The Bureau of Prohibition (or Prohibition Unit) was the federal law enforcement agency formed to enforce the National Prohibition Act of 1919, commonly known as the Volstead Act, which elaborated upon the 18th Amendment to the United States Constitution regarding the prohibition of the manufacture, sale, and transportation of alcoholic beverages. When it was first established in 1920, it was a unit of the Bureau of Internal Revenue. On April 1, 1927, it became an independent entity within the Department of the Treasury, changing its name from the Prohibition Unit to the Bureau of Prohibition. In 1930, it became part of the Department of Justice. By 1933, with the Repeal of Prohibition imminent, it was briefly absorbed into the FBI, or "Bureau of Investigation" as it was then called, and be