So held a federal district court in Dart v. Craigslist, Inc. Here’s what plaintiff, the Cook County, Illinois, Sheriff claimed:
[Sheriff Dart] ... alleges that the “erotic” (now “adult”) services section of Craigslist’s popular Internet classifieds service facilitates prostitution and constitutes a public nuisance.... The webpage located at “chicago.craigslist.org” ... displays Chicago-related listings arranged by categories (e.g., “for sale” and “services”) and subcategories (e.g., “antiques” and “computer”). Craigslist created the categories, but its users create the content of the ads and select which categories their ads will appear in. Users posting ads on the website agree to abide by Craigslist’s “Terms of Use,” which prohibit posting unlawful content. Users browsing the “erotic” subcategory — which is (or was) the website’s most popular destination — receive an additional “warning & disclaimer” stating that users entering that section agree to “flag ‘prohibited’” any content that violates Craigslist’s Terms of Use including “offers for or the solicitation of prostitution.” Below the warning is a general “erotic services” link, and links to further subcategories (e.g., “w4m” (women for men)). Craigslist also gives users the option to search through ads using a word-search function.Sheriff Dart alleges that, notwithstanding Craigslist’s warnings, users routinely post advertisements in the eroticservices category “openly promis[ing] sex for money.” Based on the samples that he cites in his complaint most of the ads are veiled (sometimes very thinly) using code words.
The court’s reasoning, which seems quite right to me: 47 U.S.C. § 230 generally immunizes Internet service providers from (among other things) being held civilly liable on the grounds that they are “publishers” of material that is supplied by their users. The Seventh Circuit has not read this as broadly as some other courts, but even under the Seventh Circuit’s reading, Craigslist immune because its alleged liability would stem precisely from the fact that it published material provided by its users. “A claim against an online service provider for negligently publishing harmful information created by its users treats the defendant as the ‘publisher’ of that information,” and is therefore preempted by § 230.
The court also considered the Ninth Circuit’s holding in Fair Housing Council v. Roommates.com (discussed here), under which a service provider could be held liable for its own actions in actively inducing people to post illegal content (some paragraph breaks added):
Sheriff Dart insists, on the other hand, that Craigslist plays a more active role than an intermediary or a traditional publisher. He claims that Craigslist causes or induces its users to post unlawful ads — by having an “adult services” category with subsections like “w4m” and by permitting its users to search through the ads “based on their preferences.” “A website operator can be both a service provider and a content provider: If it passively displays content that is created entirely by third parties, then it is only a service provider with respect to that content. But as to content that it creates itself, or is ‘responsible, in whole or in part’ for creating or developing, the website is also a content provider.” Roommates.com. This theory finds some support in Chicago Lawyers [a Seventh Circuit case], which indicated that notwithstanding § 230(c) Craigslist could be held liable for “causing” discriminatory ads if that was in fact what it had done. And we are mindful that whatever the exact parameters of § 230(c)(1) “immunity” are, it is not a “general prohibition of civil liability for web-site operators and other online content hosts.” ... “‘[I]nformation content providers’ may be liable for contributory infringement if their system is designed to help people steal music or other material in copyright.” ... But as the [Seventh Circuit] observed in Chicago Lawyers, “[n]othing in the service craigslist offers induces anyone to post any particular listing.”
We disagree with plaintiff that the “adult services” section is a special case. The phrase “adult,” even in conjunction with “services,” is not unlawful in itself nor does it necessarily call for unlawful content. Cf. Roommates.com (concluding that § 230(c)(1) did not protect a website operator whose roommate-matching service “require[d]” users to answer discriminatory questions from a menu of answers that the defendant supplied). The same is true of the subcategories. Plaintiff is simply wrong when he insists that these terms are all synonyms for illegal sexual services. A woman advertising erotic dancing for male clients (“w4m”) is offering an “adult service,” yet this is not prostitution. It may even be entitled to some limited protection under the First Amendment.
Plaintiff’s argument that Craigslist causes or induces illegal content is further undercut by the fact that Craigslist repeatedly warns users not to post such content. While we accept as true for the 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. Or if it has, it is only “in the sense that no one could post [unlawful content] if craigslist did not offer a forum.” Section 230(c)(1) would serve little if any purpose if companies like Craigslist were found liable under state law for “causing” or “inducing” users to post unlawful content in this fashion.
The fact that Craigslist also provides a wordsearch function does not change the analysis. The word-search function is a “neutral tool” that permits users to search for terms that they select in ads created by other users. It does not cause or induce anyone to create, post, or search for illegal content.

“Craigslist Not Responsible for Sex-For-Hire Ads, Judge Rules” says:
[...] The grandstanding sheriff of Cook County, Ill. is thrown out of court. More: Eugene Volokh. [...]
d-berg says:
How is this different from escort services in yellow book? Thinly veiled, yet legal.
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October 23, 2009, 2:08 pmSoronel Haetir says:
I would make the argument that with 320 behind the online publisher even the veiling isn’t needed for cl to be in the clear. The county is of course free to go after the people making illegal offers. And I would expect the courts to require cl to provide whatever pertinent records exist. None of that speaks to cl itself being liable.
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October 23, 2009, 2:28 pmJimbino says:
So, in looking for roommates, if I really want to discriminate against families with children without running afoul of the law, may I post that I am a “sex offender,” a “potential sex offender,” or that “sex offenders welcome to apply,” or that the house is run on a “clothing-optional” basis, or that the house will maintain an atmosphere of “free sex”?
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October 23, 2009, 3:40 pmEugene Volokh says:
Jimbino: You’re asking what the advertiser may himself do, a question that relates to the scope of antidiscrimination law. That’s separate from the question of when a service provider is immune from liability regardless of whether its users’ posts violate the law.
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October 23, 2009, 3:42 pmJimbino says:
What is it that would keep Al Qaeda from posting on Craigslist an invitation to help assassinate Obama, or to help harvest poppies for the Cause?
I assume that Craigslist could, under the prevailing law, choose to delete those solicitations.
Then what keeps Al Qaeda from starting an Al-Craigslist and refrain from editing anything that appears?
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October 23, 2009, 3:53 pmNickM says:
Jimbino — would al-Craigslist have an erotic services section with pictures?
Nick
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October 23, 2009, 6:08 pmUnderTheSun says:
Only if they are of burqas.
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October 23, 2009, 7:01 pmRyan Waxx says:
Mmmm, just look at the shape of that burlap...
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October 23, 2009, 8:20 pmAnthony says:
Presumably, lack of desire to be found and arrested. This prevents Craigslist from being prosecuted, but has no effect on the person who places the ad.
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October 23, 2009, 8:29 pmJimbino says:
Anthony,
The person who places the ad is in Pakistan or Afghanistan, places to which the overstretched arm of Amerikan law does not yet reach. But it seems there is nothing to stop them from founding and funding Al-Craigslist and to continue to pursue aims both legal and illegal in the posts, like specifying that you don’t want a roommate who is a breeder.
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October 23, 2009, 11:07 pmweeklyrob » Some News and Such says:
[...] ** Craigslist isn’t liable for prostitution ads. [...]
Ricardo says:
If the people placing these ads are in Pakistan or Afghanistan, chances are they are placing the ads on servers located in places also outside the arm of “Amerikan law.” Indeed, they would be stupid for doing otherwise. If the server is located within the U.S., the alphabet soup of federal agencies would have the IP address of the ad-placer before breakfast the next morning.
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October 24, 2009, 12:48 amTaxThePoor? says:
REALLY sad that Barack Obama would endorse someone like Tom Dart mulitple times when the guy obviously could care less about civil rights. How many idiots has Barack Obama endorsed, by the way? Lets see Lisa Madigan lost Lee v. Keith and won Cabballes v Illinois, and Barack Obama endorsed her after those. Sheeesh. Our President is a real doofus when it comes to his judgment on which politicians care about civil rights and our Constitution. I think he only studied the Constitution to figure out how to make it even more irrelevant. Sad.
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October 24, 2009, 2:22 pmCraigslist, Please Pass the Ass « The New Print says:
[...] Please Pass the Ass 2009 October 24 by slickricks Note to would-be netrepreneurs: if you want to avoid being sued, don’t do anything (the Craigslist way). If you are simply a passive conduit, it is quite possible that you [...]
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