Thornhill v. Alabama, 310 U.S. 88 (1940), is a US labor law case of a United States Supreme Court. It reversed the conviction of the president of a local union for violating an Alabama statute that prohibited only labor picketing. Thornhill was peaceably picketing his employer during an authorized strike when he was arrested and charged. In reaching its decision, Associate Justice Frank Murphy wrote for the Supreme Court that the free speech clause protects speech about the facts and circumstances of a labor dispute. The statute in the case prohibited all labor picketing, but Thornhill added peaceful labor picketing to the area protected by free speech.