"Effective enforcement of the alcohol ban during the Prohibition Era proved to be very difficult and led to widespread flouting of the law. The lack of a solid popular consensus for the ban resulted in the growth of vast criminal organizations, including the modern American Mafia, and various other criminal cliques. Widespread disregard of the law also generated rampant corruption among politicians and within police forces."
http://en.wikipedia.org/wiki/Prohibi..._United_States