Amicus Curiae Brief — Okello T. Chatrie, Petitioner v. United States

Supreme Court briefMar 9, 2026

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No. 25-112

In the Supreme Court of the United States

OKELLO T. CHATRIE

Petitioner,

UNITED STATES,

Respondent.

On Writ of Certiorari to the

United States Court of Appeals for the Fourth Circuit

BRIEF FOR THE RUTHERFORD INSTITUTE AS

AMICUS CURIAE IN SUPPORT OF NEITHER

PARTY

JOHN W. WHITEHEAD

ETHAN H. TOWNSEND

Counsel of Record

WILLIAM E. WINTERS

The Rutherford Institute MAURA R. CREMIN

McDermott Will & Emery LLP

109 Deerwood Road

500 North Capitol Street NW

Charlottesville, VA 22911

Washington, DC 20001

(202) 756-8000

ehtownsend@mwe.com

Counsel for Amicus Curiae

TABLE OF CONTENTS

Interest of Amicus Curiae .................................... 1

Summary of Argument ......................................... 1

Argument .............................................................. 2

I. Geofence warrants are

general warrants of the type the

Fourth Amendment is meant to

protect against ................................................. 2

The

Fourth

Amendment was designed

to prevent the issuance of

general warrants. ................................. 3

B. Geofence warrants

are general warrants. ......................... 11

II. This case offers the court an

opportunity to clarify warrant

requirements

high-tech

searches.

.................................................. 18

A. If geofence warrants

are

not

categorically

unconstitutional, the Court

should

establish

clear

warrant requirements. ....................... 18

B. This case offers an

opportunity to provide

lower courts with guidance

on a range of search tools

that continue to present

challenges after Carpenter. ................ 21

Conclusion ........................................................... 25

TABLE OF AUTHORITIES

Page(s)

Cases

California v. Dawes,

No. 19002022 (Cal. Super. Ct., Cnty.

of S. F., Sept. 30, 2022) (slip op., at

46-49) ....................................................................21

Carpenter v. United States,

585 U.S. 296 (2018) ............ 2, 16, 17, 18, 19, 21, 22

Entick v. Carrington,

19 How. St. Tr. 1029, 95 Eng. Rep.

807 (C.P. 1765) .......................................................6

Huckle v. Money,

19 How. St. Tr. 1404, 95 Eng. Rep.

768 (C.P. 1763) .......................................................5

In re Application of U.S. for an Ord.

Pursuant to 18 USC § 2703(D), 964

F. Supp. 2d 674 (S.D. Tex. 2013) .........................23

In re Cell Tower Recs. Under 18 U.S.C.

§ 2703(D), 90 F. Supp. 3d 673 (S.D.

Tex. 2015) .............................................................23

Maryland v. Pringle,

540 U.S. 366 (2003) ..............................................20

Matter of Search of Info. that is Stored

at Premises Controlled by Google

LLC,

579 F. Supp. 3d 62 (D.D.C. 2021) ........................20

Matter of Search Warrant Application

for Geofence Location Data Stored at

Google Concerning an Arson

Investigation,

497 F. Supp. 3d 345 (N.D. Ill. 2020)..............15, 20

Stanford v. Texas,

379 U.S. 476 (1965) ......................................3, 6, 11

United States v. Chatrie,

590 F. Supp. 3d 901 (E.D. Va. 2022),

aff'd, 107 F.4th 319 (4th Cir. 2024),

on reh’g en banc, 136 F.4th 100 (4th

Cir. 2025), and aff’d, 136 F.4th 100

(4th Cir. 2025). ............................. 12, 13, 14, 15, 19

United States v. Chatrie,

No. 3:19-cr-00130-MHL, 2019 WL

8227162 (E.D.Va. Dec. 20, 2019) ...................13, 14

United States v. Jones,

565 U.S. 400 (2012) (Sotomayor, J.

concurring) ......................................... 16, 18, 21, 22

United States v. Patrick,

842 F.3d 540 (7th Cir. 2016)................................22

United States v. Scott,

No. 14-20780, 2015 WL 4644963

(E.D. Mich. Aug. 5, 2015) ....................................23

iii

United States v. Smith,

110 F.4th 817 (5th Cir. 2024), cert.

denied, 146 S. Ct. 356 (2025) ............. 12, 15, 16, 19

Wells v. State,

714 S.W.3d 614 (Tex. Crim. App.),

reh’g denied, 721 S.W.3d 260 (Tex.

Crim. App. 2025) ..................................................19

Wilkes v. Wood,

98 Eng. Rep. 489 (C.P. 1763) .................................5

Ybarra v. Illinois,

444 U.S. 85 (1979) ................................................20

Constitution & Statutes

1767 Townshend Revenue Act ................................8, 9

Fourth Amendment.... 1, 2, 3, 6, 11, 19, 20, 21, 22, 23,

Bill of Rights..........................................................9, 10

U.S. Const. amend. IV ................................................3

United States Constitution .........................................9

Other Authorities

A. Reed McLeod, Geofence Warrants:

Geolocating the Fourth Amendment,

30 Wm. & Mary Bill Rts. J. 531, 534

(2021) ....................................................................12

Eric Schnapper, Unreasonable Searches

and Seizures of Papers, 71 Va. L.

Rev. 869, 874 (1985)................................. 3, 5, 6, 10

Geofence Warrants and the Fourth

Amendment, 134 Harv. L. Rev. 2508,

2512 (2021) .....................................................12, 13

James Otis, Speech Against the Writs of

Assistance (February 24, 1761) .............................8

Jeremy H. D’Amico, Cellphones,

Stingrays and Searches! An Inquiry

Into the Legality of Cellular Location

Info., 70 U. Miami L. Rev. 1252,

1296 (2016) ...........................................................22

John Dickinson, Letters from a Farmer

in Pennsylvania, Letter IX (The

Outlook Company 1903). .......................................9

Lars Daniel, Google To Stop Giving

Location Evidence To Law

Enforcement .........................................................13

Laura K. Donohue, The Original Fourth

Amendment, 83 U. Chi. L. Rev.

1181, 1208-1209 (2016)

................................................ 3, 4, 6, 7, 8, 9, 10, 11

Marlo McGriff, Updates to Location

History and New Controls Coming

Soon to Maps, Google Keyword Blog

(Dec. 12, 2023)......................................................13

Matthew Hale, 2 Historia Placitorum

Coronae 150 (Nutt and Gosling

1736) .......................................................................4

Matthew L. Brock, “If You Build It,

They Will Come”: Reverse Location

Searches, Data Collection, and the

Fourth Amendment, 57 U. Rich. L.

Rev. 649, 652 (2023)........................... 11, 13, 14, 15

Susan Freiwald & Stephen Wm. Smith,

The Carpenter Chronicle: A NearPerfect Surveillance, 132 Harv. L.

Rev. 205, 229 (2018).......................................22, 23

Thomas Y. Davies, Recovering the

Original Fourth Amendment, 98

Mich. L. Rev. 547, 655 n. 299 (1999) .....................9

William Blackstone, 4 Commentaries on

the Laws of England 287 (Clarendon

1769) .................................................................4, 16

Interest of Amicus Curiae 1

The Rutherford Institute is a nonprofit civil

liberties

organization

headquartered

Charlottesville, Virginia. Founded in 1982 by its

President, John W. Whitehead, the Institute provides

legal assistance at no charge to individuals whose

constitutional rights have been threatened or violated

and educates the public about constitutional and

human rights issues affecting their freedoms. The

Rutherford Institute works tirelessly to resist

tyranny and threats to freedom by seeking to ensure

that the government abides by the rule of law and is

held accountable when it infringes on the rights

guaranteed by the Constitution and laws of the

United States.

Summary of Argument

The Framers wrote the Fourth Amendment to

ensure the persons and property of the American

people would be secure from unreasonable search and

seizure by the federal government. The Framers had

sights trained specifically on general warrants. Those

warrants did not name the person or thing to be

seized, but just gave blanket authority to search for

wrongdoing. Without such guardrails, those warrants

gave Crown officials in England and the American

colonies virtually unrestricted ability to rummage

through the property and papers of individuals.

Outrage at this abuse was central to the colonists’

No counsel for a party authored this brief in whole or in part,

and no entity or person, other than Amicus Curiae, its members,

and its counsel, made a monetary contribution intended to fund

the preparation or submission of this brief. Counsel of record for

the parties received notice of Amicus Curiae’s intent to file this

brief at least 10 days prior to its due date.

decision to declare independence and enshrine their

rights in the Constitution.

But what is old is new again. Law enforcement is

using surveillance systems that search the data of

millions of individuals based on nothing more

incriminating than the fact that they own a cell

phone—the same pervasive piece of property as a

colonist’s quill. The geofence warrants at issue here

are one such example. This tool requires Google to

search the location data of all its users to identify

those who were in a particular place at a particular

time, regardless of whether there is a shred of

evidence linking any user to a crime.

As this Court has recognized, “an individual

maintains a legitimate expectation of privacy in the

record of his physical movements.” Carpenter v.

United States, 585 U.S. 296, 310 (2018). But the Court

has left the precise contours of that right undefined.

As a result, lower courts confronting geofence

warrants adopt divergent and often contradictory

analyses. And this has resulted in Americans’ private

data being subject to search and seizure by the

government without any probable cause. This case

provides the Court with a valuable opportunity to

clarify the scope of Fourth Amendment privacy

protections and head off further encroachments into

the rights of American citizens.

Argument

I. Geofence warrants are general warrants of

the type the Fourth Amendment is meant to

protect against

The Fourth Amendment provides that “[t]he right

of the people to be secure in their persons, houses,

papers, and effects, against unreasonable searches

and seizures, shall not be violated,” and guarantees

that warrants will not be issued except “upon

probable cause * * * and particularly describing the

place to be searched, and the persons or things to be

seized.” U.S. Const. amend. IV. The purpose of this

amendment was to ensure that Americans would

always be protected from “intrusion and seizure by

officers acting under the unbridled authority of a

general warrant.” Stanford v. Texas, 379 U.S. 476,

481 (1965).

A. The Fourth Amendment was designed to

prevent the issuance of general warrants.

“[T]he Fourth Amendment was most immediately

the product of contemporary revulsion against a

regime of writs of assistance.” Stanford, 379 U.S. at

482. Yet “its roots go far deeper.” Ibid. General

warrants have a history stretching back to at least the

16th century. Laura K. Donohue, The Original Fourth

Amendment, 83 U. Chi. L. Rev. 1181, 1208-1209

(2016). These warrants were considered particularly

offensive to individual liberty because they “failed to

name the individual possessing the things to be

searched or seized.” Eric Schnapper, Unreasonable

Searches and Seizures of Papers, 71 Va. L. Rev. 869,

874 (1985).

General warrants were reviled under 18th

century English common law.

General warrants were issued in England during

the Tudor and Stuart periods as part of the Crown’s

efforts to enforce religious orthodoxy and stifle

political dissent. Donohue, The Original Fourth

Amendment, 83 U. Chicago L. Rev. at 1208-1209.

Queen Mary I used them to try to re-establish the

Catholic Church in England. Id. at 1208. Queen

Elizabeth I established a High Commission to target

sedition and slander against the Crown. Id. at 12081209. Among the Commission’s tools were general

warrants. Id. at 1209. James I expanded the

Commission’s powers, and after discovering the

Gunpowder Plot in 1605, he signed two general

warrants to find those responsible. Id. at 1210.

English legal scholars increasingly began to

condemn general warrants. Perhaps the most

prominent critic was the jurist Sir Edward Coke.

Despite having assisted James I in executing general

warrants during the Gunpowder Plot investigations,

Coke became convinced that these warrants were

inimical to English freedoms and argued that they

violated Magna Carta. Id. at 1211-1212. No less a

titan of English jurisprudence than Sir Matthew Hale

stated in his 1736 Historia Placitorum Coronae

(“History of the Pleas of the Crown”) that a “general

warrant to search in all suspected places is not good,

but only to search in such particular places, where the

party assigns before the justice his suspicion and the

probable cause thereof, for these warrants are judicial

acts, and must be granted upon examination of the

fact.” Matthew Hale, 2 Historia Placitorum Coronae

150 (Nutt and Gosling 1736). William Blackstone

cited both Coke and Hale in his analysis of warrants

in the Commentaries. William Blackstone, 4

Commentaries on the Laws of England 287

(Clarendon 1769). Blackstone rejected the validity of

general warrants, stating “[a] general warrant to

apprehend all persons suspected, without naming or

particularly describing any person in special, is illegal

and void for its uncertainty; for it is the duty of the

magistrate, and ought not be left to the officer, to

judge of the ground of suspicion.” Id. at 288.

This growing consensus among 17th and 18th

century legal scholars about the illegality of general

warrants shaped English jurisprudence. The first

reported decision on general warrants, Huckle v.

Money, was issued in 1763. 19 How. St. Tr. 1404, 95

Eng. Rep. 768 (C.P. 1763). In that case, Huckle, a

journeyman printer, was arrested on suspicion of

having printed an allegedly libelous publication. Ibid.

Though Huckle was only detained for six hours and

was treated well while in custody, the jury

nonetheless awarded him £300 in damages. Ibid. The

court sustained the verdict on the ground that Huckle

was arrested under a general warrant, since the

warrant did not specifically order Huckle’s arrest.

Ibid. The Lord Chief Justice condemned the use of

general arrest warrants in strong terms:

To enter a man’s house by virtue of a nameless

warrant, in order to procure evidence, is worse

than the Spanish Inquisition; a law under which

no Englishman would wish to live an hour; it was

a most daring public attack made upon the liberty

of the subject.

Id. at 769.

In the same year, the court decided Wilkes v.

Wood, captioned “The Case of General Warrants.” 98

Eng. Rep. 489 (C.P. 1763); Schnapper, Unreasonable

Searches and Seizures of Papers, at 878. In that case,

government officials suspected that Wilkes, a member

of Parliament, had authored libelous materials, and

searched Wilkes’ home, seizing his papers and

manuscripts. Wilkes, 98 Eng. Rep. 489. The jury

awarded Wilkes damages of £1,000. Ibid. at 499. The

Court again upheld the verdict on the grounds that

the warrant failed to identify the suspect. Ibid. at 498.

In the landmark 1765 case Entick v. Carrington,

the court made clear that even a warrant that named

the individual suspect could be a general warrant if it

failed to identify items to be searched and seized. 19

How. St. Tr. 1029, 95 Eng. Rep. 807 (C.P. 1765).

Entick, who authored a weekly paper, was accused of

seditious libel. Ibid. In an opinion which would serve

as a “wellspring of the rights now protected by the

Fourth Amendment,” Stanford, 379 U.S. at 484, the

court held that the warrant was unlawful because it

failed to identify the items that had been targeted for

search and seizure. Entick v. Carrington, 19 How. St.

Tr. at 1067. Instead, the officers could rifle through

all of Entick’s papers unchecked, which amounted to

an illegal general warrant. Ibid.

Opposition to general warrants was a

cornerstone of the Fourth Amendment.

American colonists had, if anything, an even

greater hatred of search and seizure than their

English counterparts. The declarations of rights in

early colonial charters and constitutions generally

incorporated English common law with respect to

search and seizure. Schnapper, Unreasonable

Searches and Seizures of Papers at 913. During the

17th century, when general warrants were permitted

in England, they were far more restricted in the

colonies. Donohue, The Original Fourth Amendment

at 1241-1242. The general warrants cases in England

received immense publicity in the American colonies

and were the subject of considerable commentary.

Schnapper, Unreasonable Searches and Seizures of

Papers at 913; Donohue, The Original Fourth

Amendment at 1257-1258.

One type of general warrant that was allowed in

the colonies was the so-called writ of assistance,

which provided customs agents with the ability to

search locations ranging from ships and storehouses

to homes to search for goods that did not meet

customs regulations. Donohue, The Original Fourth

Amendment at 1242. The use of writs of assistance led

to escalating conflict between the colonies and the

Crown administration. An instructive case is that of

Edward Randolph, the chief agent of the

commissioners of customs in New England. When

Randolph reported that the Massachusetts Bay

Company was abusing its charter and tolerating

illegal trade, the Crown revoked the Company’s

charter. Ibid. During the 1689 colonial uprising,

Randolph was imprisoned and returned to England.

Id. at 1242-1243. Upon his return to the colonies in

1692, Randolph began investigating nearly all the

major ports in the colonies, relying heavily on general

warrants to identify smuggling, corruption, and poor

record keeping. Id. at 1243. Because of Randolph’s

efforts, Parliament passed new legislation to end

illicit trade in the colonies, which colonial officials

were instructed to enforce using writs of assistance.

Id. at 1242-1243. The result was mounting tension, as

colonists increasingly found their homes and

businesses subject to searches, while they had no

judicial recourse to object. Id. at 1243.

These tensions grew during the French and

Indian War and culminated in the pivotal Paxton’s

Case. In 1755, Governor William Shirley began

directing his customs agents (one of whom was named

Charles Paxton), to use writs of assistance to crack

down on illicit trade with French Canada. Id. at 12461247. By the 1760s, the practice had become widely

accepted, with Lord Chatham, the secretary of state

for the Southern Department, directing the new

Governor of the Province of Massachusetts Bay to use

writs of assistance to stop trade with the French

Indies as well. Id. at 1248.

When the writs of assistance expired in 1761, the

Society for Promoting Trade and Commerce

challenged their renewal. Ibid. The Society was

represented on a pro bono basis by prominent lawyer

James Otis. Id. at 1249. In one of the great orations of

American history, Otis forcefully condemned writs of

assistance as “the worst instrument of arbitrary

power, the most destructive of English liberty and the

fundamental principles of law, that ever was found in

an English law-book.” James Otis, Speech Against the

Writs of Assistance (February 24, 1761). The exercise

of the writ, which “places the liberty of every man in

the hands of every petty officer,” was the kind of

power that had “in former periods of history, cost one

king of England his head and another his throne.”

Ibid.

Otis’s speech received considerable attention and

was credited as helping bring the American public to

support independence. Donohue, The Original Fourth

Amendment at 1250. One particularly enthusiastic

observer of Otis’s speech was a young John Adams,

who later recalled that “[e]very man of an crowded

Audience appeared to me to go away, as I did, ready

to take up Arms against Writs of Assistants.” Id. at

1249.

Outrage at writs of assistance would only grow

with the passage of the 1767 Townshend Revenue Act,

which empowered officials “to enter houses or

warehouses, to search for and seize goods prohibited

to be imported or exported * * * or for which any

duties are payable, or ought to have been paid.”

Donohue, The Original Fourth Amendment at 1260.

The terms of this statute were at odds with practice

in the colonies, where any writs granted tended to be

specific, and American legal treatises treated the

general warrants authorized in the Townshend Act as

illegitimate. Id. at 1260-1261. For example, in his

Letters from a Farmer in Pennsylvania, John

Dickinson described the writ as “an engine of

oppression,” noting that “the greatest asserters of the

rights of Englishmen have always strenuously

contended, that such a power was dangerous to

freedom.” John Dickinson, Letters from a Farmer in

Pennsylvania, Letter IX, at 93 (The Outlook Company

1903).

By the time the colonists declared independence,

there was overwhelming consensus that general

warrants were illegitimate. See Thomas Y. Davies,

Recovering the Original Fourth Amendment, 98 Mich.

L. Rev. 547, 655 n. 299 (1999). Indeed, opposition to

general warrants was so central to the colonists’ sense

of civil liberties that it was incorporated into the

Virginia Declaration of Rights, which significantly

influenced the development of, not only later state

constitutions, but the United States Constitution.

Donohue, The Original Fourth Amendment at 1265.

The Virginia Declaration of Rights, which was passed

in 1776, unequivocally stated that “general

warrants * * * are grievous and oppressive and ought

not to be granted.” Virginia Declaration of Rights

§ 10.

The Founding Fathers’ concern about general

warrants carried through to the drafting of the Bill of

Rights. The Antifederalists condemned the

Constitution for its failure to specify individual

rights. Patrick Henry specifically condemned the

absence of protection against general warrants,

stating

I feel myself distressed because the necessity of

securing our personal rights seems not to have

pervaded the minds of men; for many other

valuable things are omitted:--for instance,

general warrants, by which an officer may search

suspected places, without evidence of the

commission of a fact, or seize any person without

evidence of his crime, ought to be prohibited.

Donohue, The Original Fourth Amendment, at 1286.

States, including New York, Rhode Island, and North

Carolina, likewise insisted on the inclusion of

protections against general warrants in the

constitution. Id. at 1289-1292. The Antifederalists

drew on the English general warrants cases, and

particularly the case of John Wilkes, to argue for

specific protections against general warrants.

Schnapper, Unreasonable Searches and Seizures of

Papers, at 914-915. In the Antifederalist Papers,

Brutus pointed to the threat of general warrants as

emblematic of the risks inherent in the absence of a

Bill of Rights.

For the security of liberty it has been declared,

* * * that all warrants, without oath or

affirmation, to search suspected places, or seize

any person, his papers or property, are grievous

and oppressive.

Brutus, New York Journal (November 1, 1787)

(quotation omitted).

The Antifederalists’ concerns about enshrining

protections for individual liberty, and particularly for

ensuring protection against unlimited search and

seizure, culminated in the inclusion of the Bill of

Rights in the Constitution. Donohue, The Original

Fourth Amendment, at *1297-1298. Not just decades

of colonial experience, but centuries of British legal

reckoning with the abuses of general warrants, led to

the protections which the Fourth Amendment

provides.

B. Geofence warrants are general warrants.

The Framers’ deep aversion to general warrants

was central to the adoption of the Fourth

Amendment. As discussed, the principal evil of these

warrants was the fact that they allowed government

officials “blanket authority to search where they

pleased” for incriminating information, without being

limited to identified individuals, locations, or

materials. Stanford, 379 U.S. at 481. By their very

nature, geofence warrants allow the government to

search unidentified individuals and trace their

movements without any probable cause tying the

subject of the search to a crime. So they are exactly

the sort of general warrant the Fourth Amendment is

designed to protect against.

Geofence warrants, which are a form of reverse

location searching, have been in use since 2016.

Matthew L. Brock, “If You Build It, They Will Come”:

Reverse Location Searches, Data Collection, and the

Fourth Amendment, 57 U. Rich. L. Rev. 649, 652

(2023). These warrants allow law enforcement to use

Location History data stored by third-party

companies to identify electronic devices located

within a particular geographic location within a

particular time. Ibid. Google is the most common

recipient of geofence warrants, largely because of the

treasure trove of data from Android phone users

(approximately 131.2 million Americans) as well as

non-Android users who visit a Google-based apps or

websites such as Google Maps or Google Photos on

their phone. Geofence Warrants and the Fourth

Amendment, 134 Harv. L. Rev. 2508, 2512 (2021); see

also United States v. Chatrie, 590 F. Supp. 3d 901,

908-1209 (E.D. Va. 2022), aff'd, 107 F.4th 319 (4th

Cir. 2024), on reh’g en banc, 136 F.4th 100 (4th Cir.

2025), and aff’d, 136 F.4th 100 (4th Cir. 2025).

Google’s Sensorvault database contains the Location

History data of all Google users that enable Google

Location History services on their Google Accounts. A.

Reed McLeod, Geofence Warrants: Geolocating the

Fourth Amendment, 30 Wm. & Mary Bill Rts. J. 531,

534 (2021). As of 2018, that number was estimated at

592 million, or approximately one-third of all Google

users. United States v. Smith, 110 F.4th 817, 823 (5th

Cir. 2024), cert. denied, 146 S. Ct. 356 (2025); see also

Chatrie, 590 F. Supp. 3d at 907 (“Google collects

detailed location data on ‘numerous tens of millions’

of its users.”).

To protect user privacy, Google has required law

enforcement seeking user Location History data to

obtain a warrant. The basis for seeking a geofence

warrant typically relies on three premises: first, a

criminal perpetrator was either seen with a cell phone

or was assumed to have had one based on the near

universality of cell phone ownership. McLeod,

Geofence Warrants, at 533. Second, many cell phones

either run on Android’s operating system or interface

with a Google Account. Ibid. Third, because of

Google’s market dominance, many phone users have

a Google Account that enables Google location

services. Ibid.

By 2018, Google developed a three-step process

for law enforcement to receive requested data, which

was generally followed by government agencies.

Brock, If You Build It, They Will Come, at 657. Police

seeking judicial approval to search for user data had

to identify some geographic search radius and time

within which the search should be conducted.

Geofence Warrants and the Fourth Amendment, at

2514. Once that approval was obtained, Google

applied its “three-step anonymization and narrowing

protocol.” Id. at 2515. (alterations incorporated). 2

In step one of this process, Google would search

the entirety of Sensorvault for all devices identified

within the parameters of the search. Ibid. Google

would provide law enforcement with an anonymized

list of the accounts, along with coordinates,

timestamps, and source information. Ibid. This was

an intrusive and resource-intensive process. See

Chatrie, 590 F.Supp.3d at 908 (“to identify users

within the relevant timeframe of a geofence, Google

has to compare all the data in the Sensorvault. “); see

also Brief of Google LLC as Amicus Curiae in Support

of Neither Party, United States v. Chatrie, No. 3:19cr-00130-MHL, 2019 WL 8227162, at *12-13 (E.D.Va.

Dec. 20, 2019) (“In order to comply with the first step

of the geofence protocol, .*.*.* Google must search

across all LH journal entries to identify users with

potentially responsive LH data, and then run a

Google announced in December 2023 that it was transitioning

Local History data to its users’ local devices, rather than in the

Sensorvault database and Google no longer uses the same threestep process. See Marlo McGriff, Updates to Location History

and New Controls Coming Soon to Maps, Google Keyword Blog

(Dec. 12, 2023), https://perma.cc/QA3X-LQT2; Lars Daniel,

Google To Stop Giving Location Evidence To Law Enforcement,

Forbes (Oct. 08, 2024),

https://perma.cc/2ULX-2R4U.

computation against every set of coordinates to

determine which LH records match the time and

space parameters in the warrant.”).

In step two, law enforcement would review the

anonymized data to identify the devices it is

interested in. Ibid. Law enforcement could request

additional location information for certain devices at

this stage to determine whether those devices were

relevant to the investigation. Ibid. Though Google

was not required to respond to this request unless the

warrant explicitly includes it, Google often did so.

Ibid. At this step, law enforcement could “compel

Google to provide additional location coordinates

beyond the time and geographic scope of the original

request.” Chatrie, 590 F. Supp. 3d at 916 (cleaned up).

And while Google “typically require[d] law

enforcement to narrow the number of users for which

it requests Step 2 data,” “Google ha[d] no firm policy

as to precisely when a Step 2 request [was]

sufficiently narrow.” Ibid. Assuming Google did not

object to the government’s request, at this stage they

would provide the government with “de-identified but

geographically unrestricted data.” Ibid.

In step three, law enforcement could “compel

Google to provide account-identifying information,”

including names and email addresses for the

individuals the government deems relevant to the

investigation. Ibid. (cleaned up). While Google seems

to have preferred the government narrow down its list

of users from Step 2, there is no policy enforcing this

preference. Brock, If You Build It, They Will Come, at

658-659. With the information procured at step three,

law enforcement could pursue leads against identified

individuals, including by securing warrants for more

intrusive investigative methods. Smith, 110 F.4th at

825.

Despite Google’s attempts to limit government

access to its users’ information, this process does not

pass constitutional muster. Geofence warrants do not

identify the individuals whose device locations are to

be searched, which means that everyone within the

set geographical boundaries at the identified time is

subject to having their movements traced by the

government, regardless of whether there is any

evidence tying them to a crime. Brock, If You Build It,

They Will Come, at 652. In considering facts very

similar to those at issue in Chatrie, the Fifth Circuit

held that the process by which geofence warrants are

executed necessarily involves searching through the

personal information of individuals who are not

suspected of any crime.

When law enforcement submits a geofence

warrant to Google, * * * 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

given

point

time * * * 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.

Smith, 110 F.4th at 837. Nor did it matter that the

government could tie the information sought to a

particular time and place—“[w]hile the results of a

geofence warrant may be narrowly tailored,

the search itself is not.” Ibid. This sort of unrestricted

rummaging is “emblematic of general warrants and

[is] highly suspect per se.” Id. at 838. (quotations

omitted).

The Fifth Circuit traced this Court’s precedent in

Carpenter and Jones with respect to the “privacy

interests inherent in location data,” the dangers of

“the government being able to comprehensively track

a person’s movement with relative ease due to the

ubiquity of cell phone possession,” and the limitations

of the third-party doctrine. Smith, 110 F.4th at 832,

834-835. Based on this analysis, the Fifth Circuit

concluded that the geofence warrant constituted a

search. Id. at 836.

Having established that the examination of

Location History data constituted a search, the Fifth

Circuit then carefully analyzed geofence warrants as

general warrants, recognizing that because these

warrants “never include a specific user to be

identified, only a temporal and geographic location

where any given user may turn up post-search,” they

are “constitutionally insufficient.” Id. at 837.

The Fifth Circuit’s approach follows the

understanding of general warrants that informed the

Founders. Eighteenth century legal thinkers on both

sides of the Atlantic rejected general warrants

because they allowed law enforcement officers to

rummage through the private lives of individuals

without linking them to a crime. See supra at 3-10. In

Blackstone’s words, “it is the duty of the magistrate,

and ought not be left to the officer, to judge of the

ground of suspicion.” Blackstone, Commentaries at

287. Yet geofence warrants place all assessment of the

grounds of suspicion in the hands of law enforcement,

since the warrant itself identifies no individual

suspect. Indeed, that is the whole point of the

warrant—to allow the government to review the

movements of a universe of private citizens to identify

those who might become suspects. That process

cannot be sufficiently particularized to pass

constitutional muster.

The overbreadth of geofence warrants is

compounded by the fact that law enforcement’s

rationale for obtaining these warrants has no limiting

principal. As discussed supra at 11, law enforcement

often applies for geofence warrants based on the

likelihood that criminals carry cell phones, given their

ubiquity in modern life. And this Court has

recognized that cell phones have become “almost a

feature of human anatomy.” Carpenter, 585 U.S. at

311. (citation omitted). That argument discards even

the pretense of particularity. If a warrant can be

obtained to search the movements of everyone in a

given area based on the likely fact that someone who

was in that area probably has a cell phone, the

government effectively has carte blanche to demand

site-tracking information on anyone at any time. It

would be as if an eighteenth-century judge had

determined that since virtually everyone had a quill

pen, the disseminators of seditious pamphlets likely

also had quill pens, and therefore searching

individuals based on quill pen ownership was

justified. That logic would make a judge of the Star

Chamber blush, yet its analogue continues to be

employed in the modern day. The ubiquity of cell

phones means government searches of unidentified

cell-phone users should be treated with greater, not

lesser, suspicion, to guard against wanton

government intrusion into the private lives of

citizens.

The Fifth Circuit’s approach is also consistent

with the principles this Court has established in other

cases about surveillance technology. In Carpenter,

this Court recognized that an individual has a

“reasonable expectation of privacy in the whole of his

physical movements.” 585 U.S. at 313. Surveillance

devices, from GPS tracking to cell-site location

information threaten that right by allowing the

government to “generate[] a precise, comprehensive

record of a person’s public movements that reflects a

wealth of detail about her familial, political,

professional, religious, and sexual associations.”

United States v. Jones, 565 U.S. 400, 415 (2012)

(Sotomayor, J. concurring). In both Carpenter and

Jones, law enforcement surveillance targeted an

identified individual who was suspected of a crime.

But here, the intrusive power of government

surveillance may be applied to any unfortunate

person who happens to be in the wrong place at the

wrong time carrying a cell phone. Such intrusion

based on a general warrant is not only plainly

unconstitutional, but a threat to the fundamental

right to privacy.

II. This case offers the court an opportunity to

clarify warrant requirements in high-tech

searches.

A. If geofence warrants are not categorically

unconstitutional, the Court should establish

clear warrant requirements.

This Court recognized in Carpenter that the

gathering of cell phone data “implicates privacy

concerns” because it is “about a detailed chronicle of a

person’s physical presence compiled every day, every

moment, over several years.” 585 U.S. at 315. Yet the

court’s decision in Carpenter was “a narrow one,”

declining to review surveillance tools like real-time

cell-site location information and “tower dumps,” or to

“address other business records that might

incidentally reveal location information.” Ibid. at 316.

As a result, lower courts have been left with limited

guidance on the constitutionality of increasingly

intrusive forms of surveillance technology. The result

has been not only a split among the circuits on the

constitutionality of geofence warrants, but a split

between some state and federal courts. Compare

Smith, 110 F.4th at 838 (finding that geofence

warrants are “categorically prohibited by the Fourth

Amendment.”) with Chatrie, 136 F.4th 100, 100 (en

banc)(per curiam) (affirming the lower court’s denial

of the motion to suppress a geofence warrant), and

Wells v. State, 714 S.W.3d 614, 626 (Tex. Crim. App.),

reh’g denied, 721 S.W.3d 260 (Tex. Crim. App. 2025)

(finding that the geofence search warrant satisfied

the Fourth Amendment’s requirements). The

resulting patchwork of rules has led to inconsistent

protections for citizens’ privacy rights depending on

where they are located and what law enforcement

body happens to be monitoring them.

Even if this Court finds that geofence warrants are

not per se unconstitutional, the Court should

establish clear requirements for these warrants. As

geofence warrants become an increasingly prevalent

part of government investigations, such requirements

will be necessary to protect citizens’ privacy rights.

And given the sweeping amount of data that is

collected in geofence searches, see supra at 10-11, it is

vital that lower courts and law enforcement officials

have guidance on constitutional requirements.

At a minimum, the Court should establish clear

guidelines for meeting the standards of particularized

probable cause necessary to satisfy the Fourth

Amendment in geofence warrant cases. This court has

held that to support a finding of probable cause, “the

belief of guilt must be particularized with respect to

the person to be searched or seized.” Maryland v.

Pringle, 540 U.S. 366, 371 (2003). “[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 v.

Illinois, 444 U.S. 85, 91 (1979).

This means that warrants that broadly sweep in

the data of private citizens, even if they likely also

include a suspect’s data, cannot survive Fourth

Amendment scrutiny. Some lower courts have

addressed this issue by requiring that warrants be

written to narrowly circumscribe the time and place

in which data can be searched. See Matter of Search

Warrant Application for Geofence Location Data

Stored at Google Concerning an Arson Investigation,

497 F. Supp. 3d 345, 357 (N.D. Ill. 2020) (finding that

a warrant adequately particularized where it was

limited to a 15-30 minute time frame and where

target locations were “narrowly crafted to ensure that

location data, with a fair probability, will capture

evidence of the crime only.”); Matter of Search of Info.

that is Stored at Premises Controlled by Google LLC,

579 F. Supp. 3d 62, 82 (D.D.C. 2021) (geofence

warrant was adequately particularized where it was

limited to 185 minutes of data spread out over a fiveand-a-half month period and was limited in space to

the front half of a building and its parking lot, since

the “inquiry here is whether the target locations are

drawn to capture location data from locations at or

closely associated with the crime.”) (cleaned up). By

establishing clear particularity requirements for

geofence warrants, the Court will at least limit the

ability of the state to gather the data of citizens who

are not suspected of any crime.

The Court could further strengthen the protection

for individual privacy by instantiating Google’s threestep process and requiring that law enforcement

secure judicial authorization at each step. Rather

than grant law enforcement unbridled discretion to

demand increasingly revealing user information, a

three-step warrant process would ensure judicial

oversight as law enforcement’s searches become more

intrusive. See California v. Dawes, No. 19002022 (Cal.

Super. Ct., Cnty. of S. F., Sept. 30, 2022) (slip op., at

46-49) (finding that Google’s “three-step process

afforded law enforcement unbridled discretion, and at

each step, law enforcement should have returned for

additional judicial review and authorization.”). Such

a rule, though not foreclosing geofence warrants

entirely, would at least ensure that individual privacy

interests are overseen by a neutral magistrate at

every step of the search process.

B. This case offers an opportunity to provide

lower courts with guidance on a range of

search tools that continue to present

challenges after Carpenter.

The risks that high-tech surveillance poses to

individual privacy are not limited to geofence

searches. This Court has addressed the privacy

concerns arising from law enforcement use of location

data in both Jones and Carpenter. In Jones, the Court

held that the physical attachment of a GPS

monitoring device to a vehicle constituted a search

under the Fourth Amendment. Jones, 565 U.S. at 404.

In Carpenter, the Court held that seven days’ worth

of data monitoring an individual’s movements via

cell-site location information was a search and was

not subject to the third-party doctrine. Carpenter, 585

U.S. at 315-316.

Still, the Court’s decisions in those cases left open

many questions about their broader applications. See

Jones, 565 U.S. at 424-425 (Alito, J. concurring)

(observing that “if long-term monitoring can be

accomplished without committing a technical

trespass * * * the Court’s theory would provide no

protection.”). In Carpenter, the Court stated that its

“decision today is a narrow one. We do not express a

view on matters not before us.” 585 U.S. at 316. With

such narrow rulings, lower courts are still facing

increasingly difficult questions about how to define

technological intrusion into Fourth Amendment

protections.

One example of these technological challenges is

cell-site simulators. Cell-site simulators work by

“superseding the signal emitted from a service

provider’s cell site within an area, causing all mobile

devices to register with it instead of the cell site.”

Jeremy H. D’Amico, Cellphones, Stingrays and

Searches! An Inquiry Into the Legality of Cellular

Location Info., 70 U. Miami L. Rev. 1252, 1296 (2016).

Because law enforcement generates the data, which

can be gathered indiscriminately, some scholars

argue that the use of cell-site simulators “raises the

specter of an illegal general warrant.” Susan Freiwald

& Stephen Wm. Smith, The Carpenter Chronicle: A

Near-Perfect Surveillance, 132 Harv. L. Rev. 205, 229

(2018); but see United States v. Patrick, 842 F.3d 540,

545 (7th Cir. 2016) (upholding the use of cell-site

simulator data to execute a location warrant,

reasoning that “[a] person wanted on probable cause

(and an arrest warrant) who is taken into custody in

a public place, where he had no legitimate expectation

of privacy, cannot complain about how the police

learned his location.”).

Similar issues are raised by cell tower dumps, in

which law enforcement obtains an order “compelling

providers to release historical cell site data for a

specific tower or towers providing service to a crime

scene.” Freiwald & Smith, The Carpenter Chronicle,

at 229. Because the police gather data from all cell

phones within a given geographical area, this

technology also “raises general warrant concerns that

were not present in Carpenter.” Ibid. Lower courts are

divided on the degree of constitutional protection

afforded historical cell site data. Compare, e.g., In re

Cell Tower Recs. Under 18 U.S.C. § 2703(D), 90 F.

Supp. 3d 673, 675 (S.D. Tex. 2015) (“cell tower logs

requested here would likewise be categorized as

ordinary business records entitled to no constitutional

protection.”) and United States v. Scott, No. 14-20780,

2015 WL 4644963, at *7 (E.D. Mich. Aug. 5,

2015)(defendant “did not have a reasonable

expectation of privacy in the data that revealed the

general historical location of his cell phone for, at

most, a ninety-minute period on a single morning.”)

with In re Application of U.S. for an Ord. Pursuant to

18 USC § 2703(D), 964 F. Supp. 2d 674, 677 (S.D. Tex.

2013) (holding that “cell site data are protected

pursuant to the Fourth Amendment from warrantless

searches.”)

As surveillance technology continues to develop,

lower courts will be forced to define the limits of

Fourth Amendment protection. In the absence of

guidance, this is likely to result in inconsistent

protections for individual rights to privacy

throughout the nation. That is already the case for

geofence warrants, as the circuit split and federalstate divide on this question have made clear. The

Court can take the opportunity presented here to

provide lower courts with valuable guidance on how

to treat the fast-developing field of surveillance

technology consistent with the protections of the

Fourth Amendment. Such an approach would not

only instruct the lower courts but would also reassure

American citizens of the robustness of their

constitutional protections.

Conclusion

The Court should reverse the judgment of the

Fourth Circuit en banc panel.

Respectfully submitted.