Participant vs Litigation Experts: Do You Know Who is in Your Corner?

Ontario personal injury lawyers are well-versed in the role of a “litigation expert” – the expert who has signed a Form 53 and complied with all other requirements listed within Rule 53.03 of the Rules of Civil Procedure. The litigation expert’s involvement in the case has arisen solely as result of the litigation and for no other purpose. A litigation expert is typically the specialist you have hired to assess your client, provide a report, and then testify on your client’s behalf at trial. There is typically no pre-existing doctor-patient relationship, however, that does not mean treating physicians cannot act as litigation experts.  

In addition to outlining the timeline for service of litigation expert reports, Rule 53.03 states:

(2.1) A report provided for the purposes of subrule (1) or (2) shall contain the following information:

  1. The expert’s name, address and area of expertise.
  2. The expert’s qualifications and employment and educational experiences in his or her area of expertise.
  3. The instructions provided to the expert in relation to the proceeding.
  4. The nature of the opinion being sought and each issue in the proceeding to which the opinion relates.
  5. The expert’s opinion respecting each issue and, where there is a range of opinions given, a summary of the range and the reasons for the expert’s own opinion within that range.
  6. The expert’s reasons for his or her opinion, including,
    i. a description of the factual assumptions on which the opinion is based,
    ii. a description of any research conducted by the expert that led him or her to form the opinion, and
    iii. a list of every document, if any, relied on by the expert in forming the opinion.
  7. An acknowledgement of expert’s duty (Form 53) signed by the expert. 

In addition to litigation experts, there exists another type of expert in Ontario: the “participant expert” (previously known as the “fact witness”). The role of the participant expert is less commonly known. A participant expert is typically a treating doctor whose evidence is limited to his or her involvement in the patient’s diagnosis, treatment and prognosis. If not for the doctor-patient relationship, the details of the file would not be known to the participant expert. They are involved in your client’s care regardless of the existence of litigation. They have directly participated in the events that have given rise to his or her opinion. 

It is when the lines between participant and litigation expert become blurred that problems can arise for counsel at trial. Lawyers must be careful to ensure the participant expert does not venture into the realm of litigation expert without ensuring the expert’s compliance with Rule 53.03. 

The leading case on this issue is the 2015 Ontario Court of Appeal decision of Westerhof v Gee Estate. In Westerhof, the appellant court offered clarity on the role of participant versus litigation experts and when compliance with Rule 53 is required, noting:  

[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.

Unlike a litigation expert, a participant expert does not create a report and testify only because they were retained to write a report contemplated by Rule 53.03. Rather, their evidence on the matter was generated “because they were involved in underlying events and, generally, have already documented their opinions in notes or summaries that do not comply with rule 53.03.” The appellant court cited emergency room and family doctors as examples of participant experts.

The court was clear that Rule 53.03 does not apply “where the non-party expert has formed a relevant opinion based on personal observations or examinations relating to the subject matter of the litigation for a purpose other than the litigation.” If the expert offers an opinion beyond these parameters, those portions of the opinion must comply with Rule 53.03 or risk being excluded by the trial judge.

Regarding the role of treating doctors in litigation, the decision of Davies v Clarington, 2016 ONSC 1079 offers additional commentary following Westerhof. The court noted that the opinions of some of the plaintiff’s treating doctors fell within the realm of participant expert while some did not. Because the evidence some doctors went “well beyond the normal role of a treating doctor in terms of history, treatment, and prognosis”, compliance with Rule 53.03 was required.

The issue was revisited by the Ontario Court of Appeal several years after Westerhof in the 2018 decision of Imeson v. Maryvale.

At trial, the appellant Maryvale was found vicariously liable for sexual assaults suffered by the respondent, Imeson. The respondent’s central witness was his treating mental health clinician, Dr. Smith. Dr. Smith created reports based upon his handwritten notes taken during his treatment of the respondent. The reports were not a verbatim repetition of his notes. They also included comments, opinions, and thematic connections that weren’t contained in his original notes.  All but one report was created over a year after the respondent ceased treatment with Dr. Smith.

The trial judge permitted the entirety of Dr. Smith’s reports to be entered into evidence and allowed Dr. Smith to testify as to the contents of the reports. The reports were admitted under section 35 of the Evidence Act and without compliance with Rule 53.03.

Maryvale appealed the decision, arguing that the trial judge erred by permitting Dr. Smith’s reports to be accepted into evidence in their entirety without compliance with Rule 53.03. The Court of Appeal upheld the appeal, finding that Dr. Smith’s role as participant expert had become “blurred” since he had ventured outside the scope of a participant expert by including things in his report that weren’t present in his original notes:

As Westerhof instructs, an opinion offered by a participant expert must be given as part of the ordinary exercise of the witness’s skill, knowledge, training and experience. Here, any opinion offered by Dr. Smith that sought to draw a causal link between the alleged sexual assaults and Mr. Imeson’s later behaviour could not have been based on his skill, knowledge, training and experience while he was involved in Mr. Imeson’s treatment. Rather, Dr. Smith testified that, in his therapeutic role, he accepted Mr. Imeson’s statements that he had been abused as true, and he confirmed that it was not his role to determine if the trauma happened, but only to trust what he was being told.

Westerhof also instructs that the opinion given by a participant expert must be based on the witness’s observation of or participation in the events at issue. Here, Dr. Smith testified as to the problems typical of survivors of childhood sexual abuse — evidence going to the issue of whether the assaults occurred. His evidence about survivors as a group was not based on his observation of, or treatment of, Mr. Imeson, and thus went beyond the proper scope of any opinion he could provide as a participant expert.

The Court of Appeal stated that as a participant expert, Dr. Smith should not have provided an opinion as to how the sexual assaults occurred and whether the respondent suffered harm as a result of said assaults. In essence, the Court of Appeal found that Dr. Smith was precluded from testifying as to causation and liability in the matter. The case was sent back down for a re-trial.

Imeson serves as a warning to Counsel to always be aware of the distinction between participant and litigation expert. Westerhof, followed by Imeson, has changed the landscape surrounding the classification of experts. A participant expert is only able to provide an opinion at trial if that opinion is based off of the expert’s direct experience in an event. If Counsel seeks to have an expert provide an opinion based on information that has only come to the expert’s knowledge as a result of litigation, then Counsel must ensure that the expert fully complies with Rule 53.03 or risk having all or part of the expert’s evidence excluded at trial. 

Written by

Heather Colman is an associate lawyer at Greg Monforton and Partners in Windsor, Ontario practicing exclusively in plaintiff-side personal injury litigation. She has a B.A. (Honours) and J.D. from the University of Windsor and is a member of the Ontario Trial Lawyers Association.