Rationale(s) for Rules of Evidence

"The" reason for rules of evidence has been discussed (though usually cursorily) many times. Many but not all of those discussions have been simplistic, and many of them (though not all) have said "the" reason for rules of evidence is the need to control jury decision making. There is a refreshing new article about the rationale(s) for rules of evidence in the English common law style (which the English themselves seem to be in the process of abandoning): Lisa Dufraimont, "Evidence Law and the Jury: A Reassessment," 53 McGill L.J. 199 (2008).

Here is the article's abstract:

The common law of evidence is counterintuitive because it seeks to facilitate the search for truth by regulating fact-finders' access to and evaluation of evidence. Since truth seems most likely to emerge when adjudicators reason freely from all available information, this puzzling strategy of seeking truth through evidentiary regulation demands some explanation. The orthodox explanation is that evidentiary regulation functions as a form of judicial control over the jury. Because juries arc untrained, non-professional adjudicators, they are said to lack the competence to evaluate evidence. On this view, evidence rules arc primarily directed at constraining jury decision making and preventing jury error. This jury-centred view has been criticized, and scholars have advanced other explanations for truth-seeking evidence rules. Some suggest that evidence law operates chiefly to promote the search for truth within the context of the adversary system, while others contend that evidence rules are primarily directed at managing the risk of witness dishonesty.

This article examines the claim that evidence law represents a form of jury control, and also considers some competing explanations for evidence rules. The author argues that no single principle explains the law of evidence. A complex set of explanations is needed to account for the historical origins of the rules and to justify them analytically. Moreover, the salience of these various explanations can only be judged in particular doctrinal contexts. Jury-related rationales are most persuasive where there are solid reasons to believe that juries have trouble evaluating the particular form of evidence at issue. Social-scientific research does not support the conclusion that juries are generally incompetent adjudicators, but it does indicate that juries struggle with specific types of evidence. Consequently, the question whether a particular evidence rule can be justified on jury-control grounds depends, first, on the specific competencies required to evaluate the evidence and, second, on what is known about jury psychology and behaviour.

Here is a statement of the article's (refreshing) thesis (which, to my eyes, runs in the tradition of American legal realism), the thesis that no single principle or rationale animates the existence and contours of rules of evidence in the common law style:

The debate over the explanatory principles of evidence law is largely a debate about whom to mistrust. Is our fear that juries may misconstrue the evidence, that adversaries may obscure the truth, or that witnesses may perjure themselves? Of whom are we afraid, and whom are we trying to control? It seems doubtful that these questions can ever be answered in any decisive way.

Certainly some authors identify one explanatory principle as the primary, underlying principle of evidence law. Thayer, among others, focused on the jury, while recently evidence scholars have suggested that the central rationale for evidence law lies elsewhere. Nance argues that the best evidence principle, which is concerned with advocate control, constitutes a superior explanatory principle to the traditional jury-centred rationale for evidence law. According to Imwinkelried, both of those explanatory principles are inferior to the dishonesty-control rationale, which he claims constitutes "the best explanatory hypothesis for the logical structure of Evidence law." [FN236] The modern theorists admit forthrightly that no one principle explains the totality of evidence law, an admission that militates in favour of interpreting their claims modestly. [FN237] But beyond arguing the explanatory power of the various rationales for evidence law, these scholars purport to choose the best, unifying theories, or even to explain the law's "logical structure". [FN238] Such ambitious claims are difficult to defend.

The search for an "organizing principle" [FN239] of evidence law is vain because evidence law is not organized around a principle. Given the ad hoc nature of evidentiary regulation, there is no reason to believe that the various possible rationales for evidence rules are mutually exclusive. A more tenable position is to recognize that various factors, including the trial features under consideration, play a role in explaining evidence law. [FN240] The origins and justifications of evidentiary rules are best uncovered in specific doctrinal contexts. And one could easily add yet more layers of complexity to the picture. Issues that cannot entirely be disentangled from the explanatory principles include extrinsic policy considerations like fairness and due process, as well as concerns about the efficient conduct of the trial process, such as affordability, speed, and finality.

It seems to me that it is no accident that two of the mentors of the author of this delightful article are Steven Duke and Mirjan Damaska of Yale Law School.

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