Please note that the content of this book primarily consists of articles available from Wikipedia or other free sources online. Right-to-work laws are statutes enforced in twenty-two U.S. states, mostly in the southern or western U.S., allowed under provisions of the Taft-Hartley Act, which prohibit agreements between trade unions and employers making membership or payment of union dues or "fees" a condition of employment, either before or after hiring. Prior to the passage of the Taft-Hartley Act by Congress over President Harry S. Truman''s veto in 1947, unions and employers covered by the National Labor Relations Act could lawfully agree to a "closed shop," in which employees at unionized workplaces are required to be members of the union as a condition of employment.