When Is Expert Testimony Useful to Courts?

You have been asked to provide expert testimony in a judicial proceeding. Even if you have done so dozens of times, you are slightly anxious. You are a scientist. You take pride in that role and consequently want to do an outstanding job. The task seems simple enough. You are familiar with the topic about which you are to testify, and the attorneys sound pleasant enough. But as you reflect a little more, you have some nagging concerns: Just what do courts expect from me? How can I more effectively perform my role? Will my participation in the legal process damage my self-respect as a scientist? Our study of the process of expert testimony may hint at tentative answers to those questions.1 While we cannot answer the questions with the certitude we would prefer, there is much to be gained by recognizing that the answer to all three questions is, "It depends." But before we explain, let's briefly review the legal rules for judicial use of expert testimony in the United States. It is these rules that provide the framework within which expert testimony is assessed. The legal system has long struggled with how to most effectively use expert knowledge to settle its wide array of disputes. Underlying this debate are the core questions of what specific needs experts should be asked to fulfill and what the optimal role of the jury and judge should be in evaluating scientific evidence. In the not-too-distant background is judicial concern about the practicality of asking nonscientists to evaluate often-conflicting scientific claims. Can science be placed in a communication format that matches the cognitive limitations and training of the judge and jury? The resulting restrictions on the admission of expert testimony can be placed on a continuum with a desire to give the jury complete independence in reaching its decision at one end and a desire to accord complete deference to the expert's conclusions at the other. Changes in these roles over time reflect ever-evolving perspectives about first, the quality of the adversaries, and second, the capabilities of the judge or jury to discover and evaluate the claims of the expert. The common law of evidence has historically deferred greatly to the fact finder's abilities. Lay witnesses testified to that which they had seen and heard, leaving all inferences or opinions from such testimony to the fact finder. The expert witness entered the scene only when references to experiences not possessed by jurors were necessary to enhance a juror's understanding. The lay or expert witness merely assisted the fact finder by providing only that information necessary to evaluate the evidence presented. The juror could then apply this "new" wisdom to resolve the questions of fact and arrive at a "just" verdict. Because the gulf between the fact finder's experience and the knowledge required to understand and evaluate issues is perhaps widest in the field of scientific testimony, a special test developed out of the common law to govern the use of scientific testimony. The test, popularly known as the "Frye test" after the court decision2 from which it arose, was designed to limit the admission of testimony regarding a particular scientific principle to that testimony "generally accepted" in its field. The Frye test assumes that other scientists in the expert's community had strained out the "junk science" before it reached the fact finder, providing greater certitude at the cost of significantly diminishing the juror's independence. Not surprisingly, determining what methods in a particular field were "generally accepted" was more difficult than the test suggested on its surface. From what community should the judge "count heads" to assess general acceptance, who should be counted in that community, how should the votes be weighted, and what constituted "general acceptance?" In addition to these ambiguities, blocking valid and relevant theories from the courtroom was arguably antidemocratic. After many years of such criticism, the pendulum swung back toward juror independence with the advent of the Federal Rules of Evidence's more liberal rules of admissibility. These rules placed greater faith in the juror to evaluate the testimony and restricted the community of experts' gatekeeping role. The shift accomplished by the Federal Rules of Evidence went perhaps too far for those with particularly strong reservations about the dangers and inefficiencies of unreliable evidence reaching the jury. The 1993 U.S. Supreme Court decision of Daubert v. Merrell Dow Pharmaceuticals represented a judicial response to these reservations. The Daubert decision forged a position somewhere between the Frye standard and the liberal standard propounded by the Federal Rules of Evidence. Daubert rejects the Frye test's deference to external groups and substantially returns the onus of evaluation to the judge. Thus, scientific testimony not "generally accepted" can enter the courtroom so long as it is relevant and reliable. The judge may make several considerations in determining what is relevant and reliable. Among the acceptable considerations are whether the theory or technique had been subjected to peer review and publication, whether the expert used the scientific method, whether a particular scientific technique had a significant rate of error, and whether the methodology was generally accepted in the relevant scientific community. The Daubert approach, in contrast to the Frye test, admits any evidence with "good grounds" and then places enormous faith in the ability of cross-examination, contrary evidence, carefully crafted jury instructions, directed verdicts, summary judgment, and court-appointed experts to safeguard from the alleged deleterious consequences of this more permissive standard. Presumably, the benefits from a more liberal and "democratic" standard far outweigh any costs incurred when these safeguards prove insufficient. This latest compromise between competing views regarding the respective roles of the experts and the fact finders has not diminished the confusion and controversy. The courts remain in conflict over the scope of Daubert and the sort of test that should be applied in determining evidentiary admissibility. Some adopt a fairly permissive approach to admissibility, citing Daubert's emphasis on the capable role of the adversarial system in exposing faulty testimony. Others have maintained the more stringent aspect of the Frye test, taking comfort in the use of experts as gatekeepers. In short, Daubert can be characterized as a "moderate" view of expert testimony admissibility, the Frye test as a "conservative" view, and the Federal Rules of Evidence as a "liberal" view. Now we have the framework for responding to your concerns about providing expert testimony. That question cannot be answered in the abstract because there is no single entity called "the court." Judges exercise discretion in their application of the Daubert rule. Some judges push Daubert as far as they can in the direction of the Frye rule. When you testify in those courts, you are presumed to be speaking on behalf of the relevant scientific community and can expect the consequent deference to the quality of your testimony. However, in the more democratized atmosphere of a court that applies Daubert in its more "liberal" form, your testimony will be presumed to represent a scientific perspective that can be evaluated by a juror. You should be psychologically prepared for a scenario in which your knowledge may be treated as merely partisan. While you may see your testimony as impartial, the adversary system can transform its essence from scientific knowledge into "purchased assistance." The jury is the arbiter where a "liberal" view of Daubert prevails. First, recognize that effectiveness of testimony is contextual. Again there is no single entity called "the court" that will respond to your testimony in a highly predictable fashion. Hence, the effectiveness of your testimony may depend on the habits and tendencies of the particular judge and local juries. Everything you can learn about these habits and tendencies is helpful to the effectiveness of your testimony. You must remind yourself that the rules in particular courts are markedly different from the rules of conduct maintained in an academic seminar. Second, your testimony can be enhanced if you will contribute to the cross-examination of any experts who disagree with your testimony. Juries can be assisted not just by what you say but also by the questions that you encourage lawyers to ask of other experts. One potential constraint on this second piece of advice is the willingness of the lawyer for whom you testified to encourage you to perform this role. The court is the attorneys' territory, and some of them would presume that they, not you, know the proper questions to ask. But skilled attorneys will want your assistance in any and all helpful forms. When you testify, you are anything but neutral. That you are testifying at all suggests that you have a point of view. When you are contacted, you realize immediately that your testimony is part of a legal strategy. Testify in a certain way, and you will assist that strategy. As opposing counsel will surely point out, your point of view appears to have been purchased. However, you can participate in this process with integrity by attempting to present impartial testimony. By "impartial" we mean the testimony that you would provide regardless of who might be paying for your time. Impartial testimony is the best antidote to any sense you may have that the court proceedings are tainting your self-respect. You owe it to yourself and to the court to resist attorneys who attempt to warp your testimony. Present your testimony as effectively as you are able, but do so in a manner that distinguishes both you and science. M. Neil Browne, Ph.D., Distinguished Teaching Professor of Economics at Bowling Green State University, is the author of nine books and more than 100 articles in professional law, economics, and higher education journals. Attorney Terri J. Keeley is an associate in the banking and commercial group at Faegre & Benson LLP in Minneapolis, where she represents secured and unsecured creditors in commercial lending, bankruptcy, and related contexts. M.N. Brown, T.J. Keeley, W.J. Hiers, "The epistemological role of expert witnesses and toxic torts," American Business Law Journal, 36:1-72, Fall 1998. Frye v. United States, 293 F. 1013 (D.C. Circuit, 1923).

When Is Expert Testimony Useful to Courts?

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