If you’re preparing to file — or already have filed — a U.S. patent application, inventorship (deciding who gets named as an inventor) may feel like a formality. You may assume you are the inventor. After all, the invention came from your company, your team, or even you personally.  But U.S. patent law does not see inventorship that way.

Inventorship is a legal requirement grounded in statute, USPTO rules, and decades of court decisions. And as the Federal Circuit recently reaffirmed, getting it wrong can invalidate an otherwise valuable patent.

What Is Inventorship Under U.S. Patent Law?

According to 35 U.S.C. § 115, a patent application “shall include, or be amended to include, the name of the inventor for any invention claimed in the application … each individual who is the inventor or a joint inventor of a claimed invention in an application shall execute an oath or declaration”.  This is not a business concept — it’s a legal one!

The Manual of Patent Examining Procedure (MPEP), which is a Patent Examiner’s Bible, explains that an inventor is someone who contributed to the conception of the invention (see MPEP § 2109). Conception means forming a definite and permanent idea of the complete invention as it appears in the patent claims.

That distinction matters because:

• Someone who merely followed instructions is not an inventor
• Someone who built, tested, or marketed the product is not automatically an inventor
• Someone who suggested a key idea that appears in the claims may be an inventor

Inventorship turns on what is claimed (i.e. what is defined by the numbered paragraphs at the end of the patent document), not who worked the hardest or who paid for development.

Joint Inventorship: More Common — and Trickier — Than You Think

Many modern inventions involve collaboration. Under MPEP §§ 602.09 and 2109.01, joint inventorship exists when multiple people contribute to the conception of the invention in at least one claim.

Key points that often surprise applicants:

• Joint inventors do not need equal contributions
• Joint inventors do not need to contribute to every claim
• Joint inventors do not need to work together at the same time

Each named inventor must have contributed to the conception of at least one claimed feature. Naming too many inventors — or too few — creates risk.

Why Getting Inventorship Right Is Critical

Inventorship isn’t clerical. It is foundational to obtaining — and maintaining — a valid patent.  If a true inventor is omitted, or a non-inventor is included, the patent can be challenged and potentially invalidated. That risk doesn’t disappear after issuance — it can surface years later, often during licensing talks or litigation.

This was underscored forcefully in April 2026, when the Federal Circuit issued its decision in Fortress Iron, LP v. Digger Specialties, Inc.

A Cautionary Tale: Fortress Iron v. Digger Specialties

In Fortress Iron, the patents at issue covered preassembled vertical cable railing panels. The original patents named two U.S.-based individuals as inventors. However, during infringement litigation, evidence showed that two overseas collaborators had proposed design changes that solved a key technical problem — and that those changes were reflected in the patent claims.

Those overseas collaborators were undisputed co-inventors.  One co-inventor was eventually added to the patent; but the other collaborator could not be located as they were no longer employed by the company.  That fact became decisive.

Fortress attempted to rely on 35 U.S.C. § 256, the statute that can sometimes “save” patents with inventorship errors. But § 256 requires that all “parties concerned” — including omitted inventors — receive notice and an opportunity to be heard.

Because the missing inventor could not be found, the correction process failed.  The result: the patents were held invalid.

The Federal Circuit made two points crystal clear:

1. Omitting a true inventor renders a patent invalid unless the error can be corrected as the statute requires; and
2. Courts cannot bypass the procedural protections owed to inventors — even if invalidation seems harsh. 

For patent owners, the lesson is sobering: Inventorship errors are not harmless, and some cannot be fixed later.

Can Inventorship Be Corrected?

Sometimes — but not always.

U.S. patent law and regulations provide mechanisms by which inventorship can be corrected, under limited circumstances.  Inventorship errors can be corrected if:

• The error occurred without deceptive intent;
• All required parties can be identified and notified; and
• Statutory and procedural requirements are met.

Fortress Iron illustrates the flip side: When correction is legally or practically impossible, the patent may simply fail.

Best Practices to Avoid Inventorship Problems

Inventorship disputes are far easier to prevent than to cure. A few practical safeguards go a long way:

1. Analyze Inventorship Claim by Claim

Inventorship depends on the claims, not the entire disclosure or overall project. Revisit inventorship whenever claim scope changes.

2. Document Contributions Early

Contemporaneous notes, emails, and design records help establish who contributed what — and when.

3. Be Careful with External Contributors

Suppliers, consultants, contractors, and overseas partners can be inventors if they contribute to conception—even informally. Under the law, their contribution cannot be altered by contract – if they are an inventor then it doesn’t matter if they agreed not to claim inventorship. Instead, name them as an inventor and get them to sign an assignment and cooperation agreement so you retain control and ownership.

4. Don’t Use “Courtesy Inventors”

Including executives or managers who didn’t contribute to conception is not harmless, and can create its own problems.

5. Reassess Before Enforcement

Before asserting or licensing a patent, confirm that inventorship holds up under scrutiny. Fix any vulnerabilities without delay.

Final Takeaway

Inventorship is one of the least glamorous aspects of patent law — and one of the most unforgiving.

As Fortress Iron demonstrates, a single omitted inventor can undo years of innovation and investment. Treat inventorship as a legal determination, not a box to check, and revisit it as your application evolves. If there’s uncertainty, addressing it early is almost always cheaper — and much safer—than dealing with it later in court.