Judges Weigh Phone Tracking

By JULIA ANGWIN And SCOTT THURM

State and federal authorities follow the movements of thousands of Americans each year by secretly monitoring the location of their cellphones, often with little judicial oversight, and it's facing legal challenges. Scott Thurm has the story on Digits.

State and federal authorities follow the movements of thousands of Americans each year by secretly monitoring the location of their cellphones, often with little judicial oversight, in a practice facing legal challenges.

Electronic tracking, used by police to investigate such crimes as drug dealing and murder, has become as routine as "looking for fingerprint evidence or DNA evidence," said Gregg Rossman, a prosecutor in Broward County, Fla.

The use of cellphone tracking by authorities is among the most common types of electronic surveillance, exceeding wiretaps and the use of GPS tracking, according to a survey of local, state and federal authorities by The Wall Street Journal.

The widening practice also presents one of the biggest privacy questions in a generation: Do police need a search warrant to follow a person's minute-by-minute movements using satellite or cellphone technology?

The Supreme Court heard arguments Tuesday in the case of Antoine Jones, whose movements were electronically tracked for a month after police attached a global positioning satellite, or GPS, device to his wife's Jeep Grand Cherokee. A drug conviction against the Washington, D.C., nightclub owner was overturned on appeal because such intrusive monitoring should require a search warrant, the appeals court said.

The U.S. government argued Tuesday that its use of GPS beepers such as the type in the Jones case was in the "low thousands" each year.

But other lawyers say the court's decision will likely affect the far more common police practice of tracking users of the nation's 327 million cellphones.

Al Gidari, a partner at law firm Perkins Coie whose clients include mobile carriers, told Congress last year that wireless service providers receive an "astronomical" number of requests for user records—including location. "It is not uncommon for law enforcement to ask for a phone to be" tracked every 15 minutes, he said.

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The Wall Street Journal filed open-records requests with the 20 largest state and local police departments in the U.S. to learn how often police track people by monitoring the locations of their cell phones. Three departments provided the logs with which they record tracking requests.

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Little is known about the practice because tracking requests are typically sealed from public view. While search warrants are generally delivered to people whose property is being searched, most people whose phones are targeted never learn about it. They typically find out only if they are charged with a crime and their tracking data are used as evidence against them.

The Journal identified more than 1,000 instances of cellphone tracking in several large U.S. cities last year through open-records requests and court documents. The data showed that the practice is a widely and increasingly used police tool.

The Los Angeles Police Department last year, for example, tracked 295 phones, up 35% from a year earlier, according to department records. Miami-Dade police said it tracked locations of 130 phones in 2010, up from 102 in 2009. Federal prosecutors in the Southern District of Florida, meanwhile, sought cellphone location data 189 times last year, up 8% from 2009, according to court records.

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Michael Stravato for The Wall Street Journal

Magistrate Stephen Smith of Houston has questioned the legal basis of authorities tracking the location of cellphones without a search warrant.

Magistrate Stephen Smith of Houston, Texas, who approves such surveillance orders, has been studying the available data and estimates that federal courts alone issue 20,000 to 30,000 cellphone tracking orders annually. By comparison, federal and state courts approved 3,194 wiretaps in 2010, according to federal records.

At issue is whether electronic tracking is comparable to such routine surveillance as following a suspect in an unmarked police car on city streets, as the federal government argues.

For years, courts have wrestled with how electronic tracking fits with the Constitution's prohibition against searching a home, for instance, unless police can persuade a judge to sign a search warrant.

The federal government says authorities can use electronic surveillance to track vehicles on public roads without a warrant, citing a 1983 Supreme Court ruling that declared there is no reasonable expectation of privacy there.

The government also contends that most cellphone tracking conforms to a lower legal standard than a search warrant, which requires authorities show probable cause to suspect connection to a crime. Instead, the government says cellphone tracking is governed by a 1986 law that requires only that police provide a judge with facts "showing that there are reasonable grounds to believe" the material sought is relevant to a criminal investigation.

But federal courts have been increasingly questioning whether these lower standards should apply to information as sensitive as a person's location.

State laws and legal precedents also vary. New York and California courts generally require search warrants to track a phone's location, but not courts in Florida.

To identify a bank robber, prosecutors in Connecticut obtained records for 169 phones in 2009 without a search warrant. Prosecutors later used phone records to show the location of suspects around the time of the robberies.

Ben Dawes of Hartford, whose phone number was among those listed in court papers, didn't know he had been tracked until told by a Journal reporter. "It's not something I'm happy about," he said. Mr. Dawes, who has no other known connection to the case, said he understood the need to examine phone records, but wished he had been told. Tom Carson, a spokesman for the U.S. Attorney's office in Hartford, declined to comment.

Police can track phones by analyzing signals from towers that connect cellphone calls or, in some cases, through GPS satellites. The precision varies. Data from a single tower in a rural area may only locate a phone within 10 miles. But combining signals from multiple towers in an urban area can locate a phone within 50 yards.

Tracking is becoming more precise as wireless companies install more towers. CTIA-The Wireless Association, a trade group, said there were 256,920 cellphone sites in the U.S. in June, up from 178,000 in 2005. GPS is more precise, but the signal doesn't work indoors and not all phones use GPS.

As the frequency of tracking has increased, more judges have raised the need for search warrants. More than a dozen magistrates have written opinions denying applications for court orders to track cellphones. The nation's roughly 500 magistrates act as assistant judges in U.S. District Courts, handling requests for search warrants and other types of surveillance.

The so-called magistrates' revolt traces its history to a 2005 opinion written by Magistrate Smith in Texas.

Magistrate Smith said he was puzzled by cellphone-tracking requests when he was new to the bench: he couldn't find a provision in the law allowing police to track a phone for as long as 60 days without a search warrant. To learn more, he visited the U.S. Marshals surveillance operation and quizzed lawyers at cellphone companies about government requests.

Prosecutors told him they had authority to track phones with a court order by combining two portions of the 1986 law: one allows collection of historical location data; the other allows the real-time collection of cellphone calling data but not location. Taken together, the government argued that it could track a cellphone's location without having to show probable cause.

On Oct. 14, 2005, Magistrate Smith denied a government request in an opinion that called the government's legal theory "undeniably creative." But "mixing and matching of statutory provisions," he said, would create a "new form of electronic surveillance" not envisioned by the law.

Within six months, nine other magistrates also denied tracking requests, relying in part on Magistrate Smith's reasoning. Other magistrates sided with the government, agreeing that cellphone locators weren't precise enough to require a search warrant.

The magistrate rebellion prompted changes in some jurisdictions. U.S. Attorneys in Los Angeles, for example, agreed to obtain search warrants for cellphone location information in federal cases.

The Justice Department recommended that prosecutors obtain search warrants when tracking phones using such "precise" technology as GPS or multiple cellphone towers, according to documents dated in 2007 obtained by the American Civil Liberties Union in a freedom-of-information request. The department continued to argue that less precise tracking of phones didn't require a warrant.

A year later, the legal battle moved from cellphone tracking to records of cellphone locations. A group of magistrates in Pennsylvania, led by Magistrate Lisa Lenihan, wrote an unusual joint decision in 2008 that denied a government application for historical records of cellphone locations, saying that cellphones were being used by authorities as personal tracking devices.

"Americans do not generally know that a record of their whereabouts is being created whenever they travel about with their cellphones," Magistrate Lenihan wrote. "Most Americans would be appalled by the notion that the government could obtain such a record without at least a neutral, judicial determination of probable cause."

Most cellphone companies keep historical records of location data for a year or more, according to a Justice Department document obtained by the ACLU through the Freedom of Information Act.

The government appealed the magistrates' ruling. Lawyers argued that cellphones were not tracking devices because the location information was only accurate within several hundred feet. The appeals court didn't fully resolve the issue and the government didn't get the cellphone records it sought.

The Jones case gave new fuel to the debate. In October, 2010, Magistrate Smith cited the case in denying a federal government request for 60 days of historical cellphone location records. "Two months' worth of hourly tracking data will inevitably reveal a rich slice of the user's life, activities and associations," he wrote. The government has appealed.

Write to Julia Angwin at julia.angwin@wsj.com and Scott Thurm at scott.thurm@wsj.com