Employee and Inventor Witnesses in Patent Trials: The Blurry Line Between Expert and Lay Testimony
Published in the Stanford Technology Law Review
Volume 16, Number 2 Winter 2013
Parties in patent infringement lawsuits frequently must choose a witness to explain complex or scientific technology behind an invention or an accused product that sits at the heart of a claim or a defense. Often, the parties select an employee witness such as an engineer, scientist, or a named inventor of the patent-in-suit who can testify based on first-hand experience with the technology in question rather than a hired expert, who must prepare an expert report and who may not share the same incentives and goals as the litigant. Because these employee witnesses testify regarding technical or scientific issues, but they do so from first-hand knowledge, courts have struggled over whether such witnesses must be designated as experts under the Federal Rules of Evidence. This has created a growing conflict among courts over how far a lay witness may go in testifying about technical and scientific matters before crossing the boundary into expert testimony. This Article addresses these conflicting cases and proposes an approach that courts can use to determine which topics in patent cases are appropriate matters only for expert witnesses and which topics may be addressed by highly skilled and knowledgeable lay witnesses.