In the case of Local No. 8-6, Oil, Chemical and Atomic Workers International Union, AFL-CIO v. Missouri (1959), the U.S Supreme Court ruled in favor of a union that was challenging a state law prohibiting picketing without an ongoing labor dispute. The court held that peaceful picketing is protected by the First Amendment's guarantee of freedom of speech even if there isn't an active labor dispute occurring at the time. This decision overturned Missouri’s statute which had made it illegal for any person to engage in public demonstrations or displays designed to influence others not to buy from or work for certain businesses unless they were directly involved in a current labor disagreement with said business. The ruling emphasized that such laws infringed upon free speech rights as long as protests remained non-violent and did not incite violence or other unlawful actions.

In the dissenting opinion for the case of Local No. 8-6, Oil, Chemical and Atomic Workers International Union, AFL-CIO v. Missouri (1959), Justice Hugo Black argued that the majority's decision to uphold a state law prohibiting peaceful picketing violated First Amendment rights to free speech and assembly. He contended that labor disputes were matters of public concern and thus deserved protection under these constitutional provisions. Furthermore, he criticized the majority for failing to provide clear guidelines on what constituted lawful versus unlawful picketing activity - a vagueness which he believed could lead to arbitrary enforcement by authorities. In his view, this lack of clarity further infringed upon workers' freedom of expression as it created an atmosphere of uncertainty around their right to protest peacefully.