When jurors decide whether a putative patent infringer is liable under the doctrine of equivalents, Federal Circuit law requires that the patent owner’s trial presentation provide “particularized evidence” and “linking argument” with respect to each prong of the classic tripartite test for liability (i.e., substantial identity of “function,” “way,” and “result” between each element of the claimed invention and accused device). The court has recognized that absent such evidentiary roadmapping, jurors are “put to sea without guiding charts.” In its August 2001 decision in Monsanto Co. v. Mycogen Plant Science, Inc., the Federal Circuit refused to extend this same evidentiary framework to an accused infringer’s affirmative defense that the patent in suit was invalid for prior invention under 35 U.S.C. § 102(g)(2). This article contends that the Federal Circuit in Monsanto improvidently deprived jurors of analytical guideposts that are essential to the kind of fully informed fact-finding that should underlie any verdict on the validity or invalidity of an issued patent. The article proposes that the evidentiary requirements for contextualization, particularization, and application of pertinent facts to applicable law, as previously required for liability determinations under the doctrine of equivalents, should likewise be mandated for all cases in which patent validity is challenged before a jury. The jury’s deliberational task is no less complex in the validity phase of a patent trial than in the liability phase, and is further informed by the presumption of validity that attaches to issued patents. The risks of juror error that warrant imposition of particularized evidentiary requirements for liability determination are even more potent in the validity setting, for a jury’s decision to sustain or invalidate an asserted patent affects not only the parties to the lawsuit but also the public at large. In keeping with its mandate to enhance predictability and uniformity in patent disputes, the Federal Circuit has the power and the responsibility to improve patent jury trial practice by requiring that validity challenges be tried under the same evidentiary ground-rules as those that the court has already established for equivalents liability.
Janice M. Mueller, At Sea in a Black Box: Charting a Clearer Course for Juries Through the Perilous Straits of Patent Invalidity, 1 J. Marshall Rev. Intell. Prop. L. 3 (2001)