The Platform for Privacy Preferences Project, or P3P, involves browser technology that allows a user to set privacy conditions and state what personal information may be seen by websites. Websites usuing P3P are supposed to respect the user’s settings. Heralded as a privacy enhancing technology when the World Wide Web Consortium recommended it in 2002, adoption of the automated tool, it has never caught on and the vast majority of consumers don’t use it.
Nevertheless, a just-released study by Pedro Giovanni Leon, Lorrie Faith Cranor, Aleecia M. McDonald and Robert McGuire of the Carnegie Mellon Cy Lab has concluded that large numbers of websites are misrepresenting their P3P privacy practices, "thus misleading users and rendering privacy protection tools ineffective." From the Abstract:
Just as a recent University of California-Berkeley study about flash cookies and privacy prompted a series of lawsuits recently against Quantcast and Clearspring and users of their technology, there is speculation that the Carnegie Mellon study may inspire new lawsuits and investigations. The websites using P3P compact policies are not without their defenses however, so it remains to be seen whether the study serves as a sturdy "platform for plaintiffs’ preferences."