Law enforcement tracking of cellphones, once the province mainly of federal agents, has become a powerful and widely used surveillance tool for local police officials, with hundreds of departments, large and small, often using it aggressively with little or no court oversight, documents show.
The practice has become big business for cellphone companies, too, with a handful of carriers marketing a catalog of “surveillance fees” to police departments to determine a suspect’s location, trace phone calls and texts or provide other services. Some departments log dozens of traces a month for both emergencies and routine investigations.
With cellphones ubiquitous, the police call phone tracing a valuable weapon in emergencies like child abductions and suicide calls and investigations in drug cases and murders. One police training manual describes cellphones as “the virtual biographer of our daily activities,” providing a hunting ground for learning contacts and travels.
But civil liberties advocates say the wider use of cell tracking raises legal and constitutional questions, particularly when the police act without judicial orders. While many departments require warrants to use phone tracking in nonemergencies, others claim broad discretion to get the records on their own, according to 5,500 pages of internal records obtained by the American Civil Liberties Union from 205 police departments nationwide.
The internal documents, which were provided to The New York Times, open a window into a cloak-and-dagger practice that police officials are wary about discussing publicly. While cell tracking by local police departments has received some limited public attention in the last few years, the A.C.L.U. documents show that the practice is in much wider use — with far looser safeguards — than officials have previously acknowledged.
The issue has taken on new legal urgency in light of a Supreme Court ruling in January finding that a Global Positioning System tracking device placed on a drug suspect’s car violated his Fourth Amendment rights against unreasonable searches. While the ruling did not directly involve cellphones — many of which also include GPS locators — it raised questions about the standards for cellphone tracking, lawyers say.
The police records show many departments struggling to understand and abide by the legal complexities of cellphone tracking, even as they work to exploit the technology.
In cities in Nevada, North Carolina and other states, police departments have gotten wireless carriers to track cellphone signals back to cell towers as part of nonemergency investigations to identify all the callers using a particular tower, records show.
In California, state prosecutors advised local police departments on ways to get carriers to “clone” a phone and download text messages while it is turned off...