Wiretaps, which have increased almost tenfold since data was first reported in 1969, are only the tip of the surveillance iceberg. In 2011 federal and state courts approved a total of 2,732 wiretaps; but government agencies made over 1.3m requests for data to mobile-phone companies. That figure includes wiretaps and pen/traps, but it also includes requests for stored text messages, device locations and tower dumps, which reveal the presence of everyone—suspects and not—within range of a particular mobile-phone tower at a particular time. Most of these requests require no warrants at all. Sometimes all it takes is a subpoena from a prosecutor.
Internet companies have also seen a sharp rise in requests from law-enforcement agencies for information about their users. Between July and December 2010 Google received 4,601 requests; in the same period last year that number jumped to 6,321. Among the things that Google is typically asked for are account information and location data. Twitter, a microblogging service, received 679 requests from American authorities for information about users in the first half of this year, which is more than it got in all of 2011. The firm says it complied with three-quarters of these requests, though it does not say whether it handed over all or simply a fraction of the information requested in each case. Google, which says it complied with 93% of the requests from American officials in its most recent reporting period, is similarly vague about what it coughs up.