On Law


August 20, 2002

August 27, 2002

Apeals court decision affects patent coverage

A recent opinion delivered by the U.S. Court of Appeals for the Federal Circuit has narrowed patent coverage of existing patents. That's the bad news regarding Johnson and Johnston Associates v. R.E. Service Co. Inc., slip op., case No. 9901976, -1179, -1180 (2002). The good news is that relatively minor changes in patent drafting strategy should allow patent owners to avoid the restrictive effects of this en banc decision. Specifically, means-plus-function patent claims provide an efficient way of avoiding the pitfalls of Johnson & Johnston.

In Johnson & Johnston, the Federal Circuit significantly narrowed the scope of the doctrine of equivalents, a doctrine designed to permit patent owners a broader interpretation of their claims. In view of this decision, patent prosecutors will be challenged to maintain broad claim scope without recourse to the diluted doctrine of equivalents.

A patent infringement lawsuit may be based upon literal infringement and/or infringement under the doctrine of equivalents. Literal infringement focuses on what the patent claims say the patent covers. Infringement under the doctrine of equivalents focuses on whether the accused system, method or apparatus contains elements substantially equivalent to each claimed element of the patented invention. In the past, one use of the doctrine of equivalents was to provide coverage for embodiments disclosed in the patent specification, but not covered by the literal words of the patent claims.

In Johnson & Johnston, the Federal Circuit held that a patent holder loses its rights to subject matter disclosed in the patent specification but not explicitly covered by the patent claims. Effectively, the court held that the patentee could not apply the doctrine of equivalents to solve unclaimed embodiment problems.

The decision resolved the tension that existed between two divergent Federal Circuit cases. In 1996, the Federal Circuit held that any material disclosed but not claimed in a patent application is dedicated to the public. Maxwell v. J. Baker Inc., 86 F.3d 1098, 39 USPQ2d 1001 (Fed. Cir. 1996). However, two years later, the court limited Maxwell to situations where the patent discloses an unclaimed alternative distinct from the claimed invention. YBM Magnex Inc. v. International Trade Commission, 145 F.3d 1317, 46 USPQ2d 1843 (Fed. Cir. 1998). In Johnson & Johnston, the Federal Circuit expressly overruled YBM Magnex by holding that any unclaimed subject matter is indeed dedicated to the public.

In Johnson, the plaintiff asserted U.S. Patent No. 5,153,050 (the '050 patent) against R.E. Service (RES). The specification of the '050 patent stated that while aluminum was the preferred material for the substrate of the laminate, steel or nickel alloys could also be employed. However, the patent claims were limited to a laminate consisting of copper foil and a sheet of aluminum. RES was making laminates consisting of copper foil and a sheet of steel, as disclosed in Johnston's patent specification. At trial, the jury found that RES had willfully infringed Johnston's patent under the doctrine of equivalents.

On appeal, the Federal Circuit agreed to decide the case to resolve a split in its case law between Maxwell and YBM Magnex. The defendant cited Maxwell, arguing that the '050 specification dedicated the subject matter concerning the steel laminate to the public since the steel laminate was disclosed but not claimed. On the other hand, the plaintiff cited YBM Magnex, arguing that the steel laminate was not dedicated to the public.

The Federal Circuit held that the plaintiff could not assert the doctrine of equivalents to cover the disclosed but unclaimed steel laminate and overruled YMB Magnex. The court stated, "When a patent drafter discloses but declines to claim subject matter, as in this case, this action dedicates that unclaimed subject matter to the public ..."

The court in Johnson & Johnston stated that an inventor cannot narrowly claim an invention to avoid rigorous prosecution scrutiny by the United States Patent and Trademark Office, then use the doctrine of equivalents to broaden the claims and establish infringement after issuance. The majority articulated that "such a result would merely encourage a patent applicant to present a broad disclosure in the specification of the application and file narrow claims, avoiding examination of broader claims that the applicant could have filed consistent with the specification."

The decision is a reminder of the care necessary when drafting a patent application. Since disclosure of unclaimed subject matter could prevent the use of the doctrine of equivalents against a potential infringer, drafters of patent applications must pay attention to ensure that all disclosed embodiments are covered by the claims.

In light of Johnson & Johnston, owners of a patent less than two years old should have a patent attorney review the issued claims to ensure that all the disclosed embodiments are covered by the patent claims. Such patent owners may file a reissue application to acquire additional coverage encompassing disclosed embodiments not covered by the original patent claims. In addition, if related applications are still pending, a patentee may file a continuation application to acquire additional patent coverage.

In the future, Johnson & Johnston will almost certainly produce an increase in the number of claims recited and a resulting increase in cost in obtaining a patent. Despite the potential danger of prosecution history estoppel, patent attorneys will be motivated to draft original claim sets that are at least as broad as the specification. As a result, means-plus-function claims may become more attractive to patent practitioners.

Means-plus-function claims provide a useful tool in drafting broad claims without the need for an excessive number of claims. Means-plus-function language can be used to claim all corresponding structure, materials or acts described in the specification and equivalents thereof without reciting the specific structure, materials or acts.

Therefore, means-plus-function claims can be used to offer expanded claim scope while avoiding unnecessary dedication of material to the public and minimizing the total number of claims. In light of Johnson & Johnston, to more completely secure intellectual property rights for patent owners, a preferred claim drafting strategy must include sets of system, method and/or apparatus claims, as well as related sets of means-plus-function claims.

Heisey is a member of the Business Practice Group in the San Diego office of Luce, Forward, Hamilton & Scripps LLP, a national full-service law firm. He can be reached at (619) 699-2494 or dheisey@luce.com.


August 20, 2002

August 27, 2002