"Whoever invents or discovers . . . ." That's how 35 U.S.C. §101 kicks off U.S. patent law. Inventing involves three stages: (1) conception, (2) activities leading toward a reduction to practice, and (3) reduction to practice (either actual or constructive). While an inventor or someone acting under an inventor's direction can perform the second and third stages (Trovan, Ltd. v. Sokymat SA, 299 F.3d 1292, 1302 (Fed. Cir. 2002)), only an inventor can complete the first stage, conception.

"The threshold question in determining inventorship is who conceived of the invention." Mueller Brass Co. v. Reading Indus., 352 F. Supp 1357(E.D. Pa 1972).

Unless a person participates in that first stage of conceiving of the invention, that person does not qualify as an inventor. In re Hardee, 223 U.S.P.Q. 1122, 1123 (Comm'r Pat. 1984).

Conception is often referred to as the mental part of the inventive activity, and it requires both a recognition of the ultimately desired result and the means to accomplish that result.

"Conception is complete only when the idea is so clearly defined in the inventor's mind that only ordinary skill would be necessary to reduce the invention to practice, without undue extensive research or experimentation." Sewall v. Walters, 21 F.3d 411, 415 (Fed. Cir. 1994).

The case law makes clear that the standard for assessing conception set forth in the Supreme Court's 1897 Mergenthaler decision still controls the question of inventorship. That is, "[f]ormation in the mind of the inventor of a definite and permanent idea of the compete and operative invention." Mergenthaler v. Scudder, 11 App D.C. 264, 1897 CD 724 (C.A.D.C. 1897).

However, inventorship is not a mathematical formula. Additional complexity may further arise in situations involving more than one inventor. That is, "[t]he exact parameters of what constitutes joint inventorship are quite difficult to define. It is one of the muddiest concepts in the muddy metaphysics of the patent law." Mueller Brass Co. v. Reading Indus., 352 F. Supp. 1357, 1372 (E.D. Pa. 1972).

The patent statute states at 35 U.S.C. § 116(a) that inventors may apply for a patent jointly even if they did not physically work together, each did not make the same type or amount of contribution, or each did not contribute to every claim in the patent. See, e.g., Vapor Point LLC v. Moorhead, 832 F.3d 1343 (Fed. Cir. 2016). However, each "joint inventor must contribute in some significant manner to the conception of the invention." Gemstar-TV Guide Int'l, 383 F.3d at 1381, (Fed. Cir. 2004) (quoting Fina Oil & Chem. Co. v. Ewen, 123 F.3d 1466, 1473 (Fed. Cir. 1997)); see also, Bard Peripheral Vascular, Inc. v. W.L. Gore & Associates, Inc., 670 F.3d 1171 (Fed. Cir. 2012).

Ideally, all issues of inventorship should be resolved before the application is filed. This typically requires identifying everyone who worked on the project and determining the extent of their contribution and whether that contribution rises to the level of inventorship. Some lawyers produce a factual memo, bereft of legal conclusions, identifying who they interviewed and what their contribution was. If done properly, that can be a helpful document if inventorship is challenged in the future.

Inventorship Implications

One implication of inventorship is on patent ownership: in the U.S., each inventor is an owner of the entire patent. According to 35 U.S.C. §262, in the absence of any agreement to the contrary, each co-owner of a U.S. patent may make, use, offer to sell, and sell the patented invention without regard to the wishes of any other co-owner. SeeFalana v.Kent State University, 669 F.3d 1349 (Fed. Cir. 2012); Ethicon, Inc. v. United States Surgical Corp., 135 F.3d 1456, 1461 (Fed. Cir.1998). See SiOnyx LLC v. Hamamatsu Photonics K.K., 981 F.3d 1339 (Fed. Cir. 2020), for an example of an "agreement to the contrary" divesting one of the inventors of ownership.

In turn, ownership may impact whether a party has standing to enforce the patent, as we saw very recently in Chromadex, Inc. v. Elysium Health, Inc., Civil No. 18-cv-1434 (D. Del. Dec. 15, 2020). See also James v. J2 Cloud Services, LLC, 887 F.3d 1368 (Fed. Cir. 2018); Diamond Coating Technologies, LLC v. Hyundai Motor America, 823 F.3d 615 (Fed. Cir. 2016). See also, https://www.finnegan.com/en/insights/blogs/prosecution-first/how-two-recent-court-decisions-show-ownership-can-be-everything-and-standing-must-be-takeninto-account.html

Furthermore, under both pre-AIA and AIA laws, inventors are subject to a duty of disclosure under 37 C.F.R §1.56 and to the best mode requirement of 35 U.S.C. § 112(a), which still exists as a requirement for patentability even though the AIA removed failure to satisfy the best mode requirement as grounds for invalidating a patent. Inventorship may also implicate derivation, compliance with §112(b), priority assertions and antedating prior art, eligibility for AIA prior art exceptions, and double patenting (with respect to the ownership aspect). Thus, inventorship is a fundamental consideration in preparing and prosecuting patent applications, as well as defending the resulting patents.

Getting it Wrong

Improper inventorship may be grounds for (1) requesting correction of inventorship, (2) invalidating a patent, (3) a derivation proceeding, or (4) a finding of inequitable conduct if the requisite deceptive intent is found. See, e.g., Ajinomoto Co., Inc. v. Archer-Daniels-Midland Co., 228 F.3d 1338 (Fed. Cir. 2000); Frank's Casing Crew & Rental Tools v. PMR Techs., 292 F.3d 1363 (Fed. Cir. 2002). Indeed, it has long been understood that "[a] patent is invalid if more or fewer than the true inventors are named." Id. at 1381, citing Jamesbury Corp. v. United States, 518 F.2d 1384 (1975). The mere existence of incorrect inventorship though, without an intent to deceive the USPTO, does not present an issue of unenforceability. Gemstar-TV Guide Int'l v. ITC, 383 F.3d 1352, n.1, (Fed. Cir. 2004).

Correcting Inventorship

A patent incorrectly identifying an inventor or inventors is invalid, unless remedied. Correction of inventorship became easier under AIA. For example, AIA's removal of "without deceptive intent" throughout Title 35 of the United States Code means a correction of inventorship no longer requires that the error in inventorship in applications or patents occurred "without deceptive intent" to be corrected. 35 U.S.C. § 116(c); AIA SEC. 20 (change applies to issued patents also).

Inventorship in patent applications must be corrected by the USPTO. Courts do not have jurisdiction to correct the inventorship of pending patent applications; only the Director of the USPTO has such authority. See, e.g., 35 U.S.C. §116(c) and 37 C.F.R. §§1.45 and 1.48.

Patents may be corrected by a federal court or the USPTO. 35 U.S.C. § 256 (see also 37 C.F.R. § 1.324). Indeed, if invalidity based on improper inventorship is raised by an opposing party in litigation, the court should allow the patentee to correct the inventorship before declaring the patent invalid. Checkpoint Systems, Inc. v. All-Tag Security S.A., 412 F.3d 1331, 1340 (Fed. Cir. 2005).


Inventorship is important; inventorship determines ownership. If an omitted inventor makes an evidentiary showing sufficient to establish that she should be named as a co-inventor on a patent, she will enjoy a presumption of ownership of the entire patent, even if her contribution pertained to a single claim in a patent having multiple claims. In addition, improper inventorship may be a ground of invalidity or, if sufficient intent to deceive is shown, unenforceability. All things considered, inventorship must be taken seriously from the beginning of the application drafting process.

The content of this article is intended to provide a general guide to the subject matter. Specialist advice should be sought about your specific circumstances.