37 CFR 41.9: Action by owner.

(a) Entire interest. An owner of the entire interest in an application or patent involved in a Board proceeding may act in the proceeding to the exclusion of the inventor (see §§ 3.71 and 3.73 of this title).

(b) Part interest. An owner of a part interest in an application or patent involved in a Board proceeding may petition to act in the proceeding to the exclusion of an inventor or a co-owner. The petition must show the inability or refusal of an inventor or co-owner to prosecute the proceeding or other cause why it is in the interest of justice to permit the owner of a part interest to act in the proceeding. An order granting the petition may set conditions on the actions of the parties during the proceeding.