On February 11, 2013, in Semiconductor Energy Laboratory Co. v. Nagata, No. 2012-1245, the Federal Circuit (Lourie, Bryson, and Wallach) affirmed a decision by the Northern District of California that dismissed a complaint for lack of subject matter jurisdiction. This case provides insight into the appropriateness of using a named inventor as a fact witness in an infringement action based on his or her patent.
In an earlier action, Semiconductor Energy Laboratory (SEL) brought suit against Samsung, Inc. for infringement of a patent, and Nagata — the co-inventor of the patent at issue, who had assigned his rights in the patent to SEL — gave testimony repudiating his signature on the assignment. SEL then brought a separate action against the co-inventor, alleging that assignor estoppel precluded the inventor from giving testimony that undermined the patent’s validity. The district court dismissed the action against the inventor, and the Federal Circuit affirmed. The Federal Circuit held that there is no federal cause of action for assignor estoppel and that the appropriate remedy for SEL would have been to challenge the inventor’s testimony during cross-examination in the patent infringement action.