The first of the Smith Act trials concluded in New York City, with eleven leaders of the Communist Party of the United States found guilty of violating the Smith Act.

The Smith Act trials of Communist Party leaders were a series of trials held from 1949 to 1958 in which leaders of the Communist Party of the United States (CPUSA) were accused of violating the Smith Act, a 1940 statute that set penalties for advocating the violent overthrow of the government. The defendants argued that they advocated a peaceful transition to socialism, and that the First Amendment's guarantee of freedom of speech and of association protected their membership in a political party. Appeals from these trials reached the US Supreme Court, which ruled on issues in Dennis v. United States (1951) and Yates v. United States (1957).

The Communist Party USA (CPUSA), officially the Communist Party of the United States of America and sometimes referred to as the American Communist Party, is a communist party in the United States. It was established in 1919 in the wake of the Russian Revolution, emerging from the left wing of the Socialist Party of America (SPA). The CPUSA sought to establish socialism in the U.S. via the principles of Marxism–Leninism, aligning itself with the Communist International (Comintern), which was controlled by the Soviet Union.

The Alien Registration Act, popularly known as the Smith Act, 76th United States Congress, 3rd session, ch. 439, 54 Stat. 670, 18 U.S.C. § 2385 is a United States federal statute that was enacted on June 28, 1940. It set criminal penalties for advocating the overthrow of the U.S. government by force or violence, and required all foreigners over the age of 14 to register with the federal government.