Note that inventorship and ownership are two different things. The determination of inventorship is easy when the inventor is an independent inventor. When there are multiple persons involved in a project that results in patentable subject matter, however, the issue of inventorship can be difficult to resolve.
The standard for joint invention is when two or more persons work on the same subject matter and make some contribution to one or more of the claims that appear in the issued application. It is not necessary for the parties to contribute to all of the claims or to contribute equally to the invention.
A person does not become a joint inventor by merely contributing manual labor, supervision of routine techniques or other non-mental contribution to a project. Also, the mere fact that a person makes a substantial mental contribution to the project does not necessarily qualify that person as a joint inventor when the contribution does not directly result in the development of the claimed invention.
An interesting problem can occur when one joint inventor wants to enforce the patent against an accused infringer but his or her co-inventor does not. The first inventor must persuade the other inventor to participate in the lawsuit or must obtain an agreement that allows each inventor to independently enforce the patent without the other’s permission. Otherwise, the patent infringement action will be dismissed for failure to join a necessary party.
This situation can occur in joint ventures where the co-inventors come from different companies. As a result, it is a good idea for the partners in the joint venture to reach an agreement prior to filing the patent application.
Another issue that should be understood is the difference between inventorship and authorship. The concept of inventorship is distinct from authorship. Often an invention will be the subject of a publication in a scientific journal or marketing publication. Courts have specifically held that inventorship and authorship have different criteria and are not equivalent. Accordingly, it is important that you do not confuse authorship with inventorship.
Finally, note that nondeceptive errors in naming inventors can be corrected when necessary.