“Based on my review of the caselaw, I conclude that principles including the following must guide this court’s determination of whether an individual may be qualified as a “participant expert” in a family law proceeding:
Under Rule 20.2
a. A witness with special skill, knowledge, training, or experience who has not been engaged by or on behalf of a party to the litigation may give opinion evidence without complying with the requirements of Rule 20.2 where the opinion is given based on the witness’s observation or on 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 (Westerhof v Gee Estate, 2015 ONCA 206 at 60; Imeson v. Maryvale(Maryvale Adolescent and Family Services), 2018 ONCA 888 [“Imeson”] at 62; Hoang v Vicentini, 2016 ONCA 723 at 28; and Girao v. Cunningham, 2020 ONCA 260 [“Girao”] at 41.
b. A party does not “engage” an expert to provide opinion evidence simply by calling the expert to testify about an opinion he or she has already formed. Westerhofat 83. The question is not on which party’s behalf the witness testifies, but whether the opinion was formed for the purpose of litigation. Attorney General (Ontario) v 855 Darby Road, Welland, et al, 2017 ONSC 4953 at 29.
c. Participant experts do not testify because they are being paid a fee to provide an expert’s report as contemplated by Rule 20.2. Rather, they testify because they were involved in underlying events and have generally documented their opinions in notes or summaries made at or about the time of their involvement.
d. As a corollary, the opinionof a participant expert is not formed for the purpose of the litigation. The opinion is formed in the ordinary exercise of the professional’s duties.
e. There is a distinction between “treatment opinions”, which involve making a diagnosis, formulating a treatment plan and making a prognosis, and opinions for the purpose of assisting the court at trial, and “litigation opinions”, which are based on consideration of information from a variety of sources for the purpose of assisting the court at trial. Westerhof, at 72.
f. Where participant experts are permitted to testify, typically the opinions sought to be introduced are found in the clinician’s notes and records or in reports prepared for the purpose of consultation. Imeson, at 61. This does not mean that the proposed participant expert may testify about anythingin his or her reports. Imeson at 75. Particular caution must be exercised regarding opinion evidence going to the question of causation. Imeson at 90, 100; Westerhof at 115.
g. While there is no longer a general rule barring opinion evidence on the “ultimate issue”, the court must apply the criteria of necessity and cost-benefit in relation to evidence dealing with the ultimate issue. Hoangat 62.
h. Once admitted, the scope of the evidence of a participant expert is limited to his or her observation of or participation in the subject matter in issue in the litigation, and his or her roles and involvement. He or she may also testify to the opinions that went to the exercise of his or her judgment. This is because the opinions are formed while participating in events and as part of the ordinary exercise of expertise. Roher v The Queen, 2017 TCC 55 at 33 and 42 citing Westerhofat 67-70. See also Davies v The Corporation of the Municipality of Clarington, 2016 ONSC 1079 at 36 and 37.
i. Because a participant expert’s opinion is restricted to his or her “observation of or participation in the events at issue”, broader evidence about others “as a group”, will go beyond the scope of the permissible evidence, as it is not based on that observation of participation in or treatment of the individual(s) in question (Imeson, at 74). In Imeson, for example, the mental health clinician was found to have strayed outside the permissible scope as a participant expert he testified as to the “problems typical of survivors of childhood sexual abuse” as opposed to about Mr. Imeson, specifically. See para. 74. In that event, a participant expert’s exemption from the requirements of Rule 20.2(2) is lost. The court must take great care to ensure that opinion evidence exceeding that scope is not elicited by counsel or accepted by the court (Imeson 7,at 58);
j. The evidence of treating physicians, pediatricians, and therapists is often found to be admissible as participant expertise. See for example: CCAS of Toronto v. T.T.L. and S.S., 2019 ONCJ 530 at 285, 286 (mother’s psychotherapist permitted to testify as participant expert, as to observations, mother’s diagnosis, prognosis, mother’s mental health and ability to parent); J.K.L.D. v. W.J.A. 2020 ONCJ 335 at 91(report of mother’s physician admitted as that of a participant expert); CAS of Toronto v S.M.T., 2018 ONCJ 540 (children’s pediatrician found to be a participant expert, not being a “puppet” or hired gun of the Society.” See para 91). See also Marchand v. The Public General Hospital Society of Chatham(2000), 2000 CanLII 16946 (ON CA), 51 O.R. (3d) 97 as quoted in Westerhof). Such evidence is often admitted without challenge “because these witnesses are essentially ‘witnesses of fact’ to the extent that they testify to the facts of their involvement, as well as ‘opinions that went into the exercise of their judgment’.” Roher at 29, 30.
k. It is notthe case that any physician or therapist retained or engaged by a children’s aid Society can be qualified only as a litigation expert. Where the evidence of such proffered witnesses is relevant and reliable and within his or her expertise, and where the individual was not retained for the purpose of litigation but rather to provide treatment or services to the child (or, I would add, to a parent), that person may be qualified as a participant expert. See Jewish Child and Family Service v K.S., 2015 ONCJ 246 at 154, 155. That parents participate in assessments provided by Society-retained physicians or psychologists to provide background information may also be relevant (see para 157).
Gatekeeping under White Burgess
l. The court retains its gatekeeper function in relation to opinion evidence of participant experts. Therefore, even where a person meets the definition of a participant expert under the Family Law Rules, the court could exclude all or part of the opinion of a participant expert or rule that all or part of such evidence is not admissible. (Westerhof, at 64)
m. White Burgess Langille Inman v Abbott and Haliburton Co,2015 SCC 23 [“White Burgess”] establishes a two-part framework for the admissibility of expert evidence. That framework applies both in the context of litigation experts as well as participant experts. See Westerhof (para 64), Imeson at 64; Hoang at 31; Girao at 39.
n. In summary, the White Burgessframework can be set out as follows:
i. First Stage, Determination of threshold admissibility: a consideration of whether the evidence is:
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- Logically relevant
- Necessary to assist the trier of fact
- Not subject to any other exclusionary rule
- The expert must be properly qualified, including the requirement that he or she be willing and able to provide evidence that is impartial, independent, and unbiased;
- In the case of novel or contested science, the underlying science must be reliable.
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ii. Second Stage: The judge balances the potential risks and benefits of admitting the evidence in order to decide whether the potential benefits justify the risks. At this stage the judge considers:
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- Legal relevance
- Necessity
- Reliability
- Absence of bias
- Consumption of time and cost.
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See White Burgess at 24.
o. “Properly qualified” in the context of a proposed participant expert, does notrequire the execution of a certificate of expert’s duty as would be required of a litigation expert. Westerhof at 81.
p. In considering whether there is an absence of bias, the issue is the nature and extent of the proposed expert’s connection with the litigation. The question is whether the relationship results in the expert being unable or unwilling to carry out his or her primary duty to the court to provide fair, non-partisan, objective assistance. White Burgess at 48, 50.
q. It will be “quite rare” for the court to exclude evidence at the first stage of White Burgessdue to lack of impartiality based on professional relationship between the proposed expert and the party. Anything less than clear unwillingness or inability to provide the court with fair, objective, and non-partisan evidence should not lead to its exclusion but would instead go to weight. White Burgess at 49.
r. The court’s role as a gatekeeper does not end with granting permission to the proposed expert to testify. The gatekeeping role continues throughout the testimony of the proffered expert, and the court must be vigilant at all times to consider the importance of guarding against the dangers of inappropriate opinion evidence.”
Children’s Aid Society of the Niagara Region, 2021 ONSC 8582 (CanLII) at 26