Fair Housing Council of San Fernando Valley v. Roommates.com, LLC, 521 F.3d 1157 (9th Cir. 2008)
In an en banc decision, the Ninth Circuit held that Roommates.com could not claim immunity under CDA § 230 where as a condition of use, it required users to choose among set answers to questions that violated anti-discrimination laws. These questions asked for users' preferences in sex, sexual orientation, and family status of a future roommate, allegedly in violation of the Fair Housing Act. The court found that by requiring these answers, the website was affirmatively "inducing third parties to express illegal preferences," making the site akin to a "co-developer" of the content. By contrast, a website could preserve its immunity if it offered users "neutral tools"—such as a general comment field where users could enter criteria or preferences in a roommate. (In a subsequent appeal, the Ninth Circuit found that the questions did not violate the Fair Housing Act.)
[P]roviding neutral tools to carry out what may be unlawful or illicit searches does not amount to 'development' for purposes of the immunity exception."
Providing neutral tools for navigating websites is fully protected by CDA immunity, absent substantial affirmative conduct on the part of the website creator promoting the use of such tools for unlawful purposes.
The salient fact in Carafano was that the website's classifications of user characteristics did absolutely nothing to enhance the defamatory sting of the message, to encourage defamation or to make defamation easier: The site provided neutral tools specifically designed to match romantic partners depending on their voluntary inputs. By sharp contrast, Roommate's website is designed to force subscribers to divulge protected characteristics and discriminatory preferences
By requiring subscribers to provide the [unlawful preference] information as a condition of accessing its service, and by providing a limited set of pre-populated answers, Roommate becomes much more than a passive transmitter of information provided by others; it becomes the developer, at least in part, of that information.
[O]rdinary search engines do not use unlawful criteria to limit the scope of searches conducted on them, nor are they designed to achieve illegal ends-as Roommate's search function is alleged to do here.