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Fortress Iron v. Digger Specialties: The Coinventor You Cannot Find

Federal Circuit, decided 2 April 2026. Read from the opinion; quotations verified against the court's text.

Holding

On April 2, 2026 the Federal Circuit held, as a matter of first impression, that an agreed-upon omitted coinventor is a "party concerned" under 35 U.S.C. § 256(b) who must be given notice and an opportunity to be heard before a court corrects inventorship, and that a patent incorrectly listing its inventors which cannot be corrected according to law is invalid.

Fortress Iron developed a cable railing system with help from two engineers who worked for a supplier's quality-control company. It patented the design and named only its own owner and employee.

Years later, in litigation, Fortress admitted both supplier engineers were coinventors. It added one of them through the Patent Office. The other, Hua-Ping Huang, it could not locate.

Because § 256 requires that an omitted coinventor get notice and a chance to be heard before a court corrects inventorship, and Fortress could not give him notice, the patents could not be fixed. And a patent that names the wrong inventors and cannot be corrected is invalid.

Two patents, gone. Not over prior art, not over eligibility, not over anything about the invention. Over who was written on the front page, and the fact that one of the people who should have been there could not be found years later.

Where This Actually Happens

The facts are unusually ordinary, which is what makes the case worth reading. Nobody set out to misname anyone. Engineers at a supplier helped solve a problem, the company that filed named its own people, and the gap surfaced only when litigation forced a close look at who contributed what.

The same shape recurs constantly in software: a contractor who reworks an algorithm, an open-source maintainer who proposes the approach that ends up in the claims, a vendor's engineer who solves an integration problem, a research collaborator at another institution. In each, the contribution is real, the relationship is not employment, and the question of who invented what never gets asked at the time.

What made this unrecoverable was not the misnaming. It was the passage of time. Fortress agreed Huang was a coinventor and still lost, because by then it could not find him.

What This Case Is Not

"Make everyone sign an assignment" is the wrong lesson, and a dangerous one. Assignment addresses ownership, meaning who holds title. This case is about inventorship, meaning who is legally the inventor. They are different questions with different rules. A signed assignment from the supplier's engineers would not have saved these patents, because the defect was the names on the patent rather than who owned it. A team that responds to this case by tightening assignment paperwork has protected itself against a different problem.
  • It does not tell you whether your contractor, vendor or reviewer is a coinventor. That is a legal determination made on the facts and the claims, and it is one where the cost of being wrong is the whole patent.
  • It does not say any particular contribution does or does not rise to inventorship.
  • It does not hold that assignments are unimportant. It holds that they answer a different question than the one that decided this case.

Read alongside Thaler v. Vidal, which addresses who is eligible to be named at all, and Omni MedSci v. Apple, which is the ownership half of the same picture.

Educational, not legal advice. Consult a qualified patent attorney about inventorship on your own applications.

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