex the actions in question, the more sceptical one has to be about claims that they were performed while sleepwalking. By contrast, Dr Swieca told the jury that a sleepwalker might engage in a long string of semi-purposeful movements, up to and including cooking a meal.

92 It is against this background that the conduct of the prosecution case at the trial must be evaluated. In our opinion, what happened following Dr Swieca's examination in chief deprived the jury of the benefit of a fair cross-examination of him, and a balanced summing-up of the prosecution case.

93 In his judgment, a draft of which we have had the benefit of reading, Ashley JA sets out portions of the cross-examination to which Dr Swieca was subjected by the prosecutor. His Honour also recounts portions of the prosecutor's final address. We will not repeat them here. It is sufficient for us to record our general agreement with his Honour's criticisms of both the cross-examination and the final address.

94 While we do not consider that the prosecutor behaved unfairly in cross-examining on the basis that an act of digital penetration without consent amounts to violence, the other aspects of the cross-examination and final address to which Ashley JA refers constituted a defect in the proceeding which deprived - or may well have deprived - the appellant of a chance which was fairly open to him of being acquitted. In other words, it is entirely possible that the impugned passages diminished or destroyed in the minds of the members of the jury those aspects of the evidence of Dr Swieca - and indeed of Professor Mullen - which tended to bolster the defence. In particular, the attack which the prosecutor made upon Dr Swieca may have induced the jury to discount the doctor's opinion about the effect which the presence of a stranger in the house may have had upon the appellant. It may at the same time have bolstered Professor Mullen's opinion about the likelihood of a sleepwalker doing what the appellant undoubtedly did.

95 Dr Swieca's evidence about the effect on the appellant's subconscious of the complainant's presence in the house was, it seems to us, especially important. Its acceptance by the jury may well have led them to a reasonable doubt about whether the prosecution had proved that the appellant's assault was a conscious and voluntary act. Yet it was evidence which was given by Dr Swieca alone, and the jury may not have been in a position to evaluate it objectively following the prosecutor's attack upon him.

96 The appellant submitted that the damage done by the prosecutor was not remedied by judicial direction. That is so. The reason might be that both his Honour and counsel for the appellant may have been distracted by a complaint made by the prosecutor about his opponent's final address. In pursuing his complaint, the prosecutor referred to Dr Swieca's response, in cross-examination, to the (incorrect, and improperly put) proposition that in Professor Mullen's opinion sleepwalkers very rarely cause harm to others. This response (so the prosecutor submitted to the trial judge) was later the subject of an impermissible comment by the appellant's counsel to the jury. The jury were told in the final address of the appellant's counsel that 'the Crown called no contrary evidence to rebut [the] proposition' about sleepwalkers causing harm. And here lay the gravamen of the prosecutor's complaint: there could have been no evidence called in rebuttal, because the Crown had closed its case.

97 In his response to this criticism, counsel for the appellant merely said that 'to some extent the Crown got back what they were inviting to get back by asking a question they didn't know the answer to.' He did not rely on the fact that the question which prompted Dr Swieca's answer was based upon a false recapitulation of Professor Mullen's evidence. Perhaps for this reason his Honour, having heard the appellant's response, thought that there was 'something' in the prosecutor's complaint. In the meantime, the opportunity to remedy, by judicial direction, the prosecutor's original sin, was lost.

98 For these reasons, it seems to us that the first ground of appeal is made out.

99 The second ground of appeal is that the learned trial judge 'erred in his directions to the jury on the issue of conscious and voluntary act.' In particular, the judge (as the appellant's written outline of submissions puts it):

... blended two elements together. Having directed the jury that the Crown were required to prove four elements the learned trial judge mixed together his direction as to conscious and voluntary act and as to the requisite intention under the one umbrella of 'state of mind of the accused'. So that the jury may not have understood that there were indeed separate concepts and which had to be considered separately.

In addition in directing the jury that in most cases there was no issue as to conscious and voluntary act and that in most cases it was safe to infer that a person had acted voluntarily/intentionally - the presumption of innocence was undermined and the jury may have been distracted from the Crown's onus of proof.

100 In our opinion, these criticisms lack substance. His Honour told the jury that:

... in order to prove the charge of sexual penetration or rape, the Crown must prove four elements of the crime to your satisfaction beyond reasonable doubt. These are the matters that must be established to your satisfaction beyond reasonable doubt. They are: one, the act of sexual penetration. Two, that the sexual penetration was intentional. Three, the lack of consent on the part of the complainant. And four, the state of mind of the accused.

101 In this passage from his charge, his Honour made a distinction between the second element - that the sexual penetration was intentional - and the fourth - the state of mind of the accused. This was a distinction without a difference, and may have been somewhat confusing. But although the appellant's state of mind 'at the time of that sexual penetration' was, as the judge told the jury, the critical issue in the case (there was no challenge to the prosecution claim that the appellant had sexually penetrated the complainant, or to the proposition that she had not consented) his state of mind in all its several relevant aspects was to be judged by whether or not he was sleepwalking when penetration occurred.

102 A short time later in his charge, his Honour said:

In this case, as you are aware, the central issue is whether at the time the accused penetrated [the complainant] he was performing a conscious and voluntary act. In order to establish the accused has committed an act which is forbidden by law ... the Crown must prove beyond reasonable doubt that it was done voluntarily. In this case you are aware the forbidden act is the sexual penetration of [the complainant] and the requisite criminal intention is that the accused was aware that [the complainant] was not consenting or else realised that she might not be consenting and determined to have sexual penetration of her whether she was consenting or not.

103 Here, his Honour again linked the concept of intention, which he had earlier identified as a separate element, with other relevant aspects of the appellant's state of mind: his awareness (or lack of it) that the complainant had not consented; and the question whether the appellant brought a conscious mind to the commission of a voluntary act. On the other hand, the judge later gave a clear direction that the Crown had to prove both (a) that at the time the appellant penetrated the complainant he was acting voluntarily and consciously, and (b) that he knew that his victim was not consenting or might not be consenting - but determined to proceed nevertheless.

104 It was this section of the charge which was criticised because in it his Honour directed the jury that 'in most cases there was no issue as to conscious and voluntary act and ... in most cases it was safe to infer that a person had acted voluntarily [or] intentionally'. It was submitted that the presumption of innocence was thereby undermined, and the jury may have been distracted from the Crown's onus of proof.

105 We reject this criticism too. The judge immediately went on to tell the jury in unmistakable terms that:

... in this case these issues do not arise, and it is therefore for the Crown to satisfy you beyond reasonable doubt that at the time the accused sexually penetrated the complainant he did this voluntarily and consciously and in the knowledge that [the complainant] was not consenting or might not be consenting but, nevertheless, determined to have sexual penetration of her whether she was consenting or not.

106 For these reasons, the second ground of appeal is not made out.

107 Nor, in our opinion, is the third. It is that the judge 'erred in his directions to the jury following the question: "What happens if we cannot reach a unanimous verdict?"'

108 After deliberating for some three and a half hours, the jury asked about the position should they be unable to reach a unanimous verdict. His Honour responded that the question did not arise. He continued:

It's important that you continue to deliberate and consider the views of other jurors. You have been out ... about three and a half hours. And our experience is that at this stage, whilst it might appear difficult to reach a conclusion unanimously, our experience is that you continue with your deliberations and consider the views of various other jurors, not put your head in the sand, as it were, be prepared to listen to other jurors ... our experience is that we do achieve unanimity. So all I can say is, members of the jury, soldier on and continue to consider the evidence.

109 It would have been better for the judge to answer the question. This direction was inadequate. He failed to answer the question. He did not tell the jury that if they were unable to reach a unanimous verdict, there would be no verdict at all. The direction did, however, avoid the trap of referring to the public inconvenience that flows when members of a jury cannot agree - a reference which, in Black v The Queen, the High Court deprecated[9] - but, having impressed upon the members of the jury that unanimity is often reached after further deliberation, it failed to inform them that, while they should strive to reach unanimity, 'if, after calmly considering the evidence and listening to the opinions of the other jurors' any member of the jury could not honestly agree with his or her colleagues, that juror must give effect to his or her own view of the evidence.[10]

110 The appellant now relies upon this point. He contends that the judge, by the words he used, created a risk that honestly held views would be abandoned in the pursuit of what the members of the jury might have thought was the only end open to them - unanimity.

111 On the other hand, no response was received when his Honour asked counsel whether anything arose out of his answer to the jury. That itself is sufficient to dispose of this ground. In the absence of any objection to his Honour's answer, and given that the jury deliberated for another three and a half hours after the judge's answer to their question, it cannot in our opinion now be said that the answer gave rise to a miscarriage of justice.

112 In the result, the application for leave to appeal should be granted because the appellant has succeeded on his first ground of appeal, although he has failed on the other two. It also follows that the appeal should be allowed.

[1] [1994] HCA 63; (1994) 181 CLR 487.

[2] [2002] HCA 4; (2002) 187 ALR 233.

[3] Ibid. Compare Gleeson CJ and Hayne J, 245-246 [46]-[47] with Gaudron J (dissenting in the result) 259-261, [116]-[121], and Gummow and Callinan JJ 274 [176].

[4] [1974] HCA 19; (1974) 131 CLR 116.

[5] [2009] VSCA 150, [55].

[7] Not only are authorities opposed to such conduct, it is inconsistent with r 20.7 of the Professional Conduct and Practice Rules _2005 (_Vic).

[8] [1983] HCA 42; (1983) 152 CLR 657, 663-4.

[9] [1993] HCA 71; (1993) 179 CLR 44, 50.