The government is increasingly monitoring Facebook, Twitter and other social networking sites for tax delinquents, copyright infringers and political protesters. A public interest group has filed a lawsuit to learn more about this monitoring, in the hope of starting a national discussion and modifying privacy laws as necessary for the online era.

Law enforcement is not saying a lot about its social surveillance, but examples keep coming to light. The Wall Street Journal reported this summer that state revenue agents have been searching for tax scofflaws by mining information on MySpace and Facebook. In October, the F.B.I. searched the New York home of a man suspected of helping coordinate protests at the Group of 20 meeting in Pittsburgh by sending out messages over Twitter.

In some cases, the government appears to be engaged in deception. The Boston Globe recently quoted a Massachusetts district attorney as saying that some police officers were going undercover on Facebook as part of their investigations.

Wired magazine reported last month that In-Q-Tel, an investment arm of the Central Intelligence Agency, has put money into Visible Technologies, a software company that crawls across blogs, online forums, and open networks like Twitter and YouTube to monitor what is being said.

This month the Electronic Frontier Foundation and the Samuelson Law, Technology and Public Policy Clinic at the University of California, Berkeley, School of Law sued the Department of Defense, the C.I.A. and other federal agencies under the Freedom of Information Act to learn more about their use of social networking sites.

The suit seeks to uncover what guidelines these agencies have about this activity, including information about whether agents are permitted to use fake identities or to engage in subterfuge, such as tricking people into accepting Facebook friend requests.

Privacy law was largely created in the pre-Internet age, and new rules are needed to keep up with the ways people communicate today. Much of what occurs online, like blog posting, is intended to be an open declaration to the world, and law enforcement is within its rights to read and act on what is written. Other kinds of communication, particularly in a closed network, may come with an expectation of privacy. If government agents are joining social networks under false pretenses to spy without a court order, for example, that might be crossing a line.

A national conversation about social networking and other forms of online privacy is long overdue. The first step toward having it is for the public to know more about what is currently being done. Making the federal government answer these reasonable Freedom of Information Act requests would be a good start.

http://www.nytimes.com/2009/12/13/opinion/13sun2.html?_r=1&1