Construction unions and unions in other industries with similar employment patterns have coped with the prohibition of closed shops by using exclusive hiring halls as a means of controlling the supply of labor. Such exclusive hiring halls do not strictly and formally require union membership as a condition of employment, but they do so in practical terms since an employee seeking to be dispatched to work through the union's hiring hall must pay union dues or a roughly-equivalent hiring hall fee. If the hiring hall is run on a non-discriminatory basis and adheres to clearly-stated eligibility and dispatch standards, it is lawful.