(a) In any case not extending to the dismissal of a commissioned officer, the sworn testimony, contained in the duly authenticated record of proceedings of a court of inquiry, of a person whose oral testimony cannot be obtained, may, if otherwise admissible under the rules of evidence, be read in evidence by any party before a court-martial if the accused was a party before the court of inquiry and if the same issue was involved or if the accused consents to the introduction of such evidence.
     (b) Such testimony may be read in evidence only by the defense in cases extending to the dismissal of a commissioned officer.
     (c) Such testimony may also be read in evidence before a court of inquiry.