In the case of National Labor Relations Board v. United Steelworkers of America, CIO, et al., 1957, the U.S Supreme Court ruled in favor of the National Labor Relations Board (NLRB). The dispute arose when a union fined members for crossing picket lines during a strike that was deemed illegal by NLRB. The court held that under section 8(b)(1)(A) of the National Labor Relations Act, it is an unfair labor practice for a union to restrain or coerce employees in their rights guaranteed by section 7 which includes refraining from any and all concerted activities. Therefore, fining members who returned to work during an unlawful strike violated this provision as it amounted to restraint or coercion. This ruling clarified unions' responsibilities towards their members and set precedent on how they should conduct themselves especially during strikes.

In the dissenting opinion for the case of NATIONAL LABOR RELATIONS BOARD v. UNITED STEELWORKERS OF AMERICA, CIO, et al., Justice Brennan disagreed with the majority's interpretation of Section 8(b)(4)(A) of the National Labor Relations Act. He argued that this section was intended to prevent unions from engaging in secondary boycotts against neutral employers, not to restrict their ability to protest unfair labor practices by their own employer. According to Justice Brennan, a union should be allowed to picket an employer who is engaged in unfair labor practices without being accused of inducing or encouraging a strike or refusal by employees. The majority's decision would effectively prohibit all forms of peaceful picketing and thus infringe upon workers' rights under federal law and potentially violate First Amendment protections as well.