Federal Circuit Invalidates Patents for Co-Inventor Omission – Fortress Iron Decision Sends Warning to Collaborative R&D

The U.S. Court of Appeals for the Federal Circuit (CAFC) issued a precedential decision on April 2, 2026, invalidating two patents for failure to name a co-inventor. In Fortress Iron LP v. Digger Specialties Inc., Judge Lourie’s opinion reaffirmed the central role of inventors in the patent system and highlighted the risks of inadequate inventorship management in collaborative R&D.

Notably, this case was decided as a matter of first impression — meaning the Federal Circuit addressed these specific legal questions for the first time — lending the decision broad precedential weight for future practice.

Background

The patents at issue were U.S. Patent No. 9,790,707 and U.S. Patent No. 10,883,290, both titled “Vertical Cable Rail Barrier” and owned by Fortress Iron LP.

The final designs covered by the patents were conceived jointly by two Fortress employees and two employees of Quan Zhou Yoddex Building Material Co., Ltd (YD), Fortress’s quality control liaison. The two YD contributors were Hua-Ping Huang and Alfonso Lin.

When Fortress sued Digger Specialties for patent infringement in January 2021, Digger discovered during litigation that the YD employees had contributed to the invention. Fortress attempted to add both as co-inventors under 35 U.S.C. § 256(a). While Lin was successfully added, Fortress could not locate Huang, making it impossible to provide the statutorily required notice.

The Court’s Reasoning

The Federal Circuit affirmed the district court on all key points, delivering several significant holdings.

Huang qualifies as a “party concerned.” Fortress argued that since adding Huang as a co-inventor would only benefit him, he should not be treated as a “party concerned” under § 256(b). The CAFC rejected this, holding that “inventors occupy the central role in the patent process. They are where it all begins, even if they eventually assign their interests to others, such as employers. Thus, their explicit references in the statutory framework cannot be taken lightly.“

Procedural protections are prerequisites, not formalities. The court stated plainly: “§ 256(b) makes those procedural protections a prerequisite to relief, not a mere formality.” Even though Fortress was unable to locate Huang, this did not waive the requirement to provide notice and an opportunity for hearing.

Uncorrectable inventorship errors invalidate the patent. Section 256(b) provides that inventorship errors “shall not invalidate the patent… if [they] can be corrected.” The CAFC held that “the necessary and opposite implication of § 256(b) is that a patent is invalid for the error of omitting inventors when that error cannot be corrected.“

“Whoever” means all inventors. Addressing 35 U.S.C. § 101, the court stated: “[Section] 101 and § 100(f), when read together with § 256(b), contemplate that when an invention has multiple inventors, they must all be listed on the patent. ‘Whoever’ does not mean less than all.“

Implications for Collaborative R&D

The decision serves as a stark warning for companies engaged in joint development with external partners. In this case, employees of a quality control subcontractor had made substantive contributions to the inventive process, yet were not named as inventors in the original filings.

What makes this case particularly concerning is that Fortress attempted to correct the error but was prevented from doing so by a practical obstacle — Huang’s whereabouts were unknown. The result was total patent invalidation, not merely a procedural setback.

M&A and Licensing Ramifications

The ramifications extend well beyond individual litigation. In M&A transactions, patent portfolios subject to due diligence will face heightened scrutiny over inventorship accuracy. Representation and warranty clauses in licensing agreements regarding the accuracy of inventor designations take on new weight.

For large enterprises that routinely collaborate with external research institutions and suppliers, building robust systems for timely identification and documentation of all co-inventors is now operationally essential.

Practical Recommendations

In light of this decision, practitioners should take several concrete steps. First, audit existing patent portfolios for any cases where external collaborators may have contributed to conception, and verify inventorship accuracy. Second, ensure that joint development agreements include explicit procedures for inventorship identification, with ongoing obligations to maintain current contact information. Third, strengthen pre-filing inventorship determination processes to properly evaluate each contributor’s role in the conception of the invention.

The CAFC’s reaffirmation that “inventors occupy the central role in the patent process” should be taken seriously by every patent practitioner and portfolio manager.