delivered the opinion of the Court:

The Board of Labor Employment are ministerial officers, and their duty in the premises did not cease to be ministerial because they rested their refusal of registration on the determination of a pure question of law involving the ascertainment of.no fact whatever. Roberts v. United States, 13 App. D. C. 38, 46, 176 U. S. 221, 231, 44 L. ed. 443, 447, 20 Sup. Ct. Rep. 376.

We do not find it necessary to enter upon the inquiry whether the petitioner, at the time of making his application for registration, was a citizen of the United States and entitled to all of the civil rights and immunities pertaining to such citizenship, because we are of the opinion that the regulation of the Navy Department, made in 1896, has been modified by regulations and rules of the civil service of the United States since made by order of the President. The original Navy Yard rules and regulations were adaptations of the principles of the civil service, though not then subject to the jurisdiction of the Civil Service Commission. 20th Rep. O. S. Com. pp. 100, 101. They were, however, brought under the supervision of the Commission by order of President Cleveland on November 2, 1896, 13th Rep. C. S. Com., p. 151.

No modification of the rule requiring an applicant for registration to be a citizen of the United States was suggested by *124any conditions existing prior to the treaty of Paris. New conditions arising thereafter were met by additional civil service rules promulgated by President Roosevelt on April 15, 1903. Of these, Rule V. provides that “no person shall be admitted to-examination unless he he a citizen of or owe allegiance to the-United States.” And thereunder it is provided that “an applicant who claims United States citizenship by virtue of residence in Porto Rico, and who shows birth or naturalization in Porto Rico, will not be required to show further evidence of’ citizenship.” 20th Rep. C. S. Com. p. 48.

Since that time, as shown in the same report (p. 16), seventy-eight residents of Porto Rico have received appointments in the-general service of the United States, eleven of these being in the service in the city of Washington.

The Board of Labor Employment having admitted that the-petitioner was a native of Porto Rico, owing allegiance to the United States, and that he possessed all of the qualifications required by the remaining regulations, it is their plain duty to-admit him to registration in accordance with his application.

That the petitioner may possibly not hereafter receive any substantial benefit from his registration is not a sufficient reason, for denying him the remedy sought. The conditions of the case-distinguish it from those of United States ex rel. Brown v. Root, 18 App. D. C. 239; United States ex rel. Edwards v. Root, 22 App. D. C. 419, upon which the respondents rely.

The order dismissing the petition will be reversed, with costs,, and the cause remanded, with directions to issue the writ as. prayed. It is so ordered. Reversed.