Festo Doctrine Law and Legal Definition
Festo doctrine refers to a principle of patents law that voluntary narrowing of a patent claim may give rise to prosecution-history estoppel. The rule was set in the case Festo Corp. v. Shoketsu Kinzoku Kogyo Kabushiki Co., 304 F.3d 1289 (Fed. Cir. 2002), from which the doctrine derives its name.