REVIEW: Expert Witness Testimony Admissibility in the Reference Manual on Scientific Evidence (4th ed.)

The Federal Judicial Center and the National Academies of Science, Engineering & Medicine published a new edition (the fourth) of the Reference Manual on Scientitfic Evidence, on December 31, 2025. The new edition arrives 14 years after the previous edition, and there was much anticipation of how the new edition would handle changes in law and in substantive areas of science. The first chapter of the new Manual addresses expert witness admissibility; the chapter's authors are well qualified for the task.

The chapter ably charts the evolution of expert witness gatekeeping in federal court under the federal rules, and the implications of the most recent amendment to Federal Rule of Evidence 702, which was designed to clarify and emphasize aspects of Rule 702, including its goal of preventing expert witnesses from overclaiming. Although the authors of this chapter carefully discuss the language and goals of the revised Rule 702, they curiously endorse a pre-amendment case that is notorious for having green lit an expert witness who overclaimed a causal conclusion based upon dubious methodology. This review explores the contradictions inherent in the new Manual's approach to Rule 702.