(a) In a case reviewable by the state judge advocate general, the state judge advocate general may act only with respect to the findings and sentence as approved by the convening authority. He may affirm only findings of guilty and the sentence or part of the sentence that he finds correct in law and fact and determines, on the basis of the entire record, should be approved. In considering the record, the state judge advocate general may weigh the evidence, judge the credibility of witnesses, and determine controverted questions of fact, recognizing that the trial court saw and heard the witnesses. If the state judge advocate general sets aside the findings and sentence, he may order a rehearing, unless the setting aside is based on lack of sufficient evidence in the record to support the findings. If the state judge advocate general sets aside the findings and sentence and does not order a rehearing, he shall order that the charges be dismissed.
(b) In a case reviewable by the state judge advocate general, the state judge advocate general shall instruct the convening authority to act in accordance with his decision on the review. If he has ordered a rehearing but the convening authority finds a rehearing impracticable, he may dismiss the charges.