Thinkpiece Thursday: Dufraimont on the Principled Approach to Evidence

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REALIZING THE POTENTIAL OF THE PRINCIPLED APPROACH TO EVIDENCE
Lisa Dufraimont
(2013) 39 Queen’s Law Journal 11-39

Excerpt: Part II

[Footnotes omitted. They are in the original that is available via the link on the title above.]

II. Evidence Principles Versus Evidence Rules

The adoption of the principled approach represents a move away from a law of evidence centred on rules toward an evidence law centred on principles.

The concepts of a “rule” and a “principle” have attracted much attention in legal theory, but the tradition in cases and commentaries on Canadian evidence law has been to treat these terms as if they were self-explanatory. This paper will break with that tradition and briefly consider what the distinction between rules and principles means in the context of the Canadian evidence revolution.

A. Defining Characteristics

Theorists distinguish rules and principles on several axes, not all of which are germane to the present analysis. However, the literature reveals three relevant dimensions on which rules and principles have been distinguished—specificity, justificatory content and weight. These dimensions are salient because they appear to reflect what the Canadian courts have in mind when they speak of the principled approach to evidence.

Some frame the distinction between rules and principles as one of specificity : relatively specific legal prescriptions are called rules, while relatively vague legal prescriptions are labelled as principles. The terminology used to describe this distinction between specific and vague legal prescriptions varies, the most common formulation in the American literature being an opposition between specific “rules” and vague “standards”.

Another dimension on which rules and principles have been distinguished involves their degree of justificatory content. Principles are bound up with and given content by the policies, values and rationales animating the law, while rules have a more attenuated relationship with the justifications behind the law. In other words, rules tend to be “opaque” to their underlying justifications, while principles allow their justifications to shine through. “Principles refer more or less directly to—indeed, they are often indistinguishable from—various values, interests, rights, policies and goals”, explained Stephen Perry, whereas “[r]ules, by contrast, usually just specify a course of action to be followed in a particular type of circumstance.”

A final dimension on which rules and principles have been distinguished is that of weight. If a legal prescription has weight, it can be assessed as having greater or lesser importance, and can be balanced against competing considerations. Principles are said to possess this quality of weight, while rules are said to lack it because, as Ronald Dworkin famously wrote, rules operate “in an all-or-nothing fashion”. Put another way, rules are conclusive because when their conditions are met, they operate automatically to demand specific outcomes. If rules conflict with one another, there is a problem. Principles, on the other hand, may point in different directions and are susceptible to being balanced against one another.

The dimensions of specificity, justificatory content and weight are related in complex ways and do not always closely track one another. For example, a legal prescription that is specific will not necessarily be conclusive. Moreover, with the arguable exception of weight, these dimensions operate not as binaries but as sliding scales. Legal prescriptions can be more or less specific, and more or less defined by their justificatory content. For this reason, we cannot expect any clear division between rules and principles to be sustainable.

Much more could, of course, be said about these three dimensions, their logical properties and their interrelationships. A full account of these matters, however, lies beyond the scope of this paper. The present analysis aims only to illuminate, somewhat more systematically than is customary in this area, what it means for the Canadian law of evidence to de-emphasize rules and embrace principles. Whatever the relationships in logic between specificity, justificatory content and weight, the idea of a principle that has developed in Canadian evidence law appears, as a matter of fact, to be a function of all three of these dimensions. Descriptively, then, when Canadian courts speak of evidence principles, they seem to mean legal prescriptions that are at once vague, closely identified with (if not identical to) their justifications, and capable of being weighed against one another. Two examples illustrate this point.

(i) Example One: Threshold Reliability

Consider the standard of “threshold reliability” that must be met before hearsay evidence can be admitted under the principled approach. Justice Charron explained that requirement in these terms in Khelawon:

Since the central underlying concern is the inability to test hearsay evidence, it follows that under the principled approach the reliability requirement is aimed at identifying those cases where this difficulty is sufficiently overcome to justify receiving the evidence as an exception to the general exclusionary rule.

She went on to explain that the dangers of hearsay could be overcome in individual cases by pointing to circumstances surrounding the making of the statement that support its reliability, by determining that its reliability could be sufficiently tested despite its hearsay character, or by applying some combination of these kinds of reasons. The principle of threshold reliability is vague in the sense that the factors that can influence the analysis are numerous and unspecified. The principle also appears inseparable from its justificatory content; it is identified on its face as a reliability principle, and its purpose is to ensure that reliable evidence is admitted and that unreliable evidence is not. Finally, the threshold reliability analysis openly calls for a case-by-case weighing of concerns about dangers of admitting hearsay against the reasons for believing that it is reliable enough to be admitted.

(ii) Example Two: Expert Evidence

The principles governing admission of expert evidence have similar qualities. In the leading case of R v Mohan, the Supreme Court held that expert evidence should only be admitted where it is broadly “relevant” and “necessary” to assist the trier of fact. Justice Sopinka explained that these principles should be applied in the context of a cost-benefit analysis. The need for the expert assistance to clarify technical matters for triers of fact should, he reasoned, be “assessed in light of its potential to distort the fact-finding process” —for example, by wasting time or confusing jurors. Like the principles of hearsay, expert evidence principles are unspecific, they have strong justificatory content, and they are intended to be weighed and balanced against one another.

B. Strengths and Weaknesses

The preceding discussion of the characteristics of rules and principles lays a foundation for considering the strengths and weaknesses of these forms of regulation. Specificity and conclusiveness, two of the characteristics of rules, carry an important disadvantage: they generate over-inclusion and under-inclusion. When specific and conclusive rules are framed in advance, and an attempt is made to apply them to new fact situations, they frequently and predictably do not work in the way their underlying rationale suggests they should, or they work in a way that their rationale suggests they should not. It is of interest to students of evidence law that these problems of over-inclusion and under-inclusion are exacerbated by uncertainty or heterogeneity in the phenomenon being regulated (what could be more uncertain or diverse than facts?).

It should come as no surprise that these over-inclusion and under-inclusion problems were recognized as pathologies of the traditional rules of evidence, and that in Canada, these problems gave momentum to the evidence revolution. For example, in her account of the development of the principled approach to hearsay, McLachlin CJC noted the “occasional arbitrariness” of the traditional category-based rules:

[T]he rule[s] became rigid and could, in some cases, exclude evidence which should have been received having regard to the underlying criteria of necessity and reliability. [They] could also occasionally lead to the admission of evidence which should be excluded, judged by these criteria.

Evidence doctrines centered on principles avoid over-inclusion and under-inclusion, because principles are unspecific and are applied in a contextual balancing process centered on the policies and values—the justifications—underlying the law.

Thus, focusing on principles would seem to be a promising way to overcome the problematic rigidity of rules, and the experience of the principled approach to evidence in Canadian law is that the rigidity of the older law has been almost entirely eliminated. Evidence doctrines from hearsay to similar facts to case-by-case privilege are now centered on principles to be applied flexibly with a view to advancing their justifications. Further assurance of a flexible analysis of evidence issues flows from the trial judge’s general discretion to exclude otherwise admissible evidence when its prejudicial effect outweighs its probative value.

However, the flexibility that comes with focusing on broad principles entails some costs. Because principles are unspecific and lack the conclusiveness of rules, they are inescapably indeterminate in application. Consistent results across similar cases are therefore harder to attain under principles than under rules. Moreover, as commentators on the principled approach to evidence have noted, principled analysis places more demands on the adjudicator both intellectually and in terms of time. Because principles have strong justificatory content and require balancing, doing a principled analysis means weighing the underlying policy considerations in light of the specific facts of the case.

One can readily appreciate that, for judges, this multifaceted process will generally be more difficult than mechanically applying a specific, conclusive rule. As David Paciocco has written, it “calls on a higher skill set. The principled approach requires far more proficiency, and far more understanding of what is at stake, than do the settled rules.” While these added intellectual demands can properly be understood as a cost of the principled approach, they can also be understood as one of its strengths. The very reason Canadian courts embraced the principled approach was because the unthinking, mechanical application of evidence rules was seen to be inadequate. If the principled approach prevents judges from thoughtlessly applying rules they do not understand, that is a good outcome, even if it comes at some cost in terms of predictability and procedural efficiency.

C. The Complexity of Principles and the Complexity of Rules

By now it is clear that the principled analysis of evidence carries its own complexity: it requires a nuanced, contextual and necessarily indeterminate balancing of the policies underlying the law. We might label this kind of complexity a “complexity of principles” since the difficulties of this type of analysis arise from the attempt to grasp the implications of broad, justificatory principles in individual cases.

The complexity of principles can be contrasted with the complexity of evidence rules, which is the principal focus of this paper and which, as we have seen, springs from the density and technical character of highly specific evidence doctrines. Rule complexity can get in the way of a principled analysis by encouraging judges to focus on the dense regulatory landscape and the technical features of the rules. Indeed, as discussed above, the excessive complexity of evidence rules was one of the driving concerns behind the evidence revolution. However, as we will see in the next section, even after the introduction of the principled approach rule complexity continues to be a problem in Canadian evidence law.