he Ontario Court of Appeal has held that the role of the trial judge in relation to expert witnesses has evolved in recent years. 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.

Medical witnesses who do not pass this test may be permitted by the Court to give only limited medical opinions, may be restricted by the Court to give no medical opinions at all, and may be denied the opportunity to be qualified as an expert entirely.

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