WASHINGTON – In an unexpected twist of modern crime-solving, Okello Chatrie’s cellphone betrayed him.

Chatrie had managed to abscond with $195,000 after robbing a bank in the suburbs of Richmond, Virginia. For a while, he successfully evaded capture, until law enforcement deployed a sophisticated digital tool. This tool essentially conjured up an invisible boundary to gather the location data of cellphones near the crime scene.

Through a geofence warrant served to Google, police discovered that Chatrie’s cellphone was one of only a few present at the bank during the robbery’s timeframe.

The Supreme Court is now poised to determine if these geofence warrants infringe upon the Fourth Amendment, which protects against unreasonable searches. This case presents another instance where the justices must interpret a centuries-old constitutional provision in the context of contemporary technology that the framers of the Constitution could not have envisioned.

Chatrie’s case is set to be argued alongside another significant legal battle on Monday. The second case involves Bayer’s appeal to prevent thousands of state lawsuits. These lawsuits accuse the company of failing to adequately warn consumers about the alleged cancer risks associated with its widely-used Roundup weedkiller.

Geofence warrants represent a pivotal shift in investigative strategy. Traditionally, law enforcement would identify a suspect first, then secure a warrant to search their home or personal devices.

With geofence warrants, police do not have a suspect, only a location where a crime took place. They work in reverse to identify people who were in the area.

Prosecutors credit the warrants with helping crack cold cases and other crimes where surveillance cameras did not reveal suspects’ faces or license plates.

Civil libertarians say that geofences amount to fishing expeditions that subject many innocent people to searches of private records merely because their cellphones happened to be in the vicinity of a crime. A Supreme Court ruling in favor of the technique could “unleash a much broader wave of similar reverse searches,” law professors who study digital surveillance wrote the court.

Investigators used geofence warrants to identify supporters of President Donald Trump who attacked the Capitol in the riot on Jan. 6, 2021, as well as in the search for the person who planted pipe bombs outside the Democratic and Republican party headquarters the night before.

Police also credit these warrants with helping identify suspects in killings in several states, including California, Georgia and North Carolina.

An academic group that works to bridge gaps between the police and communities wrote that the court should avoid an all-or-nothing approach in Chatrie’s case.

The Trump administration’s position would allow police to use geofence warrants and similar tools “with no judicial supervision or constitutional safeguards,” according to the Policing Project at the New York University School of Law. Chatrie’s lawyers want the court to rule out any use of geofence warrants at all, impeding “legitimate law enforcement activities,” the group wrote.

In Chatrie’s case, the geofence warrant invigorated an investigation that had stalled. After determining that Chatrie was near the Call Federal Credit Union in Midlothian around the time it was robbed in May 2019, police obtained a search warrant for his home. They found nearly $100,000 in cash, including bills wrapped in bands signed by the bank teller.

He pleaded guilty and was sentenced to nearly 12 years in prison. Chatrie’s lawyers argued on appeal that none of the evidence should have been used against him.

They challenged the warrant as a violation of his privacy because it allowed authorities to gather the location history of people near the bank without having any evidence they had anything to do with the robbery. Prosecutors argued that Chatrie had no expectation of privacy because he voluntarily opted into Google’s location history.

A federal judge agreed that the search violated Chatrie’s rights, but allowed the evidence to be used because the officer who applied for the warrant reasonably believed he was acting properly.

The federal appeals court in Richmond upheld the conviction in a fractured ruling. In a separate case, the federal appeals court in New Orleans ruled that geofence warrants “are general warrants categorically prohibited by the Fourth Amendment.”

In the Supreme Court’s last case on digital-age searches, in 2018, the court divided 5-4 in favor of a defendant whose movements were tracked by authorities for nearly four months, without a warrant, through the review of cellphone tower data.

An issue in that case that also appears in Chatrie’s is whether the defendant had an expectation of privacy that would trigger Fourth Amendment protections.

The Supreme Court has previously ruled that information shared with third parties cannot be considered private.

But Chief Justice John Roberts wrote in his majority opinion about the extraordinary computing power of cellphones, describing “seismic shifts in digital technology” and “the exhaustive chronicle of location information casually collected by wireless carriers today.”