Federal Circuit IP
Fortress Iron, LP v. Digger Specialties, Inc.
Fortress Iron, LP v. Digger Specialties, Inc.
Case No. 2024-2313, decided April 2, 2026
(Lourie, Hughes, Kleeh)
Issues: Whether an omitted coinventor is a “party concerned” under 35 U.S.C. § 256(b) entitled to notice and an opportunity to be heard before judicial correction of inventorship. Whether a patent that omits an inventor and cannot be corrected is invalid.
Overview: The Federal Circuit affirmed summary judgment that two patents were invalid for incorrect inventorship. The decision clarifies that an omitted coinventor is a required “party concerned,” so a patent with incorrect inventorship remains invalid if the omitted inventor cannot be given notice and an opportunity to be heard and the error therefore cannot be corrected.
Background
- Fortress developed vertical cable railing panels and worked with Chinese companies YX and YD in developing the final design.
- Fortress’s owner and employee initially conceived the product, but YD employees Hua-Ping Huang and Alfonso Lin suggested changes that were incorporated into the final design.
- The patents issued naming only Matthew Sherstad and Kevin Burt as inventors.
- During litigation, Fortress acknowledged that Lin and Huang were coinventors. Fortress successfully added Lin through the PTO process under § 256(a), but Huang could not be located after his employment ended.
- Fortress moved for partial summary judgment seeking court-ordered correction under § 256(b); Digger moved for summary judgment of invalidity.
Federal Circuit Analysis
- Section 256(b) permits judicial correction only “on notice and hearing of all parties concerned.”
- The Court held that an omitted coinventor is plainly a “party concerned.” Inventorship carries legal, ownership, and financial consequences. The Court rejected Fortress’s attempt to limit that phrase to persons with adverse economic interests.
- Because Fortress could not provide Huang notice and an opportunity to be heard, it could not satisfy § 256(b)’s prerequisites.
- The Court then held that the patents were invalid. Section 256(b) provides that omission of an inventor “shall not invalidate” a patent if the error can be corrected; the negative implication is that a patent is invalid when such an error cannot be corrected.
- The Court rejected Fortress’s argument that listing at least one true inventor is enough. That interpretation would read the statutory protection for omitted inventors out of the statute.
Holding: Affirmed. An omitted coinventor is a “party concerned” under § 256(b), and where the omitted inventor cannot be given notice and hearing, the inventorship error cannot be judicially corrected and the patent is invalid.
Takeaways
- Litigators: Inventorship may not always be a technical cleanup issue. If an omitted inventor cannot be reached and added under § 256, it can cause case-ending invalidity.
- Prosecutors: Inventorship diligence remains critical at the front end. Contributors may become increasingly difficult to locate later.