Internal Security Act of 1950

August 23, 1950

Congress passed the Internal Security Act over President Truman’s veto. Also known as the McCarran Act or the Subversive Activities Control Act, it strengthened laws against espionage, allowed investigation and deportation of immigrants who were suspected of subversive activities or of promoting communism or fascism, and allowed the limitation of free speech for national security reasons. President Truman vigorously opposed the law that he believed “would make a mockery of our Bill of Rights [and] would actually weaken our internal security measures.” In 1993, sections of the act were ruled unconstitutional by the Supreme Court.

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