The National Archives holds a copy (seen in the images above) of what is thought of as the first Standing Rock constitution. It is a set of bylaws for what was known as the Standing Rock Business Council created in 1914. Despite the name, the bylaws read like a governing document for an organization that acted for the people of Standing Rock. References to the Business Council can be found within issues of the early Standing Rock newspaper The Sioux County Pioneer, which can be read on microfilm at the library. Full-text issues can also be searched online through the Library of Congress at this link
References to the council can also be found within the minutes of the council that preceded the adoption of the current Standing Rock Constitution in 1959. Sitting Bull College Library has copies of tribal council minutes from 1934-1959 that are held at the National Archives. Though Standing Rock's is not an IRA (Indian Reorganization Act) Constitution from the New Deal era, the federal government began holding copies of the minutes at that period of time. It is unknown whether minutes and records from 1914-1934 still exist somewhere. If they do, they have important stories to tell about the early tribal government on Standing Rock.