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Plaintiffs must be added as inventors on patents

Virginia Lawyers Weekly//August 16, 2022

Plaintiffs must be added as inventors on patents

Virginia Lawyers Weekly//August 16, 2022

Where two individuals solved a problem that had prevented an inventor from conducting a successful test of his invention, and the invention would not have been viable without their efforts, they will be added as co-inventors to the US and foreign patents.


Plaintiffs bring this action against Steven Campbell and TranzGaz Inc. for correction of inventorship of United States Patent No. 9,376,049 B2. Plaintiffs contend that Gary Mackay and Dan Hewson should be added as inventors on the ’049 patent and several related foreign patents. The court held a two-day bench trial taking testimony and admitting exhibits into evidence.


The court must first construe the patent claims in dispute “to determine the subject matter encompassed” by the claims. The court must “then compare the alleged contributions of each asserted co-inventor with the subject matter of the properly construed claim[s] to … determine whether the correct inventors were named.”

To prove joint inventorship under the second step, a co-inventor must have (1) contributed in some significant manner to the conception or reduction to practice of the invention, (2) made a contribution to the claimed invention that is not insignificant in quality, when that contribution is measured against the dimension of the full invention and (3) done more than merely explain to the real inventors well-known concepts and/or the current state of the art.

In addition to the two-step process, plaintiffs must show “some quantum of collaboration” between the alleged inventors and the inventor listed on the patent. Finally, a plaintiff must provide “corroborating evidence of a contemporaneous disclosure that would enable one skilled in the art to make the invention.”


The subject matter at issue is “compression and crimping” of the port boss. Turning to step two, the question is whether the contributions of Mackay and Hewson were part of the conception of the idea or merely assistance in perfecting an idea that had already been conceived of by Campbell.

Here, the design problem required the creation of a new type of port boss. Thus, the solution was actually one of creation. Campbell had yet to create a functional version of the pressure vessel prior to Mackay’s and Hewson’s involvement. Campbell knew that he needed to attach the port boss components by some form of compression. Using the hydraulic cylinder, expanding the t-groove and adding the starburst grooves were the final steps in conceiving the idea.

Mackay and Hewson developed those ideas. These contributions solved the “slippage” problem that had prevented Campbell from conducting a successful test. Further, the designs were the result of a two-year effort by Mackay and Hewson that involved multiple drafts of designs. Prior to their involvement, Campbell did not have an idea that “required only ordinary skill … to reduce the invention to practice, without extensive research or experimentation.”

The contributions made by Mackay and Hewson were significant. Prior to their involvement, Trans Ocean Gas had at least two failed tests. Without solving the slippage issue, the invention would not be viable. Further Mackay and Hewson’s contributions were more than merely explaining the state of the art or a use of ordinary skill.

The emails with Campbell, the PowerPoint presentation that Campbell attended and the presentation recorded in the video illustrate that the parties collaborated. Finally Mackay and Hewson provided corroborating evidence in the form of dated design drafts made at the time of inventorship, the July 2007 report outlining the problems with the prior design, emails to and from Campbell, the PowerPoint presentation and the video of the successful application of the port boss.

Affirmative defenses

Plaintiffs initiated this lawsuit on Sept. 17, 2019. Thus, the “delay” was substantially less than six years, and there is no presumption of laches. While Campbell has suffered some prejudice, he did not provide evidence of material prejudice.

Equitable estoppel does not apply to this action. Given the hostilities between the parties, there was no miscommunication. Tube-Mac has been consistent in its communications with Campbell that it believed Mackay and Hewson were co-inventors. Further, Campbell has not alleged that plaintiffs were under any obligation to speak.


Gary Mackay and Dan Hewson have shown by clear and convincing evidence that they are co-inventors of the device contained in the ’049 patent.

Tube-Mac Industries Inc. v. Campbell, Case No. 2:20-cv-197, July 24, 2022. EDVA at Norfolk (Young). VLW 022-3-320. 24 pp.

VLW 022-3-320

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