Document Type
Working Paper
Publication Date
2026
Subjects
Forensic, Firearms, Courts, Canada
Abstract
Forensic firearms comparison evidence is routinely admitted in Canadian criminal trials and is often presented as a reliable means of identifying whether fired ammunition components originated from a particular firearm. For nearly 100 years, Canadian courts have admitted this evidence based largely on examiner claims about the reliability of the technique without subjecting those claims to meaningful scrutiny or limiting examiner conclusions to those that are empirically supported. Drawing on recent scientific literature, however, this article demonstrates that existing studies of forensic firearms analysis suffer from significant methodological flaws that may systematically underestimate error rates and do not establish the scientific validity of the technique. Despite these limitations, firearms examiners routinely present their conclusions in categorical and highly certain terms without adequately disclosing important limitations of the technique, creating a substantial risk that factfinders will overestimate the reliability of the evidence and assign it undue weight. Ultimately, the existing empirical literature does not support the degree of certainty to which firearms examiners routinely testify. This article uses forensic firearms comparison evidence as a case study in the broader problem of how Canadian courts evaluate expert opinion evidence and argues that courts should subject firearms identification evidence to more rigorous scrutiny at the admissibility stage and limit the scope and language of examiner conclusions to those that are empirically supported. This approach not only conforms with the current law concerning the admissibility of expert evidence but is also critical in protecting against miscarriages of justice.
Citation Details
S. Gordon, "Taking a “Persuade Me” Approach: Gatekeeping Forensic Firearms Comparison Evidence in Canadian Courts" (2026) Dalhousie Law Journal (Forthcoming).