Law in the Internet Society

Geofence Warrants: Anyone Can Be a Suspect

-- By ShahabPournaghshband - 22 Oct 2021

Introduction to Geofencewarrants

Geofence warrants grant law enforcement agencies access to corporate location databases in an effort to identify and track individuals in the vicinity of a crime. Corporations, mostly notably Google, provide law enforcement with a list of individuals near a specific area at a requested time. Because geofence warrants are not targeted toward specific individuals but rather groups of individuals in a specific area during a certain timeframe, they are quite broad in scope. This can result in police intrusions of people who are “in the wrong place at the wrong time” – witnesses to or bystanders of criminal activity who become suspects of the crimes. Understandably, geofence warrants have raised serious Fourth Amendment concerns. A couple questions remain surrounding geofence warrants, especially because their constitutionality has not been subject to Supreme Court review. Are geofence warrants constitutional? And if so, what do they tell us about the increasing access to data available to government actors?

How Do Geofencewarrants Operate?

The case of Zachary McCoy best illustrates the use of geofence warrants. McCoy, an avid biker, would use a fitness-tracker app on his phone to keep records of his progress and endurance while biking. McCoy eventually received an email from Google notifying him that unless he went to court and received an injunction, Google would be providing local law enforcement with data from his account. McCoy’s lawyer explained that law enforcement had sought a geofencewarrant in connection with a local burglary. McCoy checked his fitness-tracker app and realized that he had coincidentally biked past the victim’s home numerous times the day of the burglary. Indeed, McCoy was in the wrong place at the wrong time. And if he had not hired a lawyer and blocked the release of his data, this could have cost him his liberty.

How? Surely he could not be convicted of anything beyond a reasonable doubt merely because he had biked past one or more locations on several occasions. Let's suppose some nosy neighbor loves to stare out her window at passing bikers, and testifies that she saw McCoy each time he went by. How can her old-style proof of the same fact "cost him his liberty"?

Geofence warrants are growing in popularity, and Google is not the only company to have worked with law enforcement. Snapchat and Facebook have complied, too. There was over a 1,500% increase in the number of geofence requests Google received in 2018 compared to 2017; “and to date, the rate has increased over 500% from 2018 to 2019.” In 2020, Google received over 11,000 geofence requests from law enforcement, amounting to over 25% of all data requests the company received from law enforcement. A couple years prior, one geofence warrant resulted in the disclosure of close to 1,500 individuals to federal authorities. If these warrants seem overbroad, it is because they are. Geofence warrants offer the perfect example of how advances in technology can often encroach on our notions of safety and privacy.

What is the overbreadth? There is probable cause to believe that a crime was committed. There is probable cause to believe that Acme Co. possesses corporate records that will identify people who were in the vicinity where the rime was committed. Why is a warrant issued to search Acme Co.'s records overbroad? If Baffle Co. has a gazillion video cameras pointed at the vicinity of the crime, is it equally overbroad to issue a warrant to look at all of the video footage? Under almost all circumstances Baffle Co. won't insist on a warrant, for Heaven's sake: it'll turn the video over the minute the detectives ask the security director. So why is this different?

Potential Resolutions

Google, in an amicus brief, has argued that geofence requests constitute Fourth Amendment searches.

Because this requires argument. If not, warrants wouldn't be necessary, a subpoena or a call from a cop would do. And that argument is far from certain, as I show above.

And because users have a reasonable expectation of privacy in their location history data, a warrant should be required for geofence requests. It seems that technology has completely shattered the privacy and security Americans at one point enjoyed. Fourth Amendment doctrine must adjust to these changes in technology, just as it did in Kyllo v. United States, where the Court held that thermal imaging of a home constitutes a Fourth Amendment search and thus requires a warrant. But are Courts the correct medium through which to bring these protections?

"It seems" is not a sufficient argument for any proposition, let alone one so sweeping.

Assembly Bill A84A? has been proposed in the New York State Legislature. The bill seeks to “[p]rohibit[] the search, with or without a warrant, of geolocation and keyword data of a group of people who are under no individual suspicion of having committed a crime, but rather are defined by having been at a given location at a given time or searched particular words, phrases, character strings, or websites.”

A bill has been proposed. So?

While a court may hold that geofence requests require a warrant, legislatures have the ability to place an absolute bar on geofence activity.

Sure, as they can do many other things. But it isn't going to happen, and you haven't explained why it either will or should.

Additionally, this Bill would bar a similarly intrusive type of request: keyword requests. In a keyword request, law enforcement receives data on users who have recently searched specified terms. It is unclear when the constitutionality of these two practices will come before the Supreme Court;

It isn't clear yet why that subject is worthy of Supreme Court consideration. We are near the conclusion but we have yet to see any reason to believe it will.

legislative action therefore seems more appropriate because legislatures can be more expedient and ensure wider protections for American citizens.

More expedient, truly? What's the evidence for that proposition?


The commoditization of our data by technology companies raises its own set of issues, but they pale in comparison to the dangers presented by the use of geofence warrants. Geofence warrants are a direct threat to one of our greatest constitutional values: the protection and safeguarding of personal liberty. And as technology continues to advance and become more ingrained into each aspect of society, we have greater reason to fear that our freedoms will ultimately be in the hands of those we have come to trust the most.

What this draft has is rhetoric, and what it needs is an argument. It would have been better placed as an essay in next term's "Computers, Privacy and the Constitution," where part of my job is to provide an analytical framework for thinking through these Fourth Amendment questions. Because we're not in that course, I haven't addressed them here. You might want to listen to the recordings of last spring's CompPrivConst lectures from Part Four (which is the first part of the course, from weeks 2 to 4), to see what the basic problem is with the gap between your rhetoric and the law here.


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r2 - 29 Nov 2021 - 21:11:00 - EbenMoglen
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