By Lawrence A. Kogan, an international business, trade, and regulatory attorney and founder of the Kogan Law Group, P.C., a multidisciplinary legal services firm assisting U.S. and non-U.S.-based public and private enterprises.
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Abstract: U.S. Supreme Court precedent and federal evidentiary rules require litigants to demonstrate that the evidence their expert presents is both “reliable” and “relevant.” In order for the evidence to be reliable and thus admissible, the Court stressed in its seminal 1993 Daubert decision that the analytical methodology the expert employs must itself be reliable. Contrary to this guidance, in 2011 a federal appeals court permitted a plaintiff’s expert to utilize an inherently unreliable methodology to conclude that a specific chemical could generally cause cancer. The First Circuit held in Milward v. Acuity Special Products Group, Inc. that testimony developed through a weighing of multiple lines of evidence and an application of the “Bradford Hill criteria” was admissible. This “weight-of-the-evidence” methodology applies non-traditional abductive reasoning and places a great deal of discretion in the expert witness’s hands to pick and choose data to evaluate. Regulators, whose role is to identify possible risks and act preventatively in the “public interest,” favor weight-of-the-evidence when assessing studies for the methodology’s pliability.
Prior to Milward, some federal appeals courts and even the Second Edition of the Federal Judicial Center’s (FJC) respected Reference Manual on Scientific Evidence recognized the pitfalls of finding weight-of-the-evidence a reliable methodology for developing expert testimony. But within six months of Milward’s release, the FJC reversed course and endorsed weight-of-the-evidence as acceptable in its manual’s Third Edition. As this Working Paper documents through extensive case analysis, federal courts are increasingly following Milward’s and the FJC’s lead, admitting testimony derived from abductive reasoning. This development allows judges to take precautionary action as if it were a regulator, and also rewards plaintiffs whose claims are suspect. The Working Paper urges practitioners, policymakers, and the federal judiciary to contemplate where this drift away from reliable scientific and technical evidence is leading, and sets out options for a return to the rigorous judicial gatekeeping Daubert demands.