IP Law Daily, PATENT—Fed. Cir.: Lack of written description rejection affirmed in silver alloy dispute, (Sep 18, 2025)

By Kevin M. Finson, J.D.

A patent application for an alloy of silver was rejected for lack of written description because the specification did not include support for a negative limitation found in the claims.

The Patent Trial and Appeal Board properly determined that a patent applicant’s negative limitation requiring the exclusion of a certain element from a claimed alloy was not supported by sufficient written description, the U.S. Court of Appeals for the Federal Circuit has held. The specification listed a preferred alloy which did not include the named element, but it did not give any reason to think excluding the element was preferable (In re Butler, No. 23-2380 (Fed. Cir. Sept. 17, 2025)).

John Robert Butler and Stuller, Inc. (collectively, Butler) were the applicants under U.S. Patent Application No. 16/891,541 (the ’541 application), which claimed a hardened, corrosion resistant silver alloy. The ’541 application was a continuation of U.S. Patent Application No. 14/945,230 (the ’230 application), which was itself a continuation of U.S. Patent Application No. 13/224,116 (the ’116 application). The examiner rejected claims 1-15 for lack of written description, finding that the specification of the ’116 application lacked support for the ’541 application’s negative limitation “free of germanium.” Butler appealed to the Patent Trial and Appeal Board, which affirmed the rejection. Butler then appealed to the Federal Circuit.

Written description. Reviewing the description, the Federal Circuit held that the Board had properly applied the law, which did not require an explicit, verbatim disclosure of a negative limitation, but which did at least require something that described some reason to exclude the relevant element. Under this standard, the court agreed with the Board’s conclusion about how the specification would have been understood by a skilled artisan. The specification did not specifically refer to germanium, and a preferred alloy which happened not to include germanium was not sufficient description to support a negative limitation requiring the absence of germanium.

The court affirmed the Board’s decision.

The Case is No. 23-2380.

Judge: Reyna, J.

Attorneys: Ronald Bennett Ford (Roy Kiesel Ford Doody & North, APLC) for John Robert Butler and Stuller, Inc. Monica Barnes Lateef, U.S. Patent and Trademark Office, for Coke Morgan Stewart.

Companies: Stuller, Inc.

Cases: Patent FedCirNews USPTO