Legal Aspects of Scientific Evidence Research Paper

Courts are another large consumer of science. In both criminal and civil cases, parties believe scientific testimony will make their case stronger. As science’s role has grown, so has interest in the relationship between law and science. This essay reviews the present state of knowledge concerning the science–law relationship and mentions several areas ripe for investigation.

1. What Law Wants From Science

In both the administrative and the courtroom context, law is most frequently interested in acquiring scientific answers to practical questions of causation (e.g., does exposure to airborne asbestos cause lung cancer) and measurement (e.g., what is the alcohol level in a driver’s blood). Both of these questions entail questions as to whether specific techniques (e.g., a breathalyzer) are capable of producing reliable measurements. Theoretical questions per se are frequently of secondary interest, useful insofar as they help courts and regulators to chose among conflicting measurements, extrapolations, or causal assertions.

Courts and agencies are both interested in questions of general and specific causation. Agencies are interested in the effects of nitrous oxide on the environment and the specific level of emissions from a particular plant. Courts may be interested in whether a given level of airborne asbestos causes lung cancer. And they may need to determine if a particular plaintiff’s lung cancer was caused by asbestos exposure. It is often much more difficult to achieve a scientifically rigorous answer to this latter type of question.

An important difference between courts and agencies is the level of proof necessary to reach a conclusion. In administrative settings agencies may prevail if they can show that a substance poses a danger or a risk. In a courtroom however, in order to prevail, the plaintiff will be required to show both general and specific causation. Scientific evidence that is sufficient in the regulatory context may be considered insufficient in the court context. For example, animal studies showing a relationship between saccharin consumption and cancer may be sufficient to cause an agency to impose regulations on human exposure to the sweetener, but would not be sufficient to permit a groups of plaintiffs to prevail on a claim that they were actually injured by consuming saccharin in diet soft drinks, or even on the general causation claim that saccharin at human dose levels causes cancer in any humans.

2. Legal Control Of Scientific Evidence

One of the more interesting aspects of the use of science in courts is the legal effort to control the terms of the law–science interaction. Judicial control of scientific experts is shaped by whether the court is operating in an inquisitorial or an adversarial system (van Kampen 1998). In inquisitorial systems, e.g., Belgium, Germany, France, Japan, the judge plays a large role in the production of evidence. Experts are almost always court appointed and are asked to submit written reports. Parties may be given the opportunity to object to a particular expert, question the expert about the opinion rendered, or hire their own expert to rebut the court-appointed expert; but it is very difficult to attack the admissibility of an expert’s report successfully (Langbein 1985, Jones 1994). In adversarial systems the parties usually have far greater control over the production of evidence, including the selection and preparation of expert witnesses. Courtappointed experts are rare (Cecil and Willging 1994).

A similar pattern can be observed in the regulatory arena. Jasanoff (1991) compares the relatively closed, consensual, and non-litigious British regulatory approach to the open, adversarial and adjudicatory style found in the United States. Clearly, legal organization and legal culture shape the way in which legal systems incorporate science. In turn, legal organization is related to larger cross-cultural differences. For example, open, adversarial approaches are more pronounced in societies that are more individualistic and lower on measures of power distance (Hofstede 1980).

Judicial control of scientific expert testimony has become a high profile issue in the United States. Critics complain that the combination of adversarial processes and the use of juries in both criminal and civil trials encourages the parties to introduce bad science into the trial process. They argue, with some empirical support, that the use of experts chosen by the parties produces individuals who by their own account stray relatively further from Merton’s four norms of science—universalism, communism, disinterestedness, and organized skepticism (Merton 1973). They submit that jurors are too easily swayed by anyone who is called a scientist regardless of the quality of the science supporting the expert’s position. Many now call upon judges to play a greater role in selecting and supervising experts, a role closer to that found in inquisitorial systems (Angell 1996).

The preference for an inquisitorial style makes several assumptions about the nature of science and the proper relationship between law and science. Similar assumptions underlie the admissibility rules employed by courts. The history of admissibility decisions in American courts provides a useful way to explore these assumptions.

Precisely because the knowledge possessed by the scientist is beyond the ken of the court, the judge (or the jury) often is not in a good position to determine if what the expert is offering is helpful. In a 1923 decision a federal court offered one solution to this problem; acquiesce to the judgment of the community of elites who are the guardians of each specialized area of knowledge. Under the so-called Frye rule experts may testify only if the subject of their testimony had reached ‘general acceptance’ in the relevant scientific community. In 1993 in Daubert vs. Merrell Dow Pharmaceuticals, Inc., and subsequent opinions, the United States Supreme Court moved away from the Frye rule. In its place federal courts have developed a nonexclusive multifactor test designed to assess the validity of the science underlying the expert’s testimony. Factors the courts have mentioned include: whether the theory or technique underlying the expert’s testimony is falsifiable and had been tested; the error rate of any techniques employed; whether the expert’s research was developed independent of litigation; whether the testifying expert exercised the same level of intellectual rigor that is routinely practiced by experts in the relevant field; whether the subject matter of the testimony had been subjected to peer review and publication in refereed journals; and, in a partial retention of the Frye test, whether the theory or technique had achieved general acceptance in the relevant scientific community.

The Daubert-inspired test offers an alternative to acquiescence, a do-it-yourself effort on the part of the courts. A number of the factors are consistent with an adversarial legal system that institutionalizes mistrust of all claims to superior authority. The adversary system itself is consistent with the values of a low-power distance culture that affords relatively less legitimacy to elite authoritative opinion and, therefore, is skeptical that scientists are entitled to a privileged language of discourse from which others are excluded. It is also consistent with a view of science strongly influenced by other forces in society. These are perspectives on the scientific enterprise that are associated with those who adopt a social constructionist view of science (Shapin 1996, Pickering 1992).

3. Legal Understanding Of The Scientific Enterprise

Daubert, however, offers anything but a social constructionist test if by this we mean that scientific conclusions are solely the result of social processes within the scientific community. At its core, the opinion requires of judges that they become sufficiently knowledgeable about scientific methods so that they can fairly assess the validity of evidence offered at trial. This requirement that scientific testimony must pass methodological muster reflects a positivist approach that is slanted toward a Baconian view of science. The opinion cites with favor a Popperian view of how to distinguish the scientific enterprise from other forms of knowledge (Popper 1968). In this regard, the opinion is not unique.

In their use of scientific evidence, both courts and administrative agencies seem to distinguish the process of science from its products. They accept the constructionist insight that the process of doing science is a social enterprise and is subject to the buffeting, often distorting winds of social, political, economic, and legal influences. At the same time, courts, agencies, and legislatures cling to a realist belief that the products of science may state a truth about the world, or at least something so similar to truth as it is commonly understood at a given point in history that the particular discipline of law does not need to concern itself with the difference. The legal system’s view of science adopts a strong version of what Cole (1992, p.x) calls a realist–constructivist position, i.e., science is socially constructed both in the laboratory and in the wider community, but the construction is constrained by input from the empirical world. It rejects what he calls a relativist–constructionist position that claims nature has little or no influence on the cognitive content of science.

The focus on methods is a search for some assurance that the expert has given the empirical world a reasonable opportunity to influence and constrain the expert’s conclusions. Ultimately, the law’s epistemology with respect to science holds that there are a set of (social) practices often given the shorthand name ‘the scientific method’ which increase the likelihood that someone will make positive contributions to knowledge; a set of practices that scientists themselves frequently point to as the sources of past scientific success (Goldman 1999).

There is a large dose of pragmatism in all of this, of course, and the Daubert rule itself has been cited as an example of ‘the common law’s genius for muddling through on the basis of experience rather than logic’ (Jasanoff 1995, p. 63). Not surprisingly, some have criticized the courts for failing to adopt a philosophically coherent admissibility rule (Schwartz 1997). The court’s admissibility rulings do seem to have proceeded in happy obliviousness to the ‘science wars’ that arguably began with Fleck (1979), flourished with Kuhn (1962) and raged for much of the last half of the twentieth century between the defenders of a more traditional, positivist view of science and those critics who emphasize its historical, political, social, and rhetorical aspects (Leplin 1997, Latour 1999). The same could be said of administrative use of science.

The rejection of relativist views of science does not mean that all legal actors hold identical views. It would be valuable to map the beliefs of legal actors on central disputes in the science wars, and how these beliefs impact their use of science. For example, if, as seems likely, plaintiff personal injury lawyers in the United States hold a more relativist view of science, how, if at all, does this affect their selection and preparation of experts and, in turn, how are these experts received in courts?

4. Law–Science Interdependence

Law’s approach to science should not be understood in terms of science alone but rather in terms of the law–science interaction. There are several dimensions to this relationship. First, although modern legal systems may recognize that scientists are influenced by the social world around them, permitting radical deconstruction that would undermine science’s claim to special status is difficult to imagine (Fuchs and Ward 1994). The modern state is increasingly dependent upon science as a source of legitimacy. By turning to science for solutions to complex environmental and safety issues, legislatures are able to avoid making difficult political choices while giving the appearance of placing decision-making in the hands of apparently neutral experts who are held in very high esteem relative to other elites (Lawler 1996). The advantages of this approach are so great that agencies frequently engage in a ‘science charade’ in which they wrap their decision in the language of science even when there is very little research supporting a regulation (Wagner 1995).

Second, and related to the first observation, the law–science interaction is one of the important ways in which the state helps to produce and maintain science’s dominant position in modern Western society. In both its administrative and judicial actions, the law defines what is and what is not scientific knowledge, and thereby assists science in important boundary maintenance work of excluding many from the community of ‘scientists.’ For example, in the case of United States vs. Starzecpyzel, the court permitted the state’s handwriting experts to testify on the question of whether the defendants had forged documents, but only if they did not refer to themselves as ‘scientists.’ Moreover, legal decisions contain an implicit epistemology that reinstitutionalizes one view of the nature of scientific knowledge. When courts and other institutions of the state reject a relativist view of science that argues the empirical world has little, if any, influence on what is accepted as true by the scientific community, they help to marginalize anyone who adopts this position. There can be little doubt that the view is given little or no attention in law. A cursory search for the names of individuals most associated with these debates in American federal cases finds over 100 references to Popper alone, but no more than one or two passing references to the more prominent critics of traditional understandings of the scientific enterprise.

Third, the exact contours of the law–science interaction are shaped by a society’s legal structure and its legal culture. For example, the American legal system’s realist–constructivist understanding of science fits neatly with its own normative commitment to both ‘truth’ and ‘justice’ as legitimate dispute resolution goals. Ideally, cases should be correctly decided, should arrive at the truth. A realist view of science is consistent with the idea that a court may arrive at the correct outcome. But the truth is contested, and the courts should also give litigants the sense that they were listened to; that they received procedural justice (Tyler 1990). A constructivist understanding of the scientific enterprise legitimates the right of each party to find an expert who will present their view of the truth. We may hypothesize that all legal systems tend toward an epistemology of science and the scientific enterprise that fit comfortably within their dominant methods of law-making and dispute settlement. We might expect, therefore, that inquisitorial systems would be more skeptical of a constructivist view of the scientific enterprise than is the case in adversarial legal systems.

5. Effects Of Growing Interdependence

As this essay attests, science’s impact on legal processes grows apace. In many areas, an attorney unarmed with scientific expertise operates at a significant disadvantage. A growing number of treatises attempt to inform lawyers and judges of the state of scientific knowledge in various areas (Faigman et al. 1997). At the level of the individual case, there is some evidence that scientific norms are altering the way scientifically complex lawsuits are tried. Restrictive admissibility rules are one of several ways that courts in the United States may restrict traditional adversary processes when confronted with cases involving complex scientific questions.

What of law’s effects on science? If the supply of science on some issue is affected by demand, legal controversy should draw scientists to research topics they might otherwise have eschewed. There is evidence that this does occur. The subject matter of scientific research is shaped by legal controversy in a wide number of areas, from medical devices (Sobol 1991) to herbicides (Schuck 1986). Some have argued that law’s interest has an additional effect of causing the production of ‘worse’ science (Huber 1991), but it might also be argued that in areas such as DNA testing, law’s interest has produced better science and better technology than might otherwise have existed. On the other hand, the threat of legal controversy may impede research into some areas, such as the development of new contraceptive devices.

Even if we believe all science is produced through a process of social construction, it is also the case that most scientists believe that their work is constrained by the empirical world (Segerstrale 1993). Moreover, they often attempt to surround themselves with a social structure that keeps society at a distance. Scientific groups are increasingly attempting to propagate ethical standards for those who offer expert testimony in courts, reflecting the widespread belief that scientists who typically appear in legal arenas differ from their colleagues on these dimensions. Finally, legal use of science affects the closure of scientific debates (Sanders 1998). On the one hand, law may perpetuate controversy by supplying resources to both sides. On the other hand, it may help to bring a dispute to closure by authoritatively declaring one side to be correct.

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