FORTRESS IRON, LP v. DIGGER SPECIALTIES, INC.

Authored by: Jeremy J. Gustrowsky

Fortress Iron, LP learned a costly lesson about inventorship when the Federal Circuit affirmed that two of its patents were invalid because a coinventor could not be located and added to the patents. The case centered on U.S. Patent Nos. 9,790,707 and 10,883,290, which covered pre-assembled vertical cable railing panels. While these patents originally named only two inventors, it turned out that employees of a Chinese business partner had also contributed to the invention. When one of those missing coinventors could not be found, the patents could not be saved from invalidity.

The story began in 2013, when Fortress’s owner conceived of a vertical cable railing that could be sold as a pre-assembled panel. Fortress worked with Chinese manufacturing partners to develop a prototype, but it had problems with cables rotating during tensioning. Two employees at the Chinese partner company, Hua-Ping Huang and Alfonso Lin, suggested design changes that solved the problem and were incorporated into the final product. Despite their contributions, only Fortress’s own people were named as inventors on the resulting patents. Huang later left the Chinese company in 2016 without leaving any forwarding contact information.

When Fortress sued competitor Digger Specialties, Inc. for patent infringement, the missing inventors became a critical issue. Fortress acknowledged that both Lin and Huang were rightful coinventors. Fortress was able to locate Lin and add him to the patents through the standard correction process under 35 U.S.C. § 256(a), which requires agreement from all parties and assignees. But Huang was nowhere to be found. Fortress then turned to § 256(b), asking the district court to order the correction instead. The court refused, and Digger Specialties won summary judgment that the patents were invalid.

On appeal, the Federal Circuit agreed with the district court on both points. First, the court held that Huang was a “party concerned” under § 256(b), meaning he was entitled to notice and a hearing before any court-ordered inventorship correction. Fortress argued that Huang should not count as a “party concerned” because adding him as a coinventor would only benefit him. The court rejected this, noting that being named as an inventor carries legal, financial, and ownership consequences that a person has every right to contest. Because Fortress could not even locate Huang, let alone notify him, it could not satisfy the statute’s requirements. Second, the court held that the inability to correct the inventorship error meant the patents were invalid. The statute says an inventorship error “shall not invalidate” a patent only “if it can be corrected.” The unavoidable flip side of that language is that when the error cannot be corrected, the patent is invalid.

This case is a stark reminder of how important it is to correctly identify all inventors from the start of the patent process. Even when an inventorship mistake is honest and unintentional, failing to name all contributors can put an entire patent at risk. Patent owners who work with outside collaborators, especially those overseas, should carefully document who contributed what to an invention and ensure that all coinventors are properly named before a patent issues. If a coinventor cannot be found later, it may be fatal to the patent.