The right of workers in private employment to form unions and bargain collectively with their employers is guaranteed by the National Labor Relations Act (NLRA) and related federal laws. The NLRA is preemptive, meaning that it supersedes state law in the areas that it covers. For example, the Pennsylvania Supreme Court held that former employees could not proceed with their action against a union because the court would have had to determine whether the union committed an unfair labor practice under the NLRA (Schena v. Smiley, 413 A.2d 662 (Pa. 1980)). However, in areas not covered by the NLRA, such as the rights of public employees, and the rights of private employees who are not engaged in interstate commerce, the states are free to make their own provisions. Information on Pennsylvania law in areas not covered by the NLRA is available.