The U.S. Supreme Court case National Labor Relations Board et al. v. United Food & Commercial Workers Union, Local 23, AFL-CIO in 1987 revolved around the issue of whether a union's display of a large stationary banner near the entrance of a secondary employer was equivalent to picketing and thus constituted an unfair labor practice under federal law. The National Labor Relations Board (NLRB) had ruled that such displays were not coercive and therefore did not violate the law; however, this decision was reversed by the Court of Appeals for District Columbia Circuit which held that it amounted to picketing and hence unlawful secondary boycott activity. In its ruling, the Supreme Court sided with NLRB stating that peaceful stationary banner displays are significantly less confrontational than traditional picketing - they do not involve patrolling or creating physical or symbolic barriers to entry nor do they induce confrontation by approaching individuals before they enter an establishment. Therefore, these activities cannot be equated with picketing and should not be considered as unfair labor practices under Section 8(b)(4) of National Labor Relations Act.

In the dissenting opinion for the case of NATIONAL LABOR RELATIONS BOARD et al. v. UNITED FOOD & COMMERCIAL WORKERS UNION, LOCAL 23, AFL-CIO, Justice Brennan disagreed with the majority's interpretation of Section 8(b)(6) of the National Labor Relations Act (NLRA). He argued that this section was intended to prevent unions from extorting payments from employers in return for peace or refraining from picketing - not to prohibit union hiring halls as suggested by the majority. According to him, such an interpretation would undermine Congress' intent and purpose behind enacting NLRA which is primarily aimed at encouraging collective bargaining and protecting workers' rights. Furthermore, he pointed out that there was no evidence showing any coercive behavior on part of United Food & Commercial Workers Union towards employers who did not comply with their referral system; hence it should not be considered a violation under Section 8(b)(6). The justice concluded his dissent by expressing concern over how this ruling could potentially disrupt longstanding labor-management relations and practices across various industries.