The amendment to the Constitution that prohibits alcohol is the 18th Amendment.

Ratified in 1919, it established the prohibition of alcoholic beverages in the United States, marking a significant social experiment aimed at reducing crime and improving morality. However, the amendment led to widespread disregard for the law, and the rise of illegal speakeasies, and organized crime. Due to its unintended consequences, the 18th Amendment was eventually repealed by the 21st Amendment in 1933, ending prohibition and allowing the legal sale and consumption of alcohol once again.