The U.S. Court of Appeals for the Federal Circuit’s recent decision in Fortress Iron, LP v. Digger Specialties, Inc., No. 24-2313 (Apr. 2, 2026) provides a pointed reminder of the strict requirements surrounding patent inventorship and the limited availability of correction under 35 U.S.C. § 256. The Federal Circuit affirmed summary judgement invalidating two patents for failure to name a co-inventor and upheld the denial of a request to correct inventorship. As discussed below, inventorship cannot be corrected if the notice and hearing prerequisite of § 256 cannot be satisfied.
Background of the Dispute
Plaintiff-Appellant Fortress Iron designs and markets railing and fencing systems. Fortress’ U.S. Patent Nos. 9,790,707 and 10,883,290 relate to components used in such systems. Of particular note, Fortress worked with a Chinese manufacturer during product development. Two employees of this manufacturer, Alfonso Lin and Hua-Ping Huang, substantially contributed to this product development, but were not named as coinventors on the patents.
During the course of infringement litigation, Defendant-Appellee Digger Specialties learned that Lin and Huang had contributed to the invention and challenged the validity of the patents for failure to name Lin and Huang as coinventors. Fortress acknowledged that Lin and Huang were coinventors, located Lin, and successfully added him as coinventor to the patents following the procedure outlined in § 256. However, because Huang had not provided his contact information, Fortress Iron was unable to locate him, and thus, was unable to add him as a coinventor using that same procedure.
Fortress Iron moved for summary judgment to correct the patents by adding Huang as a coinventor; Digger Specialties opposed and moved for summary judgment of invalidity due to incorrect inventorship. The district court denied Fortress’s motion to the extent that it did not order correction of the patents, then granted Digger Specialties’ motion, holding that the patents were invalid for omission of an inventor. The Federal Circuit affirmed both rulings.
Takeaway from the Dispute: Inventorship Errors May Not Always Be Curable
Section 256, described as a “savings provision,” permits correction of inventorship errors in patents, but the Fortress Iron decision highlights important limits on that relief. Section 256(b) states that “[t]he error of omitting inventors or naming persons who are not inventors shall not invalidate the patent in which such error occurred if it can be corrected as provided in this section. The court before which such matter is called in question may order correction of the patent on notice and hearing of all parties concerned”.
Although § 256(b) provides that inventorship errors do not invalidate a patent if they can be corrected, the Federal Circuit’s decision emphasizes that correction is not automatic and may occur only “on notice and hearing of all parties concerned” as required by § 256(b). Fortress Iron conceded that it was unable to locate omitted inventor Huang, let alone provide him with notice as required by the statute. But Fortress Iron argued that Huang was not a “party concerned” because adding him as a coinventor would benefit him, not adversely affect him. But the court disagreed, noting that inventorship carries significant legal, financial, and ownership consequences, and therefore, an omitted inventor is a “party concerned.” Because Fortress could not contact Huang to provide the required notice and opportunity to be heard, the court held that the inventorship error could not be corrected under § 256.
Guidance for Patent Owners
The Federal Circuit’s decision in Fortress Iron reinforces a fundamental principle of patent law: correct inventorship is essential for patent validity, and errors can have severe consequences if not properly addressed. Thus, patent owners should consider the following.
- Do Not Overlook § 256(b)’s “Notice and Hearing” Requirement
While § 256 provides for correcting inventorship, the decision makes clear that§ 256(b) does not automatically allow a court to order correction of a patent. Rather, the court may only do so “on notice and hearing of all parties concerned.”
- Properly Assess Inventorship by the Time of Filing the Patent Application
Unless a person contributes to the conception of the invention, he or she is not an inventor. As such, proper assessment of a person’s contribution to the conception of the invention is critical to a proper determination of inventorship and should be the subject of careful and thorough analysis early on. Ideally, a review of inventorship is conducted during patent application drafting prior to filing and when an application is amended such that one (or more) of the named coinventors is no longer a joint inventor of the subject matter of any claim remaining in the application. Interviews of contributors are often best conducted by a neutral party, such as outside counsel, who can make unbiased decisions with regard to assessment of an individual’s contribution to the conception of the invention in view of the legal standards for inventorship.
- Keep Contributor Records and Contact Information Current
Moreover, the case illustrates the importance of having accurate and updated contact information for contributors, especially those who leave their employer or reside in a different country. In particular, it is best practice to ensure that any inventor leaving their employer provides an accurate forwarding address, such that they can be contacted during patent pendency and/or throughout the issued patent’s lifespan.
Lin and Huang’s involvement as employees of a contractor highlight the importance of not only contemplating IP ownership in agreements with contractors, but also requiring contractors to maintain and provide necessary contact information for project team members that may be necessary for inventorship correction.
Conclusion
In conclusion, Fortress v. Digger is a reminder of the importance of correct inventorship and the dangers of an incorrect or incomplete listing of the inventors. Further, the ruling underscores the requirements of § 256 for inventorship correction.
