The Sheriff of Cook County sued Craigslist arguing that the site's "adult" or "erotic" services section facilitated prostitution and created a public nuisance. The sheriff argued that "Craigslist plays a more active role than an intermediary or a traditional publisher... [because it] causes or induces its users to post unlawful ads-by having an 'adult services' category" and enables users to search by sexual preference. But the court held that Craigslist did not cause or induce illegal conduct: erotic services could include lawful speech protected by the First Amendment and the section featured warnings not to post prostitution-related ads. CDA § 230 therefore barred the sheriff's claims.