Our Patent Case Summaries provide a weekly summary of the precedential patent-related opinions issued by the Court of Appeals for the Federal Circuit and the opinions designated precedential or informative by the Patent Trial and Appeal Board.
Fortress Iron, LP v. Digger Specialties, Inc.
No. 2024-2313 (Fed. Cir. (N.D. Ind.) Apr. 2, 2026). Opinion by Lourie, joined by Hughes and Kleeh (sitting by designation).
Fortress owns two patents directed to vertical cable railing panels used in the construction of outdoor living spaces. Fortress sued Digger Specialties, Inc. (DSI) for infringement of both patents. During the litigation, DSI learned of two individuals that had contributed to the patented inventions but were not listed as inventors.
Fortress acknowledged that these individuals were coinventors, and Fortress successfully added one coinventor through 35 U.S.C. § 256(a). But Fortress could not locate the other coinventor. Fortress then moved for summary judgment to correct the patents by adding the remaining coinventor under § 256(a), but the district court denied the motion. At the same time, DSI moved for summary judgment of invalidity due to incorrect inventorship, which the district court granted. Fortress appealed.
The Federal Circuit affirmed.
First, the Federal Circuit held that the district court properly denied Fortress’s motion to correct inventorship. Addressing an issue of first impression, the Federal Circuit ruled that the coinventor was a “party concerned” under § 256(b) and therefore entitled to notice and an opportunity to be heard before the district court could order any correction of inventorship.
Because Fortress could not locate the missing coinventor, it could not satisfy the notice and hearing prerequisites and thus could not use § 256(b) to correct the patents.
Second, the Federal Circuit affirmed the summary judgment of invalidity due to incorrect inventorship. The district court, based on § 101, held that because the missing coinventor was not named, the patents were invalid. The Federal Circuit agreed, explaining that “§ 101 and § 100(f) [which defines the term ‘inventor’], when read together with § 256(b), contemplate that when an invention has multiple inventors, they must all be listed on the patent.” The Federal Circuit thus held that “a patent which incorrectly lists its inventor(s) and cannot be corrected according to law is invalid,” and therefore affirmed the district court’s grant of DSI’s motion for summary judgment of invalidity.