Prohibition repeal day
On December 5, 1933 the 21st Amendment to the Constitution was passed repealing the prohibition of alcohol in the United States. Prohibition, often called "The Noble Experiment", is a great example of how destructive government intervention can be. Inconsistent enforcement and unintended consequences such as the rise of organized crime all led to be the downfall of this "experiment".
This ReasonTV interview with Ken Burns is a great primer on prohibition.