5
Can Scientists and Lawyers Get Along?

“One of the questions that we ought to be considering is whether . . . [the] current system of toxic tort litigation works given these very different objectives that we have, or whether one could somehow design a system that perhaps deals better with the uncertainties in both science and the law.”

— Margaret A. Berger

It is not surprising to find that communication between legal and scientific experts in the courtroom is difficult. As a judge told the workshop, law and science are in some ways “about as different as they can be.” He enumerated some differences: (1) law is backward-looking and its findings are based on precedent. If the judiciary had a bumper sticker, said the judge, it would say “Nothing new under the sun.” Science is forward-looking in assuming that the truth is not yet fully known; (2) propositions to be tested in science are predictive; experiments are designed to be repeatable. Theories to be proved in court arise out of situations that occurred in the past and cannot be repeated; (3) scientists recognize that “truth” is mutable and may evolve over long periods of time. In adjudication, “truth,” at least for the limited purpose of resolving disputes, must become final in a relatively short time; (4) scientists are often uncomfortable in the courtroom, especially during cross-examination. The dialogue is controlled by the lawyers and the judge, not by the expert witness; (5) disputes in science are resolved over time by peer review and the scrutiny of the scientific community at large. Legal disputes are



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The Age of Expert Testimony: Science in the Courtroom - Report of a Workshop 5 Can Scientists and Lawyers Get Along? “One of the questions that we ought to be considering is whether . . . [the] current system of toxic tort litigation works given these very different objectives that we have, or whether one could somehow design a system that perhaps deals better with the uncertainties in both science and the law.” — Margaret A. Berger It is not surprising to find that communication between legal and scientific experts in the courtroom is difficult. As a judge told the workshop, law and science are in some ways “about as different as they can be.” He enumerated some differences: (1) law is backward-looking and its findings are based on precedent. If the judiciary had a bumper sticker, said the judge, it would say “Nothing new under the sun.” Science is forward-looking in assuming that the truth is not yet fully known; (2) propositions to be tested in science are predictive; experiments are designed to be repeatable. Theories to be proved in court arise out of situations that occurred in the past and cannot be repeated; (3) scientists recognize that “truth” is mutable and may evolve over long periods of time. In adjudication, “truth,” at least for the limited purpose of resolving disputes, must become final in a relatively short time; (4) scientists are often uncomfortable in the courtroom, especially during cross-examination. The dialogue is controlled by the lawyers and the judge, not by the expert witness; (5) disputes in science are resolved over time by peer review and the scrutiny of the scientific community at large. Legal disputes are

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The Age of Expert Testimony: Science in the Courtroom - Report of a Workshop resolved by cross-examination. Courts are not designed to determine whether scientific conclusions are correct. Participants discussed further comparisons between peer review and cross-examination. Research performed for the purpose of litigation may afford no opportunity for true peer review, especially if the results were obtained recently. One lawyer noted that cross-examination can perform this function and can itself be an incentive to perform good, transparent science, and can even drive science forward. He provided the example that DNA identification litigation had driven DNA technology standards for laboratories. LEGAL AND SCIENTIFIC VIEWPOINTS ON CAUSATION In trying to determine whether there is a causative connection between Product A and Health Effect B, the Daubert trilogy directed the courts to look to the underlying foundation of the scientific testimony. Consequently, said an academic legal expert, the courts sometime seem to assume that the scientific community and the courts are examining the same concept of causation. When courts see that evidence is inconclusive from a scientific perspective they may decide that it thereby fails the Trilogy standards and should be excluded. This is a simplistic formula-tion, said the scholar, because it neglects to take into account some of the qualities of science and how they differ from those of the law. Further, the speaker noted, it would be a mistake to assume that science and law are answering the same questions when asked to determine causation. The scientific process operates by testing hypotheses and rejecting those that are inconsistent with the data. The court system may exclude valuable knowledge from the deliberations when it excludes the results obtained in testing inconclusive hypotheses. The courts need to ask themselves, she said, whether such stringent scientific standards make sense in the legal setting. The legal process approaches causation in a different way. A not-proven verdict in the courtroom has a clear significance. If one party fails to make a convincing case to the jury, it does not mean that more research should be done or that an assertion should be improved. It means that the party loses the case. A “LIKELIER THAN NOT” STANDARD On many issues of causation in tort law, pointed out a lawyer, there is scientific uncertainty. Yet in order to win the plaintiff does not have to prove beyond a reasonable doubt that the defendant caused the injury; the cause must only be “likelier than not.”

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The Age of Expert Testimony: Science in the Courtroom - Report of a Workshop One lawyer urged scientists to come up with a similar standard. “If there is one core thing that we lawyers would love to have from scientists,” he said, “it is a better education of us and of judges on, if you will, a ‘science of likelier than not.’” Such a science would clarify how much and what kinds of evidence would permit a scientific expert to make an educated guess about what is “likelier than not.” He suggested that physicians must do this all the time because they have no choice. Physicians often do not know how to treat a patient, but they have to choose the best answer and treat accordingly. This is what the law would like from scientific testimony.18 Several participants discussed the idea of “relative allocation” or proportional recovery. This is done in comparative negligence cases, where, for example, multiple manufacturers have contributed to a chemical or waste spill whose effects have a long latency period. Similarly, suggested one judge, rather than requiring a bright-line, yes-or-no decision in every case based on scientific evidence, the law should be allowed to allocate responsibility and force a manufacturer to pay half of the cost, say, of a future insurance policy to clean up the spill. This would be an attempt to move the law in the direction of recognizing the uncertainties of risk and expert evidence. An industry representative reminded the workshop participants not to look at pieces of evidence in isolation. He pointed out that the law no longer requires some of the elements of traditional tort in product liability cases. The balance has already shifted, he said, in favor of plaintiffs who no longer have to prove as many elements. A BALANCE BETWEEN “TRUTH” AND USEFUL INFORMATION The workshop returned to the different approaches of science and law as they try to determine causation. First, said a social scientist, courts err in the view that scientific studies invariably rest on some verifiable truth that is being determined in studies. At the same time, a study that is not conclusive in a scientific sense should not necessarily be ruled out of consideration by a court. For example, courts that reject opinions based on epidemiological studies that fail to satisfy a .05 level of statistical significance are losing potentially valuable information. What the “correct” level of significance is, is unknown. Various areas of science have adopted certain standards of proof to achieve the objectives and policies of those 18   Developing such a standard will require collaboration between law and science. The science that is required, and therefore promoted, by the requirements of the law is only as good as the institutionally or statutorily imposed criteria for it.

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The Age of Expert Testimony: Science in the Courtroom - Report of a Workshop disciplines. Those objectives may or may not be consistent with the objectives of the legal system and should be assessed against the policies of the legal forum. Second, said a legal scholar, many courts assume that all the compo-nents of a scientist’s opinion on causation are the products of empirically validated hypotheses. In fact, many such conclusions rest on conventions or models about which there is disagreement in the scientific community. This over-simplified view of science has increased the ability of federal trial judges to exclude parties’ experts by ignoring the objectives of science and the law and by failing to examine the premises on which some scientific conclusions rest. And some courts have moved beyond science by creating new rules in the name of science that do not exist in the scientific community. Speakers who believe that some of the emerging standards are too restrictive offered the following three examples: Epidemiology studies v. animal studies: Some courts have created a hierarchy of proof by insisting on epidemiological evidence. Insisting on epidemiological proof has policy implications, because epidemiological studies require more time—often years of expo-sure—and more money than animal studies. Because of the huge number of chemicals in use, it is rare that epidemiological studies of any single chemical are conducted. While it is true that evidence from animal studies must be used with great care, it is equally true that animal evidence should not be rejected out of hand without considering the context of the case. The rule of applying a relative risk standard of 2.0, as discussed earlier: This rule assumes that background risks are independent of the risks posed by the substance in question and can be calculated separately. Some scientists would reject such a model as inconsistent with a multi-factorial theory of disease. Some courts are imposing a rigid burden on plaintiffs to show the level of exposure; without showing this specific level, they cannot win. Two examples of cases in which the plaintiff will not be able to show precise levels of exposure are a condition that requires a long latency period to develop after initial exposure and a condition that results from continued exposure over a long period of time. A law professor stated that the courts do handle causative uncertainty as a matter of course. In criminal law, he said, the court can decide that the defendant is “guilty beyond a reasonable doubt” and in tort law the court can make a “likelier-than-not” decision. A decision that would

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The Age of Expert Testimony: Science in the Courtroom - Report of a Workshop require a very high level of scientific certainty or probability, he said, exceeding likelier than not, would change the substantive law of torts. Similarly, requiring a 95 percent level of confidence that a probability estimate demonstrate an effect is an arbitrary custom chosen for the research community, but it is not necessarily dispositive in risk cases.