“In White Burgess Langille Inman v. Abbot v. Haliburton Co, 2015 SCC 23 [“White Burgess”], Cromwell J opened the judgment as follows:
Expert evidence can be a key element in the search for the truth, but it may also pose special dangers. To guard against them, the Court over the last 20 years or so has progressively tightened the rules of admissibility and enhanced the trial judge’s gatekeeping role. These developments seek to ensure that expert opinion evidence meets certain basic standards before it is admitted. See para 1.
In the child protection context, and in particular in a case such as this where the Society seeks to permanently sever the legal relationship between the children and their parents while severely restricting contact, the dangers associated with admitting potentially unreliable experts are perhaps at their highest. As noted in the Report of the Motherisk Commission, losing one’s child to an Order for extended Society care is the “capital punishment of child protection law.” Thus, the import of rigorously scrutinizing proposed expert evidence can hardly be overstated.
Under the Ontario Family Law Rules, three types of experts are contemplated: joint litigation experts, litigation experts, and participant experts. Only the latter two designations are relevant on this voir dire.
A “litigation expert” is defined in Rule 20.2 as “a person engaged for the purpose of litigation to provide expert opinion evidence.”
A “participant expert” means a person who is not engaged to provide expert opinion evidence for the purposes of litigation, but who provides expert opinion evidence based on the exercise of his or her skills, knowledge, training or experience while observing or participating in the events at issue.
Where a party seeks to call a litigation expert as a witness at trial, that party must serve an expert report at least 6 days before the settlement conference, which report must include an acknowledgement of expert’s duty (Form 20.2) signed by the expert. Other requirements include that the proposed expert must include in the report any instructions provided to him or her in relation to the case, and the expert’s reasons for his or her opinion. See the recent decision of Smith J. in Aldush v. Alani, 2021 ONSC 6410, setting out the applicable test and analysis in the case of a litigation expert.
By contrast, where a party seeks to call a “participant expert” as witness at trial, the acknowledgement of expert’s duty is not required, nor are the documents or information set out in Rule 20.2(2). The party must simply serve notice of the intent to call that proposed witness at least six days before the settlement conference, serve any written opinion of that proposed expert upon which the party intends to rely, and serve, at the other party’s request, a copy of any supporting opinion evidence the participant expert intends to provide.
Having reviewed the caselaw regarding expert evidence, it appears that in many of the reported family law cases where a participant expert is permitted to testify, it has been on consent, unopposed, or with brief consideration of the applicable principles. It seems to be generally accepted in the Ontario caselaw that in most cases, professionals such as treating physicians, treating psychologists, and treating pediatricians may testify as participant experts so long as they stay within a relatively narrow scope, that deriving directly from their involvement and the professional opinions arrived at based directly on that involvement. The court’s ongoing vigilance and gatekeeping is essential regarding the scope of testimony. Bruff-Murphy v. Gunawardena, 2017 ONCA 502; Parliament v. Conley, 2021 ONCA 261.”
Children’s Aid Society of the Niagara Region, 2021 ONSC 8582 (CanLII) at 17-24
