All rights in a patent filing for an invention initially vest with the inventor(s) of the invention. The inventor(s) can convey rights in the patent filing to a third party, such as an employer of the inventor(s). The patent rights should be assigned to the third party via a written assignment document. If one or more inventor is unavailable, an employment contract or other document can evidence an obligation of the unavailable inventor to assign the patent rights to the third party. It is preferable that the written document be recorded or otherwise submitted in the relevant patent office.