Geofencing, Reverse Warrants, and the New Data Center Law

​The risks and benefits of reverse searches are revealed in the capital murder case of Aaron Rayshan Wells. Although a security camera recorded a number of armed men entering a home in Texas where a murder took place, the lower portions of the men’s faces were covered. Wells was identified in this murder investigation by a reverse search enabled by geofencing.
 
A lower court upheld the geofence in this case as sufficiently narrow. It was near the location of a homicide and was within a precise timeframe on the day of the crime, 2:45-3:10 a.m. But ACLU in a recent amicus brief identifies dangers with this reverse search, even within such strict limits. What are the principles at stake in this practice?
 
Let’s start with the Fourth Amendment, which places hurdles government agents must clear before obtaining a warrant for a search – “no warrants shall issue, but upon probable cause, supported by Oath or affirmation, and particularly describing the place to be searched, and the persons or things to be seized.” The founders’ tight language was formed by experience. In colonial times, the King’s agents could act on a suspicion of smuggling by ransacking the homes of all the shippers in Boston. Forcing the government to name a place, and a person or thing to be seized and searched, was the founders’ neat solution to outlawing such general warrants altogether.
 
It was an ingenious system, and it worked well until Michael Dimino came along.
 
In 1995, this inventor received a patent for using GPS to locate cellphones. Within a few years, geofencing technology could instantly locate all the people with cellphones within a designated boundary at a specified time. This was a jackpot for law enforcement. If a bank robber was believed to have blended into a crowd, detectives could geofence that area and collect the phone numbers of everyone in that vicinity. Make a request to a telecom service provider, run computer checks on criminals with priors, and voilà, you have your suspect. Thus the technology-enabled practice of conducting a “reverse search” kicked into high gear.
 
Multiple technologies assist in geofenced investigations. One is a “tower dump,” giving law enforcement access to records of all the devices connected to a specified cell tower during a period of time.
 
Wi-Fi is also useful for geofencing. When people connect their smartphones to Wi-Fi networks, they leave an exact log of their physical movements. Our Wi-Fi data also record our online searches, which can detail our health, mental health, and financial issues, as well intimate relationships, and political and religious activities and beliefs.
 
A new avenue for geofencing was created on Monday by President Biden when he signed into a law a new measure that will give the government the ability to tap into data centers. The government can now enlist the secret cooperation of the provider of “any” service with access to communications equipment. This gives the FBI, U.S. intelligence agencies, and potentially local law enforcement a wide, new field with which to conduct reverse searches based on location data.
 
In these ways, modern technology imparts an instant, all-around understanding of hundreds of people in a targeted area, at a level of intimacy that Colonel John André could not have imagined. The only mystery is why criminals persist in carrying their phones with them when they commit crimes.
 
Google was law enforcement’s ultimate go-to in geofencing. Warrants from magistrates authorizing geofence searches allowed the police to obtain personal location data from Google about large numbers of mobile-device users in a given area. Without any further judicial oversight, the breadth of the original warrant was routinely expanded or narrowed in private negotiations between the police and Google.
 
In 2023, Google ended its storage of data that made geofencing possible. Google did this by shifting the storage of location data from its servers to users’ phones. For good measure, Google encrypted this data. But many avenues remain for a reverse search.
 
On one hand, it is amazing that technology can so rapidly identify suspects and potentially solve a crime. On the other, technology also enables dragnet searches that pull in scores of innocent people, and potentially makes their personal lives an open book to investigators. ACLU writes:
 
“As a category, reverse searches are ripe for abuse both because our movements, curiosity, reading, and viewing are central to our autonomy and because the process through which these searches are generally done is flawed … Merely being proximate to criminal activity could make a person the target of a law enforcement investigation – including an intrusive search of their private data – and bring a police officer knocking on their door.”
 
Virginia judge Mary Hannah Lauck in 2022 recognized this danger when she ruled that a geofence in Richmond violated the Fourth Amendment rights of hundreds of people in their apartments, in a senior center, people driving by, and in nearby stores and restaurants. Judge Lauck wrote “it is difficult to overstate the breadth of this warrant” and that an “innocent individual would seemingly have no realistic method to assert his or her privacy rights tangled within the warrant. Geofence warrants thus present the marked potential to implicate a ‘right without a remedy.’”
 
ACLU is correct that reverse searches are obvious violations of the plain meaning of the Fourth Amendment. If courts continue to uphold this practice, however, strict limits need to be placed on the kinds of information collected, especially from the many innocent bystanders routinely caught up in geofencing and reverse searches. And any change in the breadth of a warrant should be determined by a judge, not in a secret deal with a tech company.