76, enacted May 18, 1917) authorized the United States federal government to raise a national army for service in World War I through conscription.

But later, with the assistance of Captain Hugh Johnson and others, Crowder guided the bill through Congress and administered the draft as the Provost Marshal General.

A problem that came up in the writing of the bill and its negotiation through Congress was the desire of former President Theodore Roosevelt to assemble a volunteer force to go to Europe.

Creel later helped form the American Alliance for Labor and Democracy, with union leader Samuel Gompers as president, to win working-class support for the war and "unify sentiment in the nation".

The AALD had branches in 164 cities, and many labor leaders went along although "rank-and-file working class support for the war remained lukewarm ...", and the campaign was ultimately unsuccessful.

At the request of the War Department, Congress amended the law in August 1918 to expand the age range to include all men 18 to 45, and to bar further volunteering.

Section 7 of the act provided that men would be "as far as practicable...grouped into units by States and the political subdivisions of the same," the most prominent example being the "National Army" infantry divisions.

The Solicitor General's argument and the court's opinion were based primarily on Kneedler v. Lane, 45 Pa. 238, 252 (1863) and Vattel's 1758 treatise The Law of Nations.

The Provost Marshal General was relieved from duty on July 15, 1919, thereby finally terminating the activities of the Selective Service System of World War I. Conscription was by class.

[11] Draft board officials were told to tear off the lower left-hand corner of the Selective Service form of a black registrant, indicating his designation for segregated units.