Communist Party v. Subversive Activities Control Board
Communist Party of the United States v. Subversive Activities Control Board, 351 U.S. 115 (1956) and 367 U.S. 1 (1961), was a federal court case in the United States involving the compelled registration of the Communist Party of the United States, under a statute requiring that all organizations determined to be directed or controlled by the "world Communist movement" publicly disclose detailed information as to their officers, funds, and membership.
Source: Wikipedia — Communist Party v. Subversive Activities Control Board (CC BY-SA 4.0)