Many social pathologies are caused by prohibition.
It took only 14 years of alcohol prohibition for the country to realize the harms caused by prohibition, and for calls for repeal to succeed.
Primarily, violence and crime increases and is sustained by prohibition, as gangs and violent individuals use guns to settle disputes. Closely connected to that is the corruption of the law enforcement profession. That is why there is a group known as Law Enforcement Against Prohibition, LEAP. I've met several of their members and listened to their presentations. It is very powerful, and based upon the historical record regarding that 'noble experiment', the Volstead Act.
Another is the damage caused to the very fabric of society, as men turn in their brothers and mothers to the authorities. Blacks are imprisoned at a very high rate, and as fragile as the black family is, things are made far worse by the prohibition.
The Fourth Amendment has been trashed, civil forfeiture has gone crazy thanks to a counterproductive drug policy, and on and on.
http://www.leap.cc/