Why Modern Evidence Law Lacks Credibility

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Publication Information

Daniel D. Blinka, Why Modern Evidence Law Lacks Credibility, 58 Buff. L. Rev. 357 (2010)

Source Publication

58 Buffalo Law Review 357 (2010)


Witness credibility is at the heart of every trial. And while it is axiomatic that "credibility" is left to the jury, evidence law is silent about how one decides whether a witness is accurate, lying, or honestly mistaken. More precisely, a finding that a witness is accurate rests on the following so-called "testimonial assumptions": The witness accurately perceived the event; she accurately remembers those perceptions at trial; her testimony (words) accurately describes her memories; and she is sincere (not lying). Neither the law nor science provides a test for determining credibility. Rather, the jury's life experience and "common sense" are thought to be sufficient or, more accurately, the only viable alternative.

This article develops several themes. First, the testimonial assumptions recognized by evidence law are products of mainstream thought and culture, an epistemology founded upon lay common sense and popular ideas about how people perceive, remember, and describe events as well as their sincerity. Second, the legitimacy of the modern trial depends upon this correspondence between popular thought and evidence doctrine, yet that correspondence is inadequately understood at present. Third, evidence law is bereft of any systematic approach to determining credibility. Rather, impeachment doctrine consists of ad hoc techniques that lawyers use at their discretion, the assumption being that they are sufficiently adroit and skilled to draw out the strengths and weaknesses related to the testimonial assumptions (credibility).

Set against the modern trial are several notable threats. First, proof that rejects or contradicts the law's common sense epistemology, particularly social scientific or psychological evidence directed at popular "misconceptions" relating to credibility, effectively diminishes the jury's role in fact finding and threatens the trial's legitimacy. Second, trial lawyers with insufficient skill to use common law modes of impeachment fail to present the fact finder with the information popularly deemed necessary to determine credibility. Third, the "vanishing trial" risks relegating the trial jury to history's museum of curiosities while breeding a generation of lawyers lacking fundamental trial skills and adept only at settlement.

The purpose of this article is to assess the testimonial assumptions in light of the law governing the impeachment and "rehabilitation" of witnesses. Evidence law is understandably reluctant to substitute its common sense underpinnings for the infirmities of modern psychology. Nonetheless, it should strive to better understand its roots in mainstream thought and popular culture if only to better appreciate where and how cultural changes, and psychology's insights, might assist credibility determinations without undermining the trial's legitimacy. Impeachment doctrine remains overly fixated on perjury and insufficiently attentive to the problem of the honestly mistaken witness. The article recommends several significant changes in trial practice and evidence doctrine that redress this imbalance without unmooring evidence law from its roots in the community's sense of credibility.