Leary v. United States, 395 U.S. 6 (1969), is a U.S. Supreme Court case dealing with the constitutionality of the Marihuana Tax Act of 1937. Timothy Leary, a professor and activist, was arrested for the possession of marijuana in violation of the Marihuana Tax Act. Leary challenged the act on the ground that the act required self-incrimination, which violated the Fifth Amendment. The unanimous opinion of the court was penned by Justice John Marshall Harlan II and declared the Marihuana Tax Act unconstitutional. Thus, Leary’s conviction was overturned. Congress responded shortly thereafter by replacing the Marihuana Tax Act with the newly written Controlled Substances Act while continuing the prohibition of certain drugs in the United States.