The explosion of online social networking shows little sign of slowing. For example, Facebook (as accessed on June 15, 2010) reports that it alone has more than 400 million active users, 50 percent of whom log onto the site on any given day. Facebook states that its average user has 130 online “friends,” and that such a user creates 70 pieces of content (Web links, news stories, blog posts, notes, photographs, etc.) each month. And the use of such resources is not tethered to a desktop PC: Facebook relates that more than 100 million active users currently access the system through their mobile devices.

Such remarkable growth brings challenges for the operators of social networking sites. The news media is replete with reports of alleged transgressions, most notably in the context of issues regarding the privacy rights of users. But what about the potential legal liabilities of the hundreds of millions of individuals and entities that post content and otherwise contribute to social networking sites? As was the case in the early days of e-mail, the inherent informality of the medium may cause some to believe that there is greater latitude to say or do things than in more formal contexts, but that is a trap. The reality is that those who join social networking sites and disseminate information and materials run the risk of being held responsible to others as a “publisher” and for a broad range of claims based on traditional legal principles.