About: Festo Corp. v. Shoketsu Kinzoku Kogyo Kabushiki Co.

Festo Corp. v Shoketsu Kinzoku Kogyo Kabushiki Co., 535 U.S. 722 (2002), was a United States Supreme Court decision in the area of patent law that examined the relationship between the doctrine of equivalents (which holds that a patent can be infringed by something that is not literally falling within the scope of the claims because a somewhat insubstantial feature or element has been substituted) and the doctrine of prosecution history estoppel (which holds that a party who makes a change to a patent application to accommodate the requirements of patent law cannot claim infringement by equivalents of an element that was narrowed by that change).