The Canadian Bar Association
Criminal

Case shows importance of evidence-based evaluation of experts

For all participants in the criminal justice system, the turn of events in one recent case demonstrates what may happen when expert evidence is admitted without having been subjected to meaningful scrutiny, Hamilton criminal lawyer Jeffrey Manishen writes in The Lawyer’s Daily.

As Manishen, partner with Ross & McBride LLP, explains, in a recent decision, the Ontario Court of Appeal reversed a 2011 first-degree murder conviction, ruling that expert evidence it had previously found to have been wrongly excluded — that resulted in the reversal of an acquittal in 2009 — would likely not have been admitted at the retrial given the fresh evidence filed on the second appeal.

In the first trial, writes Manishen, the judge ruled that the evidence of a sociologist called by the Crown to give evidence as to the significance of a teardrop tattoo was inadmissible, as it was unreliable based on deficiencies in scientific methodology as well as internal inconsistencies in the expert’s opinion.

The sociologist relied on studies he reviewed and conducted, including interviews with gang members, as the basis for his opinion that such a tattoo could signify that the wearer had killed a rival gang member, says Manishen.

However, he writes, on appeal, the court “concluded that the trial judge had erred in subjecting the proposed testimony to such scrutiny, emphasizing that the expert’s opinion did not rest on scientific validity. As with many other experts, the reliability of his evidence was based on his specialized knowledge gained through extensive research, years of clinical experience and familiarity with the relevant academic literature.”

At the new trial, he says, the sociologist’s evidence was admitted without objection. The accused was convicted of first-degree murder.

By the time the new appeal was argued, writes Manishen, the sociologist had been called by the defence in an unrelated trial.

“He was cross-examined extensively by the Crown regarding the basis for his opinion. The questioning revealed serious flaws and misstatements in his report, including the fact that the number of gang members in his study was lower than he claimed; none of the studies indicated who had teardrop tattoos or the basis for having them; and, after having initially claimed he could get the 'masses of data' over the luncheon recess, he had to admit that, in fact, he no longer had the data to support his studies,” he writes.

This evidence was admitted on appeal, says Manishen, and the unanimous court found it would have led the trial judge to have excluded the sociologist’s evidence due to its unreliability had it been introduced at the second trial.

The court also emphasized, as commissioner Stephen Goudge did, the importance of an evidence-based approach to the evaluation of the reliability of expert evidence for a trial judge exercising their “gatekeeper” function in ruling on admissibility, says Manishen, characterizing it as “persuade me,” rather than “trust me.”

“Notwithstanding the Goudge inquiry, an expert witness can still cause a miscarriage of justice,” writes Manishen.

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