The Virginia Defamation Law Blog
Worried about liability for statements made by others in an online forum hosted by your website? Provided you don’t take an active role in editing the content posted by others, you shouldn’t have to worry about defamation liability. The Communications Decency Act (“CDA”), found at 47 U.S.C. § 230, provides that “No provider or user of an interactive computer service shall be treated as the publisher or speaker of any information provided by another information content provider.” It further provides that “No cause of action may be brought and no liability may be imposed under any State or local law that is inconsistent with this section.”
In the still-pending case of Cornelius v. DeLuca, filed in the Eastern District of Missouri, the plaintiffs, sellers of a dietary supplement called “Syntrax,” sued various competitors for libel and tortious interference with business expectancies, and also sued the owners of bodybuilding.com–a website containing a forum for Internet discussion by the public–for supposedly assisting the other defendants post false and defamatory statements to the forum. In essence, the plaintiffs tried to get around the CDA by claiming the host of the forum wasn’t a mere “provider” but an active participant in a conspiracy to post libelous, defamatory statements concerning the plaintiff’s product. The court rejected the argument and dismissed the conspiracy count.
Under the CDA, while content providers cannot be held liable for the statements of others, they can be held liable for their own statements (which is why providers need to be careful not to edit others’ statements, thereby arguably adopting the statement as 
their own). It is undoubtedly for this reason that the plaintiffs, realizing full well that the owners of bodybuilding.com did not make the statements at issue themselves, alleged that the owners conspired with the actual authors to allow the statements to be posted.