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CASE Transcripts

Court Appointed Scientific Experts

The Role of Science in Making Good Decisions
Mark S. Frankel, Ph.D.
June 10, 1998

Mr. Chairman, members of the Committee, my name is Mark Frankel. I head the Program on Scientific Freedom, Responsibility and Law in the Directorate for Science and Policy Programs at the American Association for the Advancement of Science (AAAS). Founded in 1848, AAAS is the world’s largest federation of scientific and engineering societies, with nearly 300 affiliates. This year we are celebrating our 150th anniversary.

The Association supports the House Science Committee’s undertaking of a National Science Policy Study and just last month submitted a formal statement presenting its views on key issues to be addressed in the development of a new science policy. (The May 1998 statement issued by the AAAS Board of Directors is titled, A Framework for Federal Science Policy.) I welcome, therefore, this opportunity to testify before you today on the role of science in informing legal and policy decisions that have substantial scientific or technical components.

These matters have long been an integral part of the AAAS mandate, which charges us with improving “the effectiveness of science in the promotion of human welfare.” The Association has in various public statements over the years advocated the incorporation of good scientific research and information into the public policy process. And we have put in place a series of programs intended to do just that. More than twenty years ago, AAAS created and has since administered the Congressional Science and Engineering Fellowship Program, which has sponsored more than 500 scientists and engineers who have worked on the staffs of more than 200 personal and committee offices in the House and Senate. Similar programs have placed science and engineering Fellows in the U.S. Department of State, the U.S. Agency for International Development, the Environmental Protection Agency, the White House Office of Science and Technology Policy, and other federal agencies. These programs have been widely recognized as making a valuable contribution to the use of science and technology by policy makers in both the legislative and executive branches of government.

Science, of course, is only one factor to be considered when making public policy. It is, however, a critical one because of its limiting or empowering effects on decisions. This holds true whether the decisions are being made in regulatory agencies, Congress, or the courts. It is the latter which is the focus of my testimony today.

Courts are increasingly faced with litigation that presents complex issues of science and technology. In an address to the February 1998 AAAS Annual Meeting, Associate Justice Stephen Breyer of the U.S. Supreme Court observed that the law “increasingly requires access to sound science….because society is becoming more dependent for its well-being on scientifically complex technology,…[T]his technology,” he went on to state, “underlies legal issues of importance to all of us.” He then proceeded to refer to several cases on the Supreme Court’s docket for the 1997-98 term that were profoundly affected by the presence of highly technical considerations. The consequences of such litigation have also grown due to the high stakes involved, often financial, but as the two right-to-die cases decided last year by the Supreme Court [Washington v. Glucksberg, 117 S. Ct. 2258 (1997); Vacco v. Quill, 117 S. Ct. 2293 (1997)] demonstrate, life and death as well.

In light of this increasingly complex litigation, questions have been raised about the ability of judges or juries to make reasoned decisions. Indeed, the Carnegie Commission on Science, Technology, and Government’s 1993 report, Science and Technology in Judicial Decision Making, referred to “widespread allegations that the judicial system is increasingly unable to manage and adjudicate science and technology…issues” (p. 11). The Commission went on to state that “If these claims go unanswered, or are not dealt with, confidence in the judiciary will be undermined as the public becomes convinced that the courts as now constituted are incapable of correctly resolving some of the most pressing legal issues of our day” (p. 11).

The primary way that we educate judges and juries on complex scientific matters is through the use of expert witnesses, almost always retained by the parties to the litigation, airing their differences in an adversarial setting. Serious reservations have been expressed about this approach, however, some by judges themselves. In a 1991 survey of federal trial judges, the Federal Judicial Center found that “Judges’ doubts regarding the credibility of testimony by the parties’ experts were common,” with one commenting that “The main issue is whether the parties’ experts are ‘real’ experts or simply ‘hired guns’” (Joe Cecil and Thomas Willging. “Court-Appointed Experts: Defining the Role of Experts Appointed Under Federal Rule of Evidence 706,” Federal Judicial Center, 1993).

This uneasiness with parties’ experts is heightened by the fact that the adversarial system, relying as it does on critical cross-examination to expose weaknesses in a witness’ testimony, is often ill suited to educating the trier of fact, whether it be judge or jury. Rather, what often occurs is that experts from the two parties are pitted against one another, with lawyers on each side trying to destroy the credibility of the other party’s witness. Such tactics are not likely to enlighten either judges or juries about the validity of a scientific methodology or of the conclusions drawn from disparate data.

Questions regarding the validity of scientific evidence and the credentials of some experts are the background to the Supreme Court’s 1993 decision in Daubert v. Merrell Dow Pharmaceuticals, Inc. The plaintiffs in the lawsuit were two minor children and their parents who claimed that the children’s birth defects had been caused by their mothers’ prenatal use of the anti-nausea drug, Bendectin. The Federal District Court granted the defendant summary judgment, ruling that plaintiff’s evidence did not meet a standard of “general acceptance” within the scientific community. Eventually, the Supreme Court was called upon to determine the proper standard for the admissibility of expert scientific testimony in federal trials.

AAAS joined with the National Academy of Sciences in filing an amici curiae brief in the case. Our purpose in filing this brief was not to comment on the alleged teratogenicity of Bendectin, a matter on which the Association has no particular expertise. Rather, we were motivated by our strong belief thatthe courts would benefit from an impartial view on what constitute the best procedures, methods, and standards for the courts to use in evaluating expert testimony and evidence. We took the position that the “courts have the authority and the responsibility to exclude expert testimony that is based upon unreliable or misapplied methodologies,” and urged that the courts “accomplish this difficult task by applying the same criteria that scientists themselves regularly apply in picking and choosing the theories, explanations, and methods upon which they build their own work.”

In what has turned out to be a landmark decision, the Court ruled in Daubert that federal trial judges must act as gatekeepers in order to exclude unreliable evidence from the courtroom. The Court stressed that a trial judge must determine “whether the reasoning or methodology underlying the testimony is scientifically valid,” and will “assist the trier of fact.” In urging judges to think like scientists, the Court cited the AAAS/NAS brief to the effect that “Science is not an encyclopedic body of knowledge about the universe. Instead it represents a process for proposing and refining theoretical explanations about the world that are subject to further testing and refinement” (113, S. Ct. 2795).

In December 1997, the Supreme Court issued an opinion in another case that addressed scientific evidence, General Electric Co. v. Joiner. Although the central issue in that case was the appropriate standard of appellate review following a trial judge’s decision to exclude testimony, the Court also gave further guidance for reviewing scientific evidence. While Daubert drew a distinction between how an expert draws conclusions, that is, the methods employed, and the conclusions themselves, Joiner held that methodology and conclusions are not entirely distinct and may be considered as linked together. That is, if an expert’s conclusion is not supported by valid reasoning, it should be excluded.

While it is too soon to assess the effects of the Joiner decision, Daubert’s impact has been considerable. As of January 1998, Daubert had been cited in more than 1100 decisions, about two-thirds of which were in federal courts. A review of those cases has concluded that “Most trial judges have heeded the Supreme Court’s admonition to act as gatekeepers, and their review of admissibility is generally more detailed and in depth than in pre-Daubert cases” (Bert Black. “Post-Daubert and Joiner Caselaw: The Good, the Bad, and the Ugly,” unpublished manuscript).

To respond to the challenges posed by the heavy load of cases involving complex scientific matters, generally, and by the post Daubert/Joiner decisions, particularly, AAAS has proposed a Demonstration Project that would identify highly-qualified, impartial experts to advise and educate the courts in the scientific and technical fields involved in the decisions they must make. Dauberthas asked judges to evaluate evidence for its admissibility according to criteria that scientists apply in their rigorous. review of each other’s work. Joiner has likely made this task more difficult by instructing trial judges that neither Daubert nor the Federal Rules of Evidence “requires a district court to admit opinion evidence which is connected to existing data only by the ipse dixit of the expert.[that is, when the sole authority for the assertion is the fact that the expert himself said it]. A court may conclude that there is simply too great an analytical gap between the data and the opinion proffered.”

In light of these challenges, it is reasonable to expect that judges will increasingly call upon court-appointed experts for assistance. Federal Judge Jack Weinstein thinks this way as well, observing in 1994 that due to the Daubert decision “Rule 706 of the Federal Rules of Evidence [which gives federal judges the authority to appoint their own experts] will be relied upon more frequently.Daubert hearings will be required, and a deeper appreciation of scientific issues by judges will be expected” (“Learning, Speaking, and Acting: What Are the Limits for Judges?” Judicature, 1994, p. 326 ). However, several of the judges interviewed for the Federal Judicial Center survey referred to earlier voiced concern with the difficulty in identifying such experts and commented on the need for greater access to candidates who are both independent and knowledgeable.

We are confident that judges will take advantage of the AAAS offer to provide a slate of candidates to serve as court-appointed experts in cases in which the court has determined that the traditional means of clarifying issues under the adversarial system are unlikely to yield the information that is necessary for a reasoned and principled resolution of the disputed issues. These experts can serve as a sounding board for the court as it considers the scientific significance of the evidence, and are well positioned to assess the degree to which proffered evidence conforms to scientific standards, whether it is based on methods generally accepted by the scientific community as valid and reliable, and whether the connection between data and conclusions is well reasoned.

The Demonstration Project, which has been developed over a period of several years under the auspices of the AAAS-American Bar Association Science and Technology Section National Conference of Lawyers and Scientistswould be implemented over a period of five years, be national in scope, and available to the federal courts. AAAS will serve as the locus of a coordinating mechanism between the courts and the scientific and engineering communities, working closely with other scientific and engineering societies, research institutions, and other resources. A project advisory board, composed of judges, attorneys from the defense and plaintiff’s bars and legal scholars, and representatives from the science and engineering communities, will oversee all aspects of the project. They will appoint several subcommittees to help project staff conduct the demonstration. A formal evaluation will be done by the Federal Judicial Center, the research and education arm of the federal judicial system. There will be two dimensions to the evaluation: one will focus on the operations of the coordinating mechanism and the other will be a qualitative assessment of how the demonstration affected the cases in which it was used.

I can provide more details about how the AAAS Demonstration Project will work following my oral testimony, if you wish. Let me simply conclude by noting that the appropriateness of court-appointed experts to assist trial judges in meeting their new responsibilities has been reinforced in both the Daubert and Joiner opinions. Justice Breyer, in a Concurring Opinion in Joiner, cited AAAS as an appropriate organization to fill this role. And in his address at the 1998 AAAS Annual Meeting, he specifically endorsed the AAAS Demonstration Project.

Mr. Chairman, thank you again for this opportunity to address an important set of issues, to review our proposal for responding to a critical aspect of those issues as they unfold in the decision-making processes of the judiciary, and to contribute to your development of a new science policy for the nation.

The Interdependence of Science and Law
Associate Justice Stephen G. Breyer
April 24, 1998

The practice of science depends on sound law that at a minimum supports science by offering the scientist breathing space, within which he or she may search freely for the truth on which all knowledge depends. It is equally true that the law itself increasingly requires access to sound science. This need arises because society is becoming more dependent for its well-being on scientifically complex technology, so, to an increasing degree, this technology underlies legal issues of importance to all of us. We see this conclusion illustrated throughout the legal system.

Consider, for example, the U.S. Supreme Court’s docket. Two cases the Court heard last year concerned the right to die.1 The specific legal question was whether the federal Constitution, which prohibits government from depriving “any person” of “liberty” without “due process of law,” requires a state to permit a doctor’s assistance in the suicide of a terminally ill patient. Is that “right to assisted suicide” part of the liberty that the Constitution protects? Underlying the legal question was a medical question: To what extent can medical technology reduce or eliminate the risk of dying in severe pain? The medical question did not determine the answer to the legal question, but to do our legal job properly we needed to develop an informedalthough necessarily approximateunderstanding of the state of that relevant scientific art.

Nor is the right-to-die case unique in this respect. A different case in 1992 challenged the constitutionality of a state sexual psychopath statute. The law required a determination of when a person is both dangerous and mentally ill to the point that the public safety may justify indefinite non-criminal confinement, a question that implicates science and medicine as well as law.2 One case on our docket this year concerns the sharing of responsibilityby juries, trial judges, and appellate judgesfor determining such scientific matters as the potential toxicity or carcinogenicity of chemical substances, such as Bendectin or PCBs. A different criminal case involves the reliability of polygraph lie detector tests. A third case investigates whether scientific advances in proving paternity may influence statutes that confer citizenship on children born out of wedlock.

The U.S. Supreme Court’s docket is only illustrative. Scientific issues permeate the law. Criminal courts consider the scientific validity of, say, DNA sampling, or voice prints, or expert predictions of defendants’ “future dangerousness,” which can lead courts or juries to authorize or to withhold the punishment of death. Courts review the reasonableness of administrative agency conclusions about the safety of a drug, the risks attending nuclear waste disposal, the leakage potential of a toxic waste dump, or the risks to wildlife associated with the building of a dam. Patent law cases can turn almost entirely on an understanding of the underlying technical or scientific subject matter. And, of course, tort law, which assesses civil liability for injury or death, often requires difficult determinations about the degree of risk of death or injury associated with a chemical ingredient of a pesticide or other product.

The importance of scientific accuracy in the decision of such cases reaches well beyond the case itself. A decision wrongly denying compensation in a toxic substance case, for example, can deprive not only the plaintiff of warranted compensation but can discourage other similarly situated individuals from even trying to obtain compensation and can encourage the continued use of a dangerous substance. On the other hand, a decision wrongly granting compensation, although of immediate benefit to the plaintiff, through the strong financial disincentives that accompany a finding of tort liability, can improperly force abandonment of the substance. Thus if the decision is wrong, it will improperly deprive the public of what can be far more important benefitsthose surrounding a drug that cures many while subjecting a few to less serious risk, for example. The upshot is that we must search for law that reflects an understanding of the relevant underlying science, not for law that frees companies to cause serious harm or forces them unnecessarily to abandon the thousands of artificial substances on which modern life depends.

That search is not a search for scientific precision. One could not hope to replicate the subtleties and uncertainties that characterize good scientific work. A judge is not a scientist, and a courtroom is not a scientific laboratory. Consider the remark made by the physicist Wolfgang Pauli. After a colleague asked whether a certain scientific paper was wrong, Pauli replied,3 ”Oh, no. Certainly not. That paper is not good enough to be wrong.” That is our objective. It is to avoid legal decisions that reflect that paper’s so-called science. Rather, the law must seek decisions that fall within the boundaries of scientifically sound knowledge and approximately reflect the scientific state of the art.

This objective is sometimes difficult to achieve in practice. The most obvious reason is that most judges lack the scientific training that might facilitate the evaluation of scientific claims or the evaluation of expert witnesses who make such claims. They typically are generalists, dealing with cases that can vary widely in subject matter. Their primary objective is usually process-related: that of seeing that a decision is reached fairly and in a timely way. And the decision in a court of law typically (though not always) focuses on a particular event and specific individualized evidence.

Furthermore, science itself may be highly uncertain and controversial with respect to many of the matters that come before the courts. Scientists often express considerable uncertainty about the dangers of a particular substance. And their views may differ about many related questions that courts may have to answer. What, for example, is the relevance to human cancer of studies showing that a substance causes some cancers, perhaps only a few, in test groups of mice or rats? What is the significance of extrapolations from toxicity studies with high doses of a substance to situations where the doses are much much smaller? Can lawyers or judges or anyone else expect scientists always to be certain or always to have uniform views with respect to an extrapolation from a large to a small dose, when the causes of and mechanisms related to cancer are generally not well known? Many difficult legal cases fall within the heartland of this kind of scientific uncertainty.

Finally, a court proceeding, such as a trial, is not simply a search for dispassionate truth. The law must be fair. In our country, it must always seek to protect basic human liberties. One important procedural safeguard, guaranteed by our Constitution’s Seventh Amendment, is the right to a trial by jury. Any effort to bring better science into the courtroom must respect the jury’s constitutionally specified roleeven if doing so means that, from a scientific perspective, an incorrect result is sometimes produced.

Despite the difficulties, I believe there is an increasingly important need for law to reflect sound science. I remain optimistic about the likelihood that it will do so. It is common to find cooperation between governmental institutions and the scientific community where the need for that cooperation is apparent. Today, as a matter of course, the president works with a science adviser, Congress solicits advice on the potential dangers of food additives from the National Academy of Sciences, and a scientific regulatory agency will often work with outside scientists, as well as their own, to develop a product that reflects good science.

The judiciary, too, has begun to look for ways to improve the quality of the science on which scientifically related judicial determinations will rest. In the U.S. Supreme Court, as a matter of course, we hear not only from the parties to a case but also from outside groups, which file briefs30-page amicus curiae briefsthat help us to become more informed about the relevant science. In the “right-to-die” case, we received about 60 such documents from organizations of doctors, psychologists, nurses, hospice workers, and handicapped persons, among others. Many discussed pain control technology, thereby helping us to identify areas of technical consensus and disagreement. Such briefs help to educate the judges on potentially relevant technical matters, helping to make us, not experts, but moderately educated laypersons, and that education improves the quality of our decisions.

Moreover, our Court recently made clear4 that the law imposes on trial judges the duty, with respect to scientific evidence, to become evidentiary gatekeepers. The judge, without interfering with the jury’s role as trier of fact, must determine whether purported scientific evidence is “reliable” and will “assist the trier of fact,” thereby keeping from juries testimony that, in Pauli’s sense, isn’t even good enough to be wrong. Trial judges, looking for ways to perform this function better, increasingly have used pretrial conferences to narrow the scientific issues in dispute, pretrial hearings where potential experts are subject to examination by the court, and the appointment of specially trained law clerks or scientific special masters.

Judge Weinstein of New York suggests that courts sometimes “go beyond the experts proffered by the parties” and “appoint independent experts” as the federal Rules of Evidence allow.5 Judge Rosen of Michigan recently appointed a University of Michigan Medical School professor to testify as an expert witness for the court, helping to determine the relevant facts in a case challenging a Michigan law prohibiting partial-birth abortions.6 Judge Stearns of Massachusetts, acting with the consent of the parties in a recent, highly technical, genetic engineering patent case,7 appointed a Harvard Medical School professor to serve “as a sounding board for the court to think through the scientific significance of the evidence,” to “assist the court in determining the validity of any scientific evidence,” and to “assist the court in determining the validity of any scientific evidence, hypothesis or theory on which the experts base their economy.”

These techniques are neutral, in principle favoring neither plaintiffs nor defendants. When used, they have typically proved successful. Nonetheless, judges have not often invoked their Rules-provided authority to appoint their own experts. They may hesitate simply because the process is unfamiliar or because the use of this kind of technique inevitably raises questions. Will use of an independent expert, in effect, substitute that expert’s judgment for that of the court? Will it inappropriately deprive the parties of control over the presentation of the case? Will it improperly intrude on the proper function of the jury? Where is one to find a truly neutral expert? After all, different experts, in total honesty, often can interpret the same data differently. Will the search for the expert create inordinate delay or significantly increase costs? Who will pay the expert? Judge Acker of Alabama writes:8 ”Unless and until there is a national register of experts on various subjects and a method by which they can be fairly compensated, the federal amateurs wearing black robes will have to overlook their new gatekeeping function lest they assume the intolerable burden of becoming experts themselves in every discipline known to the physical and social sciences, and some as yet unknown but sure to blossom.”

The AAAS, working with the American Bar Association and Federal Judicial Center, has begun to explore these matters with an eye toward finding practical ways to provide scientific help: a pilot project to test the feasibility of increased use of court-appointed experts in cases that present technical issues. The project “will provide a slate of candidates to serve as court-appointed experts in cases in which the court has determined that the traditional means of clarifying issues under the adversarial system are unlikely to yield the information that is necessary for a reasoned and principled resolution of the disputed issues.” The project might also examine in some detail instances in which courts have successfully used their own outside experts. How were those experts identified? How might this better be done? How did the court, while protecting the interests of the lawyers and the parties they represent, also protect the experts from unreasonable demands, say on their time? How did the court prepare the expert to encounter what may be an unfamiliar and sometimes hostile legal environment?

The project might also ask whether criteria emerge that help to determine when a court-appointed expert will prove useful and whether that expert might better serve in an adviser-type or witness-like capacity. It would undoubtedly also be helpful to recommend methods for efficiently educating (that is, in a few hours) willing scientists in the ways of the courts, just as it would be helpful to develop training that might better equip judges to understand the ways of science and the ethical, as well as the practical and legal, aspects of the matter.9 The answers to some of these questions will help determine the practicality of promising methods to help bring science and law closer together.

I believe that in this age of science we must build legal foundations that are sound in science as well as in law. Scientists have offered their help. We in the legal community should accept that offer, and we are in the process of doing so. The result, in my view, will further not only the interests of truth but also those of justice. The law will work better to resolve many of the most important human problems of our time.


1. Washington v. Glucksberg, 117 S. Ct. 2258 (1997); Vacco v. Quill,117 S. Ct. 2293 (1997).

2. Kansas v. Hendricks, 117 S. Ct. 2072 (1997).

3. P. W. Huber, in Galileo’s Revenge (Harper Collins, New York, 1991), p. 54.

4. General Electric Co. v. Joiner, 118 S. Ct. 512 (1997).

5. J. Weinstein, in Individual Justice in Mass Tort Litigation (Northwestern Univ. Press, Evanston, IL, 1995), p. 116.

6. Evans v. Kelley, 977 F. Supp. 1283 (E. D. Mich. 1997).

7. Amgen v. Biogen, 973 F. Supp. 39 (D. Mass. 1997).

8. Letter from Judge Acker to the Judicial Conference of the United States, et al., 2 January 1998.

9. G. Omenn, Environ. Health Perspect. 102, 674 (1994).

Associate Justice Stephen G. Breyer is an associate justice of the Supreme Court of the United States. The text is revised from an address given 16 February 1998 at the 150th Annual Meeting of the American Association for the Advancement of Science. Reprinted with permission from Science, April 24, 1998, 280, pp. 537­538. Copyright 1998 AAAS.


Court Appointed Scientific Experts
1200 New York Ave NW
Washington, DC 20005
Phone: (202) 326-6794
Fax: (202) 289-4950

Original funding for this project came from the Lelan Fikes Foundation and the Open Society Institute