<P> The Taft -- Hartley Act outlawed the closed shop in the United States in 1947 . The union shop was ruled illegal by the Supreme Court . States that have passed right - to - work laws go further by not allowing employers to require employees to pay the 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 can not 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 . </P>
<P> The Taft -- Hartley Act outlawed the closed shop in the United States in 1947 . The union shop was ruled illegal by the Supreme Court . States that have passed right - to - work laws go further by not allowing employers to require employees to pay the 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 can not 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 . </P>
the federal law which made closed shops and preferential shops illegal was the
the federal law which made closed shops and preferential shops illegal was the
Taft -- Hartley Act
Taft -- Hartley Act