The U.S. Justice Department used some of its most intrusive tactics against former New York Gov. Eliot Spitzer, examining his financial records, eavesdropping on his phone calls, and tailing him during its investigation of the Emperor's Club prostitution ring, says the New York Times. A review of cases shows that federal prosecutors go sparingly after owners and operators of prostitution enterprises, and usually only when millions of dollars are involved or there are aggravating circumstances, like human trafficking or child exploitation. U.S. officials defend the expenditure of resources on Spitzer as necessary because it involved the possibility of criminal wrongdoing by New York's highest elected official, who had been the state's top prosecutor.
Government officials who were not identified by the Times said was no alternative but to look into Spitzer's activities once investigators began examining reports of suspicious transactions that banks filed with the Treasury Department. The FBI has 450 active prostitution cases under investigation, almost all involving enterprises and some using techniques like wiretapping. The department has rarely, if ever, prosecuted or even identified the clients of a prostitution ring.
Link: http://www.nytimes.com/2008/03/21/nyregion/21justice.html?_r=1&hp&oref=slogin