The Internal Security Act of 1950, 64 Stat. 987, also known as the Subversive Activities Control Act of 1950, the McCarran Act after its principal sponsor Sen. Pat McCarran, or the Concentration Camp Law, is a United States federal law. Congress enacted it over President Harry Truman's veto. It required Communist organizations to register with the federal government. The 1965 U.S Supreme Court ruling in Albertson v.
