Written by: Caldwell

The front page of every patent lists the person or people responsible for inventing the patented idea. When the invention is made by a single person, inventorship is straightforward – their name is the only one on the patent because they are the only one who contributed to the claimed invention. But what about inventions with multiple inventors? Properly determining inventorship with multiple inventors can be tricky, and getting it wrong can negatively impact enforceability or even invalidate the patent entirely.

The Court of Appeals for the Federal Circuit issued a precedential opinion last month in the case of HIP Inc. v. Hormel Foods Corp.1, ruling that a man named David Howard should not be considered a joint inventor of an improvement to methods of cooking bacon despite technically contributing to the conception of at least one claim. While the importance of improved methods of cooking bacon might be obvious, this case is also interesting because it highlights some nuances about how inventorship is determined and when someone might not qualify as an inventor even if they meet the minimum requirements of inventorship.

Inventorship Requirements

Let’s start with those minimum requirements: to be an inventor on a patent, a person must contribute to the conception of subject matter in at least one claim. Conception refers to contributing to the development of the idea itself. Importantly, this does not include merely identifying a problem that needs to be solved, nor does it include performing testing that does no more than prove that a previously conceived idea works. The claims, for those new to patent practice, are the numbered sentences at or near the end of every patent that define the legal protection that the inventor or joint inventors are seeking. The claims specify the “metes and bounds” of the invention and are the legally enforceable part of the patent.

An Example of Nuances

To give an example of how determining inventorship can sometimes be a thorny task (and to borrow a bit from the scenario in HIP v. Hormel), imagine four people who work at an international meat company: Smith, Jones, Alice, and Bob. Smith heads the breakfast meats division and has been under pressure lately to boost bacon sales. He determines that sales could be improved if their bacon product was crispier and directs Alice and Bob to develop a cooking method to make that crispiness a reality.

Our porcine pioneers get to work and soon theorize that they can make crispier bacon by following a two-step process. First, they preheat the bacon to a relatively low temperature in an oven to a) brown it and b) release some fat to prevent condensation from washing away flavor; second, they finish cooking it in a different oven at a higher temperature.

Confident their method will work, but not the most gifted of chefs or engineers, Alice and Bob enlist the help of Jones, a technician of ordinary skill in the bacon arts. Jones carefully follows the method outlined by Alice and Bob and successfully demonstrates that the method works just as conceived by Alice and Bob. The company immediately files a patent on the new method. Who is properly named as an inventor?

  • Smith: No. Despite identifying the problem to be solved, Smith did not contribute to the actual solution. He is therefore not an inventor.
  • Alice: Yes. Since she contributed to the conception of ­­­the claimed invention, she is a joint inventor.
  • Bob: Yes. He would also be considered a joint inventor since he contributed to the conception of the claimed invention.
  • Jones: No. Despite performing the patented cooking method before it was patented, Jones was merely following the instructions provided by Alice and Bob and therefore did not meaningfully contribute to the conception (or reduction to practice) of at least one claim. As a result, he is not considered an inventor.

Improperly Included Inventors

The requirements for inventorship have important implications for entities applying for patents. It can sometimes be tempting to include certain people as inventors on patents as a “favor” to them, even if they didn’t contribute to the conception of at least one claim, but this is a mistake. For example, if the following people did not meaningfully contribute to the conception or reduction to practice of a claimed invention, they would not be properly considered inventors:

  • An undergraduate assistant who did no more than perform testing of an idea at the direction of the professor or graduate student who conceived of the idea.
  • A manager who directed a project that led to an invention.
  • The VP of R&D who wants to burnish their credentials for a promotion.
  • Someone who conceived of a claimed concept in a patent application, but whose contribution was removed from the claims before the patent issued.

The last example in particular can be a source of tension (e.g. in a workplace where incentives are provided to inventors for submitting patent ideas or being named on patents) – no one who expects to be listed as an inventor on a patent likes hearing that they will not be a named inventor after all.

Particulars of Inventorship – The Pannu Factors

So, what about David Howard? Earlier, we saw that the minimum requirements of inventorship were contributing to the conception of at least one claimed limitation. In the 1998 case of Pannu v. Iolab Corp.2, the Federal Circuit articulated a three-part test for qualifying as a joint inventor that more particularly defines the determination of joint inventorship. All three of the following conditions must be met for a person to be considered a joint inventor:

  1. Did the person “contribute in some significant manner to the conception or reduction to practice of the invention?”3
  2. Did the person “make a contribution to the claimed invention that is not insignificant in quality, when that contribution is measured against the dimension of the full invention?”4
  3. Did the person “do more than merely explain to the real inventors well-known concepts and/or the current state of the art?”5

In David Howard’s case, the Federal Circuit determined that even though his contribution (suggesting an infrared oven as a specific type of oven used to preheat the bacon) appeared in one of the patent’s claims, it was insignificant in quality when measured against the dimension of the full invention. In particular, his idea of using an infrared oven appeared in only one claim (alongside two other heating methods as part of a Markush group) and was mentioned in the detailed description of the invention only once. For this reason, the Federal Circuit decided that David Howard did not meet the second condition of the Pannu test and therefore did not qualify as a joint inventor.


Properly determining inventorship should always be a top priority for anyone filing patents or developing and managing a patent portfolio. In the United States, inventors start off with the rights to their invention, even if many assign those rights to their university or employer as part of an employment contract. If a company believes they have the full rights to a patent, but it later turns out that an inventor was improperly excluded and never assigned their patent rights to the company, the company can be faced with a host of headaches.

One such example occurred in Ethicon Inc. v. United States Surgical Corp.6 where an erroneously excluded inventor sold his patent rights to a competitor and potential infringer (U.S. Surgical) after inventorship was properly corrected, which prevented the patent licensee (Ethicon) from asserting infringement against the competitor. This case provides a stark lesson on how improperly determined inventorship can deal a significant blow to a business and emphasizes the necessity of proper diligence and IP language in employee onboarding contracts. Clearly-defined ownership and assignment of IP are critical when it comes to utilizing these powerful business assets.

While there are mechanisms for correcting inventorship (even after a patent has been granted), ensuring that inventorship is properly established at the time of filing pays dividends for avoiding enforcement and validity roadblocks down the line.

1. HIP, Inc. v. Hormel Foods Corp., __ F.4th __, Case No. 2022-1696, 2023 WL 3184358 (Fed. Cir. 2023).

2. Pannu v. Iolab Corp., 155 F.3d 1344 (Fed. Cir. 1998).

3. Id. at 1351.

4. Id. at 1351.

5. Id. at 1351.

6. Ethicon, Inc. v. United States Surgical Corp., 135 F.3d 1456 (Fed. Cir. 1998)