Recently, there has been a call for renewed vigiliance in exercising the gatekeeper role with respect tto the admission of expert evidence This paper discusses the jury control principle and sets out and describes the Mohan criteria for admissibility of expert evidence: relevance, necessity, not subject to an exclusionary rule, and given by a properly qualified expert.

This paper is part of a collection presented at LESA’s Criminal Law 25 program held in Calgary on June 3, 2016 and in Edmonton on June 10, 2016.