Employee and Inventor Witnesses in Patent Trials: The Blurry Line Between Expert and Lay Testimony


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...


Because patent litigation frequently involves complex scientific and technical issues, litigants in patent infringement suits face a key question that can shape an entire trial: who is the best witness to explain the technology in the case to the jury? Whether it is the patent owner trying to explain the patent-in-suit or the accused infringer describing prior art or an accused product, the choice of witnesses who can accomplish this important task normally comes down to either a retained expert or an in-house employee witness (often a scientist, engineer, or a named inventor of the patent-in suit). The choice between these two kinds of witnesses encompasses several smaller strategic questions, such as which witness the jury will find most credible or likeable, which witness knows the technology and the industry the best, and so forth. But before reaching those issues, litigants face a surprisingly difficult threshold question of whether the employee witness must be designated as an expert in order to testify or whether he may testify as a lay witness....

Originally published in the Stanford Technology Law Review - Volume 16, Number 2 - Winter 2013.

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