What impact did legalizing prostitution have on other crimes?
Obviously one doesn't want to make much of what happens in one state with a one time experiment, but the drop in rape rates there are at least suggestive. The graph above at least suggests that the rape rates fell in Rhode Island relative to the rest of the US after prostitution was legalized in 2003 (I wish that I could find exactly when in 2003 this happened).
All forms of prostitution were illegal in the state until 1980, when legislators -- while amending the existing law to speed up prosecution -- inadvertently deleted the section that addressed the actual act of prostitution. The result was that the only thing that remained illegal was street solicitation, since police mostly use anti-loitering laws to arrest streetwalkers.
This legal loophole went unnoticed and police weren't thwarted until 2003, when Providence lawyer Michael Kiselica was representing sex workers in a case before the state district court here. He acknowledged to a Providence city prosecutor that the women had offered sex for money to undercover police but asserted no state law was broken. The case was dismissed.
State legislators have tried to restore the law for years, but fell short in the face of opposition by some lawmakers, civil libertarians and academics, who said that allowing the arrest of prostitutes could end up punishing victims of human trafficking. . . .
The new momentum is partly a response to the so-called Craigslist killing. Medical student Philip Markoff was indicted in Massachusetts in June on charges of killing a woman at an upscale Boston hotel who had advertised on the "exotic services" section of Craigslist. Rhode Island officials also charged Mr. Markoff with assault and intent to commit robbery of a stripper he had arranged to meet at a hotel in the state. . . . .
The rape rate also fell faster than either the violent or property crime rates in Rhode Island, though the effect is much more obvious compared to violent crime. With property crime there was already a similar downward trend before the change up to 2002.