A House with No Foundation: Forensic Science Needs to Build a Base Rigorous Research to Establish Its Reliability

Article excerpt

Many of the forensic techniques used in courtroom proceedings, such as hair analysis, fingerprinting, the polygraph, and ballistics, rest on a foundation of very weak science, and virtually no rigorous research to strengthen this foundation is being done. Instead, we have a growing body of unreliable research funded by law enforcement agencies with a strong interest in promoting the validity of these techniques. This forensic "science" differs significantly from what most of us consider science to be.

In the normal practice of science, it is hoped that professional acculturation reduces these worries to a functional minimum. To this degree, science is based on trust, albeit a trust that is defensible as reasonably warranted in most contexts. Nothing undermines the conditions supporting this normal trust like partisanship. This is not to say that partisanship does not exist in some form in most or all of the practice of science by humans, even if it is limited to overvaluing the importance of one's own research agenda in the grand scheme of things. But science is a group activity whose individual outputs are the product of human hopes and expectations operating within a social system that has evolved to emphasize the testing of ideas and aspirations against an assumed substrate of objective external empirical fact.

The demands of the culture of science--ranging from the mental discipline and methodological requirements that constitute an important part of the scientific method to the various processes by which scientific work is reviewed, critiqued, and replicated (or not)--tend to keep human motivation-produced threats to validity within acceptable bounds in individuals; and the broad group nature of science ensures that, through the bias cancellation that results from multiple evaluation, something like progress can emerge in the long run. However, in contexts where partisanship is elevated and work is insulated from the normal systems of the science culture for checking and canceling bias, then the reasons to trust on which science depends are undermined. Nowhere is this more likely to be a serious problem than in a litigation-driven research setting, because virtually no human activity short of armed conflict or dogmatic religious controversy is more partisan than litigation. In litigation-driven situations, few participating experts can resist the urge to help their side win, even at the expense of the usual norms of scientific practice. Consider something as simple as communication between researchers who are on different sides of litigation. Although there is no formal legal reason for it, many such researchers cease communicating about their differences except through and in consultation with counsel. What could be more unnatural for normal researchers? And what purpose does such behavior serve other than ensure that scientific differences are not resolved but exacerbated?

These concerns apply not only to research undertaken for use in a particular case, but also to research undertaken for use in unspecified cases to come, as long as the litigation interest of the sponsoring party is sufficiently clear. This is what differentiates litigation-driven research from much other interest-driven research. For instance, in research directed toward Food and Drug Administration (FDA) approval of drugs, drug companies are interested not only in positive findings but also in the discovery of dangers that might require costly compensation in the future or cause their drug to be less competitive in the marketplace. In other words, built-in incentives exist to find correct answers. In addition, the research will have to be conducted according to protocols set by the FDA, and it will be reviewed by a community of regulators who are technically competent and, at least in theory, appropriately skeptical. By contrast, in much litigation-driven research, there is a single unambiguous desired result, and the research findings will be presented to a reviewing community (judges and juries) that typically is not scientifically literate. …