Patent Inventorship

Who qualifies as an inventor under US patent law?

When seeking a utility patent for an invention, it is critical to properly identify the inventors in the patent application.  In general, an inventor is a person who conceives and reduces to practice an invention that falls into one of the statutory categories of patentable subject matter under 35 USC § 101, which include methods, articles of manufacture, compositions of matter, machines, and improvements thereon.  The inventor must come up with something novel and innovative that can actually be created or practiced in the real world; it must be reduced to practice in a complete and operative form.  An idea is not enough to be considered an inventor under US patent law.  Additionally, an inventor can only be a person.  Corporations and governments cannot be considered inventors, though they may hold legal interest (e.g., an ownership stake) in the invention or patent.

An inventive act must result in a complete and operative invention

Inventorship can be separated into two distinct requirements.  The first requirement is the conception of the invention and the second is reduction to practice.  Both steps must be completed in order for an "idea" to transform into an invention.  These steps can be completed by multiple people.  For example, an engineer working on developing a device that performs a certain function may create concept for the device and plans and schematics that can be executed by a technician, and then hand the project off to a team of technicians that build the device.  The engineer and technicians jointly performed the two required steps of conception and reduction to practice.  A more in depth discussion of each step is provided below.


Conception occurs when a definite and permanent idea of a complete and operable invention is formed.  A complete conception of an invention should include every feature sought to be claimed in a patent application for the invention.  This means the idea should be so completely developed that it can be reduced to practice. There is a corollary in US patent law with respect to patent applications: a patent application must describe the invention in sufficient detail to enable someone of ordinary skill in the relevant art to practice the claimed invention (e.g., create a physical version of the invention) without inventive skill or performing extensive experimentation.  The conception step is the key to being an inventor.  Only persons that contribute to the conception of the novel aspects of an invention can be considered inventors.

Imagine a scenario where John and Alice, two engineers, are collaborating to create a new smart thermostat designed to learn a user's temperature preferences and automatically adjust the home heating and cooling system. The device consists of conventional components such as the thermostat housing, temperature sensors, a touchscreen interface, and Wi-Fi connectivity. However, the key innovation lies in an Adaptive Learning Algorithm, which uses machine learning to predict and adjust temperature settings based on user behavior, weather forecasts, and energy usage patterns.

In their collaboration, John focuses on designing the thermostat housing, selecting the temperature sensors, integrating the touchscreen interface, and setting up the Wi-Fi connectivity. He also handles the physical assembly and ensures the basic functionality of the device. Alice, on the other hand, develops the Adaptive Learning Algorithm from scratch. She programs the algorithm to interact with the other components of the thermostat and ensures that it accurately learns and predicts user preferences.

According to US patent law, an inventor is someone who contributes to the conception of the novel aspects of an invention. In this case, the Adaptive Learning Algorithm is the novel feature that sets this smart thermostat apart from conventional ones. Therefore, Alice, who conceived and developed this novel feature, is considered the inventor. While John made significant contributions to the overall project, he did not contribute to the conception of the novel Adaptive Learning Algorithm. Consequently, for the patent application of this smart thermostat, Alice would be listed as the inventor, while John, despite his important role in the development, would not be listed as an inventor. This example highlights how inventorship under US patent law is determined based on the contribution to the conception of the novel features of an invention.

Reduction to Practice

The second requirement of inventorship is reduction to practice, i.e., creating a tangible and practical form of the invention. This step is crucial to prove that the invention is more than just an abstract idea; it must be an actual, operable creation. For example, concepts like cold fusion and perpetual motion machines are often touted as revolutionary, but they have not been reduced to practice, rendering them mere ideas rather than true inventions.   An inventor can accomplish reduction to practice in two ways: actual reduction to practice or constructive reduction to practice.  Constructive reduction to practice occurs when a patent application is filed with sufficient description to allow one of ordinary skill in the art to practice the invention. Constructive reduction to practice does not require the inventor to complete performance of the invention. The inventor can establish a filing date, which serves as the date of invention, by filing a patent application that thoroughly discusses the subject matter of the invention.  However, it is worth noting that notoriously unproven technologies like cold fusion and perpetual motion must be actually reduced to practice and demonstrated to the United States Patent and Trademark Office before any patent can be issued.

Actual reduction requires a two part test: 1) the inventor constructed a tangible form which includes all of the features of the claimed invention, and 2) the invention worked for its intended purpose.  The testing of the invention does not need to be done by the inventor; it can be conducted by someone under the direction of the inventor.  The only requirement is that the inventor is informed and understands that the testing was successful.  The person(s) reducing the invention to practice may not make an inventive contribution.  John in the example above is not an inventor, even though he reduced Alice's invention to practice.

The acts of conception and reduction to practice can be muddled with some types of inventions. For example, when an inventor conceives a species or chemical compound, conception in the mind is not enough to produce an actual chemical species. The inventor may have an idea about kind of compound he seeks to produce, but the chemical species is likely produced only by extensive trial and error. Thus, both conception and the second step of reduction to practice may be simultaneous.  Until the experiment is successful, the inventor cannot envision the completed chemical species or describe with certainty the method to obtain it; i.e., conception is incomplete until the reduction to practice is successful.

There must be a patentable invention

When making a claim of inventorship, the inventor or inventors should have a reasonable belief she is the original and first inventor of the invention.  Usually, this means the inventor was the first person to conceive the idea and create a tangible form of the invention. The invention must be original or novel, i.e., something that no one else has created or used before.  Originality is the basic requirement for a patent to ensure the alleged inventor did not obtain or take the invention from another.

Inventorship should be properly established and documented

Any claim of inventorship should be supported by reliable evidence.  The evidence may include documents prepared by the inventor, circumstantial evidence about the inventive process, or oral testimony from a third-party.  The information is not an absolute requirement, but inventorship is often an issues that is raised in patent lawsuits. Patent attorneys often challenge the plaintiff's patent rights by probing inventorship. The defendant's attorney may try to establish, e.g., that the claimed invention was a joint invention and that one or more co inventors were intentionally omitted from the patent application. This is a basis for patent invalidity. In the process of determining inventorship, it is far better to have documentation than to rely purely on patent application filings and memory.

Joint inventorship

Joint inventorship occurs when two or more persons contributed to the conception of the invention.  Each person that makes an inventive contribution to the conception of the invention must be named as a joint inventor. The contribution must be to the novel aspects of the invention for the person to be a named inventor. If the individual contributes only conventional elements and features or simply followed the instructions of an inventor in reducing the invention to practice, the individual is not an inventor. In the case of a joint invention, each joint inventor has an equal ownership interest in the patent rights in the invention. Once the patent is granted, all joint inventors become joint owners and can use the patent or sell or license a share of the patent without the permission of any other joint owner.

In some circumstances, joint inventors may have developed aspects of the invention separately without working together, developing aspects of the invention independently. Such a scenario may occur within a corporate entity that has multiple teams working on similar technologies. US patent law allows a joint inventorship application to be filed even though the inventors did not physically work together or make the same type or amount of inventive contribution.  In such situations, there must be collaboration either through direct or indirect communication to have a valid patent application under joint inventorship.

It is critical to ensure correct inventorship for any patent application.  Any failure to properly include joint inventors may have serious consequences for the patent’s validity as discussed in more detail below.

Examples of inventorship

Proper inventorship: The following are requirements for proper inventorship: 1) the invention must be original or novel, i.e., something that no one has created or used before, 2) the idea must be complete conception of the invention, and 3) the idea must be actually or constructively reduced to practice.

Examples include:

  1. Conduct experiments to develop a new chemical species that has desired chemical behavior until the chemical species is successfully created in a physical form and characterized.
  2. Conceive a new form of electronic amplifier using circuit design software in a complete and manufacturable form, and prepare and file a utility patent application with sufficiently clear detail to enable one of ordinary skill in the art to make the amplifier.
  3. Conceive and construct a sensor to detect and assist in preventing a trailer jackknifing during trailer backup.

Improper inventorship

Here is a non-exhaustive list of what is not considered proper inventorship:

  1. Conceiving an idea without completing a fully fleshed out embodiment of the invention,
  2. Conceiving a full inventive concept, but not reducing it to practice,
  3. Identifying a problem to another,
  4. Only suggesting a solution or improvement,
  5. Assembling a conceived invention or performing experiments to test a conceived invention, or
  6. Stating a desired result but not how to achieve that result.

Consequences of improper listing of an inventor on the patent application

It is important to correctly name the inventors in a patent application.  Failure to do so may result in forfeiting the rights to the patent. When proper inventors are not included in a patent application, this is called nonjoinder.  Another improper listing is misjoinder, listing a person as an inventor on a patent application when that person is not an inventor.  Both nonjoinder and misjoinder render a patent application invalid and unenforceable if done intentionally. Inadvertent nonjoinder or misjoinder can be corrected.  Whether it is a patent application or an issued patent, some courts allow correction of errors for inadvertence, accident, mistake, poor judgment, or even deliberate acts (though this should be avoided).  Also, when correcting an error for not naming an inventor, i.e., nonjoinder, it is not necessary to provide specific details of what that person provided to the invention.

Patent Applications

For patent applications, the Director of the USPTO has the power and authority to amend the application.  The Director may set certain terms to allow the amendment; however, generally the USPTO will allow inventorship to be corrected if the applicant submits the appropriate documents and the processing fee.

Issued Patent

Once a patent is issued, the patent is presumed to be valid even if there are errors in inventorship.  Whether or not a third party is attempting to invalidate the patent, it is best to fix issues in inventorship as soon as possible. To fix inventorship errors on an issued patent, an inventor can correct the issue through the USPTO or through the courts.  For the USPTO to correct inventorship on an issued patent, each person being added as an inventor and each person currently listed as an inventor must make a statement that they either agree to the change of inventorship or that they have no disagreement with the change.  Any assignee or person that has received a right in the patent must also agree to the change.  Finally, the fee associated with this correction must be paid.  If any party refuses to allow the change, the change to inventorship must go through the courts.

A person desiring to amend the inventorship of a patent may be granted a court order with the information listed above.  The person seeking the inventorship change is not limited to only being an inventor.  Parties which have an economic or reputational stake in the inventorship of the patent may also seek a court order to change the inventorship. For example, an employer of the inventors may file a patent application as the assignee of the inventors' interests in the invention. The employer may seek a court order to fix the inventorship of the patent if a problem with inventorship is discovered. The employer may have a great interest in correcting the inventorship in the event that the patent covers an important product made and sold by the employer.

As discussed in the “Who Qualifies as an Inventor?” section, it is crucial to have documentation to demonstrate whether someone is an inventor and should be added to or removed from the patent.

Understanding inventorship is crucial

Understanding and accurately determining inventorship for a patent application is crucial for ensuring the integrity and enforceability of the patent. Different inventors contribute uniquely to the development of an invention, each adding distinct elements to the subject matter. The process to determine inventorship involves a careful analysis of who contributed to the inventive aspects of the claims. Not every person who contributed to the project is necessarily an inventor; only those who have made a substantial contribution to the conception of the claimed invention qualify. Each inventor named on a patent must have made a significant contribution to the subject matter as defined by the claims. Misidentifying or omitting inventors can lead to legal complications, such as challenges to the validity of the patent. It is essential to delineate clearly how each person contributes to ensure that all and only those who qualify as inventors are recognized. This careful assessment and proper listing of inventors ensure that the patent accurately reflects the contributions of those who were truly inventive, thereby safeguarding the patent’s enforceability and avoiding potential disputes or claims of inequitable conduct. In conclusion, accurately identifying and naming inventors is a foundational aspect of patent law that upholds the principles of recognition and legal protection for genuine innovation.

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