Inventorship: Why it Matters


In academia, there is a common misconception that inventorship may be assigned similarly to the selection of journal authors from a team of researchers.  For purposes of patent law, however, it is very important to ensure that all inventors, and only inventors, are included in the application for patent.  In the United States, an application to obtain a patent is submitted to the Patent and Trademark Office (USPTO) by or on behalf of the inventor,[1] who is required to state under oath “that he believes himself to be the original and first inventor.”[2]  In the case where an invention is made by more than one person, the inventors are required to apply for a patent as joint inventors.[3]  A correct inventorship determination is very important to the prosecution of a sustainable patent.  If a patent or patent application fails to identify or wrongly identifies a person as an inventor, its validity may be challenged and it will be found to be invalid unless the issue of inventorship can be corrected.  In the U.S., patent law allows for correction of inventorship in the patent application only if, through error, a person is named or is not named as an inventor.  The Director of the USPTO may permit the application to be corrected provided such error was not due to deceptive intent.[4]

The Terms “invention” and “inventor”

35 USC §100 provides that the term “invention” means “invention or discovery.”  This definition is not very helpful in determining what an invention is or when it occurs.  However, this term needs to be read in light of 35 USC §101 & 112.  35 USC §101 sets out the different classes of inventions for which patents can be obtained and §112 deals with specifications, which describe the invention and provide the requirements for setting forth the claims:

35 USC §101, Inventions patentable:  

Whoever invents or discovers any new and useful process, machine, manufacture, or composition of matter, or any new and useful improvement thereof, may obtain a patent therefor, subject to the conditions and requirements of this title.

35 USC §112, paragraphs 1 & 2, Specifications:  

The specification shall contain a written description of the invention, and of the manner and process of making and using it, in such full, clear, concise, and exact terms as to enable any person skilled in the art to which it pertains, or with which it is most nearly connected, to make and use the same, and shall set forth the best mode contemplated by the inventor of carrying out his invention. The specification shall conclude with one or more claims particularly pointing out and distinctly claiming the subject matter which the applicant regards as his invention. Thus, for purposes of U.S. patent law, an inventor can be defined as someone who invents or discovers any new and useful process, machine, manufacture, or composition of matter, or improvement thereof.  Though the claims in a patent define the invention, the invention itself is the process, machine, manufacture, or composition of matter that fall within the boundaries set forth in the claims.

Acts Conferring Inventorship 

The process of invention involves three stages, namely: (i) conception, (ii) reduction to practice, and (iii) activities performed towards reducing the invention to practice.  However, the question of inventorship is generally decided on the grounds of who conceived the invention because it is the intellectual process of the conceiving of an invention that entitles a person to be designated as the inventor.[5]  Performing activities to reduce an invention to practice under the direction of the inventor does not entitle a person to inventorship.[6]   All the three stages mentioned above are important factors in determining who the first inventor is when more than one person independently conceives the same invention and becomes an important question in determining who is entitled to a patent for the invention.  However, everyone who independently conceived the invention is regarded as an inventor of the invention.

(i) Conception of the Invention:

Only individuals who contribute to the conception of the invention are considered to be inventors.  The invention is considered to be made when the conception is complete, i.e. the intellectual process involved in the formation of a complete idea has occurred.[7]  It is a stage at which the inventor is able to make an adequate disclosure that would enable a person of ordinary skill in the art to reduce to practice the invention without extensive research or experimentation.[8]   It is important to point out that the process or manner through which an invention is made is irrelevant to the issue of whether such invention is patentable or not (see 35 USC §103(a) infra).  The conception of an invention might be achieved through extensive experimentation, through an epiphany, or just an accident.

35 USC §103(a), Conditions for patentability; non-obvious subject matter: 

A patent may not be obtained though the invention is not identically disclosed or described as set forth in section 102 of this title, if the differences between the subject matter sought to be patented and the prior art are such that the subject matter as a whole would have been obvious at the time the invention was made to a person having ordinary skill in the art to which said subject matter pertains. Patentability shall not be negatived by the manner in which the invention was made. Also, the courts have held that for conception to be complete the inventor does not need to expect that his or her invention will work for the stated purpose.[9]  Moreover, courts have accepted the use of unexpected results as a way to meet the nonobviousness requirement for patenting an invention.[10]

(ii) Reduction to Practice of an Invention: 

By itself the reduction to practice of an invention is irrelevant to the question of inventorship.[11]  However, in order to obtain the rights of an inventor, under U.S. patent law, the invention needs to be reduced to practice by the inventor or someone acting on his behalf.  For an idea to qualify as the conception of an invention, efforts to reduce it to practice must be considered.  If such efforts are successful, with few or no deviations from the intellectual conception of the invention, then the conception is probably complete and the person who conceived the invention is the true inventor.[12]  However, if changes need to be made to achieve successful reduction to practice, then anyone responsible for conceiving such deviations may qualify as the sole inventor or jointly with those responsible for the original plan.[13]  From the above discussion, it is clear that the inventor is a person who came up with the idea and a possible framework to reduce such an idea into practice and not the person who provided the labor or means to carry out such reduction to practice.

Joint Inventorship 

As mentioned earlier, an invention can be made by a single person or two or more people acting together.  For a person to be the sole inventor, that person is required to be solely responsible for the conception of his or her invention.  Likewise, joint inventorship requires that two or more people jointly contribute to the conception of the invention.[14]  Statutory treatment of joint inventorship is provided in the first paragraph of 35 USC §116.

35 USC §116, Inventors:

When an invention is made by two or more persons jointly, they shall apply for 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.  The statute enumerates the conditions under which a person should not be excluded from a claim of joint inventorship.  It, however, does not outline the circumstances under which persons should be considered joint inventors.[15]  Nor does case law provide a clear test for determining joint inventorship; each case needs to be decided on the basis of its specific facts.[16]   However, from the case law, it appears that emphasis is paid to the difference between conception and reduction to practice of an invention in determining the question of joint inventorship.  The Federal Circuit has held that “….to be a joint inventor, an individual must make a contribution to the conception of the claimed invention that is not insignificant in quality, when that contribution is measured against the dimension of the full invention”[17] and that it is necessary for this contribution to be more than the exercise of normal skill in the art.[18]  Although joint inventors do not need to physically work together or at the same time[19], the courts have held that there must be an element of joint behavior, whether direct or indirect, between the joint inventors.[20]  Also, a joint inventor neither needs to make a conceptive contribution to each and every claim nor is required to make the same level of contribution to the invention as the other inventors.[21]  An inventive contribution to only one claim is sufficient to entitle one to joint inventorship.[22]


Patent applications submitted to the USPTO are required to list the inventors.  The failure to list the correct inventors can render a patent invalid and unenforceable.  Under U.S. patent law, the USPTO and the courts will determine inventorship by establishing who actually conceived the subject matter claimed in a patent.  Generally, questions regarding inventorship are raised when there is an interference filed during the patent prosecution process or when the issued patent is challenged for invalidity, usually as a counterclaim in a lawsuit brought to enjoin patent infringement.

Kultaran Chohan
Senior Licensing Associate
Technology Transfer Office
NC State University

Shawn Troxler
Associate General Counsel
Office of General Counsel
NC State University

[1] 35 USC §111.

[2] 35 USC §115.

[3] 35 USC §116.

[4] Id.

[5] Pfaff v. Wells Elecs., Inc., 525 U.S. 55, 60-61 (1991), where the court stated that the word “invention in the Patent Act unquestionably refers to the inventor’s conception rather than to a physical embodiment of that idea.”

[6] Fina Oil & Chemical Co. v. Ewen, 123 F.3d 1466, 1473, 43 USPQ2d, 1935, 1941 (Fed. Cir. 1997).

[7] Hybritech Inc. v. Monoclonal Antibodies, Inc., 802 F.2d 1367, 1376 (Fed. Cir. 1986), in which the court stated that the conception of an invention only requires “the formation, in the mind of the inventor, of a definite and permanent idea of the complete and operative invention.”

[8] In re Tansel, 253, F.2d 241, 117 USPQ 188, 189 (CCPA 1958).

[9] Burroughs Wellcome Co. v. Barr Lab., Inc., 40 F.3d 1223, 1228 (Fed. Cir. 1994).

[10] Eli Lilly & Co. v. Premo Pharmaceutical Labs., Inc., 630 F.2d 120, 207 USPQ 719 (3rd Cir. 1980).

[11] Burroughs Wellcome Co. v. Barr Lab., Inc., 40 F.3d 1223, 1227-28 (Fed. Cir. 1994).

[12] In re Tansel, 253 F.2d 241, 117 USPQ 188, 189 (CCPA 1958).

[13] Bac v. Loomis, 252 F.2d 571, 117 USPQ 29 (CCPA 1958).

[14] Fina Oil & Chemical Co. v. Ewen, 123 F.3d 1466, 1473, 43 USPQ2d, 1935, 1941 (Fed. Cir. 1997).

[15] Burroughs Wellcome Co. v. Barr Lab., Inc., 40 F.3d 1223, 1227 (Fed. Cir. 1994); Fina Oil & Chemical Co. v. Ewen, 123 F.3d 1466, 1473, 43 USPQ2d, 1935, 1941 (Fed. Cir. 1997).

[16] Hess v. Advanced Cardiovascular Systems, Inc., 106 F.3d 976, 981 (Fed. Cir. 1997).

[17] Fina Oil & Chemical Co. v. Ewen, 123 F.3d 1466, 1473, 43 USPQ2d, 1935, 1941 (Fed. Cir. 1997).

[18] Caterpillar Inc., v. Sturman Industries, Inc., 387 F.3d 1358 (Fed. Cir. 2004).

[19] 35 USC §116.

[20] Kimberly-Clark Corp. v. Procter & Gamble Distrib. Co., 973 F.2d 911, 917, 23 USPQ2d 1921, 1926 (Fed. Cir. 1992).

[21] 35 USC §116.

[22] Ethicon, Inc. v. United States Surgical Corp., 135 F.3d 1456, 1460 (Fed. Cir. 1998).