Remember all the hoopla earlier this year when attorneys general from several states were getting bent out of shape over craigslist's erotic services ads? A sideline to that story was a lawsuit that had been filed in March against craigslist by the Cook County Sheriff in Chicago.

The suit said craigslist's erotic services ads were creating "a public nuisance." Filed by Sheriff Thomas Dart, the suit sought both to bar the site from running such ads and to recoup prostitution-related law enforcement costs.

Yesterday, a federal court in Illinois threw out the complaint, asserting that "intermediaries are not culpable for 'aiding and abetting' their customers who misuse their service to commit unlawful acts."

"The phrase 'adult,' even in conjunction with 'services,' is not unlawful in and of itself nor does it necessarily call for unlawful content," says the decision.

"While we accept as true for purposes of this motion plaintiff's allegation that users routinely flout Craigslist's guidelines, it is not because Craigslist has caused them to do so," the court ruled.

Interestingly, unlike during the attorneys general fracas, when craigslist CEO Jim Buckmaster had plenty to say, today's post on the craigslist blog is quite tame. It simply announces the judge's decision and points to an analysis of the case on the Electronic Frontier Foundation's blog.

More on the motivation behind the Cook County Sheriff's suit, after the jump.

The Cook County suit focused largely on the financial costs of prosecuting prostitution solicited via the Web site.

"Prostitution arrests in Cook County via Craigslist are incessant," the original complaint read. "Arrests consume time, money, and resources of law enforcement agencies. This civil action seeks damages, abatement costs, and injunctive relief to remedy Defendant's creation of and contribution to a public nuisance in Cook County."

The complaint described how the Sheriff's office uses craigslist to set up stings. It said 200 people had been arrested in the previous two years from encounters arranged via the site.

But, it said, "the sheer number of daily postings has made it impossible to stymie Craigslist generated prostitution."

The complaint estimated that the Sheriff's office had spent $105,081 on craigslist-enabled prostitution busts between January and November of 2008.

Those arguing on craigslist's behalf have said that the site is protected by the Communication Decency Act, which says Web sites are not responsible for material posted by third parties.

"Sheriff Dart may continue to use Craigslist's website to identify and pursue individuals who post allegedly unlawful content," said Judge John Grady of the U.S. District Court, Northern District of Illinois, in the decision. "But he cannot sue Craigslist for their conduct."