Craigslist critics: Site's size gives it 'unique' sex trade role; House Judiciary to consider

Part of the complexity with targeting Craigslist is that many other online forums, from review websites such as Yelp to any general comment board, also face challenges when their users decide to break the law and write about it online.

But Craigslist's critics hold that its fair to single out the site because problems are "very unique to Craigslist more so than other, more obscure sites that are less-known," as Bradley Myles, executive director of the Polaris Project, put it. Polaris works against human trafficking. "There's almost this effect where Craigslist begins contributing to the ease of access and the normative behavior," he said. 

The advocates added that smaller sites should also be conscientious about illegal services mentioned on their sites. The campaign against Craigslist is aimed at making it "less convenient and less normative to buy a child online for sex," Saar said.

Some analysts say Craigslist is targeted for its size — and not for some unique tolerance of illegal behavior. “Craigslist is an easy and prominent target, but the legal protections that have ensured its success are what also protect all other Internet businesses operating in America," said Thomas Burke, an attorney at Davis Wright Tremaine.

Advocates are pleased that Craigslist recently removed its adult services section, but they want the company to do the same on its international pages. They said they have not seen strong evidence that the illegal ads have simply popped up on other parts of the site, suggesting that blocking the adult services section could help mitigate illegal activities.

Craigslist has faced pressure from advocacy groups, lawmakers and a coalition of attorneys general who hold that the “adult services” section abets child trafficking and prostitution.

The site blocked the section on Friday, replacing it with the word "censored," an unusual move that has raised questions about whether the company will permanently do away with the section or whether it is simply making a political statement. Lawmakers who have pressured the company were not convinced Craigslist had reversed its previous positions.