Member’s competency as a witness

(a) At the Trial by Court-Martial. A member of a court- martial may not testify as a witness before the other members at any proceeding of that court-martial. If a member is called to testify, the military judge must give the opposing party an opportunity to object outside the presence of the members. (b) During an Inquiry into the Validity of a Finding or Sentence. (1) Prohibited Testimony or Other Evidence. During an inquiry into the validity of a finding or sentence, a member of a court-martial may not testify about any statement made or incident that occurred during the deliberations of that court-martial; the effect of anything on that member’s or another member’s vote; or any member’s mental processes concerning the finding or sentence. The military judge may not receive a member’s affidavit or evidence of a member’s statement on these matters. (2) Exceptions. A member may testify about whether: (A) extraneous prejudicial information was improperly brought to the members’ attention; (B) unlawful command influence or any other outside influence was improperly brought to bear on any member; or (C) a mistake was made in entering the finding or sentence on the finding or sentence forms.