CAFC Reverses Indefiniteness Ruling, Revives Preliminary Injunction in Firearm Magazine Patent Dispute

The U.S. Court of Appeals for the Federal Circuit (CAFC) issued a decision today reversing in part and vacating in part a series of district court rulings that had invalidated a patent covering a firearm cartridge magazine housing. Chief Judge Moore wrote for the court, joined by Circuit Judges Stoll and Stark, finding the U.S. District Court for the District of Wyoming erred by treating certain claim terms as indefinite.

Schmeisser GmbH owns U.S. Patent No. 10,866,045, directed to a housing for a firearm cartridge magazine. In 2021, Schmeisser filed a lawsuit against AC-Unity d.o.o. and RTG Parts, LLC, alleging infringement of several claims of the patent. RTG Parts settled and was dismissed from the case in 2023, while AC-Unity continued litigating. The district court initially entered a preliminary injunction against AC-Unity.

The dispute centered on four distance-related terms recited in the claims, described as the first distance, second distance, third distance, and an offset value. Following the claim construction proceedings, the district court found these terms indefinite and denied Schmeisser’s request for reconsideration. Relying on that construction, the district court granted partial summary judgment of invalidity and noninfringement in AC-Unity’s favor and dissolved the preliminary injunction. The summary judgment was only partial because it did not resolve AC-Unity’s counterclaim asserting the ‘045 patent is unenforceable due to alleged deceit and non-disclosures during prosecution.

The CAFC addressed a jurisdictional dispute between the sides over whether the court could review the claim construction and summary judgment orders in addition to the preliminary injunction dissolution. It had clear authority under 28 U.S.C. Section 1292(a)(1) to review the dissolution order. It concluded it could also reach the other rulings under the doctrine of pendent appellate jurisdiction, which the court described as allowing “limited discretion to review a ruling that is not independently appealable if jurisdiction exists over another related ruling.” The CAFC found this doctrine applicable because the dissolution of the preliminary injunction was expressly based on the district court’s prior claim construction and summary judgment proceedings, making the rulings “inextricably intertwined.”

Moreover, the CAFC applied the standard set out by the Supreme Court in Nautilus, Inc. v. Biosig Instruments, Inc. Under that standard, a patent is invalid for indefiniteness if its claims, read alongside the specification and prosecution history, fail to inform those skilled in the art, with reasonable certainty, about the scope of the invention. The CAFC found the distance related “terms are clear on their face with each distance being well-defined by the claim language and readily measurable using conventional measurement tools.” The specification explains and depicts what each term represents, and the prosecution history further supports definiteness. The claims were amended specifically to overcome an indefiniteness rejection issued by the examiner, who subsequently applied the amended claims against prior art references without difficulty.

The CAFC also pointed to the district court’s own order, which described what each distance term represented, including that the first distance is the interior distance between the front and rear walls of the magazine, and that the offset value is “simply a ratio of the difference between” the second and third distances. According to the CAFC, this was all that definiteness requires under Nautilus, which asks only that the claims “inform those skilled in the art about the scope of the invention with reasonable certainty.”

Instead of applying that standard, the district court had focused on whether a skilled artisan could calculate specific values needed to build an operable magazine housing that would not jam, said the CAFC. The opinion held that consideration is relevant to enablement under Section 112(a), not definiteness, citing precedent holding that those requirements are analytically distinct. Although the district court had reasoned the distinction between the two doctrines is not “so crisp and neat,” the CAFC responded that its precedent has repeatedly recognized the separation between definiteness and enablement.

The CAFC concluded the claims are definite because a skilled artisan would be able, with reasonable certainty, to examine a firearm magazine housing, identify the claimed distances, measure them, and determine whether the housing falls within the claim scope. Whether a skilled artisan could make the design decisions necessary to build an operable housing from the specification, the court said, goes to enablement rather than definiteness. Since the district court conflated the two standards, the CAFC held it incorrectly concluded the claims were indefinite, and reversed the indefiniteness related portions of the claim construction order.

As the summary judgment ruling in AC-Unity’s favor was expressly based on the claim construction order, the CAFC reversed that ruling as well. The court also vacated the dissolution of the preliminary injunction, since that ruling was likewise based on the claim construction and summary judgment proceedings, and remanded the case for further proceedings. The CAFC stated it had considered AC-Unity’s remaining arguments and found them unpersuasive.

The decision reverses the indefiniteness related portions of the district court’s claim construction and summary judgment orders, vacates the dissolution of the preliminary injunction, and remands the case to the District of Wyoming for further proceedings consistent with the opinion. The costs on appeal were awarded to Schmeisser.