A patent has the attributes of intangible personal property - it can be sold or mortgaged; it may be bequeathed by a will; and it may pass to the heirs of a deceased patentee. The patent law provides for the transfer or sale of a patent, or of an application for patent, by an instrument in writing. An assignment is such an instrument and may transfer the entire interest or a partial interest in the patent. The assignee becomes the owner of the patent and has the same rights that the original patentee had. There may also be a territorial grant or license that conveys the same character of interest as an assignment but only for a particularly specified part of the United States. A security interest, or mortgage, of patent property passes ownership to the mortgagee or lender until the mortgage has been satisfied and transferred back to the mortgagor, or borrower. A conditional assignment may also pass ownership of the patent until canceled by the parties or by court decree.

An assignment, grant, or conveyance of any patent or application for patent should be acknowledged before a notary public or officer authorized to administer oaths or perform notarial acts. The certificate of such acknowledgment constitutes prima facie evidence of the execution of the assignment, grant, or conveyance.

The Office records assignments, grants, and similar instruments. The recording serves as constructive notice to the world. If an assignment or conveyance of a patent or an interest in a patent or patent application is not recorded within three months from its execution date, it is void against a subsequent purchaser without notice, unless recorded prior to the subsequent purchase.

An instrument relating to a patent should include the patent number and date, as well as the name of the inventor and title of the invention. An instrument relating to an application should identify the application by its application serial number and filing date, the name of the inventor, and title of the invention. If an assignment of an application is executed at the same time the application is prepared and before it has been filed in the Office, it should adequately identify the application, as by its date of execution and name of the inventor and title of the invention, so there can be no mistake as to the application intended. If an application has been assigned and the assignment has been recorded, the patent is issued to the assignee as owner, if the name of the assignee is provided when the issue fee is paid and the patent is requested to be issued to the assignee. If the assignment is of a part interest only, the patent will be issued to the inventor and assignee as joint owners.