Introduction
Inventorship is one of the fundamental issues in U.S. patent prosecution. Identifying the correct inventor or inventors is important because U.S. patent law generally requires the application to identify the individual or individuals who invented the claimed subject matter.
Inventorship can become complicated when several people participate in research, development, testing, or preparation of a patent application. A person who helps build a prototype, performs experiments, or provides technical assistance is not necessarily an inventor. The central question is whether the person contributed to the conception of the claimed invention.
This article explains the basic principles of inventorship, joint inventorship, correction of inventorship, and several common Patent Bar issues.
What Is an Inventor?
Under 35 U.S.C. § 100(f), an inventor is an individual who invented or discovered the subject matter of the invention. For a joint invention, the inventors collectively are the individuals who invented or discovered the claimed subject matter.
The USPTO explains that the threshold question in determining inventorship is generally who conceived the invention. A person normally must contribute to conception to qualify as an inventor.
An inventor must be a natural person. A corporation, university, company, or other legal entity cannot itself be named as an inventor. This principle is discussed in MPEP § 2109 and was reaffirmed by the Federal Circuit in Thaler v. Vidal.
Conception Is Central to Inventorship
Conception is the formation in the inventor’s mind of a definite and permanent idea of the complete and operative invention.
For inventorship purposes, merely suggesting a desired result is generally not enough. The person must contribute to the conception of the invention that is actually claimed.
For example, suppose an engineer proposes:
“We should develop a device that operates more efficiently.”
That statement alone generally does not establish inventorship of a later-developed device.
Suppose instead that the engineer develops a particular arrangement of components that provides the claimed improvement. If that arrangement becomes part of the claimed invention, the engineer may have contributed to conception.
The USPTO discusses this distinction in MPEP § 2109.
Reduction to Practice Is Not Normally Required for Inventorship
An inventor does not necessarily have to personally build or test the invention.
The USPTO explains that an inventor generally does not have to be the person who performs the reduction to practice. A person who merely follows another person’s instructions and performs technical work may not become an inventor merely because that person built the prototype.
For example, assume Inventor A develops the concept and gives detailed instructions to Technician B. Technician B constructs the prototype according to those instructions.
If B merely performs the work without contributing to the conception of the invention, B is not necessarily an inventor.
This distinction is particularly important in research laboratories and engineering environments.
Who Are Joint Inventors?
Two or more people may be joint inventors when they jointly contribute to the conception of an invention.
Under 35 U.S.C. § 116, joint inventors may apply for a patent jointly even though:
- they did not physically work together;
- they did not work at the same time;
- they did not make the same type of contribution;
- they did not make contributions of equal importance; or
- each inventor did not contribute to every claim.
The USPTO discusses these principles in MPEP § 2109.01.
Equal Contributions Are Not Required
One common misconception is that joint inventors must contribute equally.
That is incorrect.
For example, suppose Inventor A develops the basic system and Inventor B develops a particular component that becomes an important limitation of one claim.
Even if A’s contribution is substantially greater in quantity, B may still be a joint inventor if B made an appropriate contribution to the conception of the claimed invention.
The USPTO specifically states that joint inventors do not have to make the same type or amount of contribution.
An Inventor Does Not Have to Contribute to Every Claim
Another important rule is that a joint inventor does not necessarily have to contribute to every claim.
Suppose a patent application contains claims 1–20.
Inventor A contributes to the conception of the subject matter of claims 1–20. Inventor B contributes to the conception of a particular feature appearing only in claims 15–20.
B may nevertheless be a joint inventor of the claimed invention.
The USPTO explains that a contribution to at least one claim can be sufficient for joint inventorship. See MPEP § 2109.01.
Collaboration Between Joint Inventors
Joint inventors do not necessarily have to work side-by-side.
For example:
- Inventor A develops an initial concept.
- Inventor B later reviews A’s work.
- B contributes an important feature.
- A and B communicate and develop the final claimed invention.
They may qualify as joint inventors even though they did not perform their work at exactly the same time or in the same location.
The USPTO explains that some degree of collaboration or connection is relevant to joint inventorship.
Inventorship Versus Ownership
Inventorship and ownership are different concepts.
An inventor is the individual who legally qualifies as an inventor of the claimed invention.
Ownership concerns who owns the patent rights.
For example, an employee may be an inventor even though an employment agreement assigns patent rights to the employer.
Thus:
Inventorship = Who invented the claimed subject matter?
Ownership = Who owns the patent rights?
An assignment can transfer ownership rights, but it does not change who actually invented the claimed subject matter.
Naming Inventors in a Patent Application
For a nonprovisional application filed under current U.S. law, the application must identify the inventor or inventors.
Under 37 C.F.R. § 1.41, the inventorship of a nonprovisional application may be established through the Application Data Sheet or inventor’s oath or declaration, subject to the applicable rules.
The USPTO also provides requirements concerning the inventor’s oath or declaration in MPEP § 602.01.
What Happens If the Wrong Inventor Is Named?
Sometimes an application is filed with an incorrect inventive entity.
For example:
- a true inventor is accidentally omitted;
- a person who is not an inventor is mistakenly named; or
- an amendment to the claims changes which individuals qualify as inventors.
The USPTO provides a procedure for correcting inventorship under 37 C.F.R. § 1.48.
The current rule generally requires an appropriate request, an Application Data Sheet identifying the inventors, the applicable processing fee, and appropriate oath/declaration requirements for an added inventor.
The specific requirements should be checked carefully because the procedure depends on the circumstances of the correction.
Correction of Inventorship After the Claims Are Amended
An important prosecution issue can arise when claims are amended.
Suppose an application originally contains claims directed to subject matter invented by A and B.
Later, the applicant cancels all claims containing B’s contribution and retains only claims directed to subject matter conceived solely by A.
The inventive entity may need to be reconsidered.
The USPTO specifically addresses situations in which amendments to the claims result in a named inventor no longer being an inventor of the subject matter of any remaining claim. See MPEP §§ 602.09 and 2109.01.
Omitted Inventor
An inventor may sometimes be omitted from an application.
For example, assume A and B jointly conceived the claimed invention, but only A is initially named.
The omission can generally be corrected under the procedures of 37 C.F.R. § 1.48, subject to the applicable requirements.
The correction of inventorship is different from simply adding a person because that person contributed technical assistance. The person being added must actually qualify as an inventor of the claimed subject matter.
What If an Inventor Refuses to Sign?
Under 35 U.S.C. § 116(b), special procedures can apply when a joint inventor refuses to join the application or cannot be found after diligent effort.
The other inventor or inventors may be able to proceed under the statutory procedure, subject to the requirements established by the statute and USPTO rules. The omitted inventor may subsequently join the application.
This is different from simply deciding that the refusing inventor is not an inventor.
Inventorship and Patent Prosecution
Inventorship can become relevant at several stages of prosecution.
A practitioner should consider inventorship when:
- preparing the initial application;
- preparing the Application Data Sheet;
- obtaining inventor declarations;
- adding or deleting claims;
- cancelling claims;
- filing continuation applications;
- filing divisional applications;
- correcting an erroneous inventorship;
- responding to USPTO requirements; and
- preparing assignments and related ownership documents.
Because the inventive entity is tied to the claimed invention, changes to the claims can sometimes require reconsideration of inventorship.
Inventorship in a Continuation Application
A continuation application can raise inventorship questions.
For example, suppose the parent application has inventors A and B, but the continuation contains only claims directed to subject matter conceived solely by A.
The appropriate inventorship of the continuation should be determined based on the subject matter actually claimed in the continuation.
The fact that B was an inventor of the parent application does not automatically mean that B must be an inventor of every continuation.
The claims and the underlying contributions to conception must be considered.
Inventorship in a Divisional Application
A similar issue can arise with a divisional application.
Suppose A and B are inventors of a parent application containing two distinct inventions. If the divisional claims only one invention, the inventorship must be determined based on who contributed to the conception of the subject matter claimed in the divisional.
Therefore, the inventorship of a divisional application does not necessarily have to be identical to the inventorship of the parent application.
Inventorship and Artificial Intelligence
Current U.S. patent law requires inventors to be natural persons.
The USPTO’s discussion of MPEP § 2109 explains that an inventor or joint inventor must be a human being. The Federal Circuit’s decision in Thaler v. Vidal, 43 F.4th 1207 (Fed. Cir. 2022), addressed the issue and held that an AI system cannot be named as an inventor under the Patent Act.
This does not mean that technology cannot be used during inventive activity. The relevant question remains whether a human individual qualifies as an inventor under applicable law.
Patent Bar Example
Question:
Inventor A develops the overall concept of a new machine. Engineer B later suggests a particular arrangement of two components that becomes a limitation of claim 5. Technician C constructs and tests the machine according to A’s instructions. Who may qualify as joint inventors?
Answer:
A and B may qualify as joint inventors if B contributed to the conception of the claimed subject matter. C does not necessarily qualify as an inventor merely because C constructed and tested the machine.
This example illustrates two important rules:
- A contribution to conception is central to inventorship.
- Reduction to practice alone does not necessarily make a person an inventor.
These principles are discussed in MPEP § 2109 and MPEP § 2109.01.
Important Patent Bar Rules to Remember
For Patent Bar preparation, the following principles are especially important:
1. Conception is central to inventorship.
A person generally must contribute to the conception of the claimed invention.
2. Reduction to practice alone does not make someone an inventor.
A person who merely follows instructions to build or test an invention is not necessarily an inventor.
3. Joint inventors do not need equal contributions.
The contributions can differ in type and amount.
4. Joint inventors do not need to contribute to every claim.
A contribution to the subject matter of at least one claim can be sufficient.
5. Joint inventors do not have to work together physically or simultaneously.
The statute permits joint inventorship despite differences in timing and location.
6. Inventors must be natural persons.
A corporation or AI system cannot be named as an inventor.
7. Inventorship is different from ownership.
An assignment can transfer ownership without changing who the inventor is.
8. Incorrect inventorship can be corrected.
See 35 U.S.C. § 116 and 37 C.F.R. § 1.48.
Conclusion
Correct inventorship is an essential part of U.S. patent prosecution. The central question is generally who contributed to the conception of the claimed invention. Joint inventors do not have to contribute equally, work together at the same time, or contribute to every claim.
Patent practitioners should also recognize that inventorship can change when the claims are amended and that the USPTO provides procedures for correcting an erroneous inventive entity.
For Patent Bar preparation, a useful framework is:
Claimed invention → Conception → Identify contributors to conception → Determine sole or joint inventorship → Name inventors correctly → Correct inventorship when necessary.
References
The following authorities are particularly useful for studying inventorship:
- 35 U.S.C. § 100(f) — Definition of inventor.
- 35 U.S.C. § 100(g) — Joint inventor and coinventor.
- 35 U.S.C. § 115 — Inventor’s oath or declaration.
- 35 U.S.C. § 116 — Inventors and joint inventors.
- 37 C.F.R. § 1.41 — Inventorship.
- 37 C.F.R. § 1.48 — Correction of inventorship.
- 37 C.F.R. § 1.63 — Inventor’s oath or declaration.
- MPEP § 2109 — Inventorship.
- MPEP § 2109.01 — Joint inventorship.
- MPEP § 602.01 — Naming the inventor; inventor’s oath or declaration.
- MPEP § 602.09 — Inventorship issues resulting from claim amendments.
The USPTO’s current MPEP provides the authoritative examination guidance for these issues.
Educational disclaimer: This article provides general educational information about U.S. patent prosecution. It is not legal advice and does not create an attorney-client relationship.