Ongoing Uncertainties With Participant Experts

Over three years have passed since the release of the Ontario Court of Appeal's decision in Westerhof v. Gee Estate1, wherein the Court definitively outlined the role of "participant experts".

In short, the Court noted that participant experts, with special skill, knowledge, training, or experience, who have not been engaged by or on behalf of a party, may give opinion evidence for the truth of its contents, without compliance with Rule 53.03, where the following conditions are met:

the opinion to be given is based on the witness' observation of or participation in the events at issue; and, the witness formed the opinion to be given as part of the ordinary exercise of his or her skill, knowledge, training and experience while observing or participating in such events. Despite the passage of time, there does not appear to have been much consideration of the role of participant experts within the framework for the admissibility of expert evidence in general, as outlined most recently by the Supreme Court of Canada in White Burgess Langille Inman v. Abbott and Haliburton Co.2 and subsequently articulated by the Ontario Court of Appeal in R. v. Abbey3.

Admissibility of Expert Evidence

The White Burgess framework sets out threshold criteria for the admissibility of expert evidence, all of which are to be met before the trial judge exercises his or her gatekeeping function in determining whether the benefits of admitting the evidence outweigh the costs of admission.

Arguably, the threshold criteria of logical relevance, necessity, and the absence of the application of an exclusionary rule require no particularly special consideration in the context of participant experts, versus litigation experts subject to Rule 53.03.

However, the same cannot be said of the threshold criterion of proper qualification, which, according to White Burgess and Abbey, requires that the expert be "willing and able to fulfil the expert's duty to the court to provide evidence that is: (i) [i]mpartial, (ii) [i]ndependent, and (iii) [u]nbiased."

The importance of this criterion cannot be overstated. Indeed, considerations of impartiality, independence and bias arise both at the threshold stage and in the gatekeeping stage of the framework.

Moreover, the Supreme Court in White Burgess held that an expert's lack of impartiality and independence and an expert's bias go both to admissibility of the evidence, as well as to the weight it ought to be given if admitted.4

Duty of...