Parliament (Litigation guardian of) v. Conley

[Indexed as: Parliament (Litigation guardian of) v. Conley]

Ontario Reports

Court of Appeal for Ontario

Huscroft, Nordheimer and Harvison Young JJ.A.

April 26, 2021

155 O.R. (3d) 161 | 2021 ONCA 261

Case Summary

Civil procedure — Appeal — Substantial wrong or miscarriage of justice — Plaintiffs suing in medical negligence in relation to child diagnosed with hydrocephalus — Defendants' expert expressing opinion that defendants met standard of care and admitting that he ignored evidence of child's mother as being irrelevant and inaccurate — Jury finding no breach of standard of care — Plaintiffs' appeal from dismissal of action allowed — Witness exceeded his role as an expert and breached his duty to be independent — Trial judge erred by not specifically instructing jury to that effect and by failing to exclude opinions on credibility and reliability — Plaintiffs had not objected at trial, but errors resulted in miscarriage of justice warranting a new trial.

Civil procedure — Trial — Jury trial — Charge to jury — Closing addresses — Plaintiffs suing in medical negligence in relation to child diagnosed with hydrocephalus — Defendants' expert expressing opinion that defendants met standard of care and admitting that he ignored evidence of child's mother as being irrelevant and inaccurate — Jury finding no breach of standard of care — Plaintiffs' appeal from dismissal of action allowed — Witness exceeded his role as an expert and breached his duty to be independent — Trial judge erred by not specifically instructing jury to that effect and by failing to exclude opinions on credibility and reliability of mother — Plaintiffs had not objected at trial, but errors resulted in miscarriage of justice warranting a new trial.

Evidence — Expert evidence — Admissibility of opinion evidence — Plaintiffs suing in medical negligence in relation to child diagnosed with hydrocephalus — Defendants' expert expressing opinion that defendants met standard of care and admitting that he ignored evidence of child's mother as being irrelevant and inaccurate — Jury finding no breach of standard of care — Plaintiffs' appeal from dismissal of action allowed — Witness exceeded his role as an expert and breached his duty to be independent — Trial judge erred by not specifically instructing jury to that effect and by failing to exclude opinions on credibility and reliability of mother — Plaintiffs had not objected at trial, but errors resulted in miscarriage of justice warranting a new trial.

A child born in 1999 was diagnosed with severe hydrocephalus at the age of four months. The child had his first check up with the family doctor, C, at three weeks. There were three check ups over six weeks, during which time C noted that the child's head circumference increased out of proportion to his increase in weight. The child's mother insisted that she raised concerns about the child's head size at each visit and that each time she was told that it was normal. C maintained that if the mother had expressed concern about the child's head size, he would have written that down. The mother subsequently took the child to a walk-in clinic and the doctor, P, made a note that the child's head was abnormally large. P had no recollection of the visit but stated that based on his notes he would have explained his concern and told the mother to take the child to the emergency room as soon as possible. According to the mother, P told her that everything was fine and that the child was in good health. Shortly thereafter the family made a planned move to another community. A family friend who was a pediatric nurse expressed concern about the child's head and an appointment was made with a pediatrician who made the hydrocephalus diagnosis. The child and his parents sued C and P for negligence, alleging that they delayed in diagnosing and treating the hydrocephalus and that the delay caused brain damage resulting in cognitive and physical disabilities. At trial, credibility and reliability as they related to standard of care were central issues revolving around what the two defendant doctors said to the mother when they examined the child, whether she followed any instructions she was given, and whether the doctors' actions or omissions met the applicable standard of care. B, an expert in family medicine and episodic care, was qualified as an expert on behalf of the defendants as to the standard of care and testified that both doctors met the standard. On cross-examination, he agreed that he ignored the mother's evidence when he wrote his report because he did not think it was relevant. He also stated that he did not think that the mother's memory was accurate, that he had put more weight on C's evidence because he had some notes, and that it was inconceivable that P had not told the mother to take the child to the emergency room. The trial judge did not give a specific instruction in the jury charge regarding B's evidence, but she did end the standard of care portion of her charge by reminding the jury that it was up to them to determine the weight to give an expert opinion by considering various factors and questions, including whether the witness seemed impartial and fair. The jury concluded that the defendants did not breach the standard of care and as such the action was dismissed. The plaintiffs appealed.

Held, the appeal should be allowed.

The trial judge erred by failing to provide a specific instruction to the jury regarding B's evidence and by failing to exclude portions of it. Although there appeared to be nothing inherently improper about B's opinion as to the applicable standard of care, B exceeded his role as an expert when he opined on the credibility and reliability of the parties, indicating that he believed the defendants and not the mother. There was a risk that the members of the jury would accept B's credibility and reliability assessments rather than assess the evidence of the witnesses and reach their own conclusion. Further, the expression of an opinion as to the credibility of witnesses was a breach of B's duty as an expert to be independent. His testimony extended well beyond expressing opinions based on hypothetical facts he was asked to assume, and to the extent that it opined on the credibility of the witnesses, it should have been excluded as part of the judge's gatekeeping role. The charge contained no specific caution about B's testimony on the issue of his view of the mother's credibility and reliability. There were two steps that the trial judge could have taken when B was testifying. First, in the absence of the jury, she could have invited submissions from the parties as to the content of a mid-trial instruction that the jury ignore any and all of B's expressions as to the credibility or reliability of the witnesses. Second, she could have included a very clear and specific instruction rather than the general instruction that it was entirely up to the jury to decide how much or how little to believe of or rely upon an expert's opinion. The failure to do so was a serious error despite the fact that the plaintiffs' counsel did not ask for either a mid-trial or closing instruction.

The plaintiffs' failure to raise the issue of B's impartiality was not fatal to their appeal. The court was permitted to exercise its jurisdiction to grant a remedy if the errors alleged on appeal constituted a substantial wrong or miscarriage of justice. Given the centrality of credibility in the case, and the absence of any caution about B's evidence, there was a very real possibility that his evidence on credibility and reliability played a significant role in the jury's decision to find that both defendants met the standard of care. The sole witness for the defendants on the issue of standard of care exceeded the admissible scope of his evidence and opined on the credibility of the witnesses, which was highly prejudicial to the plaintiffs. The impugned evidence tainted the jury's verdict and resulted in a miscarriage of justice. The verdict was set aside and a new trial ordered.

Cases Referred To

• Arland and Arland v. Taylor, [1955] O.R. 131 (ONCA)
• Hoang (Litigation guardian of) v. Vicentini, 2016 ONCA 723
• K. (G.) v. K. (D.)
• Pietkiewicz v. Sault Ste Marie District Roman Catholic Separate School Board
• R. v. Abbey, 2009 ONCA 624
• R. v. Bingley, 2017 SCC 12
• Bruff-Murphy v. Gunawardena, 2017 ONCA 502
• Harris v. Leikin Group Inc., 2014 ONCA 479
• Marshall v. Watson Wyatt & Co.
• Maurice v. Alles, 2016 ONCA 287
• R. v. Marquard
• R. v. Mohan
• R. v. Sekhon, 2014 SCC 15
• R. v. White, 2011 SCC 13
• White Burgess Langille Inman v. Abbott and Haliburton Co., 2015 SCC 23

Authorities Referred To

• Lederman, Sidney N., Alan W. Bryant and Michelle K. Fuerst, Sopinka, Lederman & Bryant: The Law of Evidence in Canada, 5th ed. (Toronto: LexisNexis Canada, 2018)

APPEAL by plaintiffs from the order of Woodley J., dated August 30, 2019, from dismissal of medical negligence action.

Counsel: Gavin MacKenzie, Brooke MacKenzie, Hilik Y. Elmaleh and Michael A. Hershkop, for appellants. Darryl Cruz, Dorothy Charach and Joseph Ur, for respondents.

The judgment of the court was delivered by

HARVISON YOUNG J.A.:

A. Overview

[1] Cole Parliament was diagnosed with severe hydrocephalus when he was around four months old. He is now 21 years old and has cognitive and physical disabilities. He and his parents, Kimberley York and John Parliament, sued the defendants and respondents on appeal, Dr. Conley and Dr. Park, for negligence, alleging that they delayed in diagnosing and treating Cole's hydrocephalus and that this delay caused his brain damage. For the purposes of this appeal, the essence of their claim was that Drs. Conley and Park had breached the respective and applicable standards of care in failing to take appropriate steps to see that Cole was followed up when they had first noted the infant's large head circumference.

[2] After a lengthy jury trial during which some 27 experts testified, the jury found that the standard of care had been met by both respondents, and the trial judge accordingly dismissed the action. The appellants seek a new trial on the basis that the only expert on standard of care for the respondents, Dr. Bruce, gave evidence that went far beyond the scope of his expertise, failed to demonstrate impartiality, and usurped the jury's proper role in opining on core credibility and factual questions which included what the doctors had actually told Cole's mother, Ms. York, and whether she had followed the advice she was given. The respondents take the position that Dr. Bruce was not biased and that his evidence fell within the appropriate bounds. Moreover, they argue, the failure of the appellants' trial counsel to object to this evidence or to the charge on these grounds precludes them from raising this on appeal.

[3] For the reasons that follow, I would allow the appeal.

B. Background

(1) Medical history and events

[4] The sequence of events between the time of Cole's birth in August 1999 until the diagnosis of hydrocephalus and his surgery in mid-December 1999 to treat his hydrocephalus is important context to the issues on this appeal, and for that reason, I will set them out chronologically.

[5] Cole Parliament was born on August 16, 1999, the first child born to his parents Kimberley York and John Parliament. Ms. York had been induced due to concerns about Cole's small size, and among other things it was recorded on the physician's record of newborn infant that Cole had needed resuscitation at birth and weighed six pounds, two ounces.

[6] Dr. Conley was the long-time family doctor of Ms. York, and Ms. York took Cole to his regular check ups with Dr. Conley. Between his first visit to Dr. Conley at the age of three weeks on September 3, 1999 and his last visit to Dr. Conley on October 15, 1999, Cole's head circumference went from the 25th percentile to over the 90th percentile. During the same period, his weight went from 3.11 kg, the 3rd percentile, to 4.98 kg, under the 50th percentile. The following chart summarizes Dr. Conley's notes on these measurements:

[QL:GRAPHIC NAME="155OR3D161-001.jpg"/]

[7] Ms. York insisted that she raised the concerns about Cole's head size at each visit and that each time she was told it was normal. Dr. Conley denied that Ms. York ever raised this concern as he would have written it down if she had. Rather, his evidence was that he was the one who raised the concern about Cole's head size. When Cole visited Dr. Conley for the last time on October 15 before the family moved to Barrie, Dr. Conley gave Ms. York Cole's immunization form, and according to Ms. York, told her that the next expected visit would be in two months' time. Ms. York said they would find another doctor in Barrie.

[8] According to Dr. Conley, his nurse had taken Cole's head circumference measurement that day (42 cm), and he remeasured and obtained a measurement of 41.5 cm. Dr. Conley testified he would have been discussing his concern with Cole's head size with Ms. York and would have recommended that she take Cole for a follow up in two to three weeks. There was no evidence that he provided her with a referral to a physician in Barrie. Nor did he provide Ms. York with Cole's chart or follow up. Dr. Conley acknowledged that he had some limited recollection of the September 3 and October 15 visits, but not the September 21 visit, and would otherwise require his notes.

[9] In addition, Ms. York took Cole to a walk-in clinic on November 13. She was concerned because Cole had developed a cough and did not seem to be eating enough. He was seen by Dr. Park. Dr. Park acknowledged at trial that he had no recollection of this visit apart from his notes. Although the visit was very short, Dr. Park measured Cole's head. His notes indicate that it was 45 cm in circumference, which Dr. Park plotted and found that it was in the 95th percentile. He testified that this was "definitely abnormal". His notes also say "large head", "[t]o ER for assessment", and "URI" for upper respiratory tract infection. Considering the ER note, Dr. Park testified that he would have explained his concern to Ms. York, and he would have told her to go to the emergency room as soon as possible. Ms. York denied that Dr. Park had expressed any concern to her about Cole's head size or that he had told her to take Cole to the emergency room that day, stating "I'm a new mom. I mean, he has a freckle on his right arm, you know, I would bring that up." According to Ms. York, Dr. Park told her that everything was fine and Cole was in good health.

[10] The young family moved to Barrie as planned at the end of November. On December 6, Ms. York took Cole to the emergency department at the Royal Victoria Hospital in Barrie because he was drooling more than usual and there were white patches on his gums. The hospital records indicate it was thrush. From what Ms. York could remember, the doctor did not measure Cole's head and his head was not an issue that day. According to Ms. York, they left with no problems, no issues.

[11] On December 11, 1999, Ms. York attended a social gathering where a family friend named Susan Williams, a pediatric nurse who worked for pediatrician Dr. Schelberg, was also present. Ms. Williams expressed concern about the size of Cole's head, and she testified that Ms. York "was surprised that I thought there was a problem with the size of the head because she had been told it was normal". Ms. Williams offered to arrange for Dr. Schelberg to see Cole. Ms. York readily agreed and took the next available appointment which took place on December 16, 1999. Dr. Schelberg examined Cole and measured his head, and his notes indicate "large head". Specifically, Dr. Schelberg documented a head circumference of 50 cm, greater than the 95th percentile.

[12] Dr. Schelberg advised Ms. York that Cole had hydrocephalus. Dr. Schelberg's clinical notes had included the phrases "dilated veins", "(+) sunset" and "(+) crackpot sign". During his examination in chief, Dr. Macnab, an expert witness for the appellants, reviewed Dr. Schelberg's findings. Dilated veins on the surface meant that the pressure from the hydrocephalus was compromising normal circulation of blood through the blood vessels. Sunsetting eyes, where you can see the whites of the eyes more than the pupil, were a sign that pressure damage had occurred to the nerve pathways that control eye movement. A cracked pot sign referred to Cole's skull bones being so pushed apart that the skull was effectively broken because of the rising pressure in his head.

[13] Dr. Schelberg referred Cole to Dr. Drake, a neurosurgeon at the Hospital for Sick Children, who saw him the next day, on December 17. According to Ms. York, Dr. Drake advised her that Cole had severe hydrocephalus. Cole needed surgery to insert a shunt, which would drain the excess fluid from his brain. Cole underwent this surgery on December 19, 1999.

[14] Dr. Conley's wife worked at Dr. Conley's office, and she testified that she had received a call from Mr. Harold York, Ms. York's father, on December 17, 1999, based on a note she had taken. The note said "Mr. York called to say Cole has been diagnosed with hydrocephalus" and "[a]lso stated Dr. C had told Kim to have head size checked". Mr. York did not recall making that call and was "sure that call never took place". He also denied having made that last statement, saying "[t]hat's absolutely not possible because Dr. Conley had always said that Cole's head size was normal".

(2) The trial

[15] The main issues at trial were standard of care, causation, and damages. On the first issue, which is also the relevant issue on this appeal, the central dispute was whether Dr. Conley and Dr. Park had met the applicable standard of care. The appellants' position was that they had not. They argued that neither doctor had told the parents that Cole's head size was a matter of concern. Even if some concern was expressed at the time, the standard of care required the doctors who saw Cole in October and November to take additional steps and actually make referrals, among other things. Further, the notion that Ms. York would not have brought Cole for assessment right away, had she been instructed to, defied common sense, particularly in light of the fact that this was a mother who was good at following up on instructions and took Cole to many medical appointments, including for small things.

[16] The respondents' position was that both doctors had expressed their concerns to Ms. York; that the doctors had taken sufficient steps because a referral was not required when Dr. Conley saw Cole on October 15 and Dr. Park had told Ms. York to take Cole to the emergency room; and that Ms. York had chosen not to take Cole for follow up with a doctor or to the emergency department despite receiving advice to do so.

[17] In short, the issues of credibility and reliability at trial as they related to standard of care were central issues revolving around what the two doctors had said to Ms. York on the various occasions that they saw Cole, whether she followed any instructions she was given, and whether the doctors' actions or omissions met the applicable standard of care.

(3) The expert evidence at trial

[18] Although there were 27 experts who testified at the trial, only four testified as to the standard of care. For the appellants, three doctors were qualified as experts as to the standard of care:

(1) Dr. James Rourke, an expert in family medicine, creator of the "Rourke Baby Record" guideline for looking after babies and infants up to the age of five used by most family doctors in Canada; (2) Dr. Andrew Macnab, an expert in pediatrics and neonatology, a subspecialty of pediatrics concerned with looking after newborn infants, and a professor at the University of British Columbia; and (3) Dr. Jan Ahuja, an expert in walk-in centre care, a walk-in and emergency medicine physician, a professor at the University of Ottawa, and a peer assessor and medical inspector for the College of Physicians and Surgeons of Ontario.

[19] For the respondents, the following doctor was qualified as an expert as to the standard of care:

(1) Dr. Barry Bruce, an expert in family medicine and episodic care, a physician practising in Carp, Ontario who has mainly worked in general family practice and episodic walk-in patient care, and former Chief of Staff at the Queensway Carleton Hospital in Ottawa.

[20] Dr. Rourke opined that the abnormal and serious clinical finding of rapidly increasing head circumference was evident by October 15, 1999, at which point it had increased from over the 25th percentile to the 50th percentile and then to the 97th percentile over a six-week period. He noted that by September 21, Cole's weight had remained on the same percentile from September 3, while the head moved up significantly, and that "at this point in time, one's got to be concerned about which is the problem". He testified that Dr. Conley fell below the standard of care on October 15, 1999 because based on Dr. Conley's notes, Dr. Conley had failed to recognize the serious implications of Cole's very abnormal head circumference growth, failed to carry out and record an assessment with respect to the serious clinical finding, and failed to make an urgent referral to a specialist.

[21] Dr. Macnab opined that the standard of care required that a baby with Cole's pattern of head growth, as documented by Dr. Conley on October 15, 1999, must be referred to a specialist immediately. Dr. Macnab explained that growth typically occurs along the centile we are born on, so when patterns of growth fall off percentiles, it is worrying because it means the growth is not following the normal curve. He plotted Dr. Conley's measurements of Cole's head circumferences and pointed out that while there was cause for concern even at the visit of September 21 because there was crossing of centiles, Cole's head measurement by October 15 was "essentially off the centile chart" and showed a "highly abnormal pattern of growth" requiring immediate action, namely referral to a specialist. When asked to assume that Dr. Conley did tell Ms. York to take Cole to have his head checked and whether a patient can be expected to follow that advice, Dr. Macnab opined that "it's not appropriate to delegate or abdicate this kind of decision, responsibility, care, next step, to a young mother" and that "with something this important, the follow-up has to be guaranteed".

[22] Dr. Ahuja opined that Dr. Park fell below the standard of care because he failed to carry out and record a complete history and physical examination related to the abnormal and significant finding of Cole's head size, he failed to discuss this abnormal finding with Ms. York, and he failed to properly and effectively refer Cole for further urgent assessment. Dr. Park did not act appropriately upon his finding of an abnormal head size. He should have provided a copy of his record of treatment clearly indicating his concerns, sent a consult note to the emergency department indicating his concerns, and made direct contact with at least a triage nurse at the emergency department of the hospital. Dr. Ahuja assumed that these things were not done because they were not documented but agreed that if something is not written down it does not necessarily mean that the act did not happen. His opinion was that Dr. Park's chart was clinically substandard.

[23] Dr. Bruce opined that both Dr. Conley and Dr. Park met the standard of care. Rather than using the "Boston Graph" that Dr. Conley had used in 1999, Dr. Bruce re-plotted Cole's head circumference measurements on the graph used by Dr. Park with different percentile curves. Dr. Bruce's plots showed that Cole's head circumference was at approximately the 75th percentile on September 3, about the 80th percentile on September 21, and about the 95th percentile on October 15. His opinion was that Cole's changing head size over the three visits in itself did not require a referral, and Dr. Conley was not obliged to make a referral for Cole on October 15, as Cole was otherwise well. Even using Dr. Conley's percentiles and plotting, the standard of care on October 15 did not require a referral, only that head circumference be remeasured again within two to four weeks. Dr. Conley had appropriately remeasured Cole's head when he identified a concern about head size, and it was appropriate to advise Ms. York to have Cole's head size followed by a new physician, if one could be found, at an appropriate time.

[24] With respect to Dr. Park, Dr. Bruce said he had met the standard of care because he recognized that Cole had a large head, he had measured it, he had assessed the measurement and found a clear abnormality, and he had decided to send Cole to the emergency room for assessment. Assuming that Dr. Park had told Ms. York that his reason for wanting her to go to the emergency room was for an assessment of Cole's head size and that he had given her a note with his findings for the emergency room doctor, that would meet the standard of care. No additional steps were required. Dr. Park was entitled and obligated to rely on Ms. York to take Cole to the emergency room.

[25] In cross-examination, Dr. Bruce agreed that he ignored Ms. York's evidence when he wrote his report, because he did not think it was relevant. He also expressed his opinion that he did not think Ms. York's memory was accurate, that he had put more weight on Dr. Conley's evidence because he had some notes, and that it was inconceivable that Dr. Park had not told Ms. York to take Cole to the emergency room.

[26] As I will discuss further below, the evidence of Dr. Conley and Dr. Park was irreconcilable with the evidence of Ms. York. Dr. Conley maintained that he expressed concern about Cole's head size in October and that Ms. York did not raise a concern about his head size during any of the visits as he would have written that down. Ms. York testified that she was the one who raised the concern and was repeatedly reassured that Cole's head size was within normal range and that she should not worry. She specifically denied that Dr. Conley told her on October 15 that she needed to have Cole's head size watched or checked, stating that she was given the immunization record and told that Cole did not need to be seen for another two months. With respect to Dr. Park, Ms. York denied that he had told her to take Cole to the emergency room, saying that she would have done so had he said that. Credibility and reliability of the lay witnesses was thus a critical issue for the jury to resolve in this trial.

(4) Issues at trial with respect to expert evidence

[27] There were no objections to the admissibility of Dr. Bruce's evidence either at the outset or in the course of his testimony and cross-examination. Following Dr. Bruce's testimony, however, the respondents attempted to qualify another doctor, Dr. Karen Fleming, as an additional expert in the standard of care. The appellants objected to Dr. Fleming being qualified as an expert because she lacked independence and impartiality and her evidence was unnecessary.

[28] The trial judge reviewed Dr. Fleming's reports and found that they included credibility assessments, inaccuracies and methodological flaws, and thus lacked objectivity. Dr. Fleming accepted the evidence of the respondent doctors and rejected the evidence of the appellants without explanation, and she was unwilling or unable to recognize or acknowledge this preference. She made improper fact-finding and credibility assessments and acted as both judge and jury. The trial judge found that there was a serious concern that the jury would accept the premise underlying Dr. Fleming's opinion as conclusive or be affected by her acceptance of certain facts. The trial judge concluded that Dr. Fleming lacked independence, rendering her incapable of providing an impartial opinion and refused to admit her evidence.

(5) Pre-charge conference and closing submissions

[29] At the pre-charge conference, counsel for the respondents made submissions clarifying the trial judge's summary of Dr. Bruce's evidence. Counsel for the appellants did not make submissions on Dr. Bruce's evidence except to clarify that Dr. Bruce had not opined on whether he accepted Harold York's evidence.

[30] During closing submissions, counsel for the respondents told the jury that they would need to make decisions on the credibility and reliability of the fact witnesses and expert witnesses. Counsel submitted that the standard of care issue in the case was driven by two main questions, namely, what actually happened between Dr. Conley and Ms. York on October 15 and between Dr. Park and Ms. York on November 13: (1) whether Dr. Conley told Ms. York on October 15 that Cole's head size needed to be followed; and (2) whether Dr. Park told Ms. York on November 13 that she should take Cole to the emergency room. The answers to these two questions should be "yes". It made no sense that both doctors would have been concerned about Cole's head size, recorded that concern, and not told Ms. York. With regard to the expert evidence on the standard of care issue for both Dr. Conley and Dr. Park, counsel encouraged the jury to accept the evidence of Dr. Bruce.

[31] Counsel for the appellants submitted that the question was not what Dr. Conley may or may not have told Ms. York, as defence counsel had framed it, but rather what he ought to have done in those circumstances. There were instances where Dr. Conley and Dr. Park appeared to change their evidence, and counsel's position was if the doctors did nothing wrong during the October and November visits, they would not need to come to court and attempt to change their evidence. Counsel for the appellants also emphasized the importance of the credibility of the witnesses and highlighted the evidence of Dr. Bruce on standard of care. Counsel submitted that Dr. Bruce did not fulfill his obligation to the court to provide objective evidence, read from a transcript of Dr. Bruce's cross-examination, and submitted that the jury could not trust Dr. Bruce.

(6) The jury charge and verdict

[32] The jury charge consisted of general principles that apply to civil jury cases, legal principles on the issues that governed the case including liability, causation and damages, the specific questions the jury would need to answer, and instructions to assist the jury with its deliberations. The trial judge told the jury that in deciding the facts in this case, they would need to weigh and judge the testimony of witnesses for credibility and reliability. She provided guidance for dealing with expert testimony, instructing the jury to take into account the expert's skill, experience, knowledge, familiarity with the facts, credibility and whether the expert seemed impartial and fair or unwilling to consider opinions other than their own. Further, the jury was entitled to reject an expert's opinion or find it less helpful if they found the facts to be different from those underlying the opinion.

[33] In reviewing the legal principles in the case, the trial judge began with negligence and the question of whether the defendants breached the required standard of care. The jury was told that if this was not proven, the plaintiffs could not succeed. The trial judge began her review of the evidence on standard of care by telling the jury that while judges have a right to comment on a witness's credibility and inferences to be drawn from the evidence, she did not intend to do so, and that it was the jury's duty to interpret the evidence. In reviewing Dr. Bruce's evidence, the trial judge mentioned the cross-examination where Dr. Bruce testified that he had accepted Dr. Conley's evidence, did not accept anything Ms. York said because she was "probably mistaken", and did not reference any of Mr. Parliament's evidence. The trial judge did not give a specific instruction in the charge regarding Dr. Bruce's evidence, but she did end the standard of care portion of her charge by reminding the jury that it was up to them to determine the weight to give an expert opinion by considering various factors and questions, including whether the witness seemed impartial and fair.

[34] The jury's verdict was that Dr. Conley and Dr. Park did not breach the standard of care. The jury made no findings on causation. The trial judge dismissed the action against Dr. Conley and Dr. Park in accordance with the jury's verdict.

C. Issues on Appeal

[35] The appellants found their appeal on the trial judge's failure to exclude Dr. Bruce's evidence, or alternatively, to provide a clear and specific instruction to the jury with respect to his lack of impartiality and the impropriety of his assessments of the parties' credibility. They argue that a new trial is required.

[36] The respondents argue that, first, the jury charge was sufficient to instruct the jury as to the concerns surrounding Dr. Bruce's evidence, and that this concern about bias simply went to the weight to be given to the opinion. Moreover, they argue that the appellants ought not to succeed on appeal on a new concern not raised at trial. Finally, they argue that the verdict was reasonable. There was no miscarriage of justice; the appellants simply failed to meet their onus of proof.

D. Analysis

(1) Did the trial judge err by failing to exclude Dr. Bruce's evidence or by failing to provide a specific instruction to the jury?

(a) Positions of the parties

[37] The appellants submit that Dr. Bruce's evidence was inadmissible in whole or in part, and that the trial judge erred in failing to so instruct the jury. Dr. Bruce's evidence was inadmissible because he failed to fulfill his duty to be independent or impartial. He accepted the version of events presented by the respondents and ignored the evidence of the appellants. Dr. Bruce not only provided his opinion on what he thought happened on central questions in dispute, but he even went so far as to purport to make findings of fact. The trial judge should have exercised her residual discretion as part of her gatekeeping role to exclude Dr. Bruce's evidence or at the very least, she should have provided a specific instruction to the jury concerning the impropriety of Dr. Bruce's evidence and his failure to fulfill his duty.

[38] The respondents argue that the appellants' closing submissions warned the jury about Dr. Bruce's alleged bias in his testimony with respect to both Dr. Conley and Dr. Park, and about Dr. Bruce ignoring Ms. York's evidence and accepting the evidence of the physicians, despite the fact that they acknowledged having no recollections of the visits while Ms. York testified that she did. The respondents also submit that the charge contained all the necessary warnings on credibility and reliability of all witnesses and reiterated the appellants' concerns with Dr. Bruce's evidence. Even if the appellants had asked the trial judge to exclude Dr. Bruce's evidence, it would have been inappropriate for her to do so. Dr. Bruce's evidence did not reveal a level of bias that would go to threshold admissibility, and any concerns about bias would appropriately go to the weight to be given to his evidence. He did not make findings of fact and he did not advocate for the position of the respondents. He was merely making assumptions and being cross-examined on those assumptions. Dr. Bruce reviewed the records and transcripts and provided an expert opinion based on that review.

(b) Impugned evidence of Dr. Bruce

[39] The credibility and reliability of the lay witnesses were critical issues for the jury to resolve in this trial. It is against this backdrop that the appellants argue that Dr. Bruce was neither independent nor impartial -- that he opined on matters going to the heart of the credibility and veracity of Ms. York, Mr. Parliament, and the two doctors, at times stating that he did not think Ms. York's evidence was relevant, that it was untruthful, or that she could not have remembered it correctly. It is necessary to review some of the impugned portions of Dr. Bruce's testimony in order to assess the submissions of the appellant.

[40] Dr. Bruce agreed on cross-examination that he chose to accept Dr. Conley's evidence over Ms. York's evidence, explaining that he could find discrepancies in their evidence, that Ms. York's evidence in discovery was not relevant, that he assumed Ms. York could not remember correctly despite Ms. York saying that she had a clear recollection and Dr. Conley saying he did not remember those visits well, and that he was not sure her memory of the events was accurate:

Q. And you proceeded on the assumption throughout your report that Ms. York is untruthful; yes? R. I did find discrepancies between what I could read in the charts and what Ms. York was saying, yes. Q. Why didn't you put down the information that Ms. York said in her discovery? A. Well, because I didn't think it was relevant. Q. Not relevant? The fact that she says that he never mentioned -- she brought to . . . Dr. Conley a concern about Cole's head size and he told her it was normal, that's not relevant? The fact that he told her that everything was normal on October 15th, that's not relevant? R. I think with so many years, that nobody could remember exactly what was said. I think that's why I was looking at -- Dr. Conley had his notes to refer to, and he had some memory of what he would have done, but there were no notes that were kept by Cole's mother. Q. [W]ere you fair and objective and nonpartisan here? A. I think so. Q. By not referring to Ms. York's evidence? Yes? A. Well, by assuming she couldn't remember correctly. Q. Why would you assume that if she says she remembers? A. It was so many years. Q. So you assume that she's just making it up? That's it; right? Under oath, she's making those statements up? That's your assumption? R. I don't think she's -- she believes that she remembers it, but I'm not sure that it was accurate. Q. So didn't you -- you perceived your role in this case to actually assess the credibility of the two parties and make a decision who you believe or who you don't believe? A. I can't answer that. Q. Well, of course you can because that's what you did. You chose to take Dr. Conley's evidence, including those things that he [had] not documented in his records just because he said it on discovery and used that to defend him. Yes or no? A. It's true.

(Emphasis added)

[41] Dr. Bruce later went on to opine in cross-examination that Dr. Conley had conducted a sufficient neurological examination despite the limited notes on Cole's neurological status on October 15 because he could "read between the lines". Dr. Bruce also assumed that Dr. Conley had told Ms. York to have Cole's head size followed, based on the note "will watch head size":

Q. I see. So how about this reading between the lines: So for everything else, you don't accept Ms. York's evidence, but for this neurological examination, whatever she told Dr. Conley is gospel for you; right? R. No. Dr. Conley made notes of it at the time and made excellent notes at the time, and, yes, it's gospel. What the mother said was relying on memory for events that had occurred many years before, so I have to be a little askance that those were remembered correctly, yes. S. There's no note in Dr. Conley's chart that says that he told the mother to go and have the head checked; correct? A. There's no note that says specifically those words, no. Q. Where do you get the fact that Dr. Conley told the mother -- as you say in your report, Dr. Conley told the mother to go and see another doctor to have the head checked. Where did you get that information from? A. I'll have to see exactly what I said. Q. You wrote: "It was appropriate for Dr. Conley in the circumstances to advise Ms. Parliament, as he did, to have Cole's head size followed by his new physician." A. Yes. Q. Where did you get that from? A. Well, that's what I assume from that one line, "will watch head size."

(Emphasis added)

[42] The appellants also point to Dr. Bruce preferring the evidence of Dr. Park over Ms. York and straying well beyond the confines of his role during his cross-examination when providing his opinion about whether Dr. Park met the standard of care:

A. He's required to prepare a note. Actually, a large head, as serious as it is, is a rather simple concept to portray.

Q. All right. You reviewed his notes. Did you find any? A. No. No, I did not. Q. But for that purpose, you -- to render your opinion, you relied on Dr. Park's evidence even though it's nowhere in the records; correct? A. Yes. Q. And, again, you ignored Ms. York's evidence on that point; right? A. Yes. Q. Well, I'm suggesting to you that it's not enough, given what we discussed, just to tell the mother. He needs to write a detailed note, call the emergency department or another physician who he's referring the patient to and have that talk so that he makes sure that the baby is seen and that his advice is understood; do you not agree? R. I think it's clear that -- no, not entirely. I think it's clear that he did. It's inconceivable that he didn't convey this, given the gravity of it, to the mother. It's inconceivable that he didn't directly tell her to go to emergency. S. Well, is it conceivable that a mother who brings the child to a doctor on a Saturday because of a cold or cough -- A. Yes. Q. -- is not going to go to the emergency, which is five to seven minutes away, when she's told your baby may have hydrocephalus, that this is a significant brain issue; do you think that is more conceivable? R. It does not sound usual to me, but it's conceivable because that's what happened.

(Emphasis added)

(c) The principles

[43] Expert evidence carries with it the risk that a jury "will inappropriately defer to the expert's opinion rather than carefully evaluate it": White Burgess Langille Inman v. Abbott and Haliburton Co., 2015 SCC 23, at para. 17; R. v. Mohan, at pp. 21-22 S.C.R. The test for admissibility of expert evidence consists of two steps. First, the proponent of expert evidence must establish that four conditions are met in order to establish its admissibility: relevance; necessity in assisting the trier of fact; absence of an exclusionary rule; and a properly qualified expert. The second stage of the inquiry requires the trial judge to conduct a cost-benefit analysis to determine whether otherwise admissible expert evidence should nevertheless be excluded because its probative value is outweighed by its prejudicial effect.

[44] The ultimate conclusion as to the credibility or truthfulness of a particular witness is for the trier of fact, and it is not the proper subject of expert opinion. The rationale for this policy is that credibility is a notoriously difficult problem, and a frustrated jury may readily accept an expert's opinion as a convenient basis upon which to resolve its difficulties: see R. v. Marquard, at p. 248 S.C.R. In addition, one of the central dangers of expert evidence is that finders of fact, and juries in particular, may be too ready to rely on experts who appear to be knowledgeable, credible and reliable. Justice Doherty explained this danger in R. v. Abbey (2009), 97 O.R. (3d) 330, 2009 ONCA 624, at para. 90, leave to appeal to S.C.C. refused [2010] S.C.C.A. No. 125:

Clearly, the most important risk is the danger that a jury will be unable to make an effective and critical assessment of the evidence. The complexity of the material underlying the opinion, the expert's impressive credentials, the impenetrable jargon in which the opinion is wrapped and the cross-examiner's inability to expose the opinion's shortcomings may prevent an effective evaluation of the evidence by the jury. There is a risk that a jury faced with a well-presented firm opinion may abdicate its fact-finding role on the understandable assumption that a person labelled as an expert by the trial judge knows more about his or her area of expertise than do the individual members of the jury.

[Citation omitted]

[45] It is well established that a trial judge's role as gatekeeper is not exhausted once a particular expert has been permitted to testify on the basis of their qualifications and the content of their report: see Bruff-Murphy v. Gunawardena (2017), 138 O.R. (3d) 584, 2017 ONCA 502, at paras. 62-66, leave to appeal to S.C.C. refused [2017] S.C.C.A. No. 343; R. v. Sekhon, [2014] 1 S.C.R. 272, 2014 SCC 15, at paras. 46-47. Rather, the trial judge must protect the integrity of the process by ensuring that the expert does not overstep the acceptable boundaries in giving evidence. As Doherty J.A. stated in Abbey, at para. 62, it is essential that trial judges ensure both "[a] cautious delineation of the scope of the proposed expert evidence and strict adherence to those boundaries, if the evidence is admitted".

[46] However, even when the content and scope of an expert's evidence is delineated in advance, the expert may stray in the course of their oral testimony. As Hourigan J.A. noted in Bruff-Murphy, at paras. 62-63:

A trial judge in a civil jury case qualifying an expert has a difficult task. She must make a decision based on an expert report that will, in most cases, never be seen by the jury. While the report provides a roadmap of the anticipated testimony and specific limits may be placed on certain areas of testimony, the trial judge obviously cannot predict with certainty the nature or content of the expert's testimony.

Where, as here, the expert's eventual testimony removes any doubt about her independence, the trial judge must not act as if she were functus. The trial judge must continue to exercise her gatekeeper function. After all, the concerns about the impact of a non-independent expert witness on the jury have not been eliminated. To the contrary, they have come to fruition. At that stage, when the trial judge recognizes the acute risk to trial fairness, she must take action.

(Emphasis added)

[47] The continuing gatekeeping role means that trial judges must not only continue to ensure that the expert's actual testimony does not overstep the appropriate scope of the expert evidence; they must also include ensuring that the expert's testimony continues to be independent in the sense that the expert does not become an advocate for the party by whom they are called.

[48] As Hourigan J.A. made clear in Bruff-Murphy, the continuing gatekeeper role of a trial judge includes the continuation of the residual discretion to exclude evidence when they are not satisfied that the testimony's probative value exceeds its prejudicial effect: at paras. 65-66; R. v. White, [2011] 1 S.C.R. 433, 2011 SCC 13, at para. 50; and R. v. Bingley, [2017] 1 S.C.R. 170, 2017 SCC 12, at para. 30.

(d) Application

[49] There does not appear to have been anything inherently improper about Dr. Bruce's opinion as to the applicable standard of care. I would note, however, that it is not clear that the issue was canvassed at the voir dire in the same manner as was the proposed evidence of Dr. Fleming, which was excluded in its entirety because the trial judge concluded that it was not independent. Rather, it seems that the appellants consented both with respect to Dr. Bruce's qualifications and the content of his report. The appellants do not argue that Dr. Bruce should not have been permitted to give expert evidence from the outset. However, they argue, and I accept, that as the extracts above demonstrate, Dr. Bruce opined on the credibility of the parties in his oral testimony, indicating that he believed the respondents and not Ms. York. The credibility and reliability of Ms. York and the two doctors were central issues for the jury to decide.

[50] There were a number of problems with Dr. Bruce's evidence as given.

[51] First, it illustrates one of the dangers of expert evidence that oversteps its boundaries: the risk that a jury, faced with difficult issues of credibility and reliability and a well-presented expert opinion, will "abdicate its fact-finding role on the understandable assumption that a person labelled as an expert by the trial judge knows more about his or her area of expertise than do the individual members of the jury": see Abbey, at para. 90; see also Marquard, at p. 248 S.C.R. Dr. Bruce exceeded his role as an expert when he opined on the credibility and reliability of the doctors and Ms. York, for example observing that Ms. York was untruthful and could not remember accurately. There was a risk that the members of the jury would accept Dr. Bruce's credibility and reliability assessments, rather than assess the evidence of the witnesses and reach their own conclusions.

[52] Second, the expression of an opinion as to the credibility of witnesses is also a breach of the expert's duty to be independent. Dr. Bruce acknowledged in his evidence that in rendering his opinion on standard of care, he disregarded Ms. York's evidence and assumed that the doctors' evidence was credible and reliable. I do not accept the respondents' argument that all Dr. Bruce was doing was making assumptions as the questions put to him asked him to do. As the extracts above indicate -- particularly "it's conceivable because that's what happened" -- it is clear that in some critical instances he was giving evidence about what actually happened, based on his view of the credibility of the witnesses. His testimony extended well beyond expressing opinions based on hypothetical facts he was asked to assume. For these reasons, this evidence was not admissible and to the extent his testimony opined on the credibility of the witnesses, it should have been excluded. These circumstances called for the trial judge to exercise her gatekeeping role and her residual discretion to exclude this evidence.

[53] I do not agree with the respondents that the appellants' closing submissions were adequate to address any prejudice caused to the appellants by the impugned aspects of Dr. Bruce's evidence. Nothing that the appellants could have said in their closing would have had the force of a clear instruction from the trial judge to the effect that the impugned aspects of Dr. Bruce's evidence were inadmissible. Juries are told that the trial judge is the judge of the law, and that they are to take their instructions from the trial judge. What the appellants said was simply argument.

[54] I also do not accept the respondents' submission that the final charge contained the necessary warnings. The vast majority of the cautions to which the respondents refer are contained in the general section of the charge and applied to all of the expert witnesses. The trial judge had explained to the jury how to assess the credibility and reliability of a witness's evidence, with additional instructions on weighing expert opinions. The jury was told to consider whether the expert struck them as being honest, impartial and fair, and told that they could reject an expert's opinion if they found the facts to be different from those which formed the basis for the expert's opinion. These general instructions came fairly early on in the charge, in what is often referred to as the "boilerplate" portion, with no reference to any of the individual experts who testified. The trial judge went on to give instructions on the burden of proof, an overview of the facts, and instructions on the legal principles for the standard of care before reviewing the lay witness and expert evidence on standard of care and recapping the instructions on weighing expert opinion.

[55] There was no specific caution about Dr. Bruce's testimony on the issue of his view of the credibility and reliability of Ms. York. The trial judge did, in her summary of the parties' evidence, include the following:

On cross-examination, Dr. Bruce testified that he had read the transcripts of the examinations for discovery and in coming to his opinions had accepted Dr. Conley's evidence. He did not accept anything that Kim said as she was "probably mistaken," nor did he reference any of John Parliament's evidence.

On cross-examination, Dr. Bruce testified that he accepted Dr. Park's evidence over Kim York's evidence. Dr. Bruce stated that it's inconceivable that he didn't convey this given the gravity of it to the mother.

When asked whether it was conceivable that a mother would not take her child to the emergency department when faced with a potential hydrocephalus or brain injury, Dr. Bruce stated:

"It does not sound usual to me. It's conceivable because that's what happened."

[56] However, there was, in short, nothing in the charge instructing the jury to disregard Dr. Bruce's evidence in relation to the credibility and reliability of the two doctors and Ms. York.

(e) What should the trial judge have done?

[57] There are two steps that the trial judge could have taken at the time that Dr. Bruce was testifying. First, she could have, in the absence of the jury, invited submissions from the parties as to the content of a mid-trial instruction that the jury ignore any and all of his expressions as to the credibility or reliability of the witnesses. Second, she could have included a very clear and specific instruction in the final charge on the point. The general comment that it was entirely up to the jury to decide "[h]ow much or how little [they] believe of or rely upon an expert's opinion" was wholly inadequate given the risk that the jury would place undue weight on Dr. Bruce's opinion. Given the large number of expert and lay witnesses who testified at trial, nothing less than a clear and specific instruction that Dr. Bruce's credibility opinions were inadmissible and should be ignored would suffice.

[58] The failure to so instruct the jury was a serious error on the part of the trial judge, despite the fact that the appellants' counsel did not ask for either a mid-trial or a closing instruction. In this case, the trial judge should have delivered a prompt and clear mid-trial instruction during Dr. Bruce's testimony and reiterated this instruction in the final charge. I recognize that both steps might not be necessary in all cases, but it was necessary in this case, given the highly prejudicial nature of the impugned aspects of Dr. Bruce's evidence to the appellants' case and the fact that the jury heard a great deal of additional evidence on subjects other than the standard of care after he testified.

[59] The defence called approximately five witnesses on causation and six on damages over the next few weeks. This was not a short, one issue trial in which it might have been reasonable to think that the evidence would be fresh and that a caution in the final charge would suffice, or that a mid-trial caution would have sufficed in the absence of a final instruction that reiterated the caution. The circumstances of this trial, including the number of experts, its length, and the complexity of the evidence on a range of issues required that this instruction be given both when Dr. Bruce overstepped his role as an expert when giving his evidence and in the course of the final instructions.

(2) Is the failure to raise the issue of Dr. Bruce's impartiality before the trial judge fatal on this appeal?

[60] Dr. Bruce's expert evidence was admitted at the outset on consent. There were no objections by the appellants' trial counsel to Dr. Bruce's evidence in chief, apart from a brief objection to require Dr. Bruce to stay within the parameters of his report when opining on the significance of a child's weight, nor to the absence of any specific reference in the charge to Dr. Bruce's lack of impartiality or bias.

(a) Positions of the parties

[61] The respondents argue that the appellants should be precluded from raising the issue of the admissibility of Dr. Bruce's evidence on appeal because they failed to object at trial to both the evidence and the jury charge. Their failure to object should be given considerable weight and should be fatal to their appeal. The appellants claim that Dr. Bruce's bias was evident in his reports. The respondents also claim that the fact that the appellants challenged Dr. Fleming's independence after Dr. Bruce had testified demonstrated that they were alive to the issue of Dr. Bruce's bias in the course of the trial. Put another way, the respondents argue, the appellants made a conscious choice not to object to Dr. Bruce's qualification, and there was no miscarriage of justice in this case to warrant ordering a new trial. As long as there is some evidence to support the jury's verdict, it should not be set aside. It was open to the jury to disbelieve the evidence of the appellants and to conclude that negligence was not proven on a balance of probabilities.

[62] The appellants submit that a substantial wrong or miscarriage of justice occurred in this case and that a new trial is warranted, despite their failure to object at trial. The integrity of the administration of justice requires that expert witnesses honour their obligations. There was a real danger that Dr. Bruce's inappropriate credibility and veracity assessments improperly influenced the jury. The jury's verdict was tainted by improper evidence and must be set aside.

(b) The principles

[63] The general principle is that a party in a civil case should not bring an appeal on the basis of some aspect of the lower court proceeding to which it did not object: see Marshall v. Watson Wyatt & Co. (2002), 57 O.R. (3d) 813, at para. 15; Harris v. Leikin Group Inc. (2014), 120 O.R. (3d) 508, 2014 ONCA 479, at para. 53; and Maurice v. Alles (2016), 130 O.R. (3d) 452, 2016 ONCA 287, at para. 25. A party's failure to object at trial weighs heavily against that party now bringing an appeal because it indicates that trial counsel did not consider that point to be important or of sufficient consequence to require an objection: see Arland and Arland v. Taylor, [1955] O.R. 131 (ONCA), at p. 361 D.L.R.; Marshall, at para. 15.

[64] An appellant cannot ask for a new trial as of right due to an error during the trial when no objection was made on the point at trial. The failure to have objected at trial is not treated lightly by an appellate court and is usually fatal to an appeal on that point: see Arland, at p. 361 D.L.R.; K. (G.) v. K. (D.), at para. 15, leave to appeal to S.C.C. refused [2000] S.C.C.A. No. 415; Marshall, at para. 15.

[65] This principle has been invoked in connection with an appellant's failure at trial to object to a jury instruction or charge: see, e.g., Bruff-Murphy, at para. 69; Pietkiewicz v. Sault Ste. Marie District Roman Catholic Separate School Board (2004), 71 O.R. (3d) 803, at para. 22. It is also applicable on the issue of the admissibility of evidence, as an objection to the admissibility of evidence on appeal will not usually succeed unless the objection is made at trial: see Hoang (Litigation guardian of) v. Vicentini, [2016] O.J. No. 5140, 2016 ONCA 723, 352 O.A.C. 358, at para. 63; Marshall, at paras. 15, 30; and Sidney N. Lederman, Alan W. Bryant and Michelle K. Fuerst, Sopinka, Lederman & Bryant: The Law of Evidence in Canada, 5th ed. (Toronto: LexisNexis Canada, 2018), at para. 2.109.

[66] A new trial may be ordered in such cases, however, when the court is satisfied that a new trial is necessary in the interests of justice: see Arland, at p. 361 D.L.R.; Marshall, at para. 15. When an objection is made on appeal that was not made at trial, the focus should be on the question of whether a substantial wrong or miscarriage of justice has occurred: see Marshall, at paras. 14-15; Arland, at pp. 364-65 D.L.R.; Pietkiewicz, at paras. 22-28.

[67] In sum, this court can exercise its discretion to grant a new trial or other remedy despite the failure of the appellants to object to the jury charge or the admissibility of Dr. Bruce's evidence if it finds that the errors alleged by the appellants were errors that constituted a substantial wrong or miscarriage of justice and that the interests of justice require granting relief.

(c) Did the errors constitute a substantial wrong or miscarriage of justice?

[68] As I have indicated above, the trial judge erred in failing to advise the jury that it could not consider Dr. Bruce's evidence on the respective credibility and reliability of the parties.

[69] It is not possible to assess with any certainty the impact of Dr. Bruce's evidence. That, however, misses the point, which is whether there has been a miscarriage of justice in this case. Given the centrality of credibility in this case, and the absence of any caution about Dr. Bruce's evidence (apart from summarizing the appellants' cross-examination of Dr. Bruce), there is a very real possibility that Dr. Bruce's evidence on credibility and reliability played a significant role in the jury's decision to find that the standard of care was met by both doctors during the October and November visits.

[70] As Hourigan J.A. wrote in Bruff-Murphy, at para. 72, "[t]his court has a responsibility to protect the integrity of the justice system. This is not a 'no harm, no foul' situation." The sole witness for the respondents on the issue of standard of care exceeded the admissible scope of his evidence and opined on the credibility of the witnesses, which was highly prejudicial to the appellants. The impugned evidence tainted the jury's verdict and the verdict must be set aside.

[71] For these reasons, I conclude that there has been a miscarriage of justice and a new trial is required.

E. Disposition

[72] I would allow the appeal, set aside the judgment below, and order a new trial. Costs of the appeal in the agreed amount of $25,000 are payable by the respondents to the appellants. The parties advised us that they had an agreement on the costs below so it is unnecessary for us to address those.

**Appeal allowed.**