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Determining Inventorship

Properly determining inventorship is an important and sometimes difficult matter. Section 116 of Title 35 of the U.S. Code (§ 116) requires each joint-inventor to make an oath that the listed inventors are the true and only inventors. Unfortunately, understanding what contributions are sufficient to establish inventorship is not always straightforward. In addition, egos and personal aspirations can sometimes blur better judgment. In research, out of academic convention or abundance of caution, inventors may mistakenly attribute inventive credit to non-inventors involved in a project. Errors in the listing of inventors on a patent application can be difficult to correct, particularly when a listed inventor needs to be removed. In egregious situations, failing to properly list inventors may lead to the invalidation of a granted patent.

The test for inventorship hinges upon a determination of whether a person materially contributed to the invention that is defined by the claimed invention. While this test is seemingly straight forward, one court has referred to the determination of inventorship as “one of the muddiest concepts in the muddy metaphysics of the patent law.”1 The mire is thickened when taking into account the complexities of the patent claim, which the courts have recognized as being one of the most difficult legal instruments to draft.

Under US law, an inventor is a party who contributes to the conception of an invention. According to § 116, “[w]hen an invention is made by two or more persons jointly, they shall apply for [a] patent jointly and each make the required oath, except as otherwise provided in this title. Inventors may apply for a patent jointly even though (1) they did not physically work together or at the same time, (2) each did not make the same type or amount of contribution, or (3) each did not make a contribution to the subject matter of every claim of the patent. There can be several joint inventors so long as each makes a significant contribution to the conception of inventive aspects of the claimed invention."2 In other words, each inventor must contribute to “the formation in the mind… of a definite and permanent idea of the complete and operative invention, as it is hereafter to be applied in practice.” 3, 4 Conception is considered complete when “only ordinary skill would be necessary to reduce the invention to practice, without extensive research of experimentation.”5

Determining whether an individual’s contribution raises to the level of inventiveness can be difficult. Generally, experimentation or reduction to practice does not raise to the level of inventiveness unless there is “a nexus between the research or experimentation and the subject for which patent protection is sought.”6 In this context, carrying out regimented testing or assisting an inventor in a laboratory may not raise to a level of contribution that is sufficient to make one a co-inventor.7 Likewise, informing inventors of well known concepts, options, or the current state of the art, is generally not a qualitative contribution.8 For example, the addition of a well known element in a claim dependent from a broader claim may not constitute a significant contribution.9 However, research and experimentation may lead to a patentable new use for a chemical structure created by others.

To complicate matters further, inventorship of a patent application is not fixed in time but may change during prosecution. The flow diagram shown here illustrates a process that has been used by attorneys to address issues of inventorship at various stages of claiming the invention. As shown, inventorship is ultimately determined not from the draft of the initially-contemplated claims, but relative to the claims examined and allowed by the Patent Office.

The changing nature of the claims stems from the need to cover variations of the described implementation without encroaching on previously known implementations. Accordingly, it is advantageous to identify which aspect are attributable to each individual inventor in order to identify and correct changes to inventorship.

Although options may be available for correcting inventorship, taking steps to ensure that the correct inventors are listed and correcting inventorship early when errors are discovered can avoid the high costs of correcting inventorship or litigation, should a dispute arise.

We invite you to contact us for more information and other assistance in addressing issues relating to patent applications, patent infringement and patents in general. You may find us on the web at

1 Mueller Brass Co. v. Reading Industries, Inc., 352 F.Supp. 1357, 1372 (E.D. Penn. 1972).

2 Eli Lilly& Co. v. Aradigm Corp., 376 F. 3d 1352, 1359 (Fed. Cir. 2004).

3 Ethicon, Inc. v. US Surgical, Inc., 135 F.3d 1456, 1460 (Fed. Cir. 1998).

4 Each joint inventor does not need to have an independent definite and permanent idea of the complete invention. Rather, the joint inventor must collectively have a definite and permanent idea of the complete invention. Vanderbilt University v. ICOS Co., No 2009-1258, Slip Op. at 14-15 (Fed. Cir. 2010).

5 Burroughs Wellcome Co. v. Barr Labs., Inc., 40 F.3d 1223, 1228 (Fed. Cir. 1994).

6 Sewell v. Walters, 21 F.3d 411, 415 n.2 (Fed. Cir. 1994).

7 Sewall v. Walters, 21 F.3d 411, 416-417 (Fed. Cir. 1994).

8 Hess v. Advanced Cardiovascular Sys., Inc., 106 F.3d 976, 981 (Fed. Cir. 1997).

9 Nartron Corp. v. Schukra USA Inc., 558 F. 3d 1352 (Fed. Cir. 2009).

© Crawford Maunu PLLC. All rights reserved. This material is for informational purposes only and should not be construed as legal advice. Also, as this material was prepared by individuals and not prepared by Crawford Maunu PLLC acting on behalf of any particular client/factual situation, this material should not be construed as providing a specific position applicable to any legal matter. Communication of this material is not intended to establish an attorney-client relationship. Legal advice should be sought from legal counsel.