What if witness testimony emerges from, or can only be understood by reference to, an experience that the fact finder lacks? Or what if the connection between what a witness says and the full import of what the witness means is so arcane that the chances are virtually zero that the jury will understand what the spoken words are intended to convey? Both cases arise surprisingly frequently in the trial of disputes. For example, the problem arises whenever a witness is not fluent in English, as it often does when the common practice of a business or trade plays a role in litigation. And of course, whenever litigation involves scientific or technical issues, there is likely to be a distance between the fact finder's experience and the body of knowledge necessary to appraise the technical matter.
The problem posed by expert testimony is that it does not fit easily into the common law model of the ideal trial. Experts are often expert because of years of specialized training, and thus there may be formidable barriers to educating the fact finder about the relevant issues at trial. Hence, pressure arises to defer to the expertise of experts as a means of keeping trials to a manageable length, but the pressure to defer constitutes a challenge to the core concept of trials. Expert testimony accordingly puts into issue our basic commitments to the ideal common law trial. Although the controversies over expert testimony purport to be about other things, they in fact are controversies over whether the common law norm of education should be supplanted by deference when someone qualified as an expert speaks, and thus they can be resolved only by addressing that issue. It is the failure to address this central question that makes the current literature interesting but unsatisfying.
Joseph S. Miller and Ronald J. Allen,
The Common Law Theory of Experts: Deference or Education?
, 87 Nw. U. L. Rev. 1131
Available at: http://digitalcommons.law.uga.edu/fac_artchop/934