In the case of National Labor Relations Board v. Automotive Maintenance Machinery Co., 1941, the U.S Supreme Court ruled in favor of the National Labor Relations Board (NLRB). The NLRB had accused Automotive Maintenance Machinery Co. of unfair labor practices for refusing to bargain with a union that represented its employees and for firing an employee due to his union activities. The company argued that it was not engaged in interstate commerce, thus placing it outside the jurisdiction of the NLRB under federal law. However, evidence showed that while most business was local, a significant portion involved out-of-state transactions which brought them within reach of federal regulation. Therefore, despite being primarily engaged in intrastate commerce, their involvement in interstate commerce was substantial enough to fall under Federal jurisdiction as per Wagner Act or National Labor Relations Act (NLRA) provisions.

In the dissenting opinion for the National Labor Relations Board v. Automotive Maintenance Machinery Co., Justice Roberts argued that there was no substantial evidence to support the majority's conclusion that Automotive Maintenance Machinery Co. had engaged in unfair labor practices. He contended that, under Section 10(e) of the National Labor Relations Act, it is not enough for a company to merely discourage union membership; they must also be shown to have restrained or coerced employees in their right to self-organization and collective bargaining. In this case, he believed there was insufficient proof of such restraint or coercion by the company against its employees who were attempting to form a union. Furthermore, he disagreed with how broadly his colleagues interpreted "employer interference," arguing instead for a narrower interpretation more consistent with Congress' intent when passing legislation on labor relations.