Overview
In Fortress Iron, LP v. Digger Specialties, Inc., No. 2024-2313 (Fed. Cir. Apr. 2, 2026), the Federal Circuit affirmed the district court’s grant of summary judgment holding that patents concerning railing cables were invalid for incorrect inventorship. The Federal Circuit also affirmed the district court’s denial of the patentee’s motion for partial summary judgment to correct inventorship under 35 U.S.C. § 256(b).
District Court Proceedings
At the district court, Digger identified two inventors that Fortress acknowledged were inadvertently left off of its patents. After being unable to locate or contact one of the inventors, Fortress moved for partial summary judgment to correct inventorship on its patents pursuant to 35 U.S.C. § 256(b). Digger moved for summary judgment that Fortress’s patents were invalid for incorrect inventorship. The district court held that inventors are “parties concerned” as described in § 256(b), and therefore must have notice of the proceedings for the court to correct inventorship. Because the inventor could not be contacted, the district court denied summary judgment to correct inventorship under § 256(b). The court granted Digger’s motion for summary judgment of invalidity for incorrect inventorship. Fortress appealed both summary judgment decisions.
Federal Circuit Decision
In this “case of first impression,” the Federal Circuit affirmed that inventors are “parties concerned” under § 256(b) because inventors occupy the central role in the patent process. The Federal Circuit rejected Fortress’s argument that “parties concerned” should only be those with an economic interest in the patent that may be adversely affected. The Federal Circuit reasoned that this would amount to rewriting the language of the statute. The Federal Circuit further clarified that § 256 is only a “savings provision” to the extent that its statutory requirements can be met and did not need to be construed “broadly and permissively.” Since the notice and hearing prerequisite of § 256(b) could not be satisfied, the provision did not apply.
The Federal Circuit also affirmed the grant of summary judgment on invalidity. Fortress argued that 35 U.S.C. § 101 uses permissive language like “[w]hoever invents . . . may obtain a patent thereof” and thus does not require all inventors to be listed. The Federal Circuit disagreed, reasoning that 35 U.S.C. §§ 101 and 100(f), when read with § 256(b), contemplates that no less than all of the inventors must be listed on a patent to be valid. Digger also argued that the repeal of § 102 (f) supported that joinder of all inventors was not necessary for validity. The Federal Circuit again disagreed, clarifying that § 102(f), repealed after the America Invents Act (AIA), stated that “[a] person shall be entitled to a patent unless he did not himself invent the subject matter sought to be patented,” and simply meant that non-inventors are not entitled to a patent, not that actual inventors need not be named.
Takeaways
This decision highlights the paramount importance of having the correct inventors on a patent. For patent owners, this decision also illustrates the strategic importance of identifying potential inventors throughout the R&D process—and maintaining channels of communication even after their departure—to safeguard intellectual property rights and avoid preventable patent invalidation. For patent challengers, this decision shows the defense of incorrect inventorship is still viable under the AIA, so defendants may wish to seek discovery on inventorship issues and raise such a defense where relevant.
