37 CFR § 42.10 - Counsel.
(b) A power of attorney must be filed with the designation of counsel, except the patent owner should not file an additional power of attorney if the designated counsel is already counsel of record in the subject patent or application.
(c) The Board may recognize counsel pro hac vice during a proceeding upon a showing of good cause, subject to the condition that lead counsel be a registered practitioner and to any other conditions as the Board may impose. For example, where the lead counsel is a registered practitioner, a motion to appear pro hac vice by counsel who is not a registered practitioner may be granted upon showing that counsel is an experienced litigating attorney and has an established familiarity with the subject matter at issue in the proceeding.
(d) A panel of the Board may disqualify counsel for cause after notice and opportunity for hearing. A decision to disqualify is not final for the purposes of judicial review until certified by the Chief Administrative Patent Judge.