It is not easy to rule on a pretrial motion that an expert should not be allowed to testify. Yet we know that in criminal cases experts have at times contributed to wrongful convictions. Jason Chin, Michael Lutsky and Itiel Dror (Sydney Law School, University of Toronto – Faculty of Law and University College London (UCL)) have posted The Biases of Experts: An Empirical Analysis of Expert Witness Challenges (Manitoba Law Journal, Forthcoming) on SSRN. Here is the abstract:

Biased expert witnesses pose a distinct challenge to the legal system. In the criminal sphere, they have contributed to several wrongful convictions, and in civil cases, they can protract disputes and reduce faith in the legal system. This has inspired a great deal of legal-psychological research studying expert biases and how to mitigate them. In response to the problem of biased experts, courts have historically employed procedural mechanisms to manage partiality, but have generally refrained from using exclusionary rules. Canada diverged from this position in 2015, developing an exclusionary rule in White Burgess Langille Inman v Abbott and Haliburton Co. In this article, we assembled a database of 229 Canadian bias cases pre- and post-White Burgess to evaluate the impact that this case had on the jurisprudence.

The data suggests that White Burgess increased the frequency of challenges related to expert biases, however, did not noticeably affect the proportion of experts that were excluded. This suggests that the exclusionary rule introduced in White Burgess did not significantly impact the practical operation of expert evidence law, as it pertains to bias. We conclude by recommending that one way for courts to better address the problem of biased experts is to recognize the issue of contextual bias.