Court of Appeal Clarifies the Difference Between Litigation and Participant Experts

26 November 2018

By Uri Snir

The Ontario Court of Appeal has further clarified the distinction between litigation expert witnesses and participant expert witnesses. The distinction is crucial in determining what type of evidence is admissible at trial.  

In this recent decision, the Court held that much of the expert evidence given at trial should have been inadmissible. It allowed the appeal and ordered a new trial in the underlying sexual assault action.

Background: At trial, the jury found in favour of the plaintiff, Jesse Imeson, in his claim for sexual assault against Maryvale Adolescent and Family Services (“Maryvale”) and its former employee. The plaintiff spent several months at the residential institution devoted to the care and education of troubled youth. Many years later, Imeson was convicted of three counts of second degree murder. While serving his sentence for those crimes, Imeson alleged that he had been sexually assaulted by an employee at Maryvale.

Participant Experts Versus Litigation Experts

One of the key witnesses at trial, Dr. Kerry Smith, a mental health clinician who treated Imeson in prison, gave evidence at trial as a participant expert. A participant expert (formerly referred to as a fact witness) is a witness who has not been engaged by or on behalf of a party to the litigation to provide an expert opinion.

As a participant expert, Dr. Smith was exempt from the requirements that apply to litigation experts under Rule 53.03 of Ontario’s Rules of Civil Procedure. Specifically, litigation experts are required to provide evidence through an expert’s report, which must contain specific listed information and be served on every party prior to trial. That expert report provides a framework for the proper scope of the expert’s testimony at trial.

In Westerhof v. Gee Estate1, the Court of Appeal previously set out the test for participant experts to give opinion evidence without complying with Rule 53.03. In that case, the Court stated:

[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.2

Dr. Smith provided therapy to Imeson from June 26, 2012 to April 13, 2015. During these sessions, Dr. Smith took handwritten notes, which he later summarized and compiled into “reports”. The original handwritten notes were destroyed.

The Trial Judge’s Ruling: The trial judge accepted Dr. Smith as a participant expert whose evidence was admissible without compliance with Rule 53.03. The judge also permitted Dr. Smith’s reports to be filed in their entirety.

Prior to Dr. Smith giving his evidence at trial, the judge instructed the jury that Dr. Smith’s evidence was admissible to provide certain opinions, and that any statements made to Dr. Smith during therapy were not to be taken as proof that the statements were true, but only that they were made. She also directed that the jury be provided with copies of Dr. Smith’s reports, which were marked as a trial exhibit.

During his examination-in-chief, Dr. Smith gave opinion evidence that went to the issue of whether the sexual assaults occurred and whether Imeson suffered harm from the assaults.

In her instructions to the jury at the end of trial, the judge identified the main issue as “whether any of the sexual assaults alleged took place” and listed all the evidence that the jury should consider, including “the observations and opinion expressed by Dr. Smith.”

The jury found in favour of the plaintiff.

The Appeal: On appeal, the Court held that Dr. Smith, as a participant expert witness, ought not to have been permitted to provide opinion evidence that went to the issues of whether the sexual assaults occurred (liability) and whether Imeson suffered harm that was caused by such assaults (causation).  

The Court relied on the test from Westerhof: the opinion offered by a participant expert must be given as part of the ordinary exercise of the witness’ skill, knowledge, training, and experience. Westerhof also instructs that the opinion given by a participant expert must be based on the witness’ observation of or participation in the events at issue.

The Court found Dr. Smith’s testimony exceeded the scope of proper opinions to be offered by a participant witness. The trial judge improperly admitted Dr. Smith’s unredacted reports into evidence and permitted him to testify about anything contained in those reports.

Although the trial judge ruled that Dr. Smith would only be able to testify about “his observations of, impressions formed regarding and treatment provided to the plaintiff as set out in the reports prepared by him”, she permitted him to testify about anything that was contained in those reports.

The Court concluded that despite the trial judge’s recognition that the role of a participant expert is restricted, she permitted Dr. Smith to exceed his proper role.

The Court found that the evidence given by Dr. Smith went beyond that of a participant expert and ordered a new trial.

The Takeaway: The decision highlights the important distinction between the evidence of fact-witness experts who participated in the events in question, and litigation experts brought in after the fact by counsel. The latter must prepare an expert’s report in accordance with Rule 53.03, which allows the expert to opine on events that go beyond their participation in an event. The former may only give opinion evidence based on their direct experience and participation in an event. 


2 Ibid at para 60.

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