"Police increasingly peeping at e-mail, instant messages":

Law enforcement organizations are making tens of thousands of requests for private electronic information from companies such as Sprint, Facebook and AOL, but few detailed statistics are available, according to a privacy researcher.

Police and other agencies have "enthusiastically embraced" asking for e-mail, instant messages and mobile-phone location data, but there's no U.S. federal law that requires the reporting of requests for stored communications data, wrote Christopher Soghoian, a doctoral candidate at the School of Informatics and Computing at Indiana University, in a newly published paper...

That's in contrast to traditional wiretaps and "pen registers," which record non-content data around a particular communication, such as the number dialed or e-mail address that a communication was sent to. The U.S. Congress mandates that it should receive reports on these requests, which are compiled by the Administrative Office of the U.S. Courts, Soghoian wrote.