Ontario Court of Appeal: “Non-Party” Experts Do Not Have to Write Formal Reports to Give Opinion Evidence at Trial

Commentary and Analysis of Westerhof v. Gee, 2015 ONCA 206


In the almost two years since the Divisional Court gave its decision in Westerhof v. Gee (Estate), all experts have been required to strictly comply with the requirements of Rule 53.03, regardless of whether they reached their opinions independent of litigation or whether they were hired by a party for the litigation itself.  All of that changed on March 26, 2015, when the Ontario Court of Appeal reversed the Divisional Court’s decision..

In reaching its decision, the Court of Appeal offered welcome guidance and arrived at a decision that will allow some of the most important expert witnesses to participate in the trial process without undue expense and complication.  In the personal injury context, the decision re-opens the door to treating physicians and other health professionals giving expert evidence based on the opinions they formed in the course of their treatment without having to comply with Rule 53.  The decision will also apply equally to other non-party experts, including investigating police officers, fire marshals, and coroners.

The Decision of the Court of Appeal

In Westerhof v. Gee (Estate) the Court of Appeal recognized three classes of expert witnesses:

  • Litigation Experts, are witnesses who are retained by a party to the proceeding, and who the party intends to call as an expert at trial. Litigation experts must comply with Rule 53.03 before they can give expert evidence at trial.
  • Participant Experts, are witnesses whose evidence is derived from their observations or involvement in the underlying facts. They include treating doctors, police reconstructionists, and fire marshals. Participant experts do not have to comply with Rule 53.03 to give expert evidence at trial.
  • Non-Party Experts, are experts hired by a non-party (such as accident benefits insurers). Non party-experts do not have to comply with Rule 53.03 to give expert evidence at trial.

The Court held that both participant experts and non-party experts 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 observations 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.

If the participant expert or non-party expert wants to give opinion evidence going beyond these limits, the expert must comply with Rule 53.03 for those opinions that extend further.

The Court specifically commented on treating physicians.  It held that a treating physician is permitted to testify about opinions that arise directly from his or her treatment of the plaintiff based on clinical notes and records, without the necessity of having to deliver reports.  This is because, in providing treatment, the doctor is not a stranger to the underlying events, but someone who has formed an opinion based on direct knowledge of underlying facts.

The Court cited the following reasons in support of this decision:

  1. The pre-2010 Rules amendment jurisprudence that supported the conclusion that participant or non-party experts are entitled to give opinion evidence arising from observation or participation in the events for the truth of its contents without complying with the former Rule 53.03.
  2. Nothing in the Osbourne Report (which formed the basis for the amendments to Rule 53.03) indicated an intention to impose controls on participant or non-party experts. Rather, the Osbourne Report was directed toward the “industry” of competing experts and associated increases in costs.
  3. The text of the 2010 amendments supports the view that Rule 53.03 is not intended to apply to participant or non-party experts. For example the language “expert engaged by or on behalf of a party to provide opinion evidence in relation to a proceeding” makes clear that this criterion is a pre-requisite to the application of the rule.
  4. The imposition of Rule 53.03-compliance on participant or non-party experts would exacerbate the problems it purports to alleviate. These witnesses do no prepare reports and give opinion evidence because they are paid a fee.  Instead, they were involved in the underlying events and have already documented their opinions in notes or summaries that do not comply with the rule.  Requiring compliance will only add to the cost of litigation, create the possibility of delay because of the potential difficulty in obtaining Rule 53.03-compliant reports, and add to unnecessarily to the workload of professionals (such as emergency room physicians, surgeons, and family doctors) who do not expect to have this obligation.

Based on this rationale, the Court held that treating physicians can give evidence of the histories they took, of their diagnoses, and their prognoses.

Practical Implications

There are a number of practical implications of the Westerhof decision, beyond the obvious one that plaintiffs may now call their treating health professionals to give expert evidence based on conclusions they reached in the course of providing treatment.  Some of these are summarized below.

Treating Doctor’s Clinical Notes and Records

A doctor’s clinical notes and records often include the records of other physicians and professionals.  If a party wants to introduce these records for the truth of their contents, the party should serve notice under s. 52 of the Evidence Act.  If the doctor gives evidence at trial, the trial judge has discretion to allow or exclude the doctor’s own clinical notes and records.

Diagnostic Imaging

What if a doctor has radiology reports in his file and he relied on those reports in coming to his opinion?  The Court of Appeal’s 1999 decision in Reimer v. Thivierge previously held that such radiology reports were admissible and could be marked as exhibits to assist the jury in assessing the weight to be given to the doctor’s evidence.  They were not admissible for the truth of their contents per se, but are admissible as “having been accepted as true by the doctors.”  In Westerhof, the Court did not go so far and held only that a physician who relies on MRI reports may testify about his diagnosis based on his review of MRI reports.

If a party wants to establish the truth of the contents of a radiology report, the party may call the radiologist who is “effectively a treating physician” without the radiologist having to comply with Rule 53.03.

Insurer Examinations

The Court also specifically considered the ability of insurer examiners to give opinion evidence at trial.  The Court appeared to be more restrictive in the type of evidence it would allow such experts to give without compliance with Rule 53.  In particular, the Court held that insurer examiners could testify about complaints, demonstrated ability to work in FAE testing, ability to return work based no functional abilities testing, and observations.  With respect to causation opinions, the Court held that a trial judge may require insurer examiners to comply with Rule 53.03.  This would depend on the witness’s expertise and the extent to which the opinions were based on sources other than the interaction with the plaintiff.


The Westerhof decision is a welcome one.  In combination with the Court’s recent decision in Moore v. Getahun, It provides much-needed clarity to the area of expert evidence.  More importantly, it recognizes the desirability of making it as inexpensive and as easy as possible for treating health professionals and other “participant experts” to give expert evidence, since these experts already bear the hallmarks of reliable witnesses.  The Court of Appeal correctly recognized that the additional requirements imposed by Rule 53.03 on “hired gun” litigation experts are unnecessary and unduly burdensome when applied to treating experts and other participant experts.  The quality of expert evidence at trial will be greatly improved by the more frequent inclusion of treating experts, whose perspectives are sorely needed.

Alexis Perlman


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