The Genuine Liberal Meaning of Rule 702

This spring, I had the chance to participate on a panel at the Defense Research Institute’s annual seminar on drug and medical device law. It was a pleasure to work with Dr. Ivan Oransky and Dr. Erica James, in organizing and presenting on the issues surrounding dodgy science and publication retractions, and how their courtroom implications. The panel was officially titled, “Fraud, Error, and Ethics Violations: Exposing Bad Science in Litigation.” Dr. Oransky’s presentation focused on his keen journalistic accounts of retractions and the unraveling of trust in peer review of scientific publications.

As part of that panel, I wrote a paper on “The Convergence of Law and Science on Epistemic Virtues and Vices,” which I hope to develop further this fall. Preparing this paper led me to expand upon aspects of the judicial gatekeeping of expert witness opinion testimony, mandated by Federal Rule of Evidence 702. Some of these thoughts are also presented in a post for the Center for Truth in Science.[1]

Critics of judicial gatekeeping often suggest that the procedures of FRE 702 and 703 run contrary to the “liberal” thrust of the Federal Rules. This interpretative strategy has led to various abuses, including shifting the statutory burden of proving foundational requirements, completely eliminating foundational requirements, and relying upon cases as precedents that were clearly abandoned by statutory enactments and amendments of Rule 702 , or otherwise overruled in Daubert, Joiner, or Kumho Tire.

The courts that have invoked “liberal” thrusts, and made-up presumptions of validity, are mistaken about what is truly liberal and liberating. Under the common law, before the Federal Rules of Evidence were adopted in 1975, expert witness opinion had to be primarily relevant, as well as given by a witness qualified by virtue of education, training, or experience. From the perspective of the fact finder and the process of adjudication, the common law was an authoritarian standard that imposed opinions upon the fact finder by virtue of witness credentials and status.

The liberal response to such an authoritarian standard is to free the court and the fact finder from authoritarian opinion and to require that proffered opinions actually meet minimal requirements of validity, in terms of their underlying data, methodology, inferences, and application ot the facts of the case. An authoritarian evidentiary regime is willing to impose upon a non-expert decision maker, and to require it to reach judgments on the ipse dixit pronouncements of expert witnesses. A liberal regime must reject this authoritarianism and require some minimal level of justification, even though it will lead to closing the gate to poorly considered, inadequately supported opinion testimony. Although fewer proffered opinions may get through the gate, the Federal Rules of Evidence ushered in a liberal regime that is focused on ascertaining the truth rather than paying obeisance to status and authority of a speaker. Properly understood, Rule 702 is indeed a liberal rule that should have always been construed to “the end of ascertaining the truth and securing a just determination.[2] Importantly, Rule 702 is not, and never was, the libertine rule sought by the lawsuit industry.


[1] Schachtman, “Why Rule 702: US judges serve as gatekeepers for the truth in science,” Center for Truth in Science (July 18, 2024).

[2] Fed. R. Evid. Rule 102. Purpose.