Written by Caroline Swiderski
Reviewed by Linette King
Introduction
In Pederson v Forget,[1] the Court of Appeal for Ontario upheld a trial judge’s decision to exclude expert evidence he found to be unreliable. In doing so, the Court reaffirmed the importance of the trial judge’s role as a gatekeeper and the deference that it attracts.
Factual Background
On March 25, 2015, Janet Pederson, an insurance adjuster, attended at the home of Michel and Annie Forget to obtain a statement. Upon entering the home, Ms. Pederson removed her shoes and ascended a wooden staircase. Ms. Pederson secured the statement and returned to the staircase to leave. However, Ms. Pederson fell down the stairs, landing on her back.[2]
Ms. Pederson brought an action in negligence against the Forgets alleging that the condition of their staircase breached the Occupiers Liability Act.[3]
The Ontario Superior Court of Justice
The cause of Ms. Pederson’s fall was a major point of contention at trial. Ms. Pederson testified that the top stair felt like a piece of ice causing her foot to slip and her to fall down the stairs. She further asserted that she had been told by the Forgets that their cleaning lady had applied Pledge to the stairs the day before her fall. However, the Forgets denied employing a cleaning lady. According to them, Ms. Forget had cleaned the stairs using Vim two days prior to Ms. Pederson’s fall.[4]
Both parties retained expert engineers to test the stairs’ slip resistance following the application of various cleaning products. Ms. Pederson called Gord Jenish as her expert witness, which the Forgets opposed.[5]
After a two day voir dire, the trial judge determined that Mr. Jenish had the necessary expertise to qualify as an expert and, contrary to the Forgets’ assertions, was not biased in favour of Ms. Pederson.[6]
Turning to Mr. Jenish’s evidence, the trial judge found that it met the threshold requirements for admissibility under White Burgess Langille Inman v Abbott and Haliburton Co.[7]
However, the judge excluded the first of Mr. Jenish’s four expert reports as its underlying testing methodology differed from the trial evidence in several critical aspects, rendering it unreliable. The trial judge specifically noted that, in preparing his first report, Mr. Jenish had:
- tested the landing and not the stairs,
- used a different Vim dilution from that used by Ms. Forget,
- waited only 30 minutes before retesting when Ms. Forget testified that the stairs had been cleaned 2 days prior to the fall, and
- failed to conduct the test using a nylon stocking or ladies’ dress sock, which has been what Ms. Pederson was wearing at the time of her fall.[8]
Ultimately, the jury returned a verdict in favour of the Forgets. The action was dismissed and Ms. Pederson appealed.[9]
Issues on Appeal
Ms. Pederson raised the following two issues on appeal:
- whether the trial judge erred in excluding Mr. Jenish’s first report; and
- if so, whether this exclusion resulted in a miscarriage of justice requiring a new trial.[10]
Analysis
(1) The trial judge did not err in excluding the first expert report
The Court of Appeal held that the trial judge did not err in excluding the first report.[11] Rather, the judge correctly applied the two-part test from White Burgess wherein the Supreme Court of Canada held that expert evidence must, first, meet the following threshold requirements of admissibility: relevance, necessity, the absence of an exclusionary rule, and a properly qualified expert. If the evidence satisfies these requirement, then the judge must act as a gatekeeper, balancing the risks and benefits of allowing this evidence to be heard.[12]
Here, the trial judge’s decision to exclude a portion of Mr. Jenish’s evidence fell squarely within his role as a gatekeeper. Given the well-known dangers of expert evidence, judges must ensure that experts testify within the confines of their qualifications, what is contained in their reports, and what is the subject of their expert opinions. A judge must remain vigilant during the course of an expert’s testimony so as to prevent any advocacy.[13] The trial judge in Pederson was entitled to determine that the risk of admitting unreliable evidence outweighed its benefit and, thus, was owed deference.
(2) The exclusion of the first expert report did not result in a miscarriage of justice
Alternatively, the Court of Appeal held that, had the trial judge erred in excluding Mr. Jenish’s first expert report, his decision did not result in a miscarriage of justice. If admitted, this evidence would not have made a difference to the trial’s outcome.[14]
The Court observed that the jury had to decide whether the state of the stairs breached the OLA, rendering the Forgets negligent. To do so, the jury was required to decide which parties’ evidence it accepted.[15]
Mr. Jenish’s excluded evidence did not prevent Ms. Pederson from advancing her theory of liability. Rather, the Court observed that there was ample evidence before the jury to decide the central issues of the case, including Mr. Jenish’s three subsequent expert reports.[16]
In light of the foregoing, the Court dismissed Ms. Pederson’s appeal and awarded the costs of the appeal to the Forgets.[17]
Takeaways
The Court of Appeal’s decision in Pederson reminds us of the potential dangers associated with expert evidence. This is especially true where a trial is being heard by a jury. Although an expert’s assistance can be necessary in allowing the fact finder to understand complex and technical evidence, that same expert may undermine trial fairness if allowed to stray outside of the bounds of his or her role.
As such, the trial judge’s gatekeeper function is critical to the interests of justice and will attract appellate deference. Even if the judge errs in excluding an expert’s evidence, an appellate court may not order a new trial if that error did not affect the trial outcome and, thus, did not result in a miscarriage of justice.
The cautionary tale of Pederson emphasizes the need for counsel to remain mindful of the role and responsibilities of experts. Otherwise, they risk incurring unnecessary costs for an expert report that will nevertheless be inadmissible.
[1] 2026 ONCA 118 [”Pederson”].
[3] RSO 1990 c O2 [“OLA”].
[4] Pederson, supra note 1 at paras 7-8.
[7] 2015 SCC 23, [2015] 2 SCR 182 [“White Burgess”].
[8] Pederson, supra note 1 at paras 12 and 19.
[12] Pederson, supra note 1 at para 17 citing White Burgess, supra note 7.
[13] Pederson, supra note 1 at paras 20-23.
[15] Ibid at paras 27 and 29-30.
[16] Ibid at paras 40-42.
