delivered the opinion of the Court:

We have stated fully the pleadings in the case as they contain the facts upon which the supposed right is based; and we have thus stated the facts fully that it may clearly appear what *429is the nature of the supposed wrong of which complaint is made, and the ground upon which relief is prayed. We have also stated fully the provisions of the act of Congress of February 2, 1901, under which the claim is made, and the construction thereof by which the action of the Secretary of War and the Adjutant General was determined.

The act of Congress of February 2, 1901, imposed upon the President and the War Department many and complicated duties in effecting the increase and reorganization of the army. In executing the various provisions of the act many perplexing questions necessarily arose, and which required for their determination, not only discretion, but the exercise of a careful and discriminating judgment. It must be borne in mind that they were required by this act, without special and detailed provisions to meet every emergency that might arise, to reorganize and systematize the entire body of the army, taking in the large increase provided for, both of officers and men; and to do that with justice and fairness to all concerned was a work of no small proportions and difficulty, and plainly required the exercise of judgment and discretion in a large and important sense. In such state of case it would require a very plain and unmistakable departure from the provisions of the statute to justify the judiciary in interposing by mandamus to control and reverse the action of the department in its work of reorganization, and fixing the rank of the officers of the Army. To interpose in any such case would almost certainly be productive of mischief and confusion in the entire organization. It is a well-settled principle in our jurisprudence and polity of government that the courts cannot substitute their own discretion and judgment for that of the Executive Department of the government in matters properly confided to it. Each department of government must work in its own proper sphere and jurisdiction.

In the case of Decatur v. Paulding, 14 Pet. 497, 10 L. ed. 559, it was held by the Supreme Court of the United States, and repeated in the recent case of United States ex rel. Riverside Oil Co. v. Hitchcock, 190 U. S. 316, 47 L. ed. 1074, 23 Sup. Ct. Rep. 698, that, in general, the official duties of the head of one of *430the Executive Departments, -whether imposed by act of Congress or by resolution, are not mere ministerial duties. The head of an Executive Department of the government, in the administration of the various and important concerns of his office, is continually required to exercise judgment and discretion. He must exercise his judgment in expounding the laws and resolutions of Congress under which he is from time to time required to act. And that was manifestly the condition of affairs under which the head of the War Department was required to act in respect to the 'matter of the present application.

It may be conceded, indeed it is doubtless true, that, when a plain official duty, requiring no exercise of discretion, is to bo performed, and performance is refused, any person who will sustain personal injury by such refusal may have a mandamus to compel its performance, and, when such duty is threatened to be violated by some positive official act, any person who will sustain personal injury thereby, for which adequate compensation cannot be had at law, may have an injunction to prevent it. In such cases, the writ of mandamus and injunction are somewhat correlative to each other. Board of Liquidation v. McComb, 92 U. S. 531, 541, 23 L. ed. 623, 628. But there is no such case presented here.

The act of 1901, for the reorganization and increase of the Army, has been construed, and that construction acted upon, by the head of the War Department in a manner that concerns a large class of officers; and, though there might be some such question made as would suggest doubt as to the strict correctness of the construction alopted, yet the court cannot be asked to solve the doubt, and thus to control and reverse the action of the department, as against the construction that has been adopted and acted upon in the administration of the affairs of the department, and by which the rights of others may affected. The principle upon this subject is well settled. It is declared by the Supreme Court of the United States, in United States v. Moore, 95 U. S. 760, 763, 24 L. ed. 588, 589, that “the construction given to a statute by those charged with the duty of executing it is always entitled to the most respectful consideration, and ought *431not be overruled without cogent reasons. Edwards v. Darby, 12 Wheat. 210, 6 L. ed. 604; United States v. State Bank, 6 Pet. 29, 8 L. ed. 308; United States v. Macdaniel, 7 Pet. 7, 8 L. ed. 589. The officers concerned are usually able men, and masters of the subject. Not unfrequentlv they are the draftsmen of the laws they are afterwards called upon to interpret.”

With respect to the interpretation given the act of 1901, by the Secretary of War, and those acting under his direction, as set forth in the answer of the appellees, this court is not at all inclined to dissent from it, or to say that such construction was improper. That construction certainly tended to produce simplicity, as well as justice among those officers entitled to rank in the same grade with the appellant. The fixing of a common date up to which the prior commissioned service should be computed would seem to be essential in order to maintain order and simplicity, as well as justice, in ranking the officers under that provision of the act.

But apart from the mere construction of the act, the appellant in his application has failed to show any real ground for the relief that he seeks. He is not at present deprived of any right that he can appeal to a court of justice to enforce. He occupies and enjoys the position of first lieutenant in the artillery corps of the Army, and he does not claim that he is entitled to any higher rank therein for the present; he only claims that he is deprived of a rank or position in the Official Army Register that might be of benefit to him in a future claim to promotion to the rank of captain. But his rank as shown by the Official Army Register is conclusive of no such right of promotion. The mere designation of lineal or relative rank in the Official Army Register does not fix and determine his rank in the Army and his right to promotion. That right depends upon other conditions. It is true the Official Army Register is an official record of the War Department, that furnishes evidence of the rank and status of officers in the various grades and classes of the officers in the army organization-; but it does not per se establish and determine any right to particular rank, much less to promotion. This latter right depends upon quite different conditions, and apart from *432the evidence furnished by the Official Army Register. Promotion is in a certain sense a new appointment, and, to the position of captain, can only be effected by the nomination of the President, with the advice and consent of the Senate. The mere entry, therefore, in the Official Army Register of the name and rank of the appellant would not operate to entitle him to or to control such promotion. That must rest primarily in the judgment and discretion of the President.

The right claimed by the appellant is of a prospective nature, and which may never be available or realized. And, such being the nature of the right claimed, it has been held that the relative rank of officers in the Army and Navy does not constitute a vested right, nor a matter of contract, but is subject to regulation by legislation of Congress and to the action of the Executive Departments, within • the scope of their discretion. United States ex rel. Hall v. Whitney, 5 Mackey, 370.

Without pursuing the subject further, we are clearly of opinion that there is no ease presented on the facts as set forth in the pleading, to warrant the granting of a mandamus; and that the court below was right in overruling the demurrer to the answer and dismissing the petition. The order appealed from must, therefore, be affirmed; and it is so ordered, with costs.

• Order affirmed.