The credibility of expert witnesses in patent claim construction: the need to amend Rule 52 under Teva Pharmaceuticals v. Sandoz, Inc.

Abstract

There has been much scholarly attention devoted to the policy implications of the recent U.S. Supreme Court ruling in Teva Pharmaceuticals v. Sandoz, Inc., in which the Court held that district court findings regarding the credibility of expert witnesses testifying in patent claim construction are findings of fact subject to clear error deference on appeal. However, no attention has been paid to the underlying problem implicated by the Teva decision: what precisely is factual about a credibility assessment? Unlike other judicial determinations traditionally afforded clear error deference, no legally operable definition of “credibility” currently exists. This Note argues that the Supreme Court of the United States should clarify how district court judges and the Court of Appeals for the Federal Circuit should arrive at determinations of expert credibility under the new clear error requirements of Teva. The best solution is for the Supreme Court to amend Rule 52 by providing specific credibility criteria to evaluate expert testimony in patent claim construction. This proposal will both give district court judges a reference point to include in their claim construction orders, and provide a solid basis for clear error review that the Federal Circuit cannot simply set aside on appeal.