Construction unions and unions in other industries with similar employment patterns have coped with that prohibition by using exclusive hiring halls as a means of controlling the supply of labor. While such exclusive hiring halls do not, in a strictly formal sense, require union membership as a condition of employment, they do so in practical terms, in that an employee seeking to be dispatched to work through the union's hiring hall must either pay union dues or pay a roughly equivalent hiring hall fee. So long as the hiring hall is run on a non-discriminatory basis and adheres to clearly stated eligibility and dispatch standards it is lawful. The Taft-Hartley Act also bars unions from requiring unreasonably high initiation fees as a condition of membership in order to prevent unions from using initiation fees as a device to keep non-union employees out of a particular industry. Also, the National Labor Relations Act permits construction employers to enter into pre-hire agreements, in which they agree to draw their workforces from a pool of employees dispatched by the union. The NLRA prohibits pre-hire agreements outside the construction industry.
For the entertainment industry, unions representing performers have as their first rule one banning any represented performer from working on any non-union production. Penalties are imposed on the union member, not on the employer, and can lead to loss of union membership. Most major productions are union productions, and non-members join the Screen Actors Guild through performing as extras and earning three union vouchers, or by being given a speaking line and entering that way. The other performance unions do not have minimum membership standards, but joining the union bars one from working on non-union productions.
Also, all four major sports leagues are union shops, even though a franchise may be located in a state that has a right-to-work law or constitutional provision.