Canada: Clarity On Participant Experts - Imeson v. Maryvale

Last Updated: December 21 2018
Article by Stephen G. Ross and Meryl Rodrigues

By Stephen Ross and Meryl Rodrigues1

Since the release of the Ontario Court of Appeal's decision in Westerhof v. Gee Estate2, there had been little judicial consideration of the role of participant experts within the framework for the admissibility of expert evidence generally.

This framework, outlined most recently by the Supreme Court of Canada in White Burgess Langille Inman v. Abbott and Haliburton Co.3 and by the Ontario Court of Appeal in R. v. Abbey4, sets out threshold criteria for the admissibility of expert evidence, which is to be met before the trial judge then exercises his or her gatekeeping function in determining whether the benefits of admitting the evidence outweigh the costs of admission.

The Ontario Court of Appeal has now provided some helpful guidance on this issue with the release of its decision in Imeson v. Maryvale5.


Imeson is a case involving liability and damages for alleged childhood sexual abuse.

At trial, Maryvale, an institution devoted to care and education of troubled youth, was found vicariously liable for sexual assaults alleged to have been committed against the plaintiff, Jesse Imeson, a convicted murderer, by its former employee, Tony "Doe".

Although the plaintiff testified that he was also sexually abused by Father Horwath, a Roman Catholic priest who was deceased by the time of trial, the jury did not accept that claim, and the action as against The Roman Catholic Episcopal Corporation for the Archdiocese of London and Father Horwath was dismissed.

At trial, the judge permitted the plaintiff's treating psychologist, Dr. Smith, to testify as a participant expert, and to proffer opinions formed as part of the ordinary exercise of his skill, knowledge, training and experience while observing or participating in the events at issue.

Dr. Smith's involvement with the plaintiff was reduced to writing, including the formation of "reports". Importantly, the reports were not a verbatim record of Dr. Smith's handwritten notes taken during his sessions with the plaintiff. They were prepared about a year after the conclusion of therapy, at the plaintiff's request.

The reports contained a number of comments and opinions, including recommendations for future treatment, and thematic connections that were not in the handwritten notes, which were themselves destroyed after the preparation of the reports.

The decision summarizes the events of the voir dire at trial, including defence counsel's objections to the evidence and the trial judge's subsequent oral and written rulings permitting Dr. Smith to testify as a participant expert as to "his observations of, impressions formed regarding and treatment provided to the plaintiff" as set out in his reports, and as to the therapy he would have recommended had the plaintiff not terminated therapy, and permitting Dr. Smith's reports to be filed in their entirety.

Justice van Rensburg, writing for the Court, highlights three opinions elicited by Dr. Smith at trial: (1) problems typical of survivors of sexual abuse; (2) negative impacts of the plaintiff's childhood abandonment and abuse on his emotional responses and relationships; and (3) the possibility that the plaintiff's index offence (the first murder of three) in the course of a sexual act arose from a re-experiencing of the sense of betrayal and rage towards his earlier abuser (i.e. at Maryvale).

Dr. Smith's admission that his role was not to determine if the abuse happened and his acceptance as truth of what the plaintiff told him is noted.

Finally, Justice van Rensburg notes the trial judge's hearsay caution to the jury regarding the plaintiff's statements made to Dr. Smith. She also highlights a key and concerning feature of the jury charge, namely the trial judge directing the jury to consider Dr. Smith's evidence on the issue of liability, in determining whether any of the alleged sexual assaults took place, over defence counsel's objection.

She also notes that, following a transgression by plaintiff's counsel of the trial judge's ruling regarding the manner and nature of the questioning of Dr. Smith, the trial judge asked the defendants if they were seeking a mistrial, which was declined.


The Court's analysis on the appeal is two-pronged. First, the Court assesses whether Dr. Smith's evidence was properly tendered as participant expert evidence. Second, the Court assesses whether Dr. Smith's evidence ought to have been admitted pursuant to the Mohan/White Burgess framework for the admissibility of expert evidence.

Westerhoff Analysis

The Court concludes that the trial judge erred in allowing Dr. Smith to exceed his proper role by permitting him to testify about anything contained in his reports and admitting the reports into evidence, without first carefully examining what opinions were included in the reports and the purpose for which the jury was to consider those opinions.

The Court endorses the proper role of a participant expert, as outlined in Westerhoff v. Gee Estate, as follows:

[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 for the truth of its contents without complying with rule 53.03 where:

  • the opinion to be given is based on the witness's 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.

The Court notes that where participant experts exceed the above-noted bounds, compliance with Rule 53.03 is necessary "with respect to the portion of their opinions extending beyond those limits".

The Court confirms that the trial judge was well familiar with the permissible scope of participant expert testimony as outlined above from Westerhoff.

However, while the trial judge focused on ensuring that Dr. Smith did not offer opinions beyond what was contained in his reports, the Court notes the trial judge's error in failing to consider the specific opinions within those reports and whether any of those opinions exceeded the scope of proper opinions to be offered by a participant expert.

In this regard, the Court states that Dr. Smith's role was "blurred" in the circumstances of this case, considering the completion of most of the reports about a year after the plaintiff discontinued treatment and the formation of thematic connections at that time, when Dr. Smith was aware that the plaintiff had commenced litigation.

The Court points out difficulty in imagining why the plaintiff would have requested the reports aside from for purposes of the litigation.

The Court concludes that Dr. Smith's opinion evidence included evidence falling outside the proper scope of evidence to be tendered by a participant expert, failing both prongs of the tests outlined in Westerhoff in that regard.

First, any opinion where Dr. Smith sought to draw a causal connection between the alleged sexual abuse and the plaintiff's later behaviour could not have been based on Dr. Smith's skills, knowledge, training and experience while involved in the plaintiff's treatment, given Dr. Smith having simply accepted the allegations of abuse as true.

Second, Dr. Smith's opinions regarding problems typical of survivors of sexual abuse, which went to the issue of whether the abuse occurred, was not based on his observation or participation in the plaintiff's treatment.

In short, Dr. Smith's opinions regarding liability and causation were not opinions that he could provide in his capacity as a participant expert, as such opinions were not based on his skills or observations while involved in the plaintiff's treatment.

Mohan/White Burgess Analysis

Although not necessary given the disposition on the first issue, the Court goes on to consider the trial judge's admissibility analysis with respect to admitting Dr. Smith's opinions on the issues of liability and causation under the Mohan/White Burgess framework.

At the first stage of the framework, the court is to assess whether the proposed expert evidence meets the threshold criteria for admissibility, namely: (i) logical relevance; (ii) necessity to assist the trier of fact; (iii) not subject to any other exclusionary rule; and (iv) a properly qualified expert willing and able to provide impartial, independent and unbiased evidence.

At the second and gatekeeping stage of the framework, the trial judge is to determine whether potential benefits of admission outweigh the potential risks to the trial process.

The Court indicates that the trial judge correctly concluded that participant experts are subject to the Mohan/White Burgess framework. However, the Court concludes that the trial judge erred in applying the framework, as on its proper application (keeping in mind the particular opinions and their intended use), Dr. Smith's opinion evidence on the issues of liability and causation should have been excluded.

In this regard, the Court points out that Dr. Smith's evidence was not necessary to the central liability question of whether the sexual abuse occurred, which was an issue dependent on an assessment of credibility. The jury did not need expert evidence to assess the plaintiff's credibility and, further, Dr. Smith's evidence as to whether the assaults occurred was based on an acceptance of the plaintiff's allegations as truth and not on any expertise.

The Court further indicates that Dr. Smith lacked the requisite qualifications to give opinion evidence as to the problems typical of sexual abuse survivors or as to the relationship between the alleged abuse and the plaintiff's subsequent difficulties. Although he had some experience treating inmates who had suffered from childhood sexual abuse, that did not make him an expert in the field.

The Court disregards further analysis of the threshold admissibility criteria (i.e. impartiality, etc.) given the findings on necessity and expertise.

The Court goes on to consider the second stage of the Mohan/White Burgess framework, and concludes that the admission of Dr. Smith's opinions carried a number of risks to the trial process.

First, there was the risk that his evidence would usurp the jury's function in assessing credibility.

Second, Dr. Smith's unedited and unredacted reports contained irrelevant material of significant oath-helping potential. The Court acknowledged that the trial judge turned her mind to the oath-helping concerns and sought to address them by way of her mid-trial instruction. However, the Court concludes that the instruction was insufficient in the circumstances of the case.


In sum, the Court of Appeal outlines the trial judge's errors as follows:

  • The trial judge erred in finding that Dr. Smith's opinions going to the issues of liability and causation were properly within the scope of opinions that could be elicited from him as participant expert. Those opinions did not meet the requirements outlined in Westerhoff.
  • Even if those opinions were within the scope of proper opinions to be offered by a participant expert, the trial judge erred in admitting them into evidence as they failed to meet the threshold criteria of necessity and proper qualification for the admission of expert evidence under the Mohan/White Burgess framework, and should not have passed the gatekeeping analysis (relevance vs. prejudice) given the risk of the admission to the trial process.

The Court concludes that the error of admission of Dr. Smith's evidence on the issues of liability and causation was sufficient to warrant a new trial.

The decision helpfully confirms that participant experts are subject to the Mohan/White Burgess framework for the admissibility of expert evidence, and are not held to a different admissibility standard.

Additionally, the Court quite firmly indicates that the analysis under Westerhoff and Mohan/White Burgess ought to be applied to the specific opinions sought to be elicited from experts, in consideration of their intended use – as opposed to applying the analyses to an expert as a whole.

In short, an important consideration as it relates to participant expert and, indeed, all expert evidence is the specific opinion(s) sought to be introduced and the purpose for which they are being tendered (i.e. liability, damages, causation, etc.).

Each opinion and its purpose must meet the relevant and applicable framework for the admissibility of expert evidence to be properly tendered into evidence at trial.

Maryvale offers necessary guidance on the scope and limits of participant experts and provides a useful refresher and broader context to the admissibility of expert opinion evidence generally.


[1] Mr. Ross and Ms. Rodrigues were counsel for the Appellant on appeal.

[2] 2015 ONCA 206.

[3] 2015 SCC 23.

[4] 2017 ONCA 640.

[5] 2018 ONCA 888.

The content of this article is intended to provide a general guide to the subject matter. Specialist advice should be sought about your specific circumstances.

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