US Supreme Court weighs how far police investigations can go in using cellphone location data

This article was originally published by Stateline.

The U.S. Supreme Court on Monday appeared likely to allow law enforcement to continue seeking warrants for the location history of cellphones near crime scenes, even as the justices wrestled with how far the government must go to protect Americans’ privacy.

Some of the justices appeared to be searching for a middle ground during oral arguments in a case out of Virginia challenging what is known as a geofence warrant that was used to catch a bank robber. Several justices asked skeptical questions of both sides, though no one voiced explicit support for prohibiting such warrants altogether.

As smartphones have become ubiquitous, along with apps that track users’ movements, the high court is once again wading into how the 4th Amendment to the U.S. Constitution, which prohibits unreasonable searches and seizures, applies in the digital era. The justices’ decision, of tremendous interest to state attorneys general, will shape how easy or difficult it is for investigators to sweep up location data.

Over the past two decades, geofence warrants have become a major tool of law enforcement. At a basic level, they allow police to identify phones within a geographic area for a certain period of time. 

The data can be tremendously valuable to investigators, offering a way to develop suspects in crimes where their identities aren’t otherwise known. Underscoring their importance, a broad bipartisan coalition of states has urged the justices to uphold the warrants.

But civil liberties advocates say geofence warrants ensnare people in digital dragnets, handing the government data on anyone who happens to be in the wrong place at the wrong time. They argue that accessing data on anyone within a certain area — the geofence — amounts to a general warrant prohibited by the Constitution.

Summing up the high court’s uncertainty in Monday’s arguments, Justice Amy Coney Barrett told U.S. Deputy Solicitor General Eric Feigin, who was arguing in favor of law enforcement access to location data, that while he had described his opponent’s position as maximalist, “there’s a risk of the government’s position being maximalist the other way.”

“I was just going to say this seems very complicated from the user’s point of view, frankly,” Barrett said at a different portion of the argument.

Credit Union Robbery

The case before the Supreme Court, Chatrie v. United States, arises from a 2019 robbery of a federal credit union in Midlothian, Virginia. Okello Chatrie was convicted of armed robbery after surveillance footage showed the robber using a cellphone. A detective then obtained a geofence warrant directed at Google for devices within 150 meters of the credit union within an hour of the robbery.

Google initially provided anonymized data in response to the warrant. The detective then requested and received additional location data on nine users. Finally, the detective received de-anonymized information on three users, without obtaining an additional warrant.

While Google has since changed the way it stores location history data to limit geofence warrants, other apps and tech firms collect the data. Lawyers for Chatrie argue that geofence warrants open the door to the authorities requesting information on everyone at a sensitive location — perhaps an abortion clinic or a political convention — at a particular time.

“The warrant authorized the government to direct Google to search every single person’s account to find those people who were within the geofence. That is a general warrant,” Adam Unikowsky, a lawyer for Chatrie, told the court.

4th Amendment Debate

The Supreme Court’s last major decision on 4th Amendment rights and phones came in 2018, when the justices ruled that law enforcement generally needs a warrant for location data derived from when phones connect to a cell site. That data is generated by just having a cellphone, and the justices found that a phone is now a basic element of participating in society.

By contrast, the Trump administration argues location history data isn’t protected by the 4th Amendment because users voluntarily share it with Google and other tech firms by turning on location tracking on their phones. Because the information was turned over with their consent, users have no reasonable expectation of privacy.

“Petitioner here is asking for an unprecedented transformation of the 4th Amendment into an impregnable fortress around records of his public movements that he affirmatively consented to allow Google to create, maintain and use,” Feigin said.

Justice Sonia Sotomayor, one of the court’s three liberal justices, argued that if the government can access location data without a warrant because Chatrie consented to sharing it with Google, then the government could obtain all sorts of other data shared with the company, such as photos and calendar entries.

“If this is consent, that means the government can seek those documents for any reason, not just the commission of a crime — or no reason, correct?” Sotomayor said.

“Correct. It would not be a search, so no search warrant would be required,” Unikowsky replied.

Red and Blue States Back Geofence Warrants

Thirty-one states and the District of Columbia have filed a court brief arguing that geofence warrants can be more precise than many traditional investigative methods when supported by probable cause and appropriately tailored. In the brief, they urged the justices not to prohibit geofence warrants altogether.

State attorneys general across the political spectrum signed on to the brief. They include Alabama, Alaska, Arkansas, Arizona, Georgia, Illinois, Indiana, Iowa, Kansas, Louisiana, Maryland, Maine, Michigan, Minnesota, Mississippi, Missouri, Montana, Nebraska, New Jersey, New Mexico, New York, North Carolina, Ohio, Oklahoma, Pennsylvania, South Carolina, South Dakota, Tennessee, Texas, Utah and Washington.

Geofence warrants can generate critical leads when the perpetrators of crimes are otherwise unknown, they wrote. When suspects are unknown but the suspected wrongdoing is linked to a specific place and time, location data provides one of the narrowest available tools for finding leads, the brief argues.

“This Court should make clear that the Constitution does not categorically ban those investigative methods,” the states’ brief reads.

Google Brief

In a court brief, Google said geofence warrants result in invasive searches that are overbroad. Geofence searches, by their nature, have a high risk of sometimes sweeping in thousands of innocent users, the company said.

Even small geographic areas covering short periods of time can include hundreds of thousands of people, Google argued. Geofence parameters set by law enforcement often cover more ground than the location of the crime, with private homes, apartments, government buildings, hotels, places of worship and busy roads all included.

Lawyers for Google wrote that the company takes no position on whether the warrant in the Chatrie case complies with the 4th Amendment.

“But Google firmly believes that, based on the private nature of Location History data, law enforcement was required to obtain a warrant to access that data,” the brief says.

Orin Kerr, a Stanford Law School professor and one of the nation’s foremost experts on the 4th Amendment, predicted after the oral argument that the justices would likely rule that geofence warrants can be constitutionally drafted. 

However, he was uncertain whether the court would rule on whether the geofence search that identified Chatrie’s phone was a search under the 4th Amendment.

“They’ll probably say that geofence warrants have to be limited in time and space,” Kerr wrote on social media.