§ 1.31 Applicant and patent owner may be represented by one or more patent practitioners or joint inventors.

(a) An applicant for patent or patent owner may file and prosecute the applicant's or patent owner's own case, or the applicant or patent owner may give power of attorney so as to be represented by one or more patent practitioners or joint inventors, except that the following persons or entities must be represented by a patent practitioner: (1) a juristic entity ( e.g., organizational assignee); (2) an applicant as defined in § 1.42, in which the domicile of at least one of the parties identified as the applicant in the application is not located within the United States or its territories; and (3) a patent owner, in which the domicile of at least one of the parties identified as the patent owner is not located within the United States or its territories. (b) The Office cannot aid in the selection of a patent practitioner. [91 FR 13519, Mar. 20, 2026]