Pennsylvania Supreme Court to Decide Whether Trial Courts May Act as Gatekeepers

Evan M. Tager, Featured Expert Contributor, Judicial Gatekeeping of Expert Evidence

Evan M. Tager, a Partner in the Washington, DC office of Mayer Brown LLP, with Jonathan S. Klein, an Associate with the firm.

May a court exclude an expert opinion reliant on scientific studies that offer no meaningful support for the expert’s conclusions? Most federal decisions (including this S.D.N.Y. decision that we recently wrote about here) correctly say “yes.” But in many states, important questions remain about the extent to which a state court can scrutinize the studies that underpin an expert opinion. In Pennsylvania, which continues to apply the Frye general‑acceptance test that preceded Daubert, the Pennsylvania Supreme Court will soon decide how closely trial courts in Pennsylvania can scrutinize the scientific evidence that purportedly underlies the expert opinion.

In Walsh v. BASF, the estate of a long‑time golf‑course groundskeeper, Thomas Walsh, sued nearly three dozen pesticide manufacturers after Walsh died from acute myelogenous leukemia. Unlike in the typical toxic‑tort action, Walsh “kept a diary of the chemicals used on the courses and the dates of their applications.” 191 A. 3d 838, 840 (Pa. Super. Ct. 2018). After years of litigation, Monsanto, Bayer, and several other defendants moved to exclude the opinions of the estate’s two experts on causation. The defendants argued that the studies cited by the  experts failed to support their conclusions and that, at bottom, the experts attempted to pass off as science what amounted to pseudo‑scientific speculation. Continue reading “Pennsylvania Supreme Court to Decide Whether Trial Courts May Act as Gatekeepers”