REASONS OF THE COURT
(Given by Miller J)
 Mr Brunsell appeals his conviction for the manslaughter of Bruce Mortimer at Nelson on 4 July 2015. He was found guilty as a party. The principal, Ronayne Dempsey, was convicted of murder.
 Mr Brunsell contends that the trial judge, Clifford J, mishandled the evidence of a Crown witness, Eric Grainger, who was asked leading questions by the Crown and ought to have been the subject of a reliability warning. He also complains that the Judge failed to direct the jury on defence of another and withdrawal.
 The appeal was filed well out of time, but the delay has been explained and we consider it is in the interests of justice to deal with the appeal on the merits. We grant the necessary extension.
 Messrs Mortimer, Dempsey and Brunsell lived at a Franklyn Village, a residential complex in a former nurses’ home at Nelson Hospital. Mr Brunsell, aged 17, and Mr Dempsey aged 27, were friends, with Mr Dempsey being the dominant person in the relationship. The evidence indicates that he was inclined to bully Mr Brunsell.
 On the evening of 2 July, Mr Brunsell and Mr Dempsey were socialising with friends in a room on Level 2 of the complex. Mr Dempsey began talking about assaulting Mr Mortimer to steal $200 which he believed Mr Mortimer had in his possession. Mr Brunsell later denied hearing this talk. Mr Dempsey also spoke sharply to Mr Brunsell for losing a set of keys.
 Mr Brunsell claimed that he declined to accompany Mr Dempsey to Mr Mortimer’s room, and it is common ground that he did return to his own room on another floor. However, he made his way back to Level 2. The Crown case was that he went there to help Mr Dempsey rob Mr Mortimer. Mr Brunsell’s account in interview was that he went there to return a phone to Mr Dempsey and followed him down the corridor to Mr Mortimer’s room, where Mr Dempsey knocked and a fight began when Mr Mortimer opened the door.
 Mr Brunsell denied getting involved in the fight in the room, but Mr Mortimer later gave a statement saying that the taller of the two men who assaulted him (Mr Brunsell) 'kept punching [him]' there.
 The fight moved to the corridor outside Mr Mortimer’s room, where a series of witnesses, mostly neighbouring occupants drawn to the scene by the commotion, observed parts of what happened next. Mr Brunsell was interviewed twice by the police. He admitted that he broke a headlock that Mr Mortimer had on Mr Dempsey, whose face was turning blue, but maintained that he was trying to break the fight up. He also admitted that Mr Dempsey had landed several punches on Mr Mortimer while Mr Brunsell had him restrained, but emphasised that he left the scene after noticing that Mr Mortimer was bleeding, and that he felt Mr Dempsey had taken things too far at that point.
 It is common ground that Mr Brunsell left and Mr Dempsey continued to attack Mr Mortimer. He stopped only when another man intervened, standing over Mr Mortimer to protect him.
 Mr Mortimer declined to go to hospital. He was admitted the next day suffering the effects of head injuries from which he later died.
 Messrs Dempsey and Brunsell were both charged with murder. The Crown case, as ultimately put to the jury, was that Mr Brunsell was a party to that crime because he intentionally encouraged or assisted Mr Dempsey to inflict the fatal injuries, knowing that Mr Dempsey intended to cause the type of bodily injury that could well kill Mr Mortimer, or alternatively knowing Mr Dempsey intended to cause Mr Mortimer grievous bodily harm for the purpose of robbery. The Crown contended that both men had attacked Mr Mortimer on the floor in the corridor outside his room.
 The Crown called a number of eyewitnesses who described Mr Dempsey attacking Mr Mortimer, claiming that he was owed money. Some witnesses recalled variously that Mr Brunsell was standing there, not participating, or trying to break it up. Others described the assault continuing after Mr Brunsell left the scene. Mr Brunsell did not give evidence but his police statements were before the jury.
 Mr Grainger was one of the witnesses who observed the assault, from a distance of some 45 metres and through two security doors, one of which had a relatively small window in it. He had also consumed alcohol and drugs. He deposed that he had seen Mr Dempsey kick Mr Mortimer twice in the face, causing his head to strike the wall and bounce off it, and Mr Brunsell kick his upper torso or head area once. Mr Grainger also said that both men were punching Mr Mortimer. Mr Brunsell then left, and Mr Dempsey continued the assault.
 Mr Grainger was induced by counsel for Mr Dempsey to accept that he may have been wrong about Mr Mortimer’s head bouncing off the wall, but he made that concession after counsel explained that a pathologist would give evidence that Mr Mortimer did not suffer an injury to the back of his head. Counsel was mistaken. The pathologist’s evidence was that Mr Dempsey suffered a fracture at the back of his skull, causing bruising and bleeding which killed him. As we go on to explain shortly, this error was rectified in re-examination.
 In the meantime, however, Mr Grainger was cross-examined by Mr Bamford (counsel for Mr Brunsell) and he resiled from his evidence about Mr Brunsell’s involvement. In particular, he admitted that he may have been completely wrong when he said that he saw Mr Brunsell standing over Mr Mortimer.
 In re-examination, Crown counsel corrected the misunderstanding about the pathologist’s evidence, having first sought the Judge’s permission to do so in chambers, and then led the following evidence about Mr Brunsell’s involvement:
Q. Now bearing that in mind, what was your memory of what happened to the head of that person when you saw Mr Dempsey kicked them?
A. Bouncing off the wall, is what I think I seen.
Q. And how many times?
A. Ah, twice.
Q. And it was put to you, who else did you see kick that man?
A. [Mr Brunsell].
Q. It was put to you - and where did you see that kick connect?
A. I thought it was the upper body, head area.
Q. All right. And what else did you see happen to that man? What other physical contact?
A. Ah, him being punched.
Q. Who punched him?
A. Ah, [Mr Brunsell] and [Mr Dempsey].
 Another witness, Mr Tipa, also gave evidence that he had seen Mr Brunsell kick Mr Mortimer, but he had been grossly intoxicated and he had also made a statement in which he identified Mr Dempsey as the only assailant.
 In closing, Crown counsel pointed to evidence suggesting that Mr Brunsell had been party to a plan to rob and had gone through with it, actively participating in the attack, despite initially, and to his credit, trying to dissuade Mr Dempsey. Mr Mortimer had said that the larger of the two men - Mr Brunsell - had punched him. Mr Brunsell’s claim that he followed Mr Dempsey because he had nothing else to do was implausible, and he had admitted being involved by 'ripping arms apart'. In the corridor Mr Brunsell was initially a bystander but Mr Grainger had said that he then kicked and punched Mr Mortimer. Mr Dempsey was seen to kick Mr Mortimer’s head during this assault, and again after Mr Brunsell walked away. Mr Grainger’s concessions in cross-examination were attributed to the misunderstanding about the pathologist’s evidence, and Crown counsel said that Mr Grainger 'came back strongly in re-examination', repeating that he had seen Mr Brunsell kick Mr Mortimer. As Mr Brunsell left he pulled his hoodie over his head to attempt to disguise himself to CCTV cameras in the corridors. The cameras did not show everything that had happened but they did point, counsel suggested, to co-ordinated action by Mr Dempsey and Mr Brunsell.
 The defence closing focused on Mr Brunsell’s degree of involvement and state of mind. Counsel drew attention to Mr Brunsell’s immaturity and lack of social awareness, for which there was evidence, and also emphasised evidence that he had been intimidated by Mr Dempsey that evening and wanted to go to bed but came back to the second floor to return Mr Dempsey’s phone. At that time Mr Dempsey was already trying to get into Mr Mortimer’s room. Mr Brunsell 'didn’t have the wherewithal to say no' when Mr Dempsey led him to the door. There was no reliable evidence of punching in the room; Mr Mortimer may have been confused, and Mr Brunsell’s hands were unmarked. Mr Brunsell had pulled Mr Mortimer’s arm back but that was because he was concerned that Mr Dempsey was turning blue. Eyewitnesses described him as a shocked bystander in the corridor. His involvement amounted to trying to break it up.
 Mr Bamford spent some time on Mr Grainger’s evidence, pointing to his limited visibility through security doors and distance from the scene, his admissions in cross-examination, and a police interview in which he spoke of only one person standing over Mr Mortimer.
 The defence did not raise self-defence or defence of another, or withdrawal as a party.
 In summing-up, the Judge accurately identified the factual premises of the defence for the jury: Mr Brunsell did not know what Mr Dempsey intended and did not mean to inflict any harm but intervened only to prevent the two men inflicting serious harm on one another. There is no criticism of the Judge’s directions about the offence or party liability. He instructed the jury that if they were not sure that Mr Brunsell intentionally assisted or encouraged Mr Dempsey to inflict Mr Mortimer’s injuries they must find him not guilty of both murder and manslaughter:
 First: If your answer to Question 1 is no, that is you are not sure that Mr Brunsell intentionally (i.e. meaning to do so) assisted or encouraged Mr Dempsey to inflict the injuries, you must find Mr Brunsell not guilty of both murder and manslaughter. Mr Brunsell was involved. He accepts that. But he says he tried to stop both of Mr Dempsey and Mr Mortimer from seriously hurting each other. If that is what he was doing, he would not be intentionally assisting Mr Dempsey to injure Mr Mortimer.
 The Judge outlined the pathways by which Mr Brunsell might be found guilty of manslaughter if Mr Dempsey was guilty of murder:
 Now if you have found Mr Dempsey guilty of murder, then you go on and consider question 2 in the question trail. And that again focuses on what Mr Brunsell knew when he intentionally assisted and encouraged, if that is what you find he has done. Charge 1: are you sure that Mr Brunsell knew that Mr Dempsey intended to cause Mr Mortimer bodily injury and that Mr Dempsey knew (i.e. actually appreciated) that bodily injury was likely to cause Mr Mortimer's death. So Mr Brunsell knew what Mr Dempsey intended to do and knew that Mr Dempsey knew bodily injury was likely to result in causing Mr Mortimer’s death.
 Alternatively, are you sure that Mr Brunsell knew that Mr Dempsey intended to cause Mr Mortimer really serious bodily injury for the purpose of facilitating the theft by Mr Dempsey of Mr Mortimer's property, that is for the purpose of robbery.
 The Judge gave a reliability warning for Mr Tipa, noting that he was extremely intoxicated, and told the jury that they might think other witnesses were also affected by alcohol and cannabis. He was not asked to give a reliability warning for Mr Grainger, but he did remind the jury of what Mr Bamford had said about that.
 During deliberations the jury asked to view CCTV footage of Mr Grainger peering through the security doors. In due course they found Mr Dempsey guilty of murder and Mr Brunsell not guilty of murder but guilty of manslaughter.
 At sentencing Clifford J recorded that the jury must have been unpersuaded that Mr Brunsell knew what sort of violence Mr Dempsey intended to inflict on Mr Mortimer. Consistent with the verdicts, the Judge found that Mr Brunsell assisted Mr Dempsey in an assault, without himself intending serious harm to Mr Mortimer or knowing what Mr Dempsey intended.
 We turn to the grounds of appeal, taking them in the order that Mr Bamford advanced them.
The evidence of Mr Grainger
 Mr Bamford submitted that Mr Grainger ought to have been the subject of a reliability warning, and further that Mr Brunsell was prejudiced by the use of leading questions in re-examination of Mr Grainger. He contended that the jury must have relied on Mr Grainger’s evidence for the conclusion that Mr Brunsell intentionally lent assistance. The jury ought to have discounted Mr Mortimer’s statement, and other witnesses to what happened in the corridor described Mr Brunsell as a bystander. Indeed, the Judge made it clear when sentencing that he regarded Mr Grainger as an unreliable witness, saying that:
 I record that I have considerable reservations about the reliability of Mr Grainger’s evidence as regards your involvement: in particular Mr Grainger’s evidence that he had seen you kicking Mr Mortimer to the upper body. I record that Mr Grainger was observing events from some 45 metres away through not one, but two, security doors, the second of which (closest to the far end of the corridor) had a relatively small window in it. Moreover, Mr Grainger, in his police interview at the time, said he had only seen one person standing over Mr Mortimer, and that was Mr Dempsey.
 In support of this argument, Mr Bamford contended that the CCTV footage was unclear about what happened, and when. The jury’s request to view it during deliberations indicated that they were focused on Mr Grainger’s evidence. They ought to have been warned about his reliability and reminded of the concessions he made in cross-examination. Counsel cited R v E for the proposition that the leading questions asked in re-examination might in themselves justify allowing the appeal.
 A warning under s 122 of the Evidence Act 2006 is discretionary, though the judge must consider whether to give one if the defence requests. This Court has said that trial judges ought to isolate potentially unreliable evidence and warn the jury about it if they think the jury might otherwise attach too much weight to it. In this case, it is evident that Clifford J did not think that a specific warning was necessary. Nor did experienced counsel ask for one. Reliability was squarely before the jury. At sentencing the Judge said that his reservations about Mr Grainger were based on the admissions made under Mr Bamford’s cross-examination. The jury had heard those admissions and the record indicates that they had also taken a view, observing for themselves the limited field of view available to Mr Grainger. For these reasons, we are not persuaded that absent a warning the jury was at risk of attaching too much weight to Mr Grainger’s evidence.
 Nor are we persuaded that the leading questions asked by Crown counsel caused a miscarriage. The questions ought not to have been asked without the Judge’s permission, and having asked them, counsel ought to have been much more circumspect than he was about relying on the answers in his closing address. But the point of the prohibition is that leading questions may give the jury a false impression of the witness’s knowledge, accuracy and veracity. That is unlikely here, given the view Mr Grainger had and the far-reaching concessions he made in crossexamination. Nor did he say these things for the first time in re-examination. He was simply repeating what he had said in chief. We think it likely that once given a correct account of the pathologist’s evidence he would have given the same evidence if asked in a non-leading way.
 Ultimately, we are not persuaded that the jury must have relied too much on Mr Grainger’s evidence. Their verdict may have been based on Mr Mortimer’s statement and Mr Brunsell’s admission about breaking Mr Mortimer’s hold and so allowing Mr Dempsey to gain the upper hand. This, coupled with the circumstantial evidence, permitted an inference that Mr Brunsell intentionally assisted Mr Dempsey in an assault.
Defence of another
 As noted, counsel did not invoke defence of another at trial. On appeal, he contended that there was a foundation for it and the Judge accordingly ought to have left it to the jury.
 We can deal with this point shortly, because we are satisfied that no miscarriage can have resulted from the way in which the Judge handled Mr Brunsell’s claim that he was trying to break up the fight. The Judge directed the jury, as noted at  above, that if Mr Brunsell was not deliberately helping Mr Dempsey to inflict injuries, but rather was trying to stop the men from seriously hurting one another, then he was not guilty of both murder and manslaughter. The Crown bore the onus of proving that he intended to do more than that.
 That being so, a direction on defence of another would add nothing of benefit to Mr Brunsell. Rather, it would complicate the jury’s task. It would require that the jury exclude the reasonable possibility that Mr Brunsell was acting in defence of another in the circumstances as he understood them to be. If he was acting in defence, the jury would then need to go on to consider whether the force was reasonable. By directing as he did, the Judge effectively instructed the jury to acquit if they answered the first of these questions in Mr Brunsell’s favour.
 Mr Bamford argued that the Judge ought also to have directed the jury on withdrawal. We do not accept that such a direction was required, for several reasons. First, it would have been contrary to the defence case, because it supposes that Mr Brunsel
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l was party to the offending in the first place. As noted, counsel did not ask for a withdrawal direction. Second, the manslaughter verdict did not depend on Mr Brunsell assisting when the final blow was struck - the offence was committed when he assisted in a continuous attack that led to Mr Mortimer’s death - and it was not suggested that Mr Brunsell was responsible for what happened after he left the scene. The Crown’s case focused rather on what happened when he was present. Third, what happened while Mr Brunsell was present could not amount to withdrawal. More would be required to undo the effect of participation. By way of explanation, Mr Brunsell admitted that the effect of breaking Mr Mortimer’s hold was to allow Mr Dempsey to gain the upper hand, but he did not claim to have done anything further to stop the attack; rather, on his own account, he simply left. Other witnesses recall him saying 'stop', but that would not suffice either in circumstances where Mr Dempsey had gained the upper hand and plainly had no intention of stopping. Result  The application for an extension of time to appeal is granted.  The appeal is dismissed. ------------------------------------------------------------------------  R v Dempsey  NZHC 3056.  We do not have a record of the jury asking for this footage, but both counsel accepted that this had happened in submissions.  R v Dempsey, above n 1, at .  R v E (CA308/06)  NZCA 404,  3 NZLR 145 at –.  Evidence Act 2006, s 122(3).  Taylor v R  NZCA 69 at .  Evidence Act, s 89(1)(c).  Ahsin v R  NZSC 153,  1 NZLR 493 at : the defendant must both clearly demonstrate, by words or conduct, that they are withdrawing from the offending; and they must take reasonable and sufficient steps to undo the effects of their previous participation in the offending.