Banishing Ipse Dixit: The Impact ofKumho Tire on Forensic Identification Science

I. Introduction From the viewpoint of conventional science, the forensic identification sciences are contenders for being the shoddiest science offered to the courts.1 After being in business for nearly a century, they still have developed little that would be recognized as a scientific foundation and, consequently, have little basic science to apply to their operational activities. For much of the twentieth century, the courts readily admitted these fields, apparently because they were flying the banner of science and not because they presented sound data supporting their claims. The decision in Daubert v Merrell Dow Pharmaceuticals, Inc.2 concluded that the duty of judicial gatekeeping of expert testimony could be met only if judges were persuaded of the soundness of an expert's underlying claims.3 No me was more surprised than the judges when they realized that subjecting the forensic identification sciences to Daubert scrutiny led to the conclusion that they should be excluded.4 Consequently, after Daubert courts began to look for ways to avoid its application to the forensic identification sciences. Moreover, some forensic identification scientists looked for ways to evade Daubert scrutiny. The solution to this problem for those judges and for pseudo-scientists was to re-classify those fields as non-science.5 But Kumho Tire Co. v. Carmichael6 patched that hole, so to say, at least by its apparent terms.7 That is to say, hauling down the science flag and hosting the non-science flag does not exempt expert evidence from Daubert scrutiny.8 Together, Daubert and Kumho Tire do a remarkably clear job of commanding judges to property scrutinize fields, presumably including the forensic identification sciences, before admitting opinions from those fields' practitioners. But one can never underestimate the ingenuity of judges in finding ways to evade rules that tell them to do something that would lead to a result contrary to the one suggested by their intuitions. The post-Daubert, pre-Kumho Tire period was telling: Obeying the letter and spirit of Daubert would lead to significant exclusion of a type of evidence that the courts welcomed for most of the twentieth century. On the other hand, a ruling to admit these fields would be both a rejection of conventional science as the criterion for admission of empirical claims and a ruling in the teeth of repeated unanimous Supreme Court opinions declaring the conventional scientific method to be the touchstone for evaluating empirical claims of all kinds. The question with which this Article is concerned is: What are the prospects that Kumho Tire will compel courts to follow the commands of Daubert and to exclude expert opinions "connected to existing data only by the ipse dixit of the expert"?9 II. Defining the Fields Let us be clear about the fields that we are discussing. There are two kinds of forensic science: On the one hand, there are normal applications of basic science. On the other hand, there is individualization science, or identification science. My focus will be on the latter, though it will not be my exclusive focus. Normal forensic science does things like determining what substance something is (e.g. …