High-tech crime-fighting, privacy rights square off in Supreme Court battle

Seven years ago, police in Midlothian, Virginia, sought to identify a bank robber by asking Google to search the records of more than 500 million people who used the company's "location history" feature. That search identified 19 devices that were in or near the bank around the time of the robbery, which police winnowed down to three people, including Okello Chatrie, the man who was ultimately convicted of the crime.

Depending on your perspective, that use of a "geofence" warrant was either an unobjectionable example of smart police work or an outrageous invasion of privacy. On Monday, the Supreme Court weighed the merits of those contending views in a case that illustrates the threat that two dubious doctrines pose to Fourth Amendment rights now that Americans routinely entrust huge volumes of personal information to tech companies that help them with myriad quotidian tasks.

In 1967, the Supreme Court said the Fourth Amendment applies only when you have a "reasonable expectation of privacy." In subsequent cases that involved bank and telephone records, the court said you have no such expectation when you voluntarily share information with third parties for their own business use.

The problems with those principles were clear in a 2018 case that addressed the FBI's tracking of a robbery suspect via location data collected by cellphone sites. Although the majority held that such tracking generally requires a warrant, that conclusion was hard to reconcile with the third-party rule, as Justice Neil Gorsuch noted in his dissent.

Chatrie's case is broadly similar, except that the information used to identify him was collected by his own phone rather than cell sites. Although Google no longer keeps such data on its servers, many commonly used apps track the whereabouts of their users, and that information is often stored remotely.

In Chatrie's case, police obtained a warrant. But his lawyers argue that such orders sweep so broadly that they violate the Fourth Amendment, which says a warrant must be based on probable cause and must "particularly" describe "the place to be searched" and "the persons or things to be seized."

The Trump administration wants the Supreme Court to reject that argument. But it also maintains that geofence inquiries do not require any sort of warrant because people who consent to location tracking have no reasonable expectation that the resulting information will be kept private.

If so, Chatrie's lawyer, Adam Unikowsky, warned during oral argument on Monday, the same logic would allow the government to search people's remotely stored emails, photos, calendars and documents at will. Several justices understandably viewed that prospect with alarm.

Although Deputy Solicitor General Eric Feigin assured the justices that his argument did not extend that far, those other examples likewise involve voluntary sharing of information with third parties, which supposedly makes the Fourth Amendment inapplicable. And even when the information is limited to location tracking, it can still reveal sensitive details of people's lives.

"The potential for abuse is breathtaking," Unikowsky notes in a Supreme Court brief. "The government need only draw a geofence around a church, a political rally or a gun shop, and it can compel a search of every user's records to learn who was there."

In addition to arguing that people reasonably view their location histories as private, Unikowsky takes a page from Gorsuch, who in 2018 questioned both that test and the third-party doctrine. Since the Fourth Amendment protects people's "papers" and "effects" against "unreasonable searches and seizures," Gorsuch suggested, the relevant question is whether the information sought by the government falls into those categories.

Gorsuch thought it was plausible to argue that people retain a property interest in their records even when they share them with others for specific purposes. That argument, which Unikowsky adopts, seems like a promising way to escape the danger posed by the third-party doctrine, which modern technology has magnified to an extent that would have dismayed the Fourth Amendment's framers.

Jacob Sullum is a senior editor at Reason magazine.