In 1993, the Supreme Court decided DAUBERT v. MERRELL DOW PHARMACEUTICALS, INC. weighing in on one of the then most pressing issues in
the law of evidence: what was the appropriate standard for admitting expert evidence in federal court? The Court directed that district judges act as "gatekeepers" by ensuring that proffered expert evidence was both relevant and reliable. To make this determination, judges were to examine the reasoning of the expert and the methods used to draw conclusions and develop opinions. In so doing, the Court rejected the mechanical test used by some courts that had restricted the district judge's role to an evaluation of whether the expert's position was "generally accepted" in the relevant field.

The real world impact of the DAUBERT decision in civil cases in federal court is the topic of Lloyd Dixon and Brian Gill's Rand Institute study. The study's bottom line is that "it appears that judges are indeed doing what they were directed to do by the Supreme Court: they are increasingly acting as gatekeepers for reliability and relevance, they are examining the methods and reasoning underlying the evidence, and they appear to be employing general acceptance as only one of many factors that enter into their reliability assessments" (p. xiii). Although modest in appearance, this study should not be underestimated. It makes a valuable, if incremental
contribution to the evolving understanding of how the DAUBERT standard is actually working.

The study is structured in eight chapters, presented along with a useful introductory summary as well as four detailed appendices devoted principally to statistical information underlying the study's conclusions. The authors begin by setting the stage for the study (Chapter 1). They then provide an overview or what they term a "conceptual analysis" of DAUBERT with respect to the disposition of challenged expert evidence, including a discussion of the respective roles of the parties and the court in the process (Chapter 2). After explaining their methodology (Chapter 3), Dixon and Gill present their empirical findings (Chapters 4 through 7). Finally,
they summarize their principal findings as well as their suggestions for future study to address areas beyond the scope of their report (Chapter 8). Overall, the structure of the report is conducive to either a quick read or a more detailed analysis.

The authors based their study on a review of 399 federal district court opinions issued between January 1980 and June 1999. The district court judges made rulings with respect to the admissibility of 601 separate

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pieces of expert evidence the parties proffered in these cases. Thirty-eight percent of these pieces of evidence were in the period prior to DAUBERT while the remaining sixty-two percent concerned post-DAUBERT evidentiary decisions (pp. 19-20).

As explained in detail in the study, the authors attempted to analyze the data in such a way as to control for variables other than the DAUBERT decision that could have had an effect on the trends noted in the admission of expert evidence. Such efforts included controlling for case type (e.g., product liability, antitrust, non-employment civil rights, etc.), federal circuit, and substantive type of evidence (e.g., medical, social science, business, etc.) (pp. 19-24). I will not try to describe the study's control efforts here. Suffice it to say, the authors provide a full and convincing explanation of their methods and the bases for the conclusions they draw from the data.

The principal contribution of the study is its well-supported conclusion that judges actually have changed their scrutiny of expert evidence after DAUBERT in accord with the Supreme Court's direction. Without such empirical work, we would be left with nothing more than a collection of anecdotes about any change. Moreover, one would never be sure if the anecdotes reflected a substantive change in the standard for admission of evidence or were merely the result of a change in terminology (i.e., simply using the word "reliability" as a means of exclusion when the substantive standard applied had not changed). In the chapters presenting their data, Dixon and Gill provide convincing support for the proposition that the changes in exclusion patterns resulted from a true shift in substance and not merely a name game (chapters 4-7).

Along the way, the study also sets out other interesting findings, equally well-supported by the data, concerning the admission of expert evidence. For example, it appears that in addition to increasing their scrutiny of expert evidence based on reliability, district judges also generally took a more detailed approach to the consideration of expert evidence after DAUBERT, including conducting a more searching review of relevance and expert qualifications (chapter 6.2). In short, it appears that judges began to feel more empowered to enter into what could have been seen as the general province of the jury before DAUBERT.

In addition, the data collected as part of the study indicate that the DAUBERT decision appears to have started an almost iterative process between judges evaluating evidence on the one hand and lawyers either proposing or challenging that evidence on the other. As explained by Dixon and Gill, for example, it seems that in the first years after DAUBERT the rate of evidence excluded based on a lack of reliability rose. In about 1997, the percentage of such excluded evidence began to decline. The authors hypothesize that this decline could have been caused by several possible factors concerning the behavior of the advocates, including, for example, a decision by proponents to be more conservative in what evidence they tried to admit (p. 31). In any event, the discussion of this process may be of interest to those who think and write about civil litigation more generally.

Of course, this study does not address all of the questions that DAUBERT and its progeny still raise. However, the authors are quite clear that they understand that their study has limits. In fact, one of the study's strengths is its recognition of what still needs to be addressed (pp. 64-66). The

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principal question that is not addressed in this study, and perhaps the single most vexing question in this area today, as well as being the major basis of Chief Justice Rehnquist's dissent in DAUBERT itself, is whether district judges are doing, or are able to do, a good job as gatekeepers. As Dixon and Gill recognize, the fact that more evidence was excluded standing alone does not mean that such evidence was properly excluded (e.g., p. 30). The authors quite rightly suggest that further work should be done to address this question.

The study is not, however, without some minor shortcomings. For example, one avenue for additional investigation that the authors do not discuss in any great detail is a comparison of the federal experience under DAUBERT with the experiences of state courts, both those that have adopted the DAUBERT standard and those that either have rejected it or have not yet considered a change in the trial judge's role. Although the authors mention two studies that did address certain issues involving state court judges' views concerning DAUBERT, neither of those studies really goes to the heart of the issues addressed here. For example, one of them dealt with the attitudes of the judges towards DAUBERT itself. Moreover, it does not appear that there has been any study of whether non-DAUBERT states experienced any similar increase in the percentage of expert evidence excluded during the relevant period (p. 6). In short, some further discussion of these earlier
studies and what the authors believe could usefully be done with respect to a comparative analysis of state courts in this area would have been helpful.

Another part of the study I found somewhat unsatisfying concerned the authors' tentative conclusion that "[c]hallenges to expert evidence increasingly resulted in summary judgment after DAUBERT" (p. 62). To begin with, it did not appear that this conclusion had the same level of support in the data with respect to causation that the authors were so good at documenting with respect to the remainder of their work. Moreover, the authors go on to state as one of their "next steps" that they have "limited information on what effect DAUBERT has had on case outcomes" (p. 65). This latter point seems at least partially at odds with the former.

The bottom line for this study is that the very minor quibbles one can have with it in no way detract from the important contribution it makes to the study of DAUBERT and the decision's real world impact in the federal courts. One can only hope that the authors, or others, will continue to explore this topic along the lines suggested in the study itself.

CASE REFERENCE:

DAUBERT v. MERRELL DOW PHARMACEUTICALS, INC., 509 U.S. 579 (1993).

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Copyright 2002 by the author, Michael P. Allen.