As is often the case in civil litigation proceedings, estate and trust litigation relies on expert evidence. This blog will lay out the general legal framework when it comes to engaging an expert and admitting expert evidence at trial.
As an overview, case law collectively establishes that:
- Expert evidence must be independent, necessary, and properly confined in scope.
- Counsel may properly interact with experts but must not compromise their independence.
- Trial judges play a robust gatekeeping role at both the admissibility and ultimate weight stages.
Lawyer–Expert Communications
In Moore v. Getahun, the Ontario Court of Appeal set the modern standard for how lawyers and experts may interact.
- Permitted draft review: The Court unanimously held that counsel may review and discuss draft expert reports with experts.
- No automatic disclosure: The Court rejected any blanket rule requiring disclosure of draft reports or all communications between counsel and experts.
- Qualified disclosure obligation: However, disclosure may be ordered where there is a factual foundation suggesting that counsel improperly influenced the expert’s opinion or interfered with the expert’s independence.
- Ethical safeguards: The Court emphasized that professional ethics, the expert’s duty of independence, and the adversarial process (including cross-examination) provide sufficient protection against improper influence.
Participant vs. Litigation Experts
In Westerhof v. Gee Estate, the Ontario Court of Appeal clarified which witnesses must comply with the formal reporting requirements under Rule 53.03 of the Ontario Rules of Civil Procedure.
- Experts retained for the purpose of litigation (“litigation experts”) must comply with Rule 53.03, including delivering a formal report acknowledging their duty to the court.
- Participant experts (or “fact witnesses”), such as treating physicians and other professionals who were directly involved in the events at issue, may give opinion evidence without complying with Rule 53.03, provided:
- Their opinions are based on first-hand observation or participation in the underlying events; and
- The opinions were formed in the ordinary course of their professional duties.
- The Court also recognized a third category of experts who were not directly involved but form opinions from reviewing records – non-party (or “hybrid”) experts. Their obligations may fall between the two categories depending on the circumstances.
- Even where Rule 53.03 does not apply, all expert evidence must still satisfy the admissibility requirements set out in R. v. Mohan (discussed below) and the expert’s duty of independence and impartiality.
Admissibility of Expert Evidence
- v. Mohan is a landmark Supreme Court of Canada (SCC) decision establishing the core framework for admitting expert evidence. The Court articulated a four-part test:
- Relevance: The evidence must be logically relevant to a material issue.
- Necessity: The evidence must be necessary to assist the trier of fact on matters beyond ordinary experience.
- Absence of an exclusionary rule: The evidence must not be barred by another evidentiary rule (e.g., character or hearsay rules).
- Properly qualified expert: The witness must be appropriately qualified through education, training, or experience.
The case involved a pediatrician charged with sexual assault who sought to introduce psychiatric “profile” evidence suggesting the perpetrator belonged to a group that did not fit the accused. The SCC upheld the exclusion of this evidence as insufficiently reliable and unnecessary.
Evolution of the Mohan Framework
Subsequent SCC jurisprudence, particularly White Burgess Langille Inman v. Abbott and Haliburton Co., has refined the admissibility analysis:
- As expert must be independent and impartial. An expert must be willing and able to fulfill their duty to provide fair, objective, and non-partisan evidence. A failure to meet this threshold may render the evidence inadmissible.
- Two-stage analysis:
- Threshold admissibility based on the Mohan factors (discussed above).
- The trial judge maintains a residual discretion to exclude the evidence even if meets the Mohan factors. The trial judge must weigh the potential benefits of the evidence against its risks (e.g., prejudice, confusion, or misuse).
Evidentiary Reliability and Scope
In Pederson v. Forget, the Ontario Court of Appeal reaffirmed limits on the scope and admissibility of expert evidence.
- Admissibility is issue specific. A witness’s general qualification as an expert does not make all aspects of their proposed testimony admissible. As such, each opinion must independently meet admissibility requirements.
- Experts must not usurp the role of the trier of fact/trial judge i.e. there are limits on expert opinion.
- Experts cannot assess or opine on the credibility of other witnesses.
Conclusion
Expert evidence can be complicated and the Court’s gatekeeping function should not be underestimated. Careful consideration and thought are required when it comes to engaging an expert and ensuring that expert evidence is admitted at trial.
