Document Type

Article

Publication Date

1-2003

Abstract

In this essay, I will offer some thoughts on how we might reframe the issues governing the admissibility of expert evidence. My principal focus is not on any particular type of expert evidence but on broader questions: the extent to which we ought to rely on rulings of admissibility, the standards that should govern admissibility rulings, and the role of the trial and appellate courts in making those rulings. To some extent, I will concentrate on the context of criminal cases, but for the most part my conclusions apply in both civil and criminal litigation. Here are my conclusions: First, the standards for treatment of expert evidence should differ depending on the litigation context. Standards should be very lenient for criminal defendants, and tougher for prosecutors, with the standards for civil litigants somewhere in between. Second, more than has been the case, the test that carries the bite with respect to expert evidence should be one of sufficiency rather than of admissibility. Third, the model created by Daubert v. Merrell Dow Pharmaceuticals, Inc.' and General Electric Company v. Joiner, and extended by Kumho Tire Company, Ltd. v. Carmichael,' in which trial courts, reviewed under an abuse of discretion standard, act as gatekeeepers to prevent jurors from being bamboozled by unreliable evidence, is not a useful one. Reliability is an inappropriate, misleading standard for testing the admissibility of expert evidence. It does not reflect the way we should think about admissibility issues, and it ought to be discarded. Moreover, trial courts are not well positioned to sort the good from the bad. Where it is appropriate to exclude evidence, the decision usually should be made as a matter of law. This is because the difficulties that are most likely to warrant exclusion usually share either or both of these characteristics: (i) they are recurrent matters (including the behavior of repeat players) for which a consistent resolution across cases is appropriate; or (ii) they involve errors, particularly inferential errors, in the way the evidence is presented that make it affirmatively misleading. Fourth, in some settings, as a less restrictive alternative to exclusion, courts should admit expert evidence but explain to the jury factors limiting the weight that the jury should accord the evidence. I believe that we should be considerably more generous than we have been with respect to expert evidence offered by the defense, and the net effect of my suggestions would probably be greater generosity with respect to expert evidence offered in civil cases. With respect to the principal focus of this article, expert evidence offered by a prosecution, my overall aim is not to argue that we should be more or less generous than we have been. But I do believe we need to restructure the way we think about the admissibility of such evidence. Sometimes the courts should exclude such evidence as a matter of law because it is affirmatively misleading, or because exclusion will induce the presentation of better evidence. Sometimes the trial court should admit the evidence but comment adversely on it. Sometimes the court should deem the evidence admissible but nevertheless hold that the evidence taken as a whole does not support a verdict. But if none of these principles apply and the expert evidence has significant probative value the court should not exclude it on the ground that it is unreliable, and rarely if at all should the court exclude it on the mere ground that the jury is likely to over-value it. Thus, I am suggesting that Daubert be squeezed out of the picture by other approaches to the problem.

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