“It is important in qualifying an expert that not only must he or she have the relevant expertise, but the testimony must be relevant and necessary in assisting the trier of fact. Most importantly for present purposes, the opinion evidence must be such as to assist the tier of fact in being “able to keep an open mind and objectively assess the worth of the evidence”: R v Mohan, 1994 CanLII 80 (SCC), [1994] 2 SCR 9. As Cromwell J. put it in White Burgess Langille Inman v. Abbott and Haliburton Co., 2015 SCC 23 (CanLII), [2015] 2 SCR 182, para 2, “Expert witnesses have a special duty to the court to provide fair, objective and non-partisan assistance. A proposed expert witness who is unable or unwilling to comply with this duty is not qualified to give expert opinion evidence and should not be permitted to do so.”
The Court of Appeal has instructed that, “in the governing framework for admissibility, the court should consider an expert’s potential bias when determining whether the expert is properly qualified at the initial threshold: Bruff-Murphy v Gunawardena, 2017 ONCA 502, para 38. Accordingly, the question of independence falls to be considered and decided “at the time the evidence is proffered and the expert witness’s qualification is requested by a party”: Ibid., para 60.”