Companies may influence unions through bargaining, labor relations, and by other means, but employer-controlled unions in the United States have been outlawed since the National Labor Relations Act of 1935. The act prohibits supervisors from joining unions as well as prohibiting employers from assisting (as in the event of unions competing in the organization of a company), or dominating any labor organization. Additionally, the two laws, passed in 1947 and 1959, respectively, were the Taft–Hartley Act and the Landrum–Griffin Act. These statutes guarantee the rights of private employees to form and join unions in order to bargain collectively. The vast majority of states have extended union rights to public employees.