(a) No charge or specification may be referred to a general court-martial for trial until a through and impartial investigation of all the matters set forth therein has been made. This investigation shall include inquiry as to the truth of the matter set forth in the charges, consideration of the form of charges, and recommendation as to the disposition which should be made of the case in the interest of justice and discipline.
(b) The accused shall be advised of the charges against him and of his right to be represented at that investigation as provided in section 838 of this title (article 38) and in regulations prescribed under that section. At that investigation full opportunity shall be given to the accused to cross-examine witnesses against him if they are available and to present anything he may desire in his own behalf, either in defense or mitigation, and the investigation officer shall examine available witnesses requested by the accused. If the charges are forwarded after the investigation, they shall be accompanied by a statement of the substance of the testimony taken on both sides and a copy thereof shall be given to the accused.
(c) If an investigation of the subject matter of an offense has been conducted before the accused is charged with the offense, and if the accused was present at the investigation and afforded the opportunities for representation, cross-examination, and presentation prescribed in subsection (b), no further investigation of that charge is necessary under this article unless it is demanded by the accused after he is informed of the charge. A demand for further investigation entitles the accused to recall witnesses for further cross-examination and to offer any new evidence in his own behalf.
(d) The requirements of this article are binding on all persons administering this chapter but failure to follow them does not constitute judicial error.