Under U.S. patent law, an inventor is someone who thought of a claimed invention. The legal term for the event of having thought up an invention is "conception" of the invention. Thus, the true inventor(s) is/are the one(s) from whose mind(s) came the element(s) or step(s) which make the claimed subject matter patentable under U.S. law.
Each named inventor must have made a contribution to conception of the subject matter of at least one claim presented in the patent application. Each inventor need not, however, have contributed to the subject matter of every claim in the application.
Conception of an invention means conceiving of the patentable advance in technology that the invention affords its users. Conception requires more than just formulating a desire to accomplish something - that is called wishing, not inventing. Conception requires that a specific, concrete way of achieving a desired result be formulated. It has been defined by the Court of Appeals for the Federal Circuit as "formation in the mind of the inventor, of a definite and permanent idea of the complete and operative invention, as it is . . . to be applied in practice." Thus, conception is complete when one of ordinary skill in the art could construct a product or perform a process with unduly extensive research or experimentation, given a disclosure of the invention.
Conception is more than identification of a problem, even if the problem solved by the invention is quite difficult to recognize or identify. This is the case even if development of a solution to the problem is quite straightforward. Conception requires participation in solving a problem, not merely identifying the problem or developing a research plan that he/she/they plan to pursue with the hope of discovering a solution to the problem.
Conception of an invention also requires more than the exercise of routine or normal skill. As the Court of Customs and Patent Appeals has explained, [i]nventors of patentable inventions, as a class, are those who bridge the chasm between the known and the obvious on the one side and that which promotes progress in useful arts or technology on the other." Thus, the contribution to conception made by an inventor must involve an inventive act. It must be a contribution that makes the invention patentable (i.e., useful, novel and non-obvious over the prior art). The contribution of ordinary scientific or engineering skill in designing an invention, like the contribution of a strong back or a pair of hands in constructing an invention, is not a contribution to conception.
The inventor(s) need not know that an invention will work for conception to have occurred. The testing of the invention or filing of a patent application that is associated with reduction to practice need not have occurred. Only the idea of the complete and operable invention need be definite for conception to have occurred. If subsequent testing reveals that the invention is not operable, however, then conception has not occurred, because there is no invention.