Law enforcement agencies got text messages and caller location (GPS data) 1.3 million times in 2011, which was the first public report of such information. The New York Times reported that a request from US Congress led to this public disclosure. The New York Times reported that:
AT&T alone now responds to an average of more than 700 requests a day, with about 230 of them regarded as emergencies that do not require the normal court orders and subpoena. That is roughly triple the number it fielded in 2007, the company said.
The New York Times article went to say that search warrants are not always obtained:
Under federal law, the carriers said they generally required a search warrant, a court order or a formal subpoena to release information about a subscriber. But in cases that law enforcement officials deem an emergency, a less formal request is often enough. Moreover, rapid technological changes in cellphones have blurred the lines on what is legally required to get data — particularly the use of GPS systems to identify the location of phones.
An important message about the cell data is that we will likely see more challenges to personal privacy in civil litigation over the use of text messages and GPS location, even though based on this report to Congress, criminal prosecutors are using text messages and GPS location quite freely.