Update: The Cook County Sheriff's Department is asking a federal judge to close the Erotic Services section of Craigslist, as well as reimburse the department $100,000 it has cost to pursue Craigslist-related prostitution investigations over the past year, according to the�Chicago Tribune.

Original Story:

The Cook County Sheriff's Department in Chicago has announced that it plans to sue Craigslist because it facilitates prostitution. Cook County Sheriff Thomas Dart said that he and the police have made dozens of arrests of people who have been involved in prostitution over Craigslist over the years, and referred to the site as "the single largest source of prostitution in the nation."

Details of the lawsuit are not yet available, though Dart held a press conference in Chicago this afternoon to announce the lawsuit. The sheriff's police arrested 76 men and women in June of 2008 on prostitution-related charges thanks to a Craigslist sting. In December of 2007, four Chicago men were charged with running a prostitution ring over Craigslist that employed girls as young as 15.

Law enforcement has long criticized the popular classifieds site for facilitating prostitution, due largely to the "Erotic Services" section on the site that doesn't try to hide what it's meant for. Craigslist makes it easy for prostitutes to make fairly anonymous listings while still generating interest. Critics point out that prostitution is illegal almost everywhere in the US, adding that it's all too easy for those exploiting children to traffic them on Craigslist, making it not only morally reprehensible, but also dangerous for kids.

Craigslist acknowledged these criticisms this past November when the company decided to impose a number of restrictions on its red-light district. As part of an agreement with the National Center for Missing and Exploited Children (NCMEC) and the Attorneys General of 40 states, the company implemented a phone verification system for listings in the Erotic Services section, which requires anyone who is listing an ad there to post a real number that will be called before the posting goes live. This not only thwarts sex-themed spammers, but also allows Craigslist to blacklist phone numbers of those who post "inappropriate" ads. Craigslist also imposed listing fees on those who post in Erotic Services (which were previously free), forcing those who want to post to provide a credit card number.

Craigslist claimed that the phone system and the fees have reduced ad volume in Erotic Services by 80 percent and increased compliance with the site's Terms of Service, though some believe that isn't enough. Sheriff Dart wants to go after the other 20 percent with his lawsuit, which asks for the closure of the Erotic Services section of the site. As long as the Erotic Services section exists, there will be people who assume this is the only way prostitutes manage to hawk their wares on the site.

This isn't true in the slightest, of course; those who use Craigslist for this purpose already have special code words to communicate who they are and how much they want, along with prepaid phone numbers and other measures for conducting business. And they don't only post in Erotic Services, either—part of the reason Erotic Services exists in the first place is to get them to stop posting in the dating sections of the site, though many still do. Needless to say, if Erotic Services were to go away, prostitutes would merely filter back into other sections of the site, making them even less detectable by law enforcement than before.

Craigslist, for its part, claims that it's doing everything it can to prevent illegal activity from appearing on the site. "We have not yet seen the complaint issued by the Cook County Sheriff," a Craigslist spokesperson told Ars, but "misuse of Craigslist to facilitate criminal activity is unacceptable, and we continue to work diligently to prevent it. Misuse of the site is exceptionally rare compared to how much the site is used for legal purposes. Regardless, any misuse of the site is not tolerated on Craigslist."