In Thornhill v. Alabama, the U.S Supreme Court ruled that a state statute prohibiting peaceful picketing was unconstitutional as it violated the First Amendment's guarantee of freedom of speech. The case involved Byron Thornhill, who had been convicted under an Alabama law for loitering and picketing near a lumber mill during a labor dispute. He argued that his conviction infringed upon his right to free expression and assembly. The court agreed with him in its 1940 decision, stating that peaceful demonstration or protest is protected by the Constitution regardless of whether others might find it annoying or offensive. This ruling significantly expanded protections for labor unions and their members' rights to strike and demonstrate peacefully.

In the dissenting opinion for Thornhill v. Alabama, Justice Frankfurter argued that the majority's decision to strike down a state law prohibiting picketing was too broad and failed to consider important nuances of labor disputes. He contended that while freedom of speech is fundamental, it does not grant an absolute right to use words or symbols in any manner at any time and place. The justice believed that states should have the authority to regulate certain forms of expression if they pose significant threats to public order or private rights. Furthermore, he suggested that peaceful picketing could quickly escalate into intimidation or violence, thereby justifying some level of government intervention. Ultimately, Justice Frankfurter disagreed with the majority's interpretation of First Amendment protections in this context.