D.C. Code § 5-105.05

The said Metropolitan Police force shall consist of 1 Chief of Police, who shall continue to be invested with such powers and charged with such duties as is provided by existing law; and also of 1 Assistant Superintendent with the rank of inspector; 4 surgeons for the Police and Fire Departments; 3 inspectors; 10 captains; 12 lieutenants, one of whom shall be Harbor Master; and such number of sergeants; and privates of class 3; privates of class 2; privates of class 1; mounted inspectors, captains, lieutenants, sergeants, and privates on horses and bicycles, and such others as said Mayor may deem necessary within the appropriations made by Congress; provided, that the inspectors shall perform the duties required on June 8, 1906, of captains in the force, that the captains shall command police precincts and perform such duty or duties in connection therewith as the laws and regulations of the said Mayor may prescribe. The Chief of Police shall be charged with the enforcement of all laws and regulations relating to the harbor, and employ the lieutenant, force, and means provided for this service in the execution of the duties appertaining thereto. The Metropolitan Police force shall consist of not less than 3,000 officers and members, in addition to the persons appointed as surgeons for the Metropolitan Police force, appointed as police matrons, or appointed as special privates pursuant to § 5-129.03 , and in addition to any retired officer or member of the Metropolitan Police force called back into service pursuant to § 5-712(a) .