Addressing the limits of correcting inventorship, the US Court of Appeals for the Federal Circuit affirmed an invalidity determination where an omitted coinventor could not be added because statutory notice requirements could not be satisfied. Fortress Iron, LP v. Digger Specialties, Inc., Case No. 24-2313 (Fed. Cir. Apr. 2, 2026) (Lourie, Hughes, Kleeh, JJ.)

Building products manufacturer Fortress Iron sued competitor Digger Specialties for infringement of two patents directed to pre assembled vertical cable railing panels. The inventions resulted from collaboration among Fortress’ owner and an employee, as well as two employees of its quality control liaison, Hua Ping Huang and Alfonso Lin, who proposed design changes to address cable tensioning issues. The issued patents, however, named only Fortress personnel and omitted Lin and Huang as coinventors.

During the litigation, Fortress acknowledged that Lin and Huang were coinventors. Fortress successfully added Lin under 35 U.S.C. § 256(a) but was unable to locate Huang, who had left the liaison company years earlier without providing contact information. The parties filed cross motions for summary judgment, with Fortress seeking correction of inventorship and Digger seeking invalidity. The district court denied Fortress’ motion and held the patents invalid for incorrect inventorship. Fortress appealed.

Fortress argued that Huang was not a “party concerned” under § 256(b) and therefore was not entitled to notice and a hearing. The Federal Circuit rejected that argument, explaining that an omitted inventor qualifies as a “party concerned” regardless of whether the inventor has a demonstrated economic interest in the patent. The Court explained that inventorship carries legal, financial, and ownership consequences that an inventor has a right to contest, and § 256(b)’s notice and hearing requirements cannot be bypassed. The Court further clarified that standing and “party concerned” status under § 256(b) are distinct legal concepts with different requirements.

The Federal Circuit also rejected Fortress’ characterization of § 256(b) as a broadly permissive “savings provision,” explaining that the statute only operates to save patents once its procedural prerequisites of notice and an opportunity to be heard are satisfied.

Turning to Fortress’ second argument, the Federal Circuit concluded that a patent that incorrectly lists its inventors and cannot be corrected under § 256 has a clear statutory basis for invalidity. Reading § 256(b) together with §§ 101 and 100(f), the Court concluded that when an invention has multiple inventors, all must be named. Allowing a patent to survive with only some inventors listed would render § 256’s corrective framework meaningless.

Practice note: The decision underscores the importance of accurate inventorship determinations and the practical risk that patents may be rendered invalid if an omitted inventor cannot be located and statutory correction requirements cannot be met.