A Social Networks Theory of Privacy

What facts are public and what facts are private? It is the fundamental, first-principles question in privacy law, and a necessary element in the two most important privacy torts, public disclosure of private facts and intrusion upon seclusion. Yet the American courts lack a coherent, consistent methodology for determining whether an individual has a reasonable expectation of privacy in a particular fact that he has shared with one or more persons. Some courts hold that when an individual discloses a sensitive fact about himself to a handful of co-workers, friends, relatives, or strangers, this disclosure renders the fact in question sufficiently public to deprive him of a tort cause of action when that fact is subsequently widely disseminated or obtained by a third party using improper means. Other courts hold that an individual can share such a fact with dozens, or even hundreds of people, and still retain a cause of action under privacy tort law. So how much disclosure is enough to transform a private fact into a public fact?