When a new invention is created (if it is worth anything), everyone wants to take credit. Figuring out whose “baby” it is, is a difficult question.

What is an inventor? Who is the inventor? One would think these questions have straightforward answers. They do not. Inventorship is one of the most difficult and gray areas of patent law.

It is easy to say what (or who) an inventor is not. An inventor is not the research technician who carries out the instructions of the lead investigator developing a new drug. An inventor is not the computer programmer who writes the code for software developed by someone else. An inventor is not the machinist who fabricates a device under the direction of the engineer. An inventor is not the CEO of the company, the most important shareholder, the leading investor, or the supportive colleague. An inventor is not a corporation or other business entity.

The inventor is the person (a natural person) who “invents” the invention. Inventing consists of three phases: conception of the invention; steps taken toward reducing the invention to practice; and reduction to practice of the invention. The person, or persons, who perform the first phase, conception, are the inventors. The person(s) who perform the second and third phases can be the inventor(s) or those acting at the direction of the inventor(s).

Conception is the formation of the definite and permanent idea of the complete and operative invention. This means that the structure and function of the invention have been fully thought out. If the inventor can describe how to make and use the invention, such that a person with ordinary skill in the art could make and use it, then there is conception. The inventor may have others help actually make the invention, but this does not make them inventors.

Any person who makes a contribution to the conception of the invention is an inventor. Multiple inventors are called joint inventors. The determination of whether a person is a joint inventor is very fact-specific. Joint inventors must be working together in some sense, although they need not work together physically or at the same time. Joint inventors cannot be working completely independently; if so, they are not joint inventors, but sole inventors of the same invention. The contributions of the joint inventors need not be of the same size or significance. The contribution of a small, minor aspect of the invention is enough to make a person a joint inventor as long as that aspect is contained in at least one claim of the patent.

If there is more than one inventor of an invention, each inventor owns an equal, undivided interest in the invention and in any patent on the invention. This is true regardless of the amount of the inventor’s contribution. Each inventor can make, use, offer to sell, or sell the invention in the United States, or import the invention into the United States, without the consent of the other joint inventors. In order to transfer all the rights to an invention, all of the joint inventors must sign an assignment.

All of the inventors must jointly file a patent application. Each inventor must sign the oath or declaration. All of the true inventors must be named as inventors, and the application cannot name a person who is not an inventor. For example, an inventor cannot be excluded because he or she is no longer employed by the company filing the patent application. Nor can a person who is not an inventor be named as an inventor simply as an acknowledgment or reward for working on the project. Errors in inventorship can be corrected by amending the patent application, or the issued patent, as long as the error was unintentional.

Inventorship problems occur frequently in companies where several employees work together on a project that results in an invention. The existence of joint inventors raises two problems. First, because each joint inventor owns, and has full rights to exploit, the invention, all of the inventors need to sign an assignment to the company if the company is to obtain clear title to the invention. It is easiest to do this before the employees are hired or, if not, before they leave the company. It is often not done until after the employee has left the company, however, and the company decides to file a patent application. Second, a patent that issues with incorrect inventorship (either omitting an inventor or including a non-inventor) is at risk of being invalidated, unless a correction is made. In other words, years after the invention was invented, when the company is in litigation to enforce its patent, the issue of inventorship can be raised as a basis for invalidating the patent. Thus, inventorship issues should be resolved as early as possible, hopefully before the patent application is filed.