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The Fourth Amendment and Geofence Warrants: A Critical Look at United States v. Chatrie

The first Article III opinion on a novel question.


Judge Lauck of the Eastern District of Virginia recently handed down the long-awaited opinion in United States v. Chatrie, on how the Fourth Amendment applies to geofencing warrants.  I believe this is the first Article III judicial opinion on the subject. Geofence warrants raise some really interesting Fourth Amendment issues, and we're likely to hear more about those issues.  Given that, I thought I would offer my take on the opinion.

My reaction, unfortunately, is pretty critical.   I really appreciate the care Judge Lauck put into the case, including building an extensive record.  But I also think the reasoning of the decision has some major problems.  In particular, I am not sure the execution of geofence warrants involve a Fourth Amendment search at all.  And if they do, then I think the Fourth Amendment standard is a lot less strict than Judge Lauck concludes it is.

This post explains my concerns. I'll start with a general background on geofence warrants and then turn to the facts of the case.   I'll next cover the court's reasoning, and explain why I think key parts of the opinion are not persuasive.  How the Fourth Amendment applies to geofence warrants raises some tricky issues. But I don't think this opinion points in the right direction to help find the answers.

I. Background on Geofence Warrants

First, some context.  Most cell phones are logged into Google these days.  And Google users often have their phones set to enable Google, by a range of means, to track their phones' location. This can be a useful tool for law enforcement.  If a crime was known to have occurred in a particular place and time, Google may have records about which phones were there.

Access to Google location data is especially important to create leads when none exist.  If the criminal had his phone on when he committed the crime, if his phone was logged into Google, and if his phone was set to let Google generate location information, Google will have a record of it that can be traced directly back to him.

Of course, you can't be sure that's the case.  And it's unlikely that the criminal's phone will be the only one around.  Other people will likely be nearby, and Google may have records of their phones in the area, too.  But as a means of generating leads, Google location records are a potentially useful way of going from a cold case to a list of possible suspects.

Some details of how Google's location service works are relevant.  As I understand the record in Chatrie, Google users need to opt-in to have Google services keep location records for their phone.   Users who opt-in to location services can also later pause the creation of the records, or delete past records created, although they need to make a point of doing that.  It's not entirely clear, though, how easy this is to do at any given time, or how widely understood it is that users can do this.

Users can also just turn their phones off, or put them in airplane mode, if they otherwise want their location tracking on when the phone is in use.  Also, Google location information can be very precise and dynamic, showing where a phone was and where and how quickly it moved,  But the records can also be uncertain. Google is sometimes unsure of exactly where a phone was, and it only has location estimates with confidence intervals rather than certain information.

It has not been clear that the government's obtaining Google location records is a Fourth Amendment search that requires a warrant.  But Google has required warrants to obtain this information, and it has specified a three-step process that it requires investigators to follow to try to protect the privacy of Google users.  In theory, an investigator could challenge this process in court rather than comply with Google's warrant requirement and process.  But there are some practical reasons why investigators haven't done this, at least yet. So at least for now, Google's process has effectively become the current way geofence warrants are carried out.

Because Google requires a warrant for these location records, the legal issues raised by government access to the records has led to judicial decisions only in the warrant context.  There have been a handful of opinions written by federal magistrate judges explaining why they did or did not agree to sign a geofencing warrant.  And now Chatrie is the first case where the legal issues are being actually litigated in the normal course before an Article III judge. A geofence warrant was issued, a suspect was found, and the suspect has moved to suppress evidence from the geofence warrant.

II.  The Facts of This Case

This particular case involves a bank robbery in 2019 in Virginia.  The suspect entered the bank, handed the teller a note explaining that this was a robbery, and then showed the teller his gun.  The robber took $195,000.  Law enforcement had no leads.  But the suspect had a cell phone with him, and the government obtained a geofence warrant from a state magistrate judge to try to identify him.  The warrant sought to identify each phone logged into Google within a 150-meter radius of the bank from 30 minutes before the robbery to 30 minutes after the robbery.

A state magistrate judge signed the warrant, and Google informed law enforcement that 19 phones were responsive to the warrant.  Google's production to the government also revealed the location patterns of the 19 phones during the hour window, showing the area the phones were thought to be in, and when, over the hour.  The government then asked for expanded location information on the 19 phones, and Google told the government the whereabouts of the 19 phones for a full hour before and a full hour after the time of the robbery.  At this point, the government had detailed tracking information on 19 phones, but no information about who had the phones.

The government then asked for the actual identity of three of the phone owners according to Google's records, reflecting the phones that investigators believed, based on the patterns of location over the two hours, were the bank robber and possible co-conspirators in the area.  Google disclosed that information, and it revealed that the phone believed to belong to the robber was registered to Okello Chatrie.  Chatrie was eventually charged with the robbery, and now has moved to suppress the fruits of the geofence warrant in his criminal case.

III.  Does Obtaining Geofence Information Constitute a "Search" At All? 

The first legal issue raised is whether obtaining geofence information is a search at all.  As this issue is litigated in the context of a motion to suppress, the legal issue is whether the defendant has standing: Were his records searched as a matter of Fourth Amendment law?  For a motion to suppress to succeed, the defendant has the burden of showing that his interests were "searched."  See Rakas v. Illinois, 439 US 128, 130 n.1 (1978).

This is a tricky issue.  Under the third-party doctrine, voluntary disclosure of information relinquishes a reasonable expectation of privacy.  Granted, the Supreme Court limited that principle in Carpenter v. United States for the creation of cell-site records on the ground that creating such records was not truly voluntary. You need to use a cell phone to participate in modern life, the Court reasoned, and you can't opt out of creating cell site location records as they are automatically and necessarily created by using a cell phone.

The question is how does this apply to Google location records that users need to affirmatively opt in to begin, and that they can stop, but that they might not know how to do.  In the framework of Carpenter, is it possible to participate in modern life without opting into Google location services?  And do we treat the generation of those records as voluntary because users can control those records or involuntary because users may not know those records are being created?

The Chatrie court does not answer this, unfortunately.  Because the court ultimately rules for the government on the good faith exception, it need not and does not take a position on whether a search occurred.  Instead, Judge Lauck mostly speculates about what the judge perceives as problems with existing doctrine and suggests that perhaps legislatures should ban geofence warrants:

[T]he Court is disturbed that individuals other than criminal defendants caught within expansive geofences may have no functional way to assert their own privacy rights. Consider, for example, a geofence encompassing a bank, a church, a nearby residence, and a hotel. Ordinarily, a criminal perpetrator would not have a reasonable expectation of privacy in his or her activities within or outside the publicly accessible bank. See United States v. Knotts, 460 U.S. 276, 281, 103 S.Ct. 1081, 75 L.Ed.2d 55 (1983) ("A person travelling in an automobile on public thoroughfares has no reasonable expectation of privacy in his movements from one place to another."). He or she thus may not be able to establish Fourth Amendment standing to challenge a time-limited acquisition of his location data at the bank.

But the individual in his or her residence likely would have a heightened expectation of privacy. Silverman v. United States, 365 U.S. 505, 511, 81 S.Ct. 679, 5 L.Ed.2d 734 (1961) ("At the very core [of the Fourth Amendment] stands the right of a [person] to retreat into his [or her] own home and there be free form unreasonable government intrusion."). Yet because that individual would not have been alerted that law enforcement obtained his or her private location information, and because the criminal defendant could not assert that individual's privacy rights in his or her criminal case, United States v. Rumley, 588 F.3d 202, 206 n.2 (4th Cir. 2009), that innocent individual would seemingly have no realistic method to assert his or her own privacy rights tangled within the warrant. Geofence warrants thus present the marked potential to implicate a "right without a remedy." Hawkins v. Barney's Lessee, 30 U.S. 457, 463, 5 Pet. 457, 8 L.Ed. 190 (1831) ("There can be no right without a remedy to secure it.").

As this Court sees it, analysis of geofences does not fit neatly within the Supreme Court's existing "reasonable expectation of privacy" doctrine as it relates to technology. That run of cases primarily deals with deep, but perhaps not wide, intrusions into privacy. See, e.g., Kyllo v. United States, 533 U.S. 27, 34, 121 S.Ct. 2038, 150 L.Ed.2d 94 (2001) (considering the validity of using thermal imaging on one's home); United States v. Jones, 565 U.S. 400, 402-03, 132 S.Ct. 945, 181 L.Ed.2d 911 (2012) (construing "the attachment of a [GPS] tracking device to an individual's vehicle" for twenty-eight days); Carpenter, 138 S. Ct. at 2217 n.3 (considering whether "accessing seven days of [an individual's cell site location information] constitutes a Fourth Amendment search").

At base, these matters are best left to legislatures. See Zach Whittaker, A Bill to Ban Geofence and Keyword Search Warrants in New York Gains Traction, TechCrunch (Jan. 13, 2022), (discussing a recently introduced New York bill that would ban the use of geofence warrants statewide). This case has arisen because no extant legislation prevents Google or its competitors from collecting and using this vast amount of data. And, as discussed below, despite its ongoing efforts to improve, Google appears to do so under the guise of consent few people understand how to disable. Even with consent, it seems clear that most Google users do not know how the consent flow to control their collection of data works, nor do they know Google is logging their location 240 times a day. It is not within this Court's purview to decide such issues, but it urges legislative action. Thoughtful legislation could not only protect the privacy of citizens, but also could relieve companies of the burden to police law enforcement requests for the data they lawfully have.

To the extent this as read as addressing the question, it's hard for me to see how it's helpful.

It seems to me that the key question for standing under Carpenter is whether opting in to Google location services is voluntary, and is not required to participate in modern life, so that the decision to have Google generate and store those records is a third party disclosure under the third-party doctrine cases that Carpenter did not disturb.

If I understand the record's explanation of the technology correctly, it sounds pretty voluntary to me.  And it's hard to think of why you would need Google location services on to participate in modern life, which seems to be the Carpenter standard.  If that's right–a big if, perhaps, but run with it for now–then I would think that access to Google location services records shouldn't be a search under the third party doctrine for any users. (For more on this view, see my chapter, Implementing Carpenter.)

Maybe the record in Chatrie is wrong on that, or some of the ambiguities in the court's view of the facts are wrong or incomplete.  And I like the idea of requiring a warrant as a matter of policy.  But if my understanding of the facts is right, I would think that the case may end there on the ground that no search occurred, and no warrant was necessary.  How the  Fourth Amendment would apply if this were a case of secret tracking–which is what the court focuses on, looking to the idea that a perpetrator doesn't have a reasonable expectation of privacy around a bank, but a person would in their home–doesn't seem particularly irrelevant unless and until you deal with that issue.

Anyway, I don't have strong feelings about this particular issue, and I'll concede that Carpenter leaves wiggle room in the voluntariness standard.  But I didn't think Chatrie addressed the standing issue well.

IV.  What is the Standard for Probable Cause?

The next issue is how the probable cause standard applies.  Assuming that collecting geofence information about the location of a person's phone is a search of their Fourth Amendment interests, what kind of probable cause must be shown to obtain a geofence warrant to collect that information?

Critically, Judge Lauck reasons that the standard is probable cause as to each specific phone discovered in the geofence.   That is, the Fourth Amendment requires probable cause that each and every phone that has records that end up being revealed was itself, considered individually, evidence of the crime:

At base, probable cause demands that law enforcement possess "a reasonable ground for belief of guilt … particularized with respect to the person to be searched or seized." Maryland v. Pringle, 540 U.S. 366, 124 S. Ct. 795, 800, 157 L.Ed.2d 769 (2003) (emphasis added); see Ybarra v. Illinois, 444 U.S. 85, 91, 100 S.Ct. 338, 62 L.Ed.2d 238 (1979) ("Where the standard is probable cause, a search or seizure of a person must be supported by probable cause particularized with respect to that person.") A "person's mere propinquity to others independently suspected of criminal activity does not, without more, give rise to probable cause to search that person." Ybarra, 444 U.S. at 91, 100 S.Ct. 338. . . .

Although cloaked by the complexities of novel technology, when stripped of those complexities, this particular Geofence Warrant lacks sufficient probable cause. The United States Supreme Court has explained that warrants must establish probable cause that is "particularized with respect to the person to be searched or seized." Pringle, 124 S. Ct. at 800. This warrant did no such thing. It first sought location information for all Google account owners who entered the geofence over the span of an hour. For those Google accounts, the warrant further sought "contextual data points with points of travel outside of the" Geofence for yet another hour—and those data points retained no geographical restriction. (ECF No. 54-1, at 4.) Astoundingly, the Government claims that law enforcement established probable cause to obtain all information (Steps 1, 2, and 3) from all users within the geofence without any narrowing measures. Yet the warrant simply did not include any facts to establish probable cause to collect such broad and intrusive data from each one of these individuals.

I don't see how that can be the correct Fourth Amendment standard.

The ordinary standard for a search warrant is that there must be probable cause that evidence will be found somewhere in the place to be searched.  There is no requirement that there must be probable cause as to each individual person's evidence being itself evidence.  For example, imagine the government has a warrant to search a home where four people live.  Investigators don't need evidence that all of the four people are involved in the crime to get the home warrant.  In fact, the government doesn't need evidence that any of the four people are involved in the crime.  All that matters is that there is probable cause to believe evidence or contraband is somewhere in the home.  They can search the place for the evidence regardless of whose stuff it is, or how many people live in the home. Given that, I don't see how the standard for a geofence warrant can be that probable cause must be shown as to each phone that will be revealed in the geofence.

Judge Lauck's opinion misses this by mistaking an exception for the rule. There is an exception to the usual rule for search warrants for searching the physical body of a person under Ybarra v. Illinois.  Ybarra involved a search of a tavern where the bartender, "Greg," was suspected of selling drugs.  Agents obtained a warrant to search the tavern and to search Greg. But when they executed the search, they searched customers at the tavern and found drugs on one of them, Ybarra.  The Supreme Court held that physically searching the person of customers not suspected of involvement the crime required its own probable cause:

Each patron who walked into the Aurora Tap Tavern on March 1, 1976, was clothed with constitutional protection against an unreasonable search or an unreasonable seizure. That individualized protection was separate and distinct from  the Fourth and Fourteenth Amendment protection possessed by the proprietor of the tavern or by "Greg." Although the search warrant, issued upon probable cause, gave the officers authority to search the premises and to search "Greg," it gave them no authority whatever to invade the constitutional protections possessed individually by the tavern's customers.

I don't see how Ybarra can be relevant to the Fourth Amendment standard for geofence warrants.  The line drawn in the cases is between (1) a search of places and things and (2) search of the body of persons, on the other.  Assuming that gathering location data from Google is a search of a person's Fourth Amendment interests somehow, it seems pretty obvious it's not actually a search of their body.  Revealing that records currently exist at Google in California indicating that a person's phone was in an area around a bank in Virginia in 2019 seems pretty clearly different from rifling through a person's pockets and otherwise subjecting their physical body to a search.

V. What is the Standard for Particularity?

The final question is, assuming there was probable cause, how broad could the search be?  This isn't definitively decided in Chatrie because the (in my view erroneous) probable cause analysis is doing so much work.  If the government must establish probable cause that each phone that appears in the geofence is involved in the crime, then the particularity requirement would seem to be defined by that: The government needs to articulate a warrant so that no innocent person has their phone included in the geofence.  It's not obvious that is possible, as Judge Lauck acknowledges.

But here's the key passage from the opinion on particularity:

Indeed, it is difficult to overstate the breadth of this warrant, particularly in light of the narrowness of the Government's probable cause showing. Law enforcement knew only that the perpetrator "had a cell phone in his right hand and appeared to be speaking with someone on the device." (ECF No. 54-1, at 6.) After the police failed to located the suspect via reviewing camera footage, speaking with witnesses, and pursuing two leads, law enforcement simply drew a circle with a 150-meter radius that encompassed the Bank, the entirety of the Church, and the Church's parking lot. The Government then requested location information for every device within that area. See Carpenter, 138 S. Ct. 2206, 2216 (2018) (describing cell phone location information as "encyclopedic").

What is more, in one instance, this Geofence Warrant captured location data for a user who may not have been remotely close enough to the Bank to participate in or witness the robbery. Because the radius of one of the users' confidence intervals stretched to around 387 meters, the Geofence Warrant might have reported that user's location data to the Government, notwithstanding the fact that he may have simply been present in any number of nearby locations. For example, that person may have been dining inside the Ruby Tuesday restaurant nearby. The person may have been staying at the Hampton Inn Hotel, just north of the Bank. Or, he or she could have been inside his or her own home in the Genito Glen apartment complex or the nearby senior living facility. He or she may have been moving furniture into the nearby self-storage business. Indeed, the person may have been simply driving along Hull Street or Price Club Boulevard. Yet the Government obtained the person's location data just the same. The Government claims that footage depicting the perpetrator holding a phone to his ear—and nothing else—justified this sweeping warrant. That, however, is simply not "[ ]reasonable." U.S. Const. amend. IV.

I'm not sure this is a particularly helpful analysis. Granted, assuming obtaining Google location information is a search, the particularity of the "place" of a geofence warrant raises some really interesting conceptual questions.  Is it like the search of that physical place?  Is it bounded by probable cause alone?  Is it based on the motion of the phone alone, without any identifying information?  Or is it based on the identification of the subscriber?  I think those are interesting and important questions, and that judges should be grappling with those questions.

But Judge Lauck seems to be focused instead on the possibility that the government might learn of the identity of someone who is not involved in the crime. It's not 'reasonable," Judge Lauck suggests, for the government to learn information about an innocent person while executing a warrant trying to identify a guilty person.  I think that's a fine concern as a matter of policy, and it's certainly understandable for Google to consider that in its business role. To the extent there is irrelevant information that the government has no interest in having, there's no point in them having it.

But it's not clear how that prospect alone makes the warrant unconstitutional.  The government comes across evidence about innocent people when executing warrants all the time.  Recall the search of a home: The government might search a house for evidence and search the bedrooms of people not involved in the crime.  That's not ideal, either for those people or for the government.  Everyone would prefer a world in which the government always finds the bad guy and never learns anything about anyone other than the bad guy.  But traditionally that has not been a Fourth Amendment requirement.

One wonders if the possibility that technology can enable the execution of warrants in a more privacy protective way than traditional warrants is leading Judge Lauck to in effect seek a new Fourth Amendment standard that requires warrants to be executed in the most privacy protective way the new technology allows.  That's an interesting idea, but would be a pretty dramatic shift in the law.  And even if that's the goal, it would seem to be better implemented through use restrictions than ex ante limits on probable cause.


Judge Lauck ends up concluding that the warrant "plainly" violates the Fourth Amendment, but that the good faith exception applies because the legal issues are novel.  This means that we may see this warrant and these legal issues raised on appeal before the Fourth Circuit eventually.  I agree that the legal issues are novel, and it will be interesting to see how other courts address them. As always, stay tuned.