Taking Deterrence Seriously: Excluding Unconstitutionally Obtained Evidence Under Section 24(2) of the Charter

Abstract

Section 24(2) of the Canadian Charter of Rights and Freedoms grants courts the authority to exclude evidence that is obtained in a manner that infringes or denies any Charter rights or freedoms, provided the admission of such evidence would bring the administration of justice into disrepute. While the problem of deciding in what circumstances to exclude illegally obtained evidence has occupied both the Supreme Court of Canada and scholarly commentators, their efforts to date have been largely devoid of theory. This article seeks to remedy this situation by developing a single, coherent exclusionary theory. To this end, Professor Penney argues that the only worthwhile reason to exclude evidence under section 24(2) is to deter constitutional violations. A deterrence rationale allows for balance of the conflicting purposes of section 24(2): encouraging constitutional compliance and convicting the factually guilty.

In Part I, Professor Penney examines the most common justifications for exclusion of illegally obtained evidence - what he calls the condonation rationale, the corrective justice rationale, and the deterrence rationale - and concludes that deterrence is the only one that is normatively plausible. He further argues that the objective of the exclusionary rule should not be maximum deterrence, but optimal deterrence. In other words, evidence should be excluded only when the benefit of increased deterrence outweighs the cost of lost convictions. Part II of the article considers the available empirical evidence on the costs and benefits of the exclusionary rule and concludes that while an exclusionary rule can have a significant deterrent effect with few lost convictions, its ability to deter is also limited by a number of phenomena, including most importantly, the complexity of constitutional rules governing investigative behaviour. In Part III, Professor Penney critiques Supreme Court section 24(2) jurisprudence in light of his exclusionary theory. Specifically, he argues that the Court should develop ways to deter violations of the Charter rights of third parties; that it should maintain its liberal approach to causation; that it should abandon both its trial fairness approach to self-incriminating evidence and its balancing approach to other evidence; and finally, that it should adopt a bright-line rule that encourages police to become reasonably well-informed about their constitutional obligations and signals to them that intentional and negligent violations will always result in exclusion. This approach would be consistent both with the wording of section 24(2) and much of the Court's jurisprudence. It would also go some way toward achieving a better balance between the rights-protection and truth seeking functions of section 24(2).

Keywords: charter, evidence, exclusion, 24(2), deterrence, economics, Canada

JEL Classification: K14