Two years ago, when the FBI was stymied by a band of armed robbers known as
the "Scarecrow Bandits" that had robbed more than 20 Texas
banks, it came up with a novel method of locating the thieves.
FBI agents obtained logs from mobile phone companies corresponding to what their cellular towers had recorded at the time of a dozen different bank robberies in the Dallas area. The voluminous
records showed that two phones had made calls around the time of all 12
heists, and that those phones belonged to men named Tony Hewitt and
Corey Duffey. A jury eventually convicted the duo of multiple bank robbery and weapons charges.
Even though police are tapping into the locations of mobile phones thousands of times a year, the legal ground rules remain unclear, and
federal privacy laws written a generation ago are ambiguous at best. On
Friday, the first federal appeals court to consider the topic will hear
oral arguments (PDF) in a case that could establish new standards for locating wireless devices.
In that case, the Obama administration has argued that warrantless tracking is permitted because Americans enjoy no "reasonable
expectation of privacy" in their--or at least their cell
phones'--whereabouts. U.S. Department of Justice lawyers say that "a
customer's Fourth Amendment rights are not violated when the phone
company reveals to the government its own records" that show where a
mobile device placed and received calls.
Those claims have alarmed the ACLU and other civil liberties groups, which have opposed the Justice Department's request and plan to
tell the U.S. Third Circuit Court of Appeals in Philadelphia that
Americans' privacy deserves more protection and judicial oversight than
what the administration has proposed.
"This is a critical question for privacy in the 21st century," says Kevin Bankston, an attorney at the Electronic Frontier Foundation who will be arguing on Friday. "If the courts do side with the
government, that means that everywhere we go, in the real world and
online, will be an open book to the government unprotected by the
Not long ago, the concept of tracking cell phones would have been the stuff of spy movies. In 1998's "Enemy of the State," Gene Hackman warned that the National Security Agency has "been in bed with
the entire telecommunications industry since the '40s--they've infected
everything." After a decade of appearances in "24" and "Live Free or
Die Hard," location-tracking has become such a trope that it was
satirized in a scene with Seth Rogen from "Pineapple Express" (2008).
Once a Hollywood plot, now 'commonplace'
Whether state and federal police have been paying attention to Hollywood, or whether it
was the other way around, cell phone tracking has become a regular
feature in criminal investigations. It comes in two forms: police
obtaining retrospective data kept by mobile providers for their own billing purposes that may not be very detailed, or prospective data that reveals the minute-by-minute location of a handset or mobile device.
Gidari says that the Third Circuit case could have a significant impact on police investigations within the court's jurisdiction, namely
Delaware, New Jersey, and Pennsylvania; it could be persuasive beyond
those states. But, he cautions, "if the privacy groups win, the case
won't be over. It will certainly be appealed."
CNET was the first to report on prospective tracking in a 2005 news article. In a subsequent Arizona case, agents from the Drug Enforcement
Administration tracked a tractor trailer with a drug shipment through a
GPS-equipped Nextel phone owned by the suspect. Texas DEA agents have
used cell site information in real time to locate a Chrysler 300M
driving from Rio Grande City to a ranch about 50 miles away. Verizon
Wireless and T-Mobile logs showing the location of mobile phones at the
time calls became evidence in a Los Angeles murder trial.
And a mobile phone's fleeting connection with a remote cell tower operated by Edge Wireless is what led searchers to the family of the late James Kim, a CNET employee who died
in the Oregon wilderness in 2006 after leaving a snowbound car to seek help.
The way tracking works is simple: mobile phones are miniature radio transmitters and receivers. A cellular tower knows the general
direction of a mobile phone (many cell sites have three antennas
pointing in different directions), and if the phone is talking to
multiple towers, triangulation yields a rough location fix. With this
method, accuracy depends in part on the density of cell sites.
The Federal Communications Commission's "Enhanced 911" (E911) requirements allowed rough estimates to be transformed into
precise coordinates. Wireless carriers using CDMA networks, such as
Verizon Wireless and Sprint Nextel, tend to use embedded GPS technology
to fulfill E911 requirements. AT&T and T-Mobile comply with E911
regulations using network-based technology that computes a phone's
location using signal analysis and triangulation between towers.
T-Mobile, for instance, uses a GSM technology called Uplink Time Difference of Arrival, or U-TDOA, which calculates a position based on precisely how long it
takes signals to reach towers. A company called TruePosition, which
provides U-TDOA services to T-Mobile, boasts of "accuracy to under 50
meters" that's available "for start-of-call, midcall, or when idle."
A 2008 court order to T-Mobile in a criminal investigation of a marriage fraud scheme,
which was originally sealed and later made public, says: "T-Mobile
shall disclose at such intervals and times as directed by (the
Department of Homeland Security), latitude and longitude data that
establishes the approximate positions of the Subject Wireless
Telephone, by unobtrusively initiating a signal on its network that
will enable it to determine the locations of the Subject Wireless
'No reasonable expectation of privacy'
In the case that's before the Third Circuit on Friday, the Bureau of Alcohol, Tobacco,
Firearms and Explosives, or ATF, said it needed historical (meaning
stored, not future) phone location information because a set of
suspects "use their wireless telephones to arrange meetings and
transactions in furtherance of their drug trafficking activities."
U.S. Magistrate Judge Lisa Lenihan in Pennsylvania denied the Justice Department's attempt to obtain stored location data without a
search warrant; prosecutors had invoked a different legal procedure.
Lenihan's ruling, in effect, would require police to obtain a search
warrant based on probable cause--a more privacy-protective standard.
Lenihan's opinion (PDF)--which, in an unusual show of solidarity, was signed by four other magistrate
judges--noted that location information can reveal sensitive
information such as health treatments, financial difficulties, marital
counseling, and extra-marital affairs.
In its appeal to the Third Circuit, the Justice Department claims that Lenihan's opinion "contains, and relies upon, numerous errors" and should be overruled. In addition to a search warrant not
being necessary, prosecutors said, because location "records provide
only a very general indication of a user's whereabouts at certain times
in the past, the requested cell-site records do not implicate a Fourth
Amendment privacy interest."
The Obama administration is not alone in making this argument. U.S. District Judge William Pauley, a Clinton appointee in New York, wrote in a 2009 opinion that a
defendant in a drug trafficking case, Jose Navas, "did not have a
legitimate expectation of privacy in the cell phone" location. That's
because Navas only used the cell phone "on public thoroughfares en
route from California to New York" and "if Navas intended to keep the
cell phone's location private, he simply could have turned it off."
(Most cases have involved the ground rules for tracking cell phone users prospectively, and judges have disagreed over what legal rules apply. Only a minority has sided with the Justice Department, however.)
Cellular providers tend not to retain moment-by-moment logs of when each mobile device contacts the tower, in part because there's no
business reason to store the data, and in part because the storage
costs would be prohibitive. They do, however, keep records of what
tower is in use when a call is initiated or answered--and those records
are generally stored for six months to a year, depending on the
Verizon Wireless keeps "phone records including cell site location for 12 months," Drew Arena, Verizon's vice president and associate general counsel for law enforcement compliance, said at a federal task force meeting
in Washington, D.C. last week. Arena said the company keeps "phone
bills without cell site location for seven years," and stores SMS text
messages for only a very brief time.
Gidari, the Seattle attorney, said that wireless carriers have recently extended how long they store this information. "Prior to a
year or two ago when location-based services became more common, if it
were 30 days it would be surprising," he said.
The ACLU, EFF, the Center for Democracy and Technology, and University of San Francisco law professor Susan Freiwald argue that the wording of the federal privacy law in question allows
judges to require the level of proof required for a search warrant
"before authorizing the disclosure of particularly novel or invasive
types of information." In addition, they say, Americans do not
"knowingly expose their location information and thereby surrender
Fourth Amendment protection whenever they turn on or use their cell
"The biggest issue at stake is whether or not courts are going to accept the government's minimal view of what is protected by the
Fourth Amendment," says EFF's Bankston. "The government is arguing that
based on precedents from the 1970s, any record held by a third party
about us, no matter how invasively collected, is not protected by the