37 CFR § 11.107 - Conflict of interest; Current clients.
(a) Except as provided in paragraph (b) of this section, a practitioner shall not represent a client if the representation involves a concurrent conflict of interest. A concurrent conflict of interest exists if:
(1) The representation of one client will be directly adverse to another client; or
(2) There is a significant risk that the representation of one or more clients will be materially limited by the practitioner's responsibilities to another client, a former client or a third person or by a personal interest of the practitioner.
(2) The representation is not prohibited by law;