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Where cops can track your location without a warrant

The legal battle over cell site location information

Police said Quartavious Davis was part of a stunning crime spree. Armed and masked, Davis, with a group of others, robbed a string of businesses in the Miami area: witnesses put him at stick-ups at Little Caesar's, a gas station, a Walgreens, an auto parts store, a beauty salon, a Wendy's, and a jewelry store. One witness claimed Davis pointed a gun at his head and robbed him. Another witness said, when he attempted to write down the plates on the getaway car, Davis opened fire. The witness fired back.

Davis was eventually found guilty and sentenced to 1,941 months in prison — nearly 162 years. At the trial, prosecutors called on an array of evidence. DNA tied Davis to the car, and surveillance video put someone matching his description at multiple robberies. Others involved in the robberies testified against him. And then there was Davis' phone: through a controversial use of records, known as cell site location data, police were able to place Davis' mobile device near the location of six of seven robberies when they occurred.

Robbery cases turned into major court battles

Cell site location data can provide police with a rough idea of a suspect's location during a given time period, or even in real time, and its use in cases like Davis' has become a rallying cry for activists around the country. Multiple robbery cases have already turned into major circuit court battles over such data, resulting in a range of decisions governing how it can be used. And that broad legal patchwork has turned into something even more complicated, as various lower courts across the country have also made rulings governing how and when the data can be obtained. The result is that a Texas cop doesn't need a warrant for some data, while a Montana cop does; Indiana police need the information in certain circumstances, but there are no protections for the information in Wisconsin.

In the Davis case, as with the other robbery cases, police obtained location records on customers without a warrant. Wireless companies — in the Davis case, the small service provider MetroPCS — keep records of which nearby cell tower carried a customer's call, or in some cases a request like an email ping, and in which direction the ping was sent. (The service providers keep the records on a rolling basis, some for a few months, some for years.) Although the science is imperfect at best, and is much more effective in cities than rural areas, prosecutors can use the evidence to sway juries.

After the verdict, Davis filed an appeal, in part based on the prosecution's use of the cell records. Without a warrant, the argument went, police were in violation of the Fourth Amendment, which protects against unreasonable searches. The government in turn argued that it only needs permission under the Stored Communications Act, or SCA, which will hand over a court order to law enforcement if "there are reasonable grounds to believe that" such records "are relevant and material to an ongoing criminal investigation." That standard is much more achievable than the "probable cause" bar needed for a warrant.

Police have to meet a bar lower than "probable cause"

The ACLU, taking up the Davis case and others, has argued that the higher standard must be applied, as the information can be extraordinarily revealing. With thousands or tens of thousands of data points, representing weeks or months of location data, police may be able to show a suspect was near a bank robbery, but will incidentally find much more. Which nights, for example, was the suspect not sleeping at home? When was the suspect at church?

"There's really a lot of private and very sensitive information at stake," says Nathan Wessler, a staff attorney on the ACLU's Speech, Privacy, and Technology Project. Police, in rebuttal, have argued that such data is no longer protected when it's handed over to a wireless service provider, under a legal theory known as "third party doctrine," which has also been used as a defense in lawsuits against the NSA.

Ultimately, after winning an early appeal, the full Eleventh Circuit Court of appeals sided with the government in the Davis case. This week, the Supreme Court rejected a request to hear the case, making Davis' conviction final.

The Supreme Court has declined to hear these cases

A similar robbery conviction in Baltimore was overturned, but is now being heard by the full Fourth Circuit court, which oversees cases in Maryland, the Carolinas, Virginia, and West Virginia. Yet another robbery — over stolen phones from a Radioshack, tracked with historical location data — is facing appeal in front of the Sixth Circuit court, affecting Kentucky, Michigan, Ohio, and Tennessee. The Fifth Circuit court — which has jurisdiction over Louisiana, Mississippi, and Texas — has determined that police don't need a warrant for historical cell site data.

Without a Supreme Court decision, various other states have moved to govern cell site data in different ways, and the ACLU recently mapped the decisions. Some, like Pennsylvania, let individual judges decide whether a warrant is required. Others require a warrant for real-time tracking of location — when a suspect is not in police custody, but can be tracked through location data — but not for historical data. In many states, including Missouri and New Mexico, no binding decisions have been made at all.

"Something that people forget about cellphones in general, of any type, is that you're leaving a permanent record of all of your physical locations as you move around," Edward Snowden told The Intercept in an interview published yesterday. The ACLU and others say that sensitive information is only becoming more sensitive. As location-tracking tech improves, the data obtainable by police will reveal more and more about our locations and habits, making it too powerful a tool to be governed idiosyncratically across states. In the worst case, the most lenient protections could mean the private lives of innocent people are more likely to be combed over by police.

Meanwhile, as the appeals and subsequent rulings sweep over the states, wireless carriers have offered a window into how frequently such requests are made by police. In recent transparency reports, the major wireless carriers have logged tens of thousands of yearly law enforcement requests for historical and real-time location information. Pending changes in law, those requests show no sign of relenting, and it's unclear if the Supreme Court will ever elect to rule on the matter. "The one thing we do know is that there will be more opportunities to take up this issue," Wessler says.