McCarran Internal Security Act 麦卡伦国内安全法
（重定向自McCarran Act）
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![Civil libertarians and radical political activists considered the McCarran Act to be a dangerous and unconstitutional infringement of political liberty, as exemplified in this 1961 poster.](/Images/godic/202501/26/61-mccarranact-poster1040.jpg")
The Internal Security Act of 1950, 64 Stat. 987 (Public Law 81-831), also known as the Subversive Activities Control Act of 1950 or the McCarran Act, after its principal sponsor Sen. Pat McCarran (D-Nevada), is a United States federal law. It was enacted over President Harry Truman's veto.