Fortress Iron, LP (patent owner) sued Digger Specialties, Inc. (DSI, accused infringer) for infringement in N.D. Ind. DSI identified two unlisted coinventors; Fortress added one via § 256(a) but could not locate the other, leading to denial of summary judgment for correction and grant of DSI's invalidity motion.[3] Judges Lourie, Hughes, and Kleeh (designated) held the missing coinventor qualified as a "party concerned" under § 256(b), requiring notice and hearing—impossible without location—thus precluding correction and rendering the patents invalid.[3]
Litigation arose during infringement proceedings after DSI discovered the inventorship issue. Fortress acknowledged one coinventor but failed on the second; district court ruled accordingly, appealed to Federal Circuit (argued post-discovery).[3] Timeline: Patents issued pre-suit; suit filed (exact date unspecified); inventorship revealed during litigation; decision Apr. 2, 2026.[3]
Newsworthy for addressing first-impression § 256(b) "party concerned" interpretation, clarifying correction limits and invalidity consequences, impacting construction patent enforcement and due process in inventorship disputes—published Apr. 10, 2026, amid active Federal Circuit patent docket.[1][3] No other cases dominate the summary.[3]