Police push to continue warrantless cell tracking

A law requiring police to obtain a search warrant before tracking Americans' cell phones may imperil criminal investigations and endanger children's lives, a law enforcement representative told Congress this week.

Obtaining a search warrant when monitoring the whereabouts of someone "who may be attempting to victimize a child over the Internet will have a significant slowing effect on the processing of child exploitation leads," said Richard Littlehale of the Tennessee Bureau of Investigation. "If that is acceptable, so be it, but it is a downstream effect that must be considered."

Littlehale's remarks to a House of Representatives subcommittee come as an industry group called the Digital Due Process coalition is prodding politicians to update a mid-1980s federal law by inserting more privacy protections. The group includes Google, Microsoft, eBay, AT&T, the ACLU, and Americans for Tax Reform.

Legislation has not yet been introduced, and coalition members have braced themselves for an extended period of negotiations among police, civil libertarians, and members of Congress that could take as long as a year or two. Meanwhile, no federal appeals court has ruled on the topic--a case is pending before one in Philadelphia--and lower courts have split over whether the U.S. Constitution requires a warrant or not.

But if law enforcement defends the idea of warrantless tracking, the coalition's task will become more complicated. It took the better part of a decade for an alliance of privacy advocates and industry representatives to surmount stiff opposition from the FBI and intelligence agencies that loathed the idea of readily available strong encryption software.

The Obama administration has argued that no search warrants are needed to track cell phone locations; it has told judges that a 2703(d) order, which requires law enforcement to show that the records are "relevant and material to an ongoing criminal investigation," is sufficient. Because it's easier to obtain than a search warrant, a 2703(d) order is also less privacy-protective.

A U.S. Department of Justice representative told CNET on Friday afternoon that the legislative office would not be able to answer questions until next week.

Littlehale, an agent in the bureau's Technical Services Unit, told the House Judiciary subcommittee on civil liberties that a recent Tennessee case involving a kidnapped four-day-old infant would have turned out differently if police were required to request a warrant from a judge. "When you are talking about that volume of process," he said, "any change in the type of process required will have an impact on how rapidly law enforcement can process leads and resolve the case, and in a case of this type, every minute counts."

"The time required to generate a search warrant and have it signed, even in cases where probable cause exists, may in and of itself hamper law enforcement's efforts to move quickly in an investigation," Littlehale said.

Rep. Rick Boucher, a Democrat from rural Virginia, circulated draft legislation (PDF) last month that takes a small step toward preserving location privacy. It says that call location information can be shared with police under a limited set of circumstances--but does not explicitly require a search warrant signed by a judge.

CNET was the first to report on the controversy over location 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 car 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 were made became evidence in a Los Angeles murder trial.

And a case currently being argued before a Connecticut federal judge shows that the FBI monitored the whereabouts of about 180 cell phones--without a warrant--while conducting surveillance of two men suspected of robbing local banks.

To locate customers, Sprint and other mobile providers that have built their networks on CDMA technology use a handset-based technique relying on GPS or assisted GPS. AT&T and other companies that have adopted GSM, on the other hand, use a network-based technique known as Uplink-Time-Difference of Arrival that estimates the device's location based on the exact moment that radio transmissions from cell towers arrive.

Such pinpoint accuracy requires special hardware called a Location Measurement Unit, or LMU. Michael Amarosa, vice president of wireless location firm TruePosition, told the House panel that his company has installed more than 100,000 of them.

A handset can communicate with dozens of LMUs, Amarosa said. "A minimum of three LMUs must receive the handset's signal to uniquely determine the location of it. Reception of the handset by more than three LMUs also enhances the accuracy of the location estimated," he said.

Probably the most interesting testimony, though, came from U.S. Magistrate Judge Stephen Smith from Texas, who ruled in 2005 that the Fourth Amendment requires that cell tracking orders be signed by a judge who has probable cause to believe that a crime is being committed.

It's unusual for a currently serving judge to show up before Congress, just as it was unusual, and perhaps even unprecedented, for five magistrate judges in Pennsylvania to jointly sign an opinion stressing a warrant was necessary for location tracking.

Some ways Congress could rewrite and improve the 1986 Electronic Communications Privacy Act include clearer standards, and notification to anyone whose location was tracked, Smith said, adding that he was not taking a position on the broader concept of ECPA reform.