He opened his address by reminding the Court that the question of their jurisdiction to try and sentence the accused was for the Court alone to decide, and that no mandate of the President, if in fact and in law the Constitution did not tolerate such tribunals in such cases, could protect any member of the Commission from the consequences of his illegal acts. He then advanced and proved the following propositions: that none but military offenses are subject to the jurisdiction of military courts, and that the offenders when they commit such offenses must be subject to military jurisdiction--in other words, must belong to the army or navy; that the President himself had no right to constitute military courts of his own motion, but that such power must first be exercised by Congress under the constitutional grant to that body to make rules for the government and regulation of the land and naval forces; that, by the fifth and sixth amendments of the constitution, every person, except those belonging to the land or naval forces or to the militia in active service in time of war, and, being such, committing a military or naval crime, is guaranteed an investigation by a grand jury as a preliminary to trial, and a speedy and public trial by an impartial jury. He then took up and examined the grounds on which the jurisdiction of the Commission was sought to be maintained. Calling the Court's attention to the constitutional provision that, if the institution of such Commission was an incident to the war power, that power was lodged exclusively in Congress and not at all in the President, and, therefore, Congress only could authorize such tribunals, he showed that, neither by the articles of war nor by the two acts, relied on, passed during the Rebellion, had Congress ever authorized any such tribunal; and that a military commission like the present and under present circumstances "is not to be found sanctioned, or the most remotely recognized, or even alluded to, by any writer on military law in England or the United States, or in any legislation of either country." And, in this connection, he pronounced the suggestion that the civil courts and juries of the District of Columbia could not safely be relied upon for the trial of these cases, "an unjust reflection upon the judges, upon the people, upon the marshal, an appointee of the President, by whom the juries were summoned, and upon our civil institutions themselves;" and he closed his remarks upon this branch of his subject by saying that the foregoing suggestion,