Privacy in Peril: Opposing rulings set up Supreme Court showdown over police cell phone tracking

Two federal appeals courts have taken starkly different views on one of the government 's newer electronic dragnet tools – geofence warrants that track people via their cell phones – setting up a likely showdown before the U.S. Supreme Court that could define privacy in the digital era for decades to come.

Last week, the 5th U.S. Circuit Court of Appeals ruled that such geofence warrants are “categorically prohibited by the Fourth Amendment” protection against unlawful search and seizure. The judges concluded the mass gathering of Americans’ cell phone geographic locations to identify a single suspect in a postal worker’s armed robbery amounted to the sort of general warrant that the Founding Fathers steadfastly rejected at America’s birth as their new country broke from British rule.

“It is undeniable that general warrants are plainly unconstitutional,” that appeals court ruled. The 5th Circuit oversees appeals from Louisiana, Mississippi, and Texas federal district courts.

A few states over, the 4th U.S. Circuit of Appeals came to a different conclusion, ruling that when law enforcement gathers two hours of all a cell phone users’ records in Google’s database for a certain location near a crime it didn’t violate privacy because more than a half-billion cell phone users had opted to turn on the geo-tracking capabilities of their to make their apps work better. Such opt-ins, the 4th Circuit ruled, amounted to a waiver of privacy. The 4th Circuit oversees appeals from Maryland, Virginia, West Virginia, North Carolina, and South Carolina federal district courts.

The dueling interpretations of two appeals courts – known in legal parlance as circuit splitting – sets up a likely path for the issue to be resolved by the nation’s nine justices at the U.S. Supreme Court. Privacy experts like the Electronic Frontier Foundation predict the justices are more likely to side with the 5th Circuit.

“Police around the country have increasingly relied on geofence warrants and other reverse warrants, and this opinion should act as a warning against narrow applications of Fourth Amendment precedent in these cases,” EFF wrote in a blog piece this week that heralded the 5th Circuit ruling.

Law enforcement have argued that such geofence warrants are essential to solving crimes and protecting Americans during an attack like the Jan. 6 Capitol riots. The FBI issued the largest-ever known geofence warrant in that case, covering more than four hours of time and four acres of geography around the Capitol that ensnared about 1,500 people as potential suspects.

U.S. District Court Judge Rudolph Contreras upheld the warrant on the grounds that law enforcement acted in “good faith” for public safety. That rationale is being appealed in the D.C. Circuit Court of Appeals.

“Geofence warrants have become an investigation tool of choice after law enforcement discovered that Google had been maintaining its Sensorvault, a treasure trove collecting over a decade of highly precise location data of persons using Google applications,” the American Bar Association declared earlier this month.

Meanwhile, the 4th and 5th Circuit rulings refer to each other’s cases that affected crimes outside of the nation’s capital. The primary difference is that the 4th Circuit believed the generic opt-ins cell phone users make when they accept to install an app with geo-location services turned on amounted to a de facto waiver of their 4th Amendment rights should government come calling for the data later.

The 5th Circuit Circuit disagreed, saying the mere fact that a half billion people have accepted geo-location tracking was proof that consumers were making a decision of convenience and not a waiver of privacy from government surveillance.

“When law enforcement submits a geofence warrant to Google, Step 1 forces the company to search through its entire database to provide a new dataset that is derived from its entire Sensorvault,” the 5th Circuit decision noted. “In other words, law enforcement cannot obtain its requested location data unless Google searches through the entirety of its Sensorvault—all 592 million individual accounts— for all of their locations at a given point in time. Moreover, this search is occurring while law enforcement officials have no idea who they are looking for, or whether the search will even turn up a result."

“Indeed, the quintessential problem with these warrants is that they never include a specific user to be identified, only a temporal and geographic location where any given user may turn up post-search. That is constitutionally insufficient,” the appellate court ruled.

In other words, using a digital dragnet to search millions of Americans location records to identify an unknown assailant or two amounted to a fishing exercise tantamount to the “general warrants” the Constitution’s framers rejected handily two centuries earlier.

Google has revealed that the number of geo-warrants has gone from rare in 2016 to overwhelming – more than 10,000 annually – a decade later. The tech giant announced last year it was shutting down its ability to store all users’ geo location data in its own database known as Sensorvault and instead leaving it on each consumer’s cell phone where it must be obtained by individual warrant.

No matter how Google changes their practices, the breadth of digital searching that law enforcement can still do in 2024 from other vendors leaves most experts certain the issue of geofencing and tactics likely will be decided by the U.S. Supreme Court.