The Age of Expert Testimony: Science in the Courtroom, Report of a Workshop

Review by Elizabeth B. Juliano and Sara S. Pakrashi, JD

A central part of civil litigation is the role of expert testimony. Within this arena, tension exists between the legal and scientific community regarding the process which qualifies an expert. It is this tension that the Science, Technology, and Law Panel of the National Research Council explores in the book, The Age of Expert Testimony: Science in the Courtroom, Report of a Workshop. The book is a summary of various panel discussions at a workshop held on September 7, 2000 and reviewed in 2002. The purpose of the workshop was not to offer conclusions, but to fairly evaluate all viewpoints, both legal and scientific.

Addressing many current issues on the subject, The Age of Expert Testimony offers all sides of the argument. Given a historical progression of issues, the reader easily grasps the intricacies of the subject. For example, the authors point out that the interest in the debate over expert testimony has increased due to a recent series of Supreme Court cases. These cases, referred to as “The Supreme Court Trilogy”¹ not only alter the way in which expert testimony is evaluated, but change the role of the judge to a "gatekeeper of information." These cases were incorporated in to Federal Rule of Evidence 702. Now, scientific, technical, and "other specialized knowledge"² is evaluated upon the same principles.

It is this greater role of the judge as gatekeeper that acts as the starting point for the debate. The authors assert that the degree of scrutiny given to expert testimony and evidence is by no means standardized within the legal forum. Frequently, the amount of scrutiny changes depending upon the court, the stakes and the function of the evidence. Due to the growth of toxic tort litigation and its far-reaching implications for both the plaintiffs and defendants, there has been a need to develop standards for admitting scientific evidence. As the authors observed, the ability to draw such well-defined lines remains elusive.

To illustrate this point, the participants discussed the basis of certain expert testimony. While there seemed to be a consensus that "junk" science should be thrown out, there appeared to be no consensus as to the definition of "junk" science. One workshop participant claimed that "junk" science was a term used to describe evidence intended to favor plaintiffs in toxic tort cases. Another participant applied the term to studies conducted by scientists employed by corporations on whose behalf the scientist later testified at trial. By having all sides present at the workshop, it was easy to demonstrate the difficulty in standardizing "acceptable" science.

Other issues explored by the workshop involved the tension between legal and scientific viewpoints. The participants acknowledged the inequity of requiring expert witnesses to uphold higher standards of accuracy in the courtroom than in the world of science. Also cited was the issue of the absence of data. A case can be won or lost due to the lack of data, but that does not necessarily refute causation. It was observed that a variety of situations could result in a lack of data. A study may not have been feasible due to the lack of technology or funding. Alternatively, it may have been feasible, but not undertaken. Discussion of this issue provided an appreciation of the difficulties in acquiring reliable evidence.

This is one of the many reasons why scientists may be reluctant to testify. The legal system is an adversarial one. Some of the scientific participants voiced concerns about being embarrassed publicly, or misunderstood. As some of the scientific participants observed, it is very possible for two scientists to disagree on a subject in good faith, without implying that a theory is either weak or strong. No hypothesis can be labeled "permanently true" because the available data are constantly changing. Therefore, in the legal forum, it is unrealistic to expect a scientist to give an absolute answer. The authors discussed options for providing the courts a better understanding of the information being presented, as well as its limitations.

Perhaps one of the largest topic addressed was causation. The discussion of relative risk within the book brings forth an issue that is paramount in toxic tort cases. Because there are no uniform standards, some courts adopt their own. Some of these courts require a relative risk higher than 2.0 in order to establish causality.³ However, scientists are concerned about such distinct parameters. Among the list of reasons is the observation that there is no basis to use the 2.0 standard as opposed to any other standard. Such a standard would permit entering evidence showing a 2.0 risk, but evidence with a 1.9 standard would be excluded. Therefore, if an agent or condition is associated with a risk level of less than 2.0, the court will not determine it to be likely causation for a plaintiff's injury, even if there is some evidence that the agent or condition is associated with a higher risk.⁴ This problem demonstrates the gap between legal and scientific disciplines which can only be closed through improved communication.

Through its diverse participants, this workshop successfully portrayed the issues faced by the legal community while assessing expert testimony. This report is a valuable guide to important issues in evaluating the admission or exclusion of scientific evidence. It is available at www.nap.edu.

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¹ See, Daubert v. Merrrel Dow Pharmaceuticals, Inc., 113 S. Ct. 2786 (1993), General Electric Co. v. Joiner, 118 S.Ct. 512 (1997), Kumho Tire Co. LTD. v. Carmichael, 119 S.Ct. 1167 (1999).

² Fed. R. of Ev. 702.

³ "By definition, an agent that creates a health risk of 2.0 is said to double the risk. Similarly, an agent that creates a health risk of 1.2 is said to increase a risk by 20 percent, and so on." Science, Technology, and Law Panel, National Research Council, The Age of Expert Testimony: Science in the Courtroom, Report of a Workshop 20 (2002).

⁴ Science, Technology, and Law Panel, National Research Council, The Age of Expert Testimony: Science in the Courtroom, Report of a Workshop 20 (2002).

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