(a) Pretrial, trial, and post-trial procedures, including modes of proof, for cases arising under this chapter triable in courts-martial, military commissions and other military tribunals, and procedures for courts of inquiry, may be prescribed by the President by regulations which shall, so far as he considers practicable, apply the principles of law and the rules of evidence generally recognized in the trial of criminal cases in the United States district courts, but which may not, except as provided in chapter
47A of this title, be contrary to or inconsistent with this chapter.