the clayton antitrust act of 1914 and the robinson-patman act of 1936 outlawed what
Robinson–Patman Act The law grew out of practices in which chain stores were allowed to purchase goods at lower prices than other retailers. An amendment to the Clayton Antitrust Act, it prevented unfair price discrimination for the first time, by requiring that the seller offer the same price terms to customers at a given level of trade. The Act provided for criminal penalties, but contained a specific exemption for "cooperative associations".
Closed shop The Taft–Hartley Act outlawed the closed shop in the United States in 1947. The union shop was ruled illegal by the Supreme Court.[4] States that have passed right-to-work laws go further by not allowing employers to require employees to pay a form of union dues called an agency fee. An employer may not lawfully agree with a union to hire only union members, but it may agree to require employees to join the union or pay the equivalent of union dues to it, within a set period after starting employment. Similarly, while a union could require an employer that had agreed to a closed shop contract prior to 1947 to fire an employee who had been expelled from the union for any reason, it cannot demand that an employer fire an employee under a union shop contract for any reason other than failure to pay those dues that are uniformly required of all employees.