Doctrine of equivalents

Lowell v. Lewis, 15 Fed. Cas. 1018 (1817) United States Circuit Court, D. Massachusetts.

This case concerned three main issues in the context of patent infringement litigation: (1) who bears the burden of proving validity or invalidity of the patent; (2) what is required for an invention to be “useful” or “capable of industrial application”; and (3) what degree of similarity is needed for an accused product to infringe a patent. The Circuit Court of Massachusetts/United States decided that the plaintiff in a patent infringement suit bears the burden of proving the validity of its patent by establishing novelty and industrial application.

Scripps Clinic Research Foundation v. Genentech Inc Scripps Clinic & Research Foundation (1991) (U.S. Court of Appeals)

The Federal Circuit remanded for trial (further clarification of facts) to the district court a number of motions for summary judgment regarding the validity and the infringement of certain product claims and product-by-process claims. The Federal Circuit inter alia decided that in litigation (concerning patent infringement and validity), patent claims must be construed in a similar manner as under patent prosecution (concerning the grant of a patent).

Festo Corp. v Shoketsu Kinzoku Kogyo Kabushiki Co., 535 U.S. 722 (2002)

The United States Supreme Court ruled that amending (i.e. narrowing) a patent claim during prosecution does not necessarily result in a complete bar to the doctrine of equivalents. It rejected the Federal Circuit’s decision that a complete bar to equivalents always results when a claim is narrowed during prosecution and thereby confirmed its own case law.

Atlantic Thermoplastics Co., v. Faytex Corp. (United States Court of Appeals, Federal Circuit, Jul 13, 1992. 970 F.2d 834 (Fed. Cir. 1992)

The Federal Circuit deviates from earlier precedent (Scripps Clinic, see case summary) in applying different treatment to patent claims in the context of patent prosecution on the one hand and in the context of patent litigation on the other hand. This case concerns in particular the scope of product-by-process claims. It also provides a useful illustration of how to examine infringement of a process claim in terms of literal infringement and the doctrine of equivalents.