As reported in a prior post, the Court of Appeals for the Federal Circuit (CAFC) recently had the opportunity to revisit the legal standard for invalidating reissue patent claims under the original patent requirement.
In Forum US, Inc. v. Flow Valve, LLC, the CAFC affirmed a district court grant of partial summary judgment that certain reissue claims were invalid under the original patent requirement of 35 U.S.C. § 251. In the process, the Federal Circuit reaffirmed the legal standard set forth in a 2014 CAFC decision, Antares Pharma, Inc. v. Medac Pharma Inc., 771 F.3d 1354 (Fed. Cir. 2014). In Antares Pharma, the Federal Circuit held that to comply with the original patent requirement, an invention claimed in a reissue patent must either be for: (i) the same invention disclosed in the original patent or (ii) a newly claimed invention “clearly and unequivocally” disclosed as a separate invention in the original patent. See id. at 1362-1363.
In Forum US, the plaintiff sought a declaratory judgment that claims 14-20 of U.S. Reissue Patent 45,878 were invalid. The original patent related to the machining of pipe joints used in the oil and gas industry. Each of the thirteen original patent claims required “a plurality of arbors.” The summary of the invention likewise referred to a plurality of arbors, while the identical specification of the original and reissue patents disclosed only embodiments with arbors. See Forum US, 2019 U.S. App. LEXIS 18055, at *3.
The asserted reissue claims omitted the “plurality of arbors” limitation. The plaintiff argued that these claims were invalid under the original patent requirement because the original patent specification did not indicate in an explicit and unequivocal manner that the invention could be practiced without a plurality of arbors. The patentee, in contrast, “argued that a person of ordinary skill in the art would understand that the [original] patent disclosed multiple inventions, consisting of embodiments with and without arbors[,]” and submitted a supporting declaration from an experienced machinist. See id. at *6. The CAFC disagreed that the declaration raised a genuine issue of material fact, reasoning that “[e]ven if a person of ordinary skill in the art would understand that the newly claimed, arbor-less invention would be possible, that is insufficient to comply with the standard set forth in [U.S.] Industrial Chemicals [Inc. v. Carbide & Carbon Chemicals Corp.] and Antares.” See id. at *11-*12.
The decision should be analyzed by accused infringers defending against reissue patent claims that extend to embodiments absent from the original patent. See Forum US, 2019 U.S. App. LEXIS 18055, at *10 (“the face of the original  patent d[id] not disclose an arbor-less embodiment of the invention.”) The decision should also be read by patent owners considering reissue as a way to extend patent coverage to previously unclaimed embodiments.