Admissibility of scientific evidence post-Daubert

Proof of medical causation is the key element in cases involving alleged radiation injury. Until 1993, the use of scientific testimony in the courtroom was governed by the Frye doctrine requiring that a theory be "generally accepted" before it can be the basis of an expert's opinion. Applying that rule trial courts adopted a "let it all in" approach resulting in a near overdose of pseudoscience presented to juries. With its decision in Daubert v. Merrell Dow Pharmaceuticals, Inc., 509 U.S. 579, 113 S. Ct. 2786 (1993), the U.S. Supreme Court announced a new five-factor, non-exclusive test for federal district courts to consider when assessing the opinion of scientific experts. The Court further directed that the trial courts, acting as a gatekeeper for expert evidence, must evaluate whether there is an adequate "fit" between the expert's data and the opinion offered. This article examines how the Daubert standard has been implemented in federal court to combat junk science. Examples from recent case law dealing with operational health physics issues are presented as an illustration of the use of the five-factor test to challenge questionable testimony on causation. Guidance is offered to prospective expert witnesses in radiation-related litigation to insure that proposed testimony will be admissible in district court.