The convening authority may not approve a sentence while the accused lacks the mental capacity to cooperate and understand post-trial proceedings. RCM 1107(b)(5). Likewise, an appellate authority may not affirm the findings when the accused lacks the ability to understand and cooperate in appellate proceedings. RCM 1203(c)(5). See Thompson v. United States , 60 M.J. 880 (N-M. Ct. Crim. App. 2005) (holding that appellant demonstrated lack of mental capacity to assist in appeal; appeal stayed).