Judges as Gatekeepers for Necessary Expert Evidence

• Author: Omar Ha-Redeye
• Date: January 11, 2015

Expert evidence is often perceived as a necessary evil by many judges. The “evil” of these experts is that they tend to enhance the adversarial nature of litigation, unduly complicate proceedings, and often add unnecessary costs for the parties.

What is the role of the court in excluding or managing this evidence?

Concerns over the excessive use of experts has been identified in several jurisdictions. A 2002 study by Carol Krafka in the US found that judges are becoming more recalcitrant towards accepting expert evidence post-Daubert. The 2009 Jackson Report in the UK accepted the manner in which expert evidence is tendered, but found that it was often done so unnecessarily.

The test for expert evidence in Canada, derived from R. v. Mohan, is as follows:

1. the evidence must be relevant;
2. it must be necessary to assist the trier of fact;
3. it must not be subject to an exclusionary rule; and
4. the expert must be properly qualified.

The Ontario Court of Appeal recently released a decision in Meady v. Greyhound Canada Transportation Corp which elaborated on the second part of the test, whether the expert is necessary to assist the trier of fact.

The trial judge, Justice Platana, excluded the testimony of two experts brought by the plaintiffs, who were passengers on a Greyhound bus in northern Ontario. An individual with mental health problems had boarded the bus, lunged at the driver, causing the bus to swerve and topple, resulting in one death and 32 injured passengers.

The plaintiffs had sought to sue the mentally ill passenger, but also Greyhound, the bus driver, OPP officers who had encountered the mentally ill passenger prior to boarding, and the Crown who employed the officers. Justice Platana dismissed the action against all the defendants except for this mentally ill passenger, who did not defend the action and was noted in default.

Central to this finding was that he excluded the testimony of two experts, one in police training and the other in bus safety, which the plaintiffs claim would have established negligent behaviour on behalf of the bus drivers and the officers in preventing the incident.

Justice Dickson stated in R. v. Abbey,

An expert’s opinion is admissible to furnish the Court with scientific information which is likely to be outside the experience and knowledge of a judge or jury. If on the proven facts a judge or jury can form their own conclusions without help, then the opinion of the expert is unnecessary.
[emphasis added]

This “help”...