On April 2, in Fortress Iron, LP v. Digger Specialties, Inc., the Federal Circuit affirmed the district court’s holding that incorrect inventorship rendered two patents owned by Fortress Iron, LP (Fortress) invalid. The key question was whether inventorship can be corrected under 35 U.S.C. § 256 when a known, omitted inventor cannot be notified or given an opportunity to be heard.
The Fortress patents at issue are U.S. Patents 9,790,707 (’707) and 10,883,290 (’290), related to a vertical cable design used in railing and fencing products. In 2013, Hua-Ping Huang and Alfonso Lin, employees of a Chinese manufacturing company that Fortress had worked with to manufacture their products, suggested changes that were incorporated into the final cable design; however, both individuals were omitted as inventors when the patent applications were filed in 2015.
In 2021, during infringement litigation, Digger Specialties, Inc. (DSI) asserted that Huang and Lin should have been included as coinventors. Fortress subsequently admitted that both should have been included as inventors, and added Lin as a coinventor to the ’707 and ’290 patents following the procedure outlined in 35 U.S.C. § 256(a). Huang could not be located, and Fortress moved for partial summary judgment to add him as a coinventor using the judicial mechanism under § 256(b). DSI alternatively moved for summary judgment for invalidity due to incorrect inventorship. The district court granted DSI’s motion and denied Fortress’s request for partial summary judgment. Fortress then appealed.
U.S. patent law requires that a patent accurately names all individuals who contributed to an invention claimed in a patent. The Patent Act also mandates that inventors submit an oath or declaration confirming their contributions. 35 U.S.C. § 256(b) allows for the correction of inventorship if an inventor is erroneously omitted from an issued patent, thereby preventing the patent from being declared invalid. The Federal Circuit, in this holding, clarified that before making any correction to inventorship a critical prerequisite must be met: a coinventor, being a party concerned, must be notified and given an opportunity to be heard. The Federal Circuit held that in situations like Fortress’s, where the omitted inventor could not be located and given notice, § 256(b) cannot be used to correct inventorship.
The Federal Circuit went on to note that a patent may be declared invalid under 35 U.S.C. § 101 if it fails to meet statutory requirements, properly declaring inventorship being one of them. While § 256(b) is a “savings provision” and provides that the error of omitting inventors or naming individuals who are not inventors shall not invalidate a patent if the error can be corrected, here, the omitted inventor could not be located and given notice and hearing, making this statutory correction process unavailable. Thus, the Federal Circuit held the Fortress patents were invalid because inventorship was incorrect and could not be corrected according to law.
The Fortress decision offers several practical takeaways:
- all actual inventors must be named on a patent, including overseas contributors
- correction is not guaranteed if an inventor cannot be found
- the savings provision only applies when its requirements are strictly satisfied
- inventorship diligence during product development is critical, especially with third‑party collaborators
For more information on this topic, please contact Fitch Even patent agent Lindsay Boehme, Ph.D., author of this alert.
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Lindsay Boehme, Ph.D.
Lindsay Boehme, Ph.D., is a skilled Technical Writer with expertise in patent application preparation and prosecution across a range of scientific and engineering disciplines. Her work draws on more than a decade of experience in chemical engineering, materials science, and electrochemical technology development.