In the case of National Labor Relations Board v. Nevada Consolidated Copper Corp., 1941, the Supreme Court ruled in favor of the National Labor Relations Board (NLRB). The NLRB had accused Nevada Consolidated Copper Corporation and its subsidiary companies of engaging in unfair labor practices by refusing to bargain with a union that represented their employees. The defendants argued that they were not obligated to negotiate because some members of the union worked for other employers as well. However, the court held that this did not exempt them from their duty under Section 9(a) and Section 8(5) of the National Labor Relations Act to bargain collectively with representatives chosen by a majority of their employees. Therefore, it was concluded that an employer cannot refuse to negotiate on these grounds.

In the dissenting opinion for the case of NATIONAL LABOR RELATIONS BOARD v. NEVADA CONSOLIDATED COPPER CORP., Justice Roberts disagreed with the majority's decision to uphold an order by the National Labor Relations Board (NLRB) that required Nevada Consolidated Copper Corp. to reinstate employees who had been fired for union activities. He argued that there was insufficient evidence to prove that these employees were dismissed due to their union involvement, as opposed by other valid reasons such as insubordination or inefficiency at work. Furthermore, he contended that it was not within NLRB’s jurisdictional power and authority under Wagner Act (National Labor Relations Act), which only allows them to prevent unfair labor practices affecting commerce but does not give them a blanket right over all employment matters in industries affecting commerce.