D.C. Code § 49-308
All appointments to the grade of 2nd lieutenant shall be from the enlisted men, under regulations prescribed by the Commanding General, and subject to the examination required by law.
Mar. 1, 1889, 25 Stat. 775, ch. 328
as added Feb. 18, 1909, 35 Stat. 630, ch. 146, § 16
1973 Ed., § 39-209.
1981 Ed., § 39-308.