In the 1997 case of Allentown Mack Sales and Service, Inc. v. National Labor Relations Board, the U.S Supreme Court ruled in favor of Allentown Mack Sales and Service, Inc., reversing a decision by the National Labor Relations Board (NLRB). The dispute arose when Allentown conducted a poll to determine if its employees still supported their union representation after receiving an anonymous letter suggesting they did not. The NLRB argued that this was an unfair labor practice as it interfered with employee rights under Section 8(a)(1) of the National Labor Relations Act (NLRA). However, the Supreme Court disagreed stating that there was substantial evidence showing lack of support for union representation among employees which justified conducting such a poll. Therefore, it held that employers could question or challenge existing unions if they had reasonable grounds to doubt their majority status.

The dissenting opinion in the case of Allentown Mack Sales and Service, Inc. v. National Labor Relations Board argued that the majority's decision to overturn a ruling by the NLRB was inappropriate because it failed to respect established principles of administrative law. The dissenters believed that courts should defer to agency expertise unless their decisions are unreasonable or unsupported by substantial evidence, which they did not believe was true in this case. They also disagreed with the majority's interpretation of what constitutes "anti-union animus," arguing that an employer can have legitimate reasons for questioning union support without necessarily being anti-union. Furthermore, they criticized the majority for failing to give adequate weight to circumstantial evidence presented by the NLRB indicating possible unfair labor practices.