• Gabriel Stettler
Keywords: scientific evidence, relationship between science and law, expert evidence, admissibility of evidence, Daubert, Mohan, reliability of science, gatekeeper of scientific evidence, pseudoscience, civil procedure, adversarial system, expert impartiality


Scientific evidence plays an essential role in many areas of civil law. Technological developments have had a particular impact in the area of civil liability, where the sheer amount of technical expert evidence can hinder court proceedings. In addition to the cost and time required to hear it, the presentation of all this evidence can have a paralyzing effect on legal decision making. Limiting the introduction of scientific evidence into civil proceedings has therefore become a major issue in modern procedural law.

The legal systems of North America have taken a novel approach to addressing this issue: the admissibility of scientific evidence is limited by having the reliability of the evidence assessed by the judge, who has effectively become a “gatekeeper of scientific evidence.” This article provides an overview of the implementation and appropriateness of this standard for reliability, nearly 25 years after it was established by Daubert in the United States and Mohan in Canada.

This retrospective finds that this test of reliability fails to align with its intended objectives, as demonstrated by its excessive application in the United States and its relatively poor application in Canada. These phenomena can be attributed to the complexity of the standard; its flexibility, which allows arbitrary positions to exert undue influence; and the difficulty for judges untrained in science to apply the standard. More importantly, this test of reliability is based on an inaccurate legal perception of science, which impedes the functioning of the law.

The question is then: how can this standard evolve? Based on a trend in Canadian law, legal efforts could be redirected toward applying the standard to those presenting scientific evidence at trial, rather than to the evidence itself; this redirection would require a larger rethinking of the adversarial system.


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