R v Aubrey-Lafreniere, [2018] OJ No. 5589

This was a voir dire ruling on whether a Crown witness should be qualified as an expert witness and permitted to give opinion evidence on veterinary medicine. The court applied the two-part test in R v Mohan (1994) 2 SCR and held the evidence was admissible.

First stage (threshold) – the expert evidence must:

  • be relevant
  • be necessary in assisting the trier of fact
  • be absent of any exclusionary rule
  • be from a properly qualified expert

Second stage (gatekeeper) – the trial judge must exercise discretion by balancing any potential risks and benefits of admitting evidence.

Issues of bias, independence and impartiality must be taken into account at both stages.

The defendants argued that the witness, Dr Johnson, was biased. Dr Johnson had facilitated the call to the OSPCA to report the accused, he was aware that staff at the clinic he worked at believed the accused should not have animals and he was aware of negative comments being made about the accused.

Dr Johnson said that he had a legal duty to report pursuant to Ontario legislation and none of the comments affected his opinion or decision to report.

In admitting Dr Johnson’s expert testimony, the court held that the fact that circumstances may give rise to some appearance of bias is not relevant to the threshold stage – the appearance of bias is not equivalent to actual bias. Further, any argument that his opinions may have been influenced subconsciously could go to the weight of his witness evidence, but did not exclude it from being admitted in the first place.