Expert Evidence – The New Normal

Once an expert attests or swears to this duty, there is an eviden- tial burden on the party opposing admission to show a realistic concern that the expert is unable or unwilling to comply with a duty of impartiality, independence, and lack of bias. If shown, the burden returns to the proffering party to “establish on a bal- ance of probabilities this aspect of the admissibility threshold” (White Burgess, para. 48.
As Madame Justice Donegan noted in Whaley

[49] This threshold requirement is not particularly onerous and it will likely be quite rare that a proposed expert’s evidence would be ruled inadmissible for failing to meet it. The trial judge must determine, having regard to both the particular circumstances of the proposed expert and the substance of the proposed evidence, whether the expert is able and willing to carry out his or her primary duty to the court. For example, it is the nature and extent of the interest or connection with the litigation or a party thereto which matters, not the mere fact of the interest or connection; the existence of some interest or a relationship does not automatically render the evidence of the proposed expert inadmis- sible. In most cases, a mere employment relationship with the party calling the evidence will be insufficient to do so. On the other hand, a direct financial inter- est in the outcome of the litigation will be of more concern. The same can be said in the case of a very close familial relationship with one of the parties or situations in which the proposed expert will probably incur professional liability if his or her opinion is not accepted by the court. Similarly, an expert who, in his or her proposed evidence or otherwise, assumes the role of an advocate for a party is clearly unwilling and/ or unable to carry out the primary duty to the court. I emphasize that exclusion at the threshold stage of the analysis should occur only in very clear cases in which the proposed expert is unable or unwilling to provide the court with fair, objective and non-partisan evidence. Anything less than clear unwillingness or inability to do so should not lead to exclusion, but be taken into account in the overall weighing of costs and benefits of receiving the evidence.

Following this “Threshold Enquiry”, the trial judge must be satisfied that the cost of admitting the evidence does not out- weigh its benefits. The Court referred to this as the “Gatekeeping Exclusionary Discretion” stage. The judge must consider factors such as questions of relevance, necessity, reliability, and absence of bias, independence, and impartiality. Where the probative value of the expert opinion evidence is outweighed by its prejudicial effect, it should be excluded: R. v. Bingley, 2017 SCC 12 at para. 16 Note that concerns regarding impartiality or bias come into play in both the Threshold Requirement criterion as well as in the gatekeeping cost/benefit analysis: J.P. v. British Columbia, 2017 BCCA 308 where the CA ordered a new trial because of the failure of the trial judge to properly perform his gatekeeper function.

The court’s initial ruling on admissibility does not end the court’s gatekeeper function. The judge must play an ongoing role to ensure that, throughout the expert’s testimony, the testimony remains within the proper boundaries of expert evidence (R. v. Abbey, 2009 ONCA 624). As noted in that case at para. 62:

The admissibility inquiry is not conducted in a vacuum. Before deciding admissibility, a trial judge must determine the nature and scope of the proposed expert evidence. In doing so, the trial judge sets not only the boundaries of the proposed expert evidence but also, if necessary, the language in which the expert’s opinion may be proffered so as to mini¬mize any potential harm to the trial process. A cautious de-lineation of the scope of the proposed expert evidence and strict adherence to those boundaries, if the evidence is ad-mitted, are essential. . . .

Whether the trial is a judge alone or a jury trial does not affect the application of the Mohan criteria; expert opinion evidence either satisfies the Mohan admissibility criteria or it does not: Maras v. Seemore Entertainment Ltd., 2014 BCSC 1109 at para. 20. Nevertheless, the judge’s gatekeeping role requires particular caution when the trier of fact is a jury: Karpowicz v. Glessing, 2018 BCSC 887, at para. 14, citing Justice Abrioux, as he then was, in Maras at para. 20.
One final point should be mentioned. The issue that comes up from time to time is whether giving discovery transcripts to experts renders their evidence inadmissible. The answer is “no”. This issue comes up as a result of the judgment in Croutch (Guardian ad litem of) v. B.C. Women’s Hospital & Health Centre, 2001 BCSC 995, aff’d 2003 BCCA 472, where the trial judge said:

[17] In my view, expert witnesses should not base their opinions on discovery evidence which may or may not be read in at trial. Indeed, as a general rule, I do not consider they should be given access to discovery transcripts. The assessment of evidence is not their function, and there is no place for the delivery of an expert’s opinion when it is based on facts drawn by the expert from what was said on discovery. The facts un- derlying an opinion are within the purview of counsel. It is counsel who must be satisfied they are facts that can be proven, and it is for counsel to settle with an expert witness the facts that are to be assumed for the purpose of the opinion. It is those facts that must then be set out clearly in the statement that is to be delivered in compliance with the Rules.

This led many to argue that merely giving an expert access to discovery transcripts effected admissibility. That notion was dispelled by Smith, J. in Keefer Laundry Ltd. v. Pellerin Milnor Corporation, 2007 BCSC 899, who stated:

[46] … There may be situations where an expert is asked to comment directly on the conduct of a party, as in a case alleging professional negligence, and it is more convenient for counsel to simply provide an expert with portions of a discovery transcript, along with instruc- tions to assume the facts contained in that testimony. However, in those cases the expert must clearly identify the facts and assumptions he or she has drawn from the discovery transcript. There should also be no suggestion that the expert has weighed the discovery testimony against other evidence and chosen the facts that will be assumed.

The key issue is whether the trier of fact is able to determine what facts in the discovery transcript inform the expert’s opinion. In Friebel v. Omelchenko, 2013 BCSC 948, the Court said:

[18] Chief Justice Brenner identified the crux of the problem which has led some judges to criticize the practice of providing experts with material such as transcripts of examinations for discovery. The problem does not arise as a result of the expert’s review of the transcript, but where the transcripts are relied upon in the report in such a way that the trier of fact is unable to determine what facts form the basis for the expert’s opinion. …

See also Edwards v. Parkinson’s Heating Ltd., 2018 BCSC 593 at paras. 234–236.