Citation: Bruff-Murphy v. Gunawardena
Court of Appeal for Ontario
Heard: 15 May 2017
On appeal from the judgment of Justice Paul B. Kane of the Superior
Court of Justice, sitting with a jury, dated August 22, 2016.
The law regarding expert witnesses has evolved considerably over the
last 20 years. Gone are the days when an expert served as a hired gun
or advocate for the party that retained her. Today, expert witnesses
are required to be independent, and their function is to provide the
trier of fact with expert opinion evidence that is fair, objective and
The role of the trial judge in relation to expert witnesses has also
evolved. Appellate courts have repeatedly instructed trial judges that
they serve as gatekeepers when it comes to the admissibility of expert
opinion evidence. They are required to carefully scrutinize, among
other things, an expert witness’s training and professional experience,
along with the necessity of their testimony in assisting the trier of
fact, before the expert is qualified to give evidence in our courts.
This gatekeeper role is especially important in cases, such as this
one, where there is a jury who may inappropriately defer to the
expert’s opinion rather than evaluate the expert evidence on their own.
In the present case, the trial judge qualified an expert to
testify on behalf of the defence despite some very serious reservations
about the expert’s methodology and independence. It became apparent to
the trial judge during the expert’s testimony that he crossed the line
from an objective witness to an advocate for the defence. Despite his
concerns, the trial judge did nothing to exclude the opinion evidence
or alert the jury about the problems with the expert’s testimony.
On appeal, the appellants advance several arguments to the effect that
trial fairness was breached, such that a new trial is necessitated. All
of these arguments focus on the impugned expert.
In my view, the appeal must be allowed and a new trial ordered. I
reach this conclusion because the trial judge failed to properly
discharge his gatekeeper duty at the qualification stage. Had he done
so, he would have concluded that the risks of permitting the expert to
testify far outweighed any potential benefit from the proposed
In addition, the trial judge’s concerns about the expert’s testimony
were substantially correct; the witness crossed the boundary of
acceptable conduct and descended into the fray as a partisan advocate.
In these circumstances, the trial judge was required to fulfill his
ongoing gatekeeper function and exclude in whole or in part the
expert’s unacceptable testimony. Instead, the trial judge did nothing,
resulting in trial fairness being irreparably compromised.
I would grant the appeal, set aside the judgment below, and order a new
trial. I would award the appellants their costs of the appeal in the
amount of $22,000, inclusive of fees, disbursements and applicable
The parties may make written submissions on the issue of the costs of the first trial.
“C.W. Hourigan J.A.”
“I agree. P. Lauwers J.A.”
“I agree M.L. Benotto J.A.”
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