In the case of National Labor Relations Board v. District 50, United Mine Workers of America et al., the U.S Supreme Court ruled in favor of the National Labor Relations Board (NLRB). The dispute arose when several non-union employees were fired by their employer for refusing to join a union, which was contrary to Section 8(a)(3) and (1) of the National Labor Relations Act that prohibits employers from influencing their employees' decision regarding joining or forming labor organizations. The NLRB held that these dismissals were unfair labor practices and ordered reinstatement with back pay. However, on appeal, it was argued that since these workers had been employed under an agreement between the company and another union not involved in this case - they weren't covered by said act. Rejecting this argument, Justice Brennan delivered his opinion stating any employee who has suffered due to such unfair practices can seek relief irrespective of whether he is part of a bargaining unit or not.

In the dissenting opinion for the case of NATIONAL LABOR RELATIONS BOARD v. DISTRICT 50, UNITED MINE WORKERS OF AMERICA, Justice Brennan disagreed with the majority's decision to deny District 50 representation rights based on their affiliation with United Mine Workers (UMW). He argued that this ruling was inconsistent with previous decisions and could potentially undermine labor unions' ability to effectively represent workers. Brennan contended that there was no evidence suggesting any wrongdoing or unfair practices by District 50 due to its association with UMW. Furthermore, he believed that denying representation rights solely based on union affiliation contradicted principles of freedom of association and collective bargaining enshrined in national labor laws. Therefore, he dissented from the majority's judgment.