In the 1950 case of Amalgamated Association of Street, Electric Railway & Motor Coach Employees of America, Division 998, et al. v. Wisconsin Employment Relations Board, the Supreme Court ruled in favor of the Wisconsin Employment Relations Board (WERB). The dispute arose when a union representing Milwaukee's public transit workers went on strike and WERB issued an order to cease all strikes and picketing activities. The union argued that this violated their First Amendment rights to free speech and assembly. However, the Supreme Court upheld WERB's decision stating that states have a legitimate interest in maintaining peace and order during labor disputes which can justify restrictions on certain forms of protest such as strikes or pickets.

In the dissenting opinion for the case of Amalgamated Association of Street, Electric Railway & Motor Coach Employees of America, Division 998, et al. v. Wisconsin Employment Relations Board (1950), Justice Black argued that the majority's decision was a departure from established principles governing labor disputes and collective bargaining rights under federal law. He contended that by upholding state authority to prohibit peaceful picketing aimed at persuading customers not to patronize a business involved in a labor dispute, the Court had effectively sanctioned state interference with federally protected union activities. Furthermore, he expressed concern about potential implications on free speech rights as well as interstate commerce regulation if states were allowed to restrict such forms of protest and persuasion commonly used by unions during labor disputes.