In a sentencing proceeding following a guilty plea to importing heroin, the Crown sought to qualify an RCMP officer as an expert on heroin trafficking, consumption, and user behaviour to support an aggravating inference that the drugs were imported for trafficking rather than personal use.
The defence challenged several areas of the proposed expert evidence, arguing the officer lacked qualifications in pharmacology, toxicology, and behavioural science.
Applying the framework for admissibility of expert evidence from R. v. Mohan and R. v. Abbey, the court carefully delineated the permissible scope of the officer’s expertise.
The officer was qualified to testify regarding observable effects of heroin use, typical methods and rates of consumption, habits of users, drug pricing, packaging, purity, and trafficking practices based on extensive police experience.
However, the court excluded opinions requiring medical, pharmacological, or toxicological expertise, including assertions about physiological consequences of prolonged heroin consumption.
The ruling permitted limited expert evidence but restricted the officer from offering medical or scientific conclusions outside his demonstrated expertise.