Conflicts of interest in scientific expert testimony.

• Author: Patterson, Mark R.

INTRODUCTION

Bias in privately funded scientific research has been much in the news recently.(1) Research bias causes problems in various contexts, from medical decisionmaking(2) to regulatory evaluations, (3) but the problems it presents are particularly acute in litigation. Scientific evidence is difficult for lay fact finders to assess under the best of circumstances. Bias exacerbates this difficulty because the same unfamiliarity with the practice of science that makes it difficult for laypersons to assess scientific evidence also makes it difficult for them to appreciate how bias can corrupt that evidence. Therefore, even though bias in general is a problem with which the adversary process is familiar, bias in scientific research may require an approach tailored to the particular difficulties that arise in that context.

Of course, the problem of bias in scientific evidence has not gone unnoticed by courts and commentators.(4) But most efforts to address the problem have focused on biased witnesses rather than on biased researchers.(5) These efforts, in other words, have focused on bias introduced in the process of testifying and have assumed that the underlying research record itself is unbiased.(6) An important example, because of its influence, is the Ninth Circuit's opinion in Daubert v. Merrell Dow Pharmaceuticals, Inc.(7) In that opinion--to which this Article will refer as Daubert II--the court asked "whether the experts are proposing to testify about matters growing naturally and directly out of research they have conducted independent of the litigation, or whether they have developed their opinions expressly for purposes of testifying."(8) The court then went on to treat research conducted independent of litigation as reliable, ignoring the many other, nonlitigation sources of research bias.(9)

The weakness in this approach is apparent when one considers that a court would admit, apparently without further scrutiny, testimony regarding research funded by parties to litigation, so long as the research was not conducted in connection with the litigation. For example, in a suit challenging the safety of a drug, it would admit--again, without further scrutiny--research on the safety of the drug that was funded by its manufacturer, if the research predated the litigation. Yet the scientist conducting that research would be no less aware of the result desired by the manufacturer than would a scientist conducting similar research in connection with the litigation. Hence, Daubert II's litigation-based test does not draw an appropriate line for admissibility.

Daubert II is surely correct, though, in treating bias as part of the more general problem of evidentiary reliability that was the focus of the Supreme Court in its Daubert opinion.(10) In Daubert, the Court held that, when considering scientific evidence, "evidentiary reliability will be based on scientific validity."(11) Bias certainly is an element of reliability; therefore, although Daubert did not discuss bias problems specifically, the opinion at least suggested that the Court would have bias issues decided in court as science decides them. Indeed, science has adopted procedures for dealing with bias that are in some respects similar to other scientific practices--such as peer review--to which the Court directed judges to defer.(12)

This Article argues, however, that a reading of Daubert that requires a scientific approach to conflicts would be inappropriate. Bias is no more a valid part of scientific fact finding than it is of legal fact finding. The approaches of scientists to managing conflicts of interest therefore are not themselves scientific, but are simply efforts to preserve the objectivity of science. There is no particular reason to think that the same methods would be appropriate for ensuring objectivity in litigation, which is a very different discipline.

Moreover, even in litigation, different sorts of conflicts present different problems. The focus of Daubert II was on conflicts introduced by the litigation process. These conflicts may indeed be serious ones, but it is not clear that they are difficult ones for fact finders to appreciate. They are, after all, the same sorts of conflicts that are presented by the testimony of interested fact witnesses. The conflicts of scientists whose pre-litigation research is the subject of testimony are very different. Those conflicts may be reflected in subtle research choices whose implications will be very difficult for legal fact finders to assess. Hence, it may be that in making admissibility decisions courts should be more careful regarding purely "scientific" conflicts than they are regarding litigation-related ones.(13)

Part I of this Article outlines the holding and rationale of Daubert, noting that the reasoning of the Court in that case generally applies to conflicts of interest as well as to the specific aspects of scientific practice the Court discussed. Part II then reviews current treatment of the conflicts of scientific expert witnesses in the lower courts and shows that it is inconsistent in several respects with scientific treatment of such conflicts. Part III argues, as suggested above, that the courts are nevertheless correct in developing their own approach to conflicts because conflicts pose different dangers in legal fact finding than they do in science. Finally, Part IV proposes an approach to conflicts of interest in scientific expert testimony that not only takes into account the different contexts of law and science, but also recognizes the distinction between the conflicts of scientific expert witnesses and those of scientific researchers.

1. CONFLICTS OF INTEREST AND THE DAUBERT FRAMEWORK

   The starting point in considering the admissibility of scientific evidence is Daubert v. Merrell Dow Pharmaceuticals, Inc.(14) in which the Supreme Court set out criteria for trial judges to use in making admissibility decisions.(15) Although the Court did not explicitly consider the issue of bias,(16) its rationale for directing judges to apply scientific standards in making admissibility decisions appears as applicable in the context of bias as in other aspects of evidentiary reliability.

   1. Daubert

      Federal Rule of Evidence 702 provides that an expert may testify to "scientific ... knowledge" that "will assist the trier of fact."(17) In Daubert, the Supreme Court read these two quoted phrases to impose two more or less independent criteria for admissibility: reliability and "fit," or relevance.(18) It is the former criterion that applies to the issues addressed in this Article; the latter asks only whether the proffered scientific evidence "properly can be applied to the facts in issue."(19)

      In articulating a reliability requirement, the Supreme Court began from the reference in Rule 702 to "scientific knowledge": "The adjective scientific implies a grounding in the methods and procedures of science. Similarly, the word knowledge connotes more than subjective belief or unsupported speculation."(20) The Court then provided a set of five factors that it held were relevant to determining whether proffered testimony is both "scientific" and sufficiently well supported to constitute "knowledge."(21) The factors are: (1) whether the expert's "theory or technique" can be, and has been, tested; (2) whether it has been subjected to peer review and publication; (3) whether, if the expert's testimony is the product of a "particular scientific technique," the technique has an acceptable known or potential rate of error; (4) whether, again if a particular technique is involved, the application of that technique complies with any standards governing its operation; and, finally, (5) whether the testimony is generally accepted in the scientific community.(22) Each of these factors--except perhaps the third: error rate--is a reference to scientific theory or practice.

      Notably absent from this list is any mention of the possible biases or conflicts of interest of the expert. The Court made clear, however, that its list of factors is not exhaustive.(23) This caveat suggests that conflicts would be a legitimate factor to consider, at least to the extent that they affect evidentiary reliability. The manner in which courts would take conflicts into account is unclear, though. The Court indicated that other approaches to the reliability issues it addressed could "have merit," but apparently only "[t]o the extent that they focus on the reliability of evidence as ensured by the scientific validity of its underlying principles."(24) This statement seems to suggest that conflicts, like other issues of reliability, should be assessed based on their scientific significance, but this is not the approach the lower federal courts have taken.

   2. Conflicts of Interest and Evidentiary Reliability

      Conflicts of interest-or, more generally, biases--can affect evidentiary reliability. Courts generally handle biases of expert witnesses in the same way they handle biases of fact witnesses, by permitting cross-examination about the biases and allowing the fact finder to assess the overall credibility of the witnesses.(25) As suggested above, though, conflicts of interest may present particular problems for scientists and for laypersons assessing their testimony. Perhaps, therefore, courts should treat biases in scientific expert testimony differently than biases in other expert testimony.(26) It is, of course, exactly that sort of distinct treatment of scientific expert testimony that the Supreme Court established in Daubert when it wrote that, in regard to such testimony, "evidentiary reliability will be based on scientific validity."(27)

      Some lower courts, however, have taken a different, and perhaps inconsistent, approach.(28) These courts have considered issues of bias in the admissibility decision, as the unique characteristics of scientific evidence suggest might be appropriate. But instead of...