delivered the opinion of the Court:

Section 15 of the act, approved June 29, 1906, makes it the duty of the United States district attorneys,” “upon affidavit showing good cause therefor,” to institute proceedings for the purpose of setting aside and canceling a certificate of citizenship, on the ground of fraud, or that the certificate had been illegally procured. 34 Stat. at L. 601, chap. 3592, U. S. Comp. Stat. Supp. 1909, p. 485.

This suit is not brought by the Attorney General, or by his direction, and we need not consider whether in such case it could be maintained without the authority of the statute aforesaid.

While there is no specific statute empowering the Attorney General to bring actions and suits in the name of the United States, the power resides in him as the head of the Department of Justice. United States v. San Jacinto Tin Co. 125 U. S. 273-279, 31 L. ed. 747-749, 8 Sup. Ct. Rep. 850. But there is no such power vested in the district attorneys of the United States. Their powers are defined in the several statutes creating the office and defining its duties. The special power conferred by sec. 15, aforesaid, to bring suits to cancel certificates *126of citizenship, is coupled with the condition that they shall be founded upon affidavits showing -cause therefor. The naturalization act of Congress was intended to remedy the evils that had resulted from the loose administration of former general laws regulating naturalization. A stricter procedure was substituted, and a remedy provided for the correction of frauds that might still be perpetrated. But Congress was not unmindful of the value of a certificate of citizenship, and, in providing the remedy, coupled therewith the condition that an affidavit should be presented to the district attorney, stating the facts necessary to the maintenance of the suit. The language used could, in our opinion, have no other purpose than the creation of a condition precedent to the exercise of the power conferred. This view is expressed by Attorney General Bonaparte in an opinion given to the Secretary of Commerce and Labor, March 26, 1907. The supporting affidavit, being essential, should appear in the record, either by reference and contemporaneous filing with the petition, or by allegations therein sufficient to show compliance with the statute, and to warrant its production if denied.

It is a well-established general principle that where a power is exercised under a statute prescribing its course, that course must be followed and the necessary conditions made to appear. Every material requirement of the statute must be complied with. Thatcher v. Powell, 6 Wheat. 119, 127, 5 L. ed. 221, 223; Shelby v. Bacon, 10 How. 56—69, 13 L. ed. 326—331; see also Calpin v. Page, 18 Wall, 350, 371, 21 L. ed. 959, 964. The recent decision of the Supreme Court of the United States (United States v. Morgan, 222 U. S. 274, 56 L. ed.—, 32 Sup. Ct. Rep. 81) does not, as contended, govern the present case. That was a prosecution under the pure food and drug act which, under certain conditions, requires the board of chemistry to make analysis of suspected articles, and if, after notice to parties, it appears that the law has been violated, the Secretary of Agriculture shall certify the fact to the proper district attorney, whose duty it is then made, without delay, to institute proceedings for the prosecution, condemnation, etc. After *127discussing different provisions of the statute regulating prosecutions, to which the aforesaid condition did not apply, Mr. Justice Lamar, who delivered the opinion of the court, said: “In providing for notice in one case, and permitting prosecutions without it in another, the statute clearly shows that there was no intent to make notice jurisdictional.” lie further said that the statute did not repeal, by implication, the provisions of the Revised Statutes, making it the duty of the district attorneys to prosecute all delinquents for crimes and offenses cognizable under the authority of the United States, Secs. 771-1022, U. S. Comp. Stat. 1901, pp. 601-720. Consequently, if the Executive Department failed to report violations of the law, it would leave untouched the duty of the district attorney to prosecute under the sections of the Revised Statutes before mentioned. There is no such situation here. The statute is plain and unambiguous, and it does not create an offense which it is made the duty of the district attorney to prosecute, as it is his duty to do where crimes have been committed. It is a civil proceeding the course of which is plainly laid down, and there is no general provision of the law authorizing the institution of such suits by district attorneys.

This conclusion makes it unnecessary to consider any other ground of demurrer than the one stated.

Uie petition failing to set forth the condition required by the statute to confer authority to maintain the suit, the demurrer ought to have been sustained.

The decree will be reversed, with direction to sustain the demurrer on the ground stated, and, unless the petition may be amended to show the existence of a proper affidavit at the time it was filed, to dismiss the petition without prejudice.

Reversed.