16 Once the possibility is allowed that the applicants were responsible only for bashing the deceased, the level of intoxication of each applicant adds significantly to the possibility of a conviction for manslaughter as opposed to murder. For so long as it is assumed that the applicants not only bashed the deceased over the head with a concrete cable pit cover but also slashed his throat and stabbed him in the front and in the back, then, despite the degree of their intoxication, it presents as most unlikely that the applicants could have done those things with an intention falling short of intent to kill or inflict really serious physical injury. If, however, Mitchell did no more than bash the deceased over the head with the concrete cable pit cover, and Gill was somehow complicit in that conduct, then, because of the degree of the applicants' intoxication, it becomes a more realistic possibility that Mitchell's state of mind fell short of an intention to kill or inflict really serious injury and that Gill's rose no higher.
17 Putting it at the lowest, it is not altogether easy to exclude as a reasonable possibility that a seriously intoxicated man might bash another with a pit cover, with the intention of causing harm, but without being capable of thinking through how much harm would be inflicted, and that another seriously intoxicated man might stand by with a less than complete comprehension of what was taking place.[16] This is, of course, a quintessential jury question, which jurors would determine on the basis of their own experience and judgment.
18 Fourthly, in as much as it was part of the Crown case that Gill stood to be convicted as having aided and abetted Mitchell, once the possibility is allowed that Mitchell's state of mind fell short of an intention to kill or inflict really serious injury, and thus that Mitchell was properly to be convicted of manslaughter rather than murder, there is a realistic possibility that Gill also should have been convicted of manslaughter rather than murder.[17]
19 It would be different if Gill were convicted on the basis that he was acting in concert with Mitchell. In those circumstances it would be enough to render Gill guilty of murder that he had participated in a joint criminal enterprise to kill or inflict really serious injury, and that in carrying out that enterprise the deceased was killed, even if when Mitchell struck the fatal blow his mens rea fell short of intent to kill or inflict really serious injury. But we are inclined to think that counsel for Gill was correct in his submission that, in practical terms, any doubt as to Mitchell's mens rea would before a jury tend to accrue to the benefit of the Gill (given that it was Mitchell who was said to have caused the death).[18]
20 Finally, from Gill's point of view, there is a further possibility of a verdict of manslaughter even if Mitchell were convicted of murder. Assuming that Gill were convicted on the basis that he was acting in concert with Mitchell, it could still be that the scope of the joint criminal enterprise extended no further than inflicting actual bodily harm. In that event it would follow that, although Mitchell had gone beyond the scope of the enterprise in committing murder, Gill would still be guilty of no more than manslaughter.[19] Views may differ as to how likely that is. But, given Gill's state of intoxication, we do not think it unrealistic to posit that he went with Mitchell to inflict some harm on the deceased and that he picked up and dropped the pit cover near to the deceased with the intent of doing some harm to the deceased but to a level falling short of really serious injury. Then, in the state of intoxication and confusion which prevailed, Mitchell moved so quickly beyond the scope of the understanding that Gill was uncomprehending of what was happening as Mitchell crashed down the pit cover onto the deceased with the intent to kill him.
21 Admittedly, Stanbury's evidence as to the conversation on the return journey to Mitchell's house is opposed to that possibility. But, as it appears from the transcript, Stanbury was a most unsatisfactory witness - indeed, so bad that the prosecutor urged the jury to accept that it was open to convict without placing any reliance on Stanbury's testimony - and it may be that the jury would not have accepted that part of his testimony. Objectively, it was improbable. Stanbury was interviewed by police several times and made three statements, but it was not until he made his third statement, more than three years after the killing, that he mentioned the conversation. Moreover, Stanbury had every reason to minimise his own involvement and to maximise the liability of the applicants. As the judge correctly directed the jury, it would be dangerous to convict on the basis of Stanbury's evidence unless corroborated.[20] In point of fact, there was no corroboration of his evidence as to the conversation on the way back from the killing to Mitchell's home.[21]
22 All in all, we consider that upon one possible view of the facts it was open to convict the applicants of manslaughter rather than murder. It follows that, in failing to leave manslaughter to the jury as an available alternative verdict, the judge must now be taken to have committed an appealable error (even though as the law was understood at the time of trial, the judge acted correctly in accordance with it).
23 That leaves the question of whether it is open to apply the proviso.[22] In Gillard, it was said that the test of whether failure to leave manslaughter to the jury as an available alternative verdict is productive of a miscarriage of justice is whether it is clear that leaving manslaughter to the jury could not have made a difference. [23] According to that approach, one asks whether there is any doubt that, if the jury had been properly instructed on both murder and manslaughter, and were persuaded beyond reasonable doubt that the accused intended to commit the unlawful and dangerous act or acts which killed the deceased, the jury would have returned a verdict of murder. In our view there is a doubt.
24 The verdicts of guilty of murder imply that the jury were satisfied that each applicant was capable of forming the intent to kill or inflict really serious injury. Logic implies, therefore, that it could not have made a difference if the jury had been told that it was open to convict of manslaughter. But in this area of the law logic is no longer determinative. Consistently with Gilbert and Gillard, one is now to assume that juries do not reason "mechanistically" or "divorced from the realities."[24] Rather, as Gleeson, C.J. and Gummow, J. said in Gilbert -