Washington DC's gun ban (1976) prohibited anyone other than law-enforcement officers from carrying a firearm in the city. Residents were even barred from keeping guns in their homes for self-defense. The gun ban had an unintended effect: It emboldened criminals because they knew that law-abiding District residents were unarmed and powerless to defend themselves. Violent crime increased after the law was enacted, with homicides rising to 369 in 1988, from 188 in 1976 when the ban started. By 1993, annual homicides had reached 454.
Declared unconstitutional, gun ban was struck down, and murders in the District have steadily gone down, from 186 in 2008 to 88 in 2012, less than half the number in 1976.