His Lordship highlighted the judicial concern about impartiality of expert witnesses, and the tendency for experts to try to help those who retain them. As noted in para. 18, “The point is to preserve trial by judge and jury, not devolve to trial by expert.” The Court mandated a two stage process to govern the introduc- tion of expert evidence at trial. These two stages are explained below: (Note: the following is largely adopted by the excellent analysis conducted by Madam Justice S. Donegan in Whaley v. Bryant (2020) BCSC 531)
[9] First, the proffering party must demonstrate the existence of certain pre-conditions (the “Threshold Requirements”):- The evidence must be logically relevant (to a material issue);
- The evidence must be necessary to assist the trier of fact;
- The evidence must not be subject to any other exclusionary rule;
- The expert must be properly qualified, which includes a requirement that the expert be willing and able to fulfill the expert’s duty to the court to provide evidence that is impartial, independent, and unbiased; and
- For opinions based on novel or contested science or science used for a novel purpose, the underlying science must be reliable for that purpose.
The relevance issue relates to an examination of the pleadings and the issues raised in the case, and to determine whether, as a matter of logic and human experience, the expert opinion will tend to prove or disprove the fact in issue (See for example: R. v. Arp, 1998 CanLII 769 (SCC), [1998] 3 S.C.R. 339 at 360).
The necessity criterium is satisfied when expert opinion evidence:
- provides information that is likely to be outside the experience or knowledge of the trier of fact;
- will assist the trier of fact to appreciate technical dimen- sions of the matter in issue; and
- relates to something about which ordinary people are unlikely to form a correct opinion without expert as- sistance: Mohan at 23- 24.
Thus, both relevance and necessity must be determined on a case by case basis.
Argument in the guise of an expert opinion is by definition not necessary (Sengbusch v. Priest, 1987 CanLII 2796 (BCSC)
An example of an exclusionary rule is the rule against allowing an expert to opine on issues of credibility (see, for example, R. v. Sekhon (supra).
A “properly qualified expert” means an expert who has special or peculiar knowledge acquired through study or experience: Mohan at 25. They must also be impartial, independent, and unbiased. The Court in White Burgess explained at para. 10, in part:
… expert witnesses have a duty to the court to give fair, objective and non-partisan opinion evidence. They must be aware of this duty and able and willing to carry it out. If they do not meet this threshold requirement, their evidence should not be admitted.
This means actual bias, not apprehension of bias:
…The concept of apparent bias is not relevant to the question of whether or not an expert witness will be un- able or unwilling to fulfill its primary duty to the court. When looking at an expert’s interest or relationship with a party, the question is not whether a reasonable observer would think that the expert is not independent. The question is whether the relationship or interest results in the expert being unable or unwilling to carry out his or her primary duty to the court to provide fair, non-partisan and objective assistance. White Burgess at para. 50.
