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 OF AMERICA,

Respondent.

——————————

ON WRIT OF CERTIORARI

TO THE UNITED STATES COURT OF APPEALS

FOR THE FOURTH CIRCUIT

——————————

BRIEF OF THE POLICING PROJECT AT

NEW YORK UNIVERSITY SCHOOL OF LAW

AS AMICUS CURIAE IN SUPPORT OF

NEITHER PARTY

——————————

BARRY FRIEDMAN

MARIA PONOMARENKO

MAX ISAACS

KATIE KINSEY

POLICING PROJECT AT

NYU SCHOOL OF LAW

40 Washington Sq. S.

New York, NY 10012

NICHOLAS ROSELLINI

Counsel of Record

LATHAM & WATKINS LLP

500 Montgomery Street

Suite 2000

San Francisco, CA 94111

(415) 395-8165

nick.rosellini@lw.com

SUMER GHAZALA

MAHSHAD BADII

LATHAM & WATKINS LLP

555 11th Street, NW

Suite 1000

Washington, DC 20004

Counsel for Amicus Curiae

TABLE OF CONTENTS

Page

TABLE OF AUTHORITIES ..................................... iii

INTEREST OF AMICUS CURIAE ............................1

INTRODUCTION AND SUMMARY OF

ARGUMENT .........................................................2

ARGUMENT ...............................................................3

RAPIDLY ADVANCING TECHNOLOGY

POSES

DIFFICULT

FOURTH

AMENDMENT

QUESTIONS

THAT

CALL FOR CAUTION IN DECIDING

THIS CASE ...........................................................3

A. Modern Technologies Offer Promise

For Policing And Peril For Civil

Liberties...........................................................4

B. A Rigid All-Or-Nothing Approach To

These Critical Issues Is Undesirable ...........10

II. THIS CASE SHOULD BE RESOLVED

NARROWLY

NOT

EMBARRASS THE FUTURE ............................16

A. Obtaining Users’ Location History Was

A Fourth Amendment “Search” ....................17

B. The Ultimate Touchstone Of The

Fourth Amendment Is Reasonableness .......21

TABLE OF CONTENTS—Continued

Page

1. Precedent Permits Departures

From The Usual Requirement Of A

Warrant Supported By Probable

Cause .......................................................21

2. The Court Should Conduct A

Reasonableness Analysis Informed

By The Unique Nature Of These

Investigative Tools..................................23

III. THE COURT’S ANALYSIS CAN AND

SHOULD

STRUCTURED

ENCOURAGE LEGISLATION ..........................26

A. This Court Has Tools To Promote

Urgently Needed Legislative Action ............27

B. Tying

The

Fourth

Amendment

Analysis To Compliance With A

Constitutionally Adequate Statutory

Scheme Would Encourage Legislation .........29

C. Unresolved Statutory Questions Could

Impact The Constitutional Analysis In

This Case .......................................................32

CONCLUSION ..........................................................34

iii

TABLE OF AUTHORITIES

Page(s)

CASES

Barnes v. Felix,

605 U.S. 73 (2025) ..................................................1

Berger v. New York,

388 U.S. 41 (1967) ..........................................27, 28

Brigham City v. Stuart,

547 U.S. 398 (2006) ..........................................3, 21

Brinegar v. United States,

338 U.S. 160 (1949) ..............................................24

California v. Acevedo,

500 U.S. 565 (1991) ..............................................15

California v. Ciraolo,

476 U.S. 207 (1986) ................................................4

Camara v. Municipal Court of the City &

County of San Francisco,

387 U.S. 523 (1967) ............................ 21, 22, 25, 29

Carpenter v. United States,

585 U.S. 296 (2018) ................... 3-4, 6-7, 11-13, 17,

19-20, 23, 27-28, 32

City of Los Angeles v. Patel,

576 U.S. 409 (2015) ........................................30, 33

Commonwealth v. Almonor,

120 N.E.3d 1183 (Mass. 2019) .............................11

Commonwealth v. Wilkerson,

156 N.E.3d 754 (Mass. 2020) ...............................11

TABLE OF AUTHORITIES—Continued

Page(s)

Commonwealth v. Yusuf,

173 N.E.3d 378 (Mass. 2021) ...............................14

Delaware v. Prouse,

440 U.S. 648 (1979) ..............................................26

Donovan v. Dewey,

452 U.S. 594 (1981) ..............................................29

Illinois v. Lidster,

540 U.S. 419 (2004) ........................................22, 25

Katz v. United States,

389 U.S. 347 (1967) ..............................................10

Kyllo v. United States,

533 U.S. 27 (2001) .................................. 3, 4, 10, 19

Leaders of a Beautiful Struggle v. Baltimore

Police Department,

2 F.4th 330 (4th Cir. 2021) ..........................7, 8, 12

Maryland v. King,

569 U.S. 435 (2013) .................................. 22, 23, 25

Michigan Department of State Police v. Sitz,

496 U.S. 444 (1990) ..............................................22

New York v. Burger,

482 U.S. 691 (1987) .............................. 3, 22, 26, 29

Olson v. County of Grant,

127 F.4th 1193 (9th Cir. 2025) ............................14

People v. Harris,

92 N.Y.S.3d 863 (N.Y. Sup. Ct. 2019) .................11

TABLE OF AUTHORITIES—Continued

Page(s)

People v. Jiles,

68 N.Y.S.3d 787 (N.Y. App. Div. 2017) ...............11

Riley v. California,

573 U.S. 373 (2014) .............................. 4, 20, 24, 33

Stanford v. Texas,

379 U.S. 476 (1965) ..............................................24

United States v. Dionisio,

410 U.S. 1 (1973) ..................................................12

United States v. Jackson,

No. 21-CR-331, 2022 WL 1498191 (M.D.

Ala. Mar. 15, 2022) ..............................................11

United States v. Jones,

565 U.S. 400 (2012) .................. 8, 11, 12, 18, 27, 28

United States v. Knotts,

460 U.S. 276 (1983) ................................................9

United States v. Microsoft,

584 U.S. 236 (2018) ................................................1

United States v. Riley,

858 F.3d 1012 (6th Cir. 2017)..............................11

Virginia v. Moore,

553 U.S. 164 (2008) ..............................................30

STATUTES

U.S. Const. amend. IV ..............................................21

18 U.S.C. §§ 2510-2522 .............................................28

18 U.S.C. § 2703 ........................................................32

TABLE OF AUTHORITIES—Continued

Page(s)

18 U.S.C. § 2703(a)..............................................30, 33

18 U.S.C. § 2703(b)....................................................30

18 U.S.C. § 2703(c) ....................................................30

18 U.S.C. § 2703(d)....................................................30

Pub. L. No. 90-351, Title III, 82 Stat. 197, 211

(1968) ....................................................................28

Md. Code Ann., Crim. Proc. § 2-503(a)(i) .................31

Mont. Code Ann. § 44-15-106(2)(a) ...........................31

Tenn. Code Ann. § 55-10-302(b) ...............................32

Utah Code Ann. § 41-6a-2004 ...................................32

Utah Code Ann. § 77-23e-103(2)(c)(i) .......................31

Va. Code Ann. § 19.2-70.3 .........................................32

Va. Code Ann. § 19.2-70.3(C) ....................................33

OTHER AUTHORITIES

AI and policing: The benefits and challenges

of artificial intelligence for law

enforcement, Europol Innovation Lab

(2024), https://www.europol.europa.eu/

cms/sites/default/files/documents/AI-andpolicing.pdf. ............................................................5

Anthony G. Amsterdam, Perspectives on the

Fourth Amendment, 58 Minn L Rev 349

(1974) ....................................................................11

vii

TABLE OF AUTHORITIES—Continued

Page(s)

Devlin Barrett, Gun-Show Customers’ License

Plates Come Under Scrutiny, Wall St. J.

(Oct. 2, 2016), https://www.wsj.com/

articles/gun-show-customers-licenseplates-come-under-scrutiny-1475451302 ..............8

Nicole M. Bennett, When the government can

see everything: How one company Palantir - is mapping the nation’s data,

The Conversation (Aug. 27, 2025),

https://theconversation.com/when-thegovernment-can-see-everything-how-onecompany-palantir-is-mapping-the-nationsdata-263178 ...........................................................7

Tebah Browne & Barry Scheck, Regulating

Forensic Investigative Genetic Genealogy:

The Case for Judicial Oversight and the

Bipartisan Model Legislation Passed in

Maryland, The Judges’ Journal (June 11,

2024), https://www.americanbar.org/

groups/judicial/resources/judges-journal/

2024-spring/regulating-forensicinvestigative-genetic-genealogy ............................4

Garance Burke & Jason Dearen, How an

obscure cellphone tracking tool provides

police ‘mass surveillance on a budget’, PBS

News (Sept. 1, 2022), https://www.pbs.org/

newshour/politics/how-an-obscurecellphone-tracking-tool-provides-policemass-surveillance-on-a-budget ...........................14

viii

TABLE OF AUTHORITIES—Continued

Page(s)

Danielle Keats Citron, The Fight for Privacy

(2022) ....................................................................13

Combine knowledge graphs and large

language models to speed up criminal

network analysis, GraphAware (July 28,

2025), https://graphaware.com/blog/

combine-knowledge-graphs-and-llms-tospeed-up-crime-analysis ........................................6

Joseph Cox, Police Are Buying Access to

Hacked Website Data, Vice (July 8, 2020),

https://www.vice.com/en/article/policebuying-hacked-data-spycloud ..............................14

3 Debates in the Several Conventions on the

Adoption of the Federal Constitution

(Jonathan Elliot ed., 1974) ....................................6

Jonathan Dienst, Ransomware Attack at NJ

County Police Department Locks Up

Criminal Investigative Files, NBC New

York (Apr. 7, 2023),

https://www.nbcnewyork.com/

investigations/ransomware-attack-at-njcounty-police-department-locks-upcriminal-investigative-files/4219341 ...................10

Matt Egan, AI helped the feds catch $1 billion

of fraud in one year. And it’s just getting

started, CNN (Oct. 17, 2024),

https://www.cnn.com/2024/10/17/

business/ai-fraud-treasury ....................................5

TABLE OF AUTHORITIES—Continued

Page(s)

Matt Egan, AI is Uncle Sam’s new secret

weapon to fight fraud, CNN (Feb. 28,

2024), https://www.cnn.com/2024/

02/28/business/artificial-intelligencefraud-treasury-ai/index.html.................................5

Bridget A. Fahey, Data Federalism, 135 Harv.

L. Rev. 1007 (2022) ................................................7

Andrew Guthrie Ferguson, Video Analytics

and Fourth Amendment Vision, 103 Tex.

L. Rev. 1253 (2025) ..........................................5, 15

Barry Friedman, The Constitutionality of

Indiscriminate Data Surveillance, 174 U.

Pa. L. Rev. 293 (2026) ............. 11, 13, 15-17, 30-32

Barry Friedman, Lawless Surveillance, 97

N.Y.U. L. Rev. 1143 (2022) ...................... 30, 31, 32

Barry Friedman et al., Policing Police Tech: A

Soft Law Solution, 37 Berkeley Tech. L.J.

701 (2022) ...............................................................9

Georgia Gee, Un-Alarmed: AI Tries (and

Fails) to Detect Weapons in Schools, The

Intercept (May 7, 2023),

https://theintercept.com/2023/05/07/aigun-weapons-detection-schools-evolv ...................9

TABLE OF AUTHORITIES—Continued

Page(s)

Adam Goldman & Matt Apuzzo, With

Cameras, Informants, NYPD Eyed

Mosques, Associated Press (Feb. 23, 2012),

https://www.ap.org/media-center/ap-inthe-news/2012/with-cameras-informantsnypd-eyed-mosques ................................................8

Drew Harwell & Craig Timberg, How

America’s surveillance networks helped the

FBI catch the Capitol mob, Wash. Post

(Apr. 2, 2021),

https://www.washingtonpost.com/

technology/2021/04/02/capitol-siegearrests-technology-fbi-privacy ...............................5

Tonja Jacobi & Dustin Stonecipher, A

Solution for the Third-Party Doctrine in A

Time of Data Sharing, Contact Tracing,

and Mass Surveillance, 97 Notre Dame L.

Rev 823 (2022) .....................................................13

Zolan Kanno-Youngs, U.S. Watched George

Floyd Protests in 15 Cities Using Aerial

Surveillance, N.Y. Times (June 19, 2020),

https://www.nytimes.com/2020/06/19/

us/politics/george-floyd-protestssurveillance.html ...................................................8

Orin Kerr, The Case for the Third-Party

Doctrine, 107 Mich. L. Rev. 561 (2009) ...............16

TABLE OF AUTHORITIES—Continued

Page(s)

Tim Lau, Predictive Policing Explained,

Brennan Ctr. for Just. (Apr. 1, 2020),

https://www.brennancenter.org/ourwork/research-reports/predictive-policingexplained ................................................................6

Liberty and Security in a Changing World:

Report and Recommendations of The

President’s Review Group on Intelligence

and Communications Technologies (Dec.

12, 2013), https://obamawhitehouse.

archives.gov/sites/default/files/docs/201312-12_rg_final_report.pdf ....................................20

Erin Murphy, The Politics of Privacy in the

Criminal Justice System: Information

Disclosure, the Fourth Amendment, and

Statutory Law Enforcement Exemptions,

111 Mich. L. Rev. 485 (2013). .................. 26, 31, 32

Alfred Ng, DHS accused of using surveillance

tech to track legal observers in Maine,

Politico (Feb. 23, 2026),

https://www.politico.com/news/2026/02/23/

dhs-accused-of-using-surveillance-tech-totrack-legal-observers-in-maine-00792722 ............8

Off. of the Dir. of Nat'l Intel., Senior Advisory

Grp., Panel on Commercially Available

Info., Report to the Director of National

Intelligence (2022), https://perma.cc/BE3L8A5L .....................................................................13

xii

TABLE OF AUTHORITIES—Continued

Page(s)

Shira Ovide, Scanning Technology is coming

to Detect Child Porn. Here’s what it means,

Wash. Post (June 24, 2025),

https://www.washingtonpost.com/

technology/2025/06/24/child-sex-abusecrime-fighting-technology ......................................5

Aaron Parseghian, Controversial technology

helped investigators track gunman in

Brown University and MIT professor

shootings, CBS News (Dec. 19, 2025),

https://www.cbsnews.com/boston/news/

brown-university-mit-professor-shootingflock-cameras-car ...................................................4

Police chief gets caught, WKRC (Aug. 18,

2024), https://local12.com/news/nationworld/police-chief-gets-caught-usinglicense-plate-cameras-to-track-his-exgirlfriend-228-times-arrests-chargesprobation-flock-safety-follow-stalk-newboyfriend-broke-up-out-of-town-misuse ..............10

Vanessa Romo, No Charges for Colorado

Officers Who Held Black Children At

Gunpoint, NPR (Jan. 8, 2021),

https://www.npr.org/2021/01/08/

955165485/no-charges-for-coloradoofficers-who-held-black-children-atgunpoint .................................................................9

Carey Shenkman et al., Legal Loopholes and

Data for Dollars (2021),

https://perma.cc/4DJA-93GD...............................13

xiii

TABLE OF AUTHORITIES—Continued

Page(s)

Christopher Slobogin, The Liberal Assault on

the Fourth Amendment, 4 Ohio St. J.

Crim. L. 603 (2007) ..............................................16

Christopher Slobogin, Virtual Searches:

Regulating the Covert World of

Technological Policing (2022) ..............................30

Christopher Slobogin & Sarah Brayne,

Surveillance Technologies and

Constitutional Law, 6 Ann. R. Crim. 219

(2023) ......................................................................9

State of Minn. Off. of the Legis. Auditor,

Law Enforcement’s Use Of State

Databases (2013),

https://www.auditor.leg.state.mn.us/

ped/pedrep/ledatabase.pdf ...................................10

Zach Whittaker, A hack at ODIN Intelligence

exposes a huge trove of police raid files,

TechCrunch (Jan. 21, 2023),

https://techcrunch.com/2023/01/21/odinintelligence-breach-police-surveillance/. .............10

INTEREST OF AMICUS CURIAE

The Policing Project at New York University

School of Law is dedicated to strengthening policing

through democratic governance.1

The Project

facilitates public engagement on policing policies and

practices, with the twin aims of giving communities a

voice in how they are policed and developing greater

mutual trust between them and law enforcement.

The Project is committed to the proper governance of

emerging policing technologies in ways that advance

public safety while safeguarding civil liberties. The

Project works with law enforcement to develop rules

governing use of these technologies, promotes the

adoption of legislative frameworks to govern them,

and has a keen interest in their proper treatment

under the Fourth Amendment. The Project has

previously filed merits-stage amicus briefs addressing

these issues in United States v. Microsoft, 584 U.S.

236 (2018), and Barnes v. Felix, 605 U.S. 73 (2025).

The Policing Project is affiliated with New York

University School of Law, but this brief does not purport to

represent the school’s official views. No counsel for any party

authored this brief in whole or in part, and no party, counsel for

a party, or person or entity other than amicus curiae, its

members, and its counsel made a monetary contribution

intended to fund the brief’s preparation or submission.

INTRODUCTION AND

SUMMARY OF ARGUMENT

By obtaining Location History data belonging to

Okello Chatrie and innocent Google users while

investigating a bank robbery, the Government

conducted a search of their personal “papers” under

the Fourth Amendment. Chatrie argues that the

geofence warrant issued here is an unconstitutional

“general warrant” because it required searching

Google’s entire Location History database. The

Government takes the polar opposite view, insisting

that obtaining Google users’ Location History did not

even implicate the Fourth Amendment.

This Court should reject both extremes. Given the

availability of massive data and AI-powered analytic

tools, the Government’s request for carte blanche to

use them with no judicial supervision or

constitutional safeguards imperils all our liberties.

But Chatrie’s approach is flawed as well. Data-driven

tools can help identify people who have done—or

would do—great harm.

Deeming any order

authorizing use of these tools an unconstitutional

general warrant, such that they cannot be used at all,

would impede legitimate law enforcement activities.

Fortunately, this Court’s jurisprudence compels

neither extreme. Although warrants supported by

probable cause make sense for traditional searches,

novel investigative techniques call for novel solutions.

Reverse-identification tools—i.e., methods for

identifying unknown suspects, rather than obtaining

evidence against known suspects—do not fit neatly

within the usual Fourth Amendment framework. Nor

do the many rapidly emerging technologies that soon

will find their way before this Court. Given the

potential benefits to public safety from some of these

tools, but also the enormous risks to personal liberties

and security, the Court should decide this case

narrowly, so as not to “embarrass the future.”

Carpenter v. United States, 585 U.S. 296, 316 (2018).

“[T]he ultimate touchstone of the Fourth Amendment

is ‘reasonableness,’” after all. Brigham City v. Stuart,

547 U.S. 398, 403 (2006).

The solution to the challenges posed by rapidly

advancing technology is, at least in the first instance,

legislative.

The complex nature of data-driven

investigation and surveillance methods cries out for

statutory regulation. And legislative frameworks will

make the Fourth Amendment analysis easier by

enabling courts to determine whether the governing

statute establishes a constitutionally “adequate

substitute for a warrant.” New York v. Burger, 482

U.S. 691, 702-03 (1987). A balanced decision in this

case—one making clear that the Fourth Amendment

applies, while inviting deference to compliance with

adequate statutory safeguards—would encourage

much-needed legislative action.

ARGUMENT

I. RAPIDLY

ADVANCING

TECHNOLOGY

POSES DIFFICULT FOURTH AMENDMENT

QUESTIONS THAT CALL FOR CAUTION IN

DECIDING THIS CASE

This case once again requires this Court to

confront the “power of technology to shrink the realm

of [constitutionally] guaranteed privacy.” Kyllo v.

United States, 533 U.S. 27, 34 (2001). That crucial

task requires this Court to “tread carefully.”

Carpenter v. United States, 585 U.S. 296, 316 (2018).

With that in mind, the Court should reject an

all-or-nothing approach to the question presented.

Modern Technologies Offer Promise For

Policing And Peril For Civil Liberties

Over the last half century, this Court has grappled

repeatedly with Fourth Amendment questions raised

by technological advances, including investigation

and surveillance carried out using aircraft, thermal

imagers, smartphones, and cell-site location data.

See, e.g., California v. Ciraolo, 476 U.S. 207, 209

(1986); Kyllo, 533 U.S. at 29; Riley v. California, 573

U.S. 373, 384-85 (2014); Carpenter, 585 U.S. at 305.

The pace of innovation is increasing rapidly, with

great promise for policing and grave peril for civil

liberties.

1. Cutting-edge investigation methods, driven

by new and powerful advances in artificial

intelligence (AI), are reshaping law enforcement in

ways that have assisted criminal investigations and

protected public safety.

To name just a few examples, officers deployed

automated license plate readers to help identify the

Brown University gunman.2 Investigators identified

the “Golden State Killer” using AI-powered genealogy

tools.3 Authorities have used AI scanning technology

See Aaron Parseghian, Controversial technology helped

investigators track gunman in Brown University and MIT

professor

shootings,

CBS

News

(Dec.

19,

2025),

https://www.cbsnews.com/boston/news/brown-university-mitprofessor-shooting-flock-cameras-car.

Tebah Browne & Barry Scheck, Regulating Forensic

Investigative Genetic Genealogy: The Case for Judicial Oversight

and the Bipartisan Model Legislation Passed in Maryland, The

Judges’ Journal (June 11, 2024), https://www.americanbar.org/

to identify online child grooming and sexual abuse

material.4 Sophisticated algorithms have helped

detect billions of dollars’ worth of financial crimes.5

Meanwhile, face- and voice-recognition systems have

facilitated the rescue of kidnapping victims and the

arrest of January 6 rioters.6

Many of these law enforcement tools rely

increasingly on anomaly detection systems, which

flag deviations from expected patterns to help officers

detect theft, fraud, and other illegal activities that

otherwise might escape notice. See Andrew Guthrie

Ferguson, Video Analytics and Fourth Amendment

Vision, 103 Tex. L. Rev. 1253, 1275-76 (2025). Some

AI-powered technologies even purport to forecast

groups/judicial/resources/judges-journal/2024-spring/regulatingforensic-investigative-genetic-genealogy (login required).

Shira Ovide, Scanning Technology is coming to Detect

Child Porn. Here’s what it means, Wash. Post (June 24, 2025),

https://www.washingtonpost.com/technology/2025/06/24/childsex-abuse-crime-fighting-technology.

Matt Egan, AI helped the feds catch $1 billion of

fraud in one year. And it’s just getting started, CNN (Oct. 17,

2024),

https://www.cnn.com/2024/10/17/business/ai-fraudtreasury; Matt Egan, AI is Uncle Sam’s new secret weapon to

fight fraud, CNN (Feb. 28, 2024), https://www.cnn.com/

2024/02/28/business/artificial-intelligence-fraud-treasury-ai/

index.html.

Drew Harwell & Craig Timberg, How America’s

surveillance networks helped the FBI catch the Capitol mob,

Wash. Post (Apr. 2, 2021), https://www.washingtonpost.com/

technology/2021/04/02/capitol-siege-arrests-technology-fbi-privacy;

AI and policing: The benefits and challenges of artificial

intelligence for law enforcement 24, Europol Innovation Lab

(2024),

https://www.europol.europa.eu/cms/sites/default/files/

documents/AI-and-policing.pdf.

where future crimes may occur—and who will commit

them.7

2. The very same data-driven investigative and

surveillance tools can present serious threats to

privacy and civil liberties. These “seismic shifts in

digital technology” offer considerable promise for

effective policing and public safety precisely because

they have “made possible the tracking” of almost

every facet of American life. Carpenter, 585 U.S. at

313. That unprecedented capability threatens the

Fourth Amendment’s dual aims of “secur[ing] ‘the

privacies of life’ against ‘arbitrary power’” and

“‘plac[ing] obstacles in the way of a too permeating

police surveillance.’” Id. at 305. Those bedrock

constitutional values must not be left to “‘the mercy of

advancing technology.’” Id.

These threats are not abstract—they are

unfolding now. By compiling internet browsing

history, purchase records, biometric data, and social

media activity, today’s AI-powered surveillance

technology generates a “detailed, encyclopedic, and

effortlessly compiled” portrait of each of us. Id. at

309. It allows officers to “[m]easure[] everything you

eat, drink, and wear.” 3 Debates in the Several

Conventions on the Adoption of the Federal

Constitution 448-49 (Jonathan Elliot ed., 1974). And

it empowers them to discern a person’s friends,

family, colleagues, and associates with remarkable

accuracy.8

Tim Lau, Predictive Policing Explained, Brennan Ctr.

for Just. (Apr. 1, 2020), https://www.brennancenter.org/ourwork/research-reports/predictive-policing-explained.

Combine knowledge graphs and large language models

to speed up criminal network analysis, GraphAware (July 28,

Such synthesis risks exposing all of our “familial,

political, professional, religious, and sexual

associations.” Carpenter, 585 U.S. at 311. Extended

data retention magnifies this concern: The more data

sits and accumulates, the more revealing it can

become. Increasingly, law enforcement agencies are

aggregating data from various databases and other

sources, analyzing it with AI-powered tools, and

capturing “an intimate window” into our lives.

Carpenter, 585 U.S. at 311; see also Bridget A. Fahey,

Data Federalism, 135 Harv. L. Rev. 1007, 1017 (2022).

New investigative platforms offered by private

technology companies empower law enforcement

officers to “take[] fragmented data, scattered across

various agencies and stored in different formats, and

transform[] it into a unified searchable web.”9

Baltimore police, for instance, recently pooled data

from aerial cameras, CCTV, and license plate readers,

“‘mak[ing] all the systems work together’” to “glean

insights from the whole of individuals’ movements.”

Leaders of a Beautiful Struggle v. Balt. Police Dep’t, 2

F.4th 330, 344-45 (4th Cir. 2021).

Even for one-off events, technologies like location

tracking and facial recognition software pose risks.

Such tools can identify people visiting sensitive

locations, like private residences, healthcare

2025), https://graphaware.com/blog/combine-knowledge-graphsand-llms-to-speed-up-crime-analysis.

Nicole M. Bennett, When the government can see

everything: How one company – Palantir – is mapping the

nation’s data, The Conversation (Aug. 27, 2025),

https://theconversation.com/when-the-government-can-seeeverything-how-one-company-palantir-is-mapping-the-nationsdata-263178.

facilities, places of worship, and political rallies. See

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

(Sotomayor, J., concurring). Officers already have

come under scrutiny for using such tools for tracking

attendees at gun shows and mosques.10 So too with

their efforts to surveil and track demonstrators

following George Floyd’s death in 202011—and, more

recently, anti-ICE protesters.12

The geographic reach and temporal scope of

modern surveillance methods—especially “persistent

surveillance” techniques—are nothing short of

remarkable. Baltimore’s “Persistent Surveillance

System” filmed 90% of the city, 40 hours a week, for

six months. See Leaders of a Beautiful Struggle, 2

F.4th at 334. Each image taken over that period could

have been “magnified to a point where people and cars

[we]re individually visible,” giving officers the power

to track nearly every resident of Baltimore wherever

they went. Id. It is scarcely an exaggeration to say

that authorities can now conduct “twenty-four hour

Devlin Barrett, Gun-Show Customers’ License Plates

Come Under Scrutiny, Wall St. J. (Oct. 2, 2016),

https://www.wsj.com/articles/gun-show-customers-license-platescome-under-scrutiny-1475451302 (login required); Adam

Goldman & Matt Apuzzo, With Cameras, Informants,

NYPD Eyed Mosques, Associated Press (Feb. 23,

2012),

https://www.ap.org/media-center/ap-in-the-news/2012/

with-cameras-informants-nypd-eyed-mosques.

Zolan Kanno-Youngs, U.S. Watched George Floyd

Protests in 15 Cities Using Aerial Surveillance, N.Y. Times

(June 19, 2020), https://www.nytimes.com/2020/06/19/us/politics/

george-floyd-protests-surveillance.html.

Alfred Ng, DHS accused of using surveillance tech to

track legal observers in Maine, Politico (Feb. 23, 2026),

https://www.politico.com/news/2026/02/23/dhs-accused-of-usingsurveillance-tech-to-track-legal-observers-in-maine-00792722.

surveillance” of not just “any citizen of this country,”

United States v. Knotts, 460 U.S. 276, 283 (1983), but

all of them—all at once.

3. Modern technologies pose another kind of

threat: Even the most advanced systems fail often,

further jeopardizing the public’s sense of safety and

trust in law enforcement.

For example, an

AI-powered weapons-detection system deployed in

New York misidentified a child’s lunchbox as a bomb,

while failing to detect an actual knife carried by

another student.13 And in Colorado, a woman and

four children were pulled over and detained at

gunpoint after a license-plate reader misidentified

her SUV as a stolen motorcycle.14 Such mistakes

underscore a broader problem: “[T]he effectiveness of

these surveillance technologies in achieving the

government’s aims is largely unstudied, as is their

empirical validity and reliability.”

Christopher

Slobogin & Sarah Brayne, Surveillance Technologies

and Constitutional Law, 6 Ann. R. Crim. 219, 220

(2023); see Barry Friedman et al., Policing Police

Tech: A Soft Law Solution, 37 Berkeley Tech. L.J. 701,

710 (2022).

The danger of data misuse compounds these

concerns. Some officers have used law enforcement

databases improperly to collect information on former

See Georgia Gee, Un-Alarmed: AI Tries (and Fails) to

Detect Weapons in Schools, The Intercept (May 7, 2023),

https://theintercept.com/2023/05/07/ai-gun-weapons-detectionschools-evolv (login required).

Vanessa Romo, No Charges for Colorado Officers

Who Held Black Children At Gunpoint, NPR (Jan. 8,

2021), https://www.npr.org/2021/01/08/955165485/no-chargesfor-colorado-officers-who-held-black-children-at-gunpoint.

romantic partners, business associates, neighbors,

and journalists—all for purely private reasons.15 And

security breaches are not uncommon. In one case,

hackers attacked a police software vendor and stole

nearly twenty gigabytes of highly sensitive data.16

Numerous police departments themselves have been

the target of ransomware attacks.17

A Rigid All-Or-Nothing Approach To

These Critical Issues Is Undesirable

To assess law enforcement activities, this Court’s

Fourth Amendment precedents require answering

two main questions: (1) “whether or not a Fourth

Amendment ‘search’ [or seizure] has occurred” and, if

so, (2) whether that search or seizure was

“unreasonable.” Kyllo, 533 U.S. at 31-33. Searches

and seizures are usually “per se unreasonable”

without a warrant supported by probable cause. Katz

v. United States, 389 U.S. 347, 357 (1967). That

See, e.g., State of Minn. Off. of the Legis. Auditor,

Law Enforcement’s Use Of State Databases 26 (2013),

https://www.auditor.leg.state.mn.us/ped/pedrep/ledatabase.pdf;

Police chief gets caught, WKRC (Aug. 18, 2024),

https://local12.com/news/nation-world/police-chief-gets-caughtusing-license-plate-cameras-to-track-his-ex-girlfriend-228-timesarrests-charges-probation-flock-safety-follow-stalk-new-boyfriendbroke-up-out-of-town-misuse.

Zach Whittaker, A hack at ODIN Intelligence exposes a

huge trove of police raid files, TechCrunch (Jan. 21, 2023),

https://techcrunch.com/2023/01/21/odin-intelligence-breach-policesurveillance/.

See, e.g., Jonathan Dienst, Ransomware Attack at

NJ County Police Department Locks Up Criminal

Investigative Files, NBC New York (Apr. 7, 2023),

https://www.nbcnewyork.com/investigations/ransomware-attackat-nj-county-police-department-locks-up-criminal-investigativefiles/4219341.

general rule creates an all-or-nothing problem: On

the one hand, “[t]o label any police activity a ‘search’

or ‘seizure’ is to” require probable cause and a

warrant. Anthony G. Amsterdam, Perspectives on the

Fourth Amendment, 58 Minn L Rev 349, 388 (1974).

Given how these new technologies operate, that may

disable their use altogether. On the other hand, if use

of a new technology is deemed neither a search nor a

seizure, “it is subject to no significant restrictions of

any kind.”

Id.; see Barry Friedman, The

Constitutionality

Indiscriminate

Data

Surveillance, 174 U. Pa. L. Rev. 293, 347 (2026). This

doctrinal dynamic poses dilemmas at both steps of the

Fourth Amendment analysis.

1. In recent cases involving data-driven policing,

the threshold question whether the Government has

conducted a search or seizure has required assessing,

in effect, how much is too much. See Carpenter, 585

U.S. at 310 n.3 (declining to decide “how long” location

data must be tracked to become a search). This mode

of analysis poses “vexing problems.” Jones, 565 U.S.

at 412. Courts are struggling to apply it, often

reaching contradictory results.18

The task will

Compare People v. Harris, 92 N.Y.S.3d 863, 866-67 (N.Y.

Sup. Ct. 2019) (three days of cell site location information (CSLI)

was a search), with People v. Jiles, 68 N.Y.S.3d 787, 791 (N.Y.

App. Div. 2017) (four days of CSLI was not a search); compare

Commonwealth v. Wilkerson, 156 N.E.3d 754, 765-66 (Mass.

2020) (six hours of CSLI was a search), with United States v.

Jackson, No. 21-CR-331, 2022 WL 1498191, at *4 (M.D. Ala.

Mar. 15, 2022) (six hours of GPS tracking was not a search);

compare Commonwealth v. Almonor, 120 N.E.3d 1183, 1197

(Mass. 2019) (single ping of cell phone was a search), with United

States v. Riley, 858 F.3d 1012, 1018 (6th Cir. 2017) (single ping

was not a search).

become only more difficult as digital tools diversify in

kind and advance in scale and precision.

The first fault line, one this Court already has

confronted, concerns duration. Carpenter addressed

CSLI obtained from wireless providers, which enables

officers to reconstruct an individual cell phone user’s

movements over time. 585 U.S. at 300-01. The Court

held that “accessing seven days of CSLI constitutes a

Fourth Amendment search,” while leaving open the

possibility that accessing CSLI for a “more limited”

period would not. Id. at 310 n.3; see Jones, 565 U.S.

at 430 (Alito, J., concurring) (concluding that “the

point at which the tracking of this vehicle became a

search” was “surely crossed before the 4-week mark”).

Courts also are grappling with the “how much is

too much” question in the context of non-continuous

data collection. Baltimore’s persistent surveillance

program, for instance, was limited to daylight hours.

Leaders of a Beautiful Struggle, 2 F.4th at 342-43.

And as discussed, even one-off snapshots can disclose

sensitive details. Supra at 7-8.

Technological advancement also raises new

questions about what kind of data is constitutionally

protected. Case in point: Carpenter acknowledged the

traditional rule that “an individual has no reasonable

expectation of privacy in [his] public movements,” but

recognized that “pervasive tracking” made effortless

by CSLI required a different result. 585 U.S. at

314-15. Similarly, while the Fourth Amendment has

generally been understood not to shield a person’s

“facial characteristics” or “voice,” United States v.

Dionisio, 410 U.S. 1, 14 (1973), widespread use of

face- and voice-recognition technology still might

invite constitutional scrutiny. So too for social media:

Viewing one public Facebook post might warrant

different legal treatment than mining years of online

activity to build a comprehensive dossier of a person’s

belief system. Tonja Jacobi & Dustin Stonecipher, A

Solution for the Third-Party Doctrine in A Time of

Data Sharing, Contact Tracing, and Mass

Surveillance, 97 Notre Dame L. Rev 823, 825-26, 880

(2022).

The realities of modern technology also are

making application of the third-party doctrine more

problematic. Carpenter recognized that people do not

“voluntarily” share CSLI in any meaningful sense,

because carrying a phone is such a “pervasive and

insistent part of daily life.” 585 U.S. at 315. And

countless people download apps to store and use

personal data to improve their health, deepen

relationships, and ease their lives—while reasonably

expecting that their data will not be shared with the

Government. See Friedman, Constitutionality, supra,

at 300, 309-11; infra at 18-19.

Still more difficult questions arise when, rather

than collecting data themselves, officers buy location

data, browsing histories, and consumer profiles on the

open market.19 The scale of data available for officers

to purchase is staggering: As of 2020, more than

4,000 data brokers had dossiers on 98% of

Americans.20 And some vendors advertise “billions”

of location data points going back 180-plus days, far

Off. of the Dir. of Nat’l Intel., Senior Advisory Grp.,

Panel on Commercially Available Info., Report to the Director of

National Intelligence 19-20 (2022), https://perma.cc/BE3L-8A5L.

Danielle Keats Citron, The Fight for Privacy 11 (2022);

see Carey Shenkman et al., Legal Loopholes and Data for Dollars

10, 22 (2021), https://perma.cc/4DJA-93GD.

exceeding Carpenter’s seven-day threshold.21 Some

agencies have even purchased stolen data.22 If

subpoenaing certain data constitutes a search, what

about simply buying and holding it indefinitely?

Courts also are grappling with how even lawfully

obtained data can be used later on. Some already

have held that the initial collection and subsequent

use of data are distinct Fourth Amendment events,

each of which demands constitutional scrutiny. See

Olson v. County of Grant, 127 F.4th 1193, 1199 (9th

Cir. 2025) (holding that examining cell phone data

beyond the scope of the original consent violated the

Fourth Amendment); Commonwealth v. Yusuf, 173

N.E.3d 378, 395-97 (Mass. 2021) (same for reviewing

lawfully recorded body-camera footage of a residence

in connection with an unrelated investigation).

Whether these courts’ analysis is correct holds

significant consequences for both policing and

personal privacy.

2. Assessing the “reasonableness” of modern

data-driven

investigation

and

surveillance

techniques presents its own difficulties.

If a warrant supported by probable cause is

required for all indiscriminately collected data,

critical investigations may never get off the ground.

Traditional investigations generally proceed from a

See Garance Burke & Jason Dearen, How an obscure

cellphone tracking tool provides police ‘mass surveillance on a

budget’, PBS News (Sept. 1, 2022), https://www.pbs.org/

newshour/politics/how-an-obscure-cellphone-tracking-tool-providespolice-mass-surveillance-on-a-budget.

Joseph Cox, Police Are Buying Access to Hacked Website

Data, Vice (July 8, 2020), https://www.vice.com/en/article/policebuying-hacked-data-spycloud.

known suspect to incriminating evidence. But digital

investigations often proceed in reverse—from masses

of data to a previously unknown perpetrator. An

officer might trawl through a biometric database,

deploy algorithms to crawl social media posts, or

conduct persistent aerial surveillance to discern

individuals traveling to and from a crime scene. But

because the perpetrator’s identity is precisely what

the officer seeks, requiring probable cause before

these identification methods may be used can impose

an impossible prerequisite. Forbidding these kinds of

searches would result in a Fourth Amendment that

permits far more invasive techniques without a

warrant—stakeouts, pat-downs, covert recording—

while barring preliminary digital queries that

represent a far “less intrusive step.” California v.

Acevedo, 500 U.S. 565, 584 (1991) (Scalia, J.,

concurring in the judgment).

Even more elusive—but increasingly common—

are data uses based on no particularized suspicion

whatsoever. These include efforts to detect anomalies

or make predictions, both of which can involve

intrusive investigations into personal data. See

Ferguson, supra, at 1308-10, 1318.

Situations where useful data is found on thirdparty servers pose even more difficulty. Supra at

13-14.

Officers often rely on various kinds of

third-party data early in an investigation—before

probable cause exists—to develop leads and identify

suspects. Some private companies holding such data

will happily comply with government requests,

without regard for privacy interests—a problem in its

own right. See Friedman, Constitutionality, supra, at

312-13. But many others will not comply absent a

court order, on the theory that “[p]rotecting customer

privacy is good for business.” Orin Kerr, The Case for

the Third-Party Doctrine, 107 Mich. L. Rev. 561, 598

(2009). Imposing a blanket warrant-supported-byprobable-cause requirement—as opposed to some

other sort of predicate, see infra at 30-31—would

hamstring legitimate law enforcement attempts to

obtain evidence from third parties.

As a doctrinal matter, then, “rigid adherence” to

the traditional warrant requirement places enormous

pressure on judges deciding the threshold question

whether a search occurred in the first place.

Christopher Slobogin, The Liberal Assault on the

Fourth Amendment, 4 Ohio St. J. Crim. L. 603, 607

(2007). Under that regime, “the only way” for courts

to preserve vital investigative tools is “to deny that

what the police or prosecutors are doing constitutes a

‘search.’” Friedman, Constitutionality, supra, at 319.

Invasive law enforcement activities could thus go

completely unregulated.

See Slobogin, Liberal

Assault, supra, at 607. An absolutist approach risks

giving us a Fourth Amendment that either becomes

less protective as modern investigation and

surveillance techniques grow more sophisticated, or

becomes a straightjacket prohibiting the use of

valuable investigative tools.

Either path is

intolerable, but there is another way.

II. THIS CASE SHOULD BE RESOLVED

NARROWLY SO AS NOT TO EMBARRASS

THE FUTURE

In this case, the parties stake out diametrically

opposed positions. The Government argues that

obtaining geofence data was no search at all because

users “voluntarily” disclosed their Location History to

Google, and the Government sought only two hours’

worth of location data within a confined perimeter.

BIO.10. Chatrie’s top-line position, by contrast, is

that Location History can never be constitutionally

obtained because any warrant authorizing such a

search is a per se unconstitutional “general warrant”

authorizing “the search of millions of separate

accounts.” Pet’r.Br.42-43.

This Court should chart a middle course. Geofence

warrants like this one are neither totally immune

from Fourth Amendment scrutiny nor irredeemably

unconstitutional. The Court should hold that, at

every step, obtaining Google users’ Location History

constituted a search. But the Court then should

evaluate the search’s reasonableness under

something other than the requirement for a

traditional warrant based on probable cause. This

approach accounts for both the promise and peril of

modern investigative techniques. See Friedman,

Constitutionality, supra. A narrow decision along

these lines will avoid “embarrass[ing] the future” as

technology continues to advance. Carpenter, 585

U.S. at 316.

Obtaining Users’ Location History Was A

Fourth Amendment “Search”

When the Government obtained users’ Location

History from Google, it conducted a search under the

Fourth Amendment.

1. The Fourth Amendment protects people from

government searches of their “papers.” Google users’

Location History fits comfortably within that text.

Today, mobile apps and online platforms serve as

digital substitutes for the journaling and

correspondence that historically was done on physical

“papers.” Apps let us interact with loved ones, store

photographs, track our reading and listening habits,

and organize ideas for professional and creative

projects. While some apps require that we enter

information manually, many now collect personal

data automatically through various sensors. Fitness

apps record our step counts, running routes, and sleep

patterns; navigation apps log our driving routes and

daily routines; and health apps track our heart rates

and other medical data. And they do so automatically

without further action.

That is precisely what Google users do with their

Location History.

This detailed compilation of

personal movements, though “acquire[d] and store[d]”

on Google’s services, is created for users’ personal

benefit. Pet.App.270a. A user’s Location History “is

off by default,” but users can opt in, manage retention,

and export or delete records as they see fit.

Pet.App.273a, 281a-84a. When users opt in, Location

History chronicles their movements in a “sweeping,

granular, and comprehensive” way. Pet.App.270a.

Google users accordingly have both a property

interest and a reasonable expectation of privacy in

their Location History. See Jones, 565 U.S. at 409.

They possess core property rights in their Location

History, including the right to use, enjoy, dispose, and

exclude—and their contractual relationship with

Google made clear that Google was just a bailee. See

Pet’r.Br.15-22. Google users also reasonably expect

that this detailed log of their precise movements—

pinpointed to within three meters and collected every

two minutes—would remain protected from prying

eyes, especially the Government’s. Id. at 22-25.

It should be of no consequence that this personal

recordkeeping is accomplished through modern

mobile devices, rather than ballpoint pens and paper

(or quill and parchment, for that matter). Though

virtual, they are “papers” nonetheless—and as such

are entitled to Fourth Amendment protection. Any

other conclusion would fall short of protecting the

“degree of privacy” that “existed when the Fourth

Amendment was adopted.” Kyllo, 533 U.S. at 34.

In this regard, Location History differs materially

from the CSLI considered in Carpenter. CSLI is a

“species of business record.” Carpenter, 585 U.S. at

318. “Wireless carriers collect and store [it] for their

own business purposes, including finding weak spots

in their network and applying ‘roaming’ charges when

another carrier routes data through their cell sites.”

Id. at 301.

Location History, by contrast, “is not a business

record, but a journal of a user’s location and travels

that is created, edited, and stored by and for the

benefit of Google users.”

JA15 (capitalization

normalized); see Pet.App.268a n.5. As explained, it is

a digitized personal record stored in the user’s

password-protected account, at the user’s behest,

analogous to “emails on Google’s Gmail service” and

“documents on Google Drive.” JA20. The user

maintains full control and can “review, edit, or delete”

their data as they please. Pet.App.281a, 283a. If that

does not qualify as someone’s personal “papers,”

nothing does.

2. It also makes no difference that users’

Location History was stored on Google’s servers.

“Even our most private documents—those that, in

other eras, we would have locked safely in a desk

drawer or destroyed—now reside on third party

servers.” Carpenter, 585 U.S. at 387 (Gorsuch, J.,

dissenting). Location History fits that description: It

is a comprehensive “digital record” of users’ physical

movements. Riley, 573 U.S. at 395. The subset of

Location History data obtained in this case could have

swept in users’ journeys to private residences,

hospitals, houses of worship, or political rallies.

Pet.App.296a; see Pet.App.299a-300a. And for those

users whose data was de-anonymized, the

Government could have connected them to all of these

sensitive places. See Pet.App.296a, 300a-01a.

Nor does it matter that Google may have used

users’ Location History for limited and consented-to

purposes. Smartphones “are ‘such a pervasive and

insistent part of daily life’ that carrying one is

indispensable to participation in modern society.”

Carpenter, 585 U.S. at 315. Today, people should

have the “ability to use such services and the right to

maintain their privacy when they do so.” Liberty and

Security in a Changing World: Report and

Recommendations of The President’s Review Group on

Intelligence and Communications Technologies

111-12 (Dec. 12, 2013), https://obamawhitehouse.

archives.gov/sites/default/files/docs/2013-12-12_rg_

final_report.pdf. A contractual bargain with private

companies to perform the necessary functions of

modern life in exchange for allowing the provider

some use of the data cannot defensibly be deemed a

wholesale waiver of Fourth Amendment protection in

a modern “free society.” Id. Now more than ever,

“[c]onsenting to give a third party access to private

papers is not the same thing as consenting to a search

of those papers by the government.” Carpenter, 585

U.S. at 390 (Gorsuch, J., dissenting) (emphasis

omitted).

The Ultimate Touchstone Of The Fourth

Amendment Is Reasonableness

Because collecting Google users’ Location History

was a search of their “papers,” the Court must grapple

with whether that search was “reasonable.”

U.S. Const. amend. IV. While this Court’s precedents

have required a warrant supported by probable cause

for traditional searches, they also recognize that “the

ultimate touchstone of the Fourth Amendment is

‘reasonableness.’”

Brigham City v. Stuart, 547

U.S. 398, 403 (2006). That flexibility leaves room for

carefully tailored, context-specific rules for modern,

data-driven investigation and surveillance methods.

1. Precedent Permits Departures From

The Usual Requirement Of A

Warrant Supported By Probable

Cause

Time and again, this Court has recognized that

certain investigative techniques do not fit the

traditional

warrant-supported-by-probable-cause

model. But rather than declare such techniques

categorically unconstitutional, the Court has adopted

alternative doctrinal frameworks to assess their

reasonableness under the Fourth Amendment.

Start with Camara v. Municipal Court of the City

& County of San Francisco, 387 U.S. 523 (1967).

There, a housing inspector attempted to conduct a

“routine annual inspection” of an apartment building

without a warrant. Id. at 526-27. Such inspections

were essential to prevent the “unintentional

development of conditions which are hazardous to

public health and safety”—but also posed “significant

intrusions upon the interests protected by the Fourth

Amendment.” Id. at 533-35. To accommodate both

concerns, the Court held that a neutral authority

could issue “area” warrants based not on

individualized suspicion, but on generalized criteria

standards”—such as “the passage of time, the nature

of the building, or the condition of the area.” Id. at

538-39; accord New York v. Burger, 482 U.S. 691,

702-03 (1987) (upholding warrantless searches for

“closely regulated” businesses so long as “inspection

program” provides “a constitutionally adequate

substitute for a warrant”).

This Court also has upheld many programmatic

checkpoint searches. In Michigan Department of

State Police v. Sitz, the Court upheld a drunk-driving

prevention program where “[a]ll vehicles passing

through a checkpoint would be stopped and their

drivers briefly examined for signs of intoxication.”

496 U.S. 444, 447 (1990). The Court reached that

conclusion by balancing “the State’s interest in

preventing drunken driving, the extent to which this

system can reasonably be said to advance that

interest, and the degree of intrusion upon individual

motorists who are briefly stopped.” Id. at 455. It

emphasized that “checkpoints are selected pursuant

to [state] guidelines,” thus constraining individual

officer discretion. Id. at 453. And in Illinois v.

Lidster, the Court upheld a police checkpoint seeking

help identifying the perpetrator of a fatal hit-and-run

accident that occurred nearby. 540 U.S. 419, 422

(2004). Thus, “the stop’s objective was to help find the

perpetrator of a specific and known crime, not of

unknown crimes of a general sort.” Id. at 427.

More recently, in Maryland v. King, the Court

upheld the collection and analysis of DNA samples

from detainees via buccal swab, conducted pursuant

to a state statute. 569 U.S. 435, 440-41 (2013). The

Court emphasized that “the touchstone of the Fourth

Amendment is reasonableness, not individualized

suspicion.” Id. at 448. After weighing the “minor

intrusion” of the buccal swab against the “significant

state interests” in identifying arrestees, the Court

concluded that “DNA identification of arrestees is a

reasonable search that can be considered part of a

routine booking procedure.” Id. at 465.

These cases underscore the ability of the Fourth

Amendment’s

reasonableness

requirement

accommodate novel measures to ensure public safety,

while still guarding against “arbitrary invasions by

governmental officials.” Carpenter, 585 U.S. at 303.

2. The Court Should Conduct A

Reasonableness Analysis Informed

By The Unique Nature Of These

Investigative Tools

The Government obtained Location History for

several Google users (including Chatrie) by following

a three-step process designed by Google for handling

law

enforcement

requests

for

user

data.

Pet.App.286a-91a. At Step One, a magistrate issued

a geofence warrant directing Google to disclose

anonymized Location History data for “every device”

within a 150-meter radius of the crime scene during a

one-hour window. Pet.App.294a-95a. At Step Two,

Google provided expanded data for nine users

covering two hours and removing all geographic

limits,

without

further

judicial

approval.

Pet.App.296a, 299a-300a. At Step Three, again

without consulting a judge, Google gave the

Government identifying information for three likely

suspects. Pet.App.290a-91a, 300a-01a. Rather than

being constrained by the traditional warrant

approach, this Court should assess the search’s

reasonableness in keeping with the Fourth

Amendment’s core purpose of protecting people from

“officers’ whim or caprice.” Brinegar v. United States,

338 U.S. 160, 176 (1949).

1. Chatrie argues that the geofence warrant

issued at Step One was a per se unconstitutional

“general warrant” because it “did not identify the

‘place to be searched’ with particularity but instead

authorized the search of millions of distinct ‘places.’”

Pet’r.Br.32. But on that understanding, location data

maintained in a database like Google’s can never be

constitutionally obtained, even with a warrant. Id.

“The sheer breadth” of that position “is disquieting.”

Pet.App.30a (Wilkinson, J., concurring). And it is

wrong: The targeted geofence warrant here was not

a “general warrant.”

During the Founding Era, general warrants

granted officers unfettered discretion to “rummage

through homes in an unrestrained search for evidence

of criminal activity.” Riley, 573 U.S. at 403. By

contrast, the geofence warrant here was tied to a

specific crime that occurred at a particular time and

place. Pet.App.291a-92a. The warrant also specified

with precision the items to be seized: anonymous

location data associated with devices within 150

meters of the bank when the robbery was committed.

Pet.App.294a-95a. And Google, not the Government,

accessed the database where the data was kept. That

targeted procedure is a far cry from the “blanket

authority to search where [officers] pleased” that “had

so bedeviled the colonists” during the Founding Era.

Stanford v. Texas, 379 U.S. 476, 481 (1965); see

Pet.App.18a.

2. The question remains whether obtaining

users’ Location History in this case was “reasonable.”

This Court could sensibly resolve the question either

way. However the Court resolves the issue, though,

it should structure the analysis in a way that

encourages sorely needed legislative direction.

For several reasons, the search arguably was

reasonable. A neutral magistrate approved a staged

process where the “objective was to help find the

perpetrator of a specific and known crime.” Lidster,

540 U.S. at 427. That process swept in relatively few

users (nineteen) in the initial geofence warrant, while

imposing a relatively “minor intrusion” given the

steps taken to preserve their anonymity. King, 569

U.S. at 465. Additional Location History data was

disclosed for only a subset of those potential suspects.

And data was ultimately de-anonymized only for the

three users whose movements suggested involvement

in the robbery.

At the same time, a “neutral magistrate” did not

conduct an “individualized review” of the

Government’s expanded requests at Steps Two and

Three. Camara, 387 U.S. at 532-33. Crucial stages of

the investigatory process were left to ad hoc

negotiations between the Government and Google,

with no legally established rules and procedures for

them to resolve disputes. No “statutory safeguards”

were placed on the Government’s ability to use or

retain the data it received. King, 569 U.S. at 465.

Whatever the Court concludes, its holding should

be framed narrowly. Not all geofence warrants are as

limited as this one. Some demands for Location

History data have been extremely broad, threatening

to sweep in thousands of users had Google not refused

to comply. See Google Amicus Br. 22-26 (compiling

examples). And not every company is Google. Many

will lack the gumption or resources to resist demands

for sensitive data—and some, like data brokers, have

a profit motive to give the Government whatever it

wants. Accordingly, the Court should keep in mind

the broader landscape of bulk-data surveillance,

much of which lacks a close nexus to a specific crime.

Supra at 14-15.

Ultimately, it will fall on this Court to determine

whether and how these tools can be lawfully used.

But the Court need not go it alone. Legislative bodies

can establish a constitutionally “adequate substitute

for a warrant” by fashioning detailed rules and

procedures to govern the use of cutting-edge

investigation and surveillance techniques. Burger,

482 U.S. at 702-03. Looking to such legislative

guidance

assess

Fourth

Amendment

reasonableness would permit effective policing, while

guarding against the kind of “standardless and

unconstrained discretion” deplored by the Framers.

Delaware v. Prouse, 440 U.S. 648, 661 (1979).

III. THE COURT’S ANALYSIS CAN

SHOULD

STRUCTURED

ENCOURAGE LEGISLATION

AND

Regulating privacy in the twenty-first century “is

simply too complex” to leave to one branch alone. Erin

Murphy, The Politics of Privacy in the Criminal

Justice System: Information Disclosure, the Fourth

Amendment, and Statutory Law Enforcement

Exemptions, 111 Mich. L. Rev. 485, 537-38 (2013).

Fortunately, this Court can decide this case—and

others still to come—in a way that helps push

Congress and other legislative bodies to assume their

share of the regulatory burden.

This Court Has Tools To Promote

Urgently Needed Legislative Action

“In

circumstances

involving

dramatic

technological change, the best solution to privacy

concerns may be legislative.” Jones, 565 U.S. at 429

(Alito, J., concurring in the judgment). “A legislative

body,” after all, “is well situated to gauge changing

public attitudes, to draw detailed lines, and to balance

privacy and public safety in a comprehensive way.”

Id. at 429-30. It is “positive law,” not “judicial

intuition,” that can provide the most nuanced and

“detailed guidance on evolving technologies.”

Carpenter, 585 U.S. at 394, 402 (Gorsuch, J.,

dissenting); see id. at 338 (Kennedy, J., dissenting)

(urging deference to legislative judgments).

Legislation

essential

for

data-driven

investigation and surveillance methods.

Such

methods increasingly involve obtaining the data of

individuals for whom there is no suspicion. See supra

at 14-15. Data is collected and held, often for long

periods of time, and then analyzed using tools that

themselves involve varying degrees of intrusiveness.

See id. And the utility of these tools often depends on

private entities’ business decisions about what data to

collect—and whether to disclose it. See id. What is

needed are clear rules that set appropriate bounds for

law enforcement when using personal data and new

analytic capabilities.

Legislation can address the myriad issues arising

in technology-driven policing in detailed and

comprehensive ways that case-by-case judicial

analysis cannot. But this Court can encourage

solutions. In Berger v. New York, for example, the

Court considered a New York eavesdropping statute,

which permitted ex parte orders authorizing

electronic surveillance where there was “reasonable

ground to believe that evidence of crime may be thus

obtained.” 388 U.S. 41, 54 (1967). The Court

invalidated that statute under the Fourth

Amendment, reasoning that the law established “no

requirement for particularity in the warrant as to

what specific crime has been or is being committed,

nor ‘the place to be searched,’ or ‘the persons or things

to be seized.’” Id. at 56. Congress responded with

Title III, which regulates wiretapping through

calibrated predicates, minimization requirements,

time limits, and judicial oversight. See Title III of the

Omnibus Crime Control and Safe Streets Act of 1968,

Pub. L. No. 90-351, 82 Stat. 197, 211 (codified as

amended at 18 U.S.C. §§ 2510-2522).

Other Fourth Amendment decisions from this

Court have not sparked similarly comprehensive

legislation—but there is a reason.

Jones and

Carpenter held that the usual warrant-supported-byprobable-cause rule applied to certain GPS tracking

and CSLI, respectively. See Carpenter, 585 U.S. at

316; Jones, 565 U.S. at 404-05. Although several

Justices emphasized the need for legislation, the

Court’s decision to resolve both cases under the

traditional

Fourth

Amendment

rules—while

appropriate on those specific facts—may have dulled

the urgency for broader legislative action. The result

is a statutory void for many modern investigation and

surveillance tools that do not fit comfortably within

the usual Fourth Amendment framework.

This Court can encourage much-needed

legislation in this area by holding that law

enforcement’s use of such tools: (1) often constitutes a

Fourth Amendment search or seizure; and (2) does

not necessarily require application of traditional

warrant principles; but (3) can survive constitutional

scrutiny only with sufficient safeguards in place, such

as a statute that provides a constitutionally adequate

substitute for a warrant.

Tying The Fourth Amendment Analysis

To Compliance With A Constitutionally

Adequate Statutory Scheme Would

Encourage Legislation

For data-driven investigation and surveillance

techniques, this Court can and should hold that

compliance with an adequate statutory scheme

provides a sufficient alternative to a traditional

warrant supported by probable cause.

In determining what is adequate, courts must bear

in mind the Fourth Amendment’s central purpose:

combatting “arbitrary invasions by governmental

officials.” Camara, 387 U.S. at 528. Searches

conducted pursuant to statutory standards and

procedures enacted by the People’s representatives

naturally pose a lesser danger of arbitrary authority,

as this Court’s precedents recognize. In Camara, for

example, the Court held that administrative

inspection programs may be constitutionally

reasonable when conducted pursuant to neutral

“legislative or administrative standards,” despite the

lack of a traditional warrant supported by probable

cause. Id. at 538. And several times since, the Court

has upheld searches conducted pursuant to statutory

schemes that “provide[] a constitutionally adequate

substitute for a warrant.” Donovan v. Dewey, 452

U.S. 594, 603 (1981) (mine inspections under federal

statute); see, e.g., Burger, 482 U.S. at 702-03

(junkyard inspections under state statute).

Of course, mere compliance with—or a violation

of—a statutory scheme cannot dictate the Fourth

Amendment analysis entirely. See Virginia v. Moore,

553 U.S. 164, 168-76 (2008). This Court has not

hesitated to invalidate deficient legislative schemes

and prescribe their constitutional cures. See, e.g.,

City of Los Angeles v. Patel, 576 U.S. 409, 420-21

(2015) (invalidating hotel registry inspection

ordinance).

But by inviting deference to law

enforcement activities that comply with a duly

enacted statutory scheme—so long as the scheme

establishes appropriate safeguards—this Court can

help “break the public-choice logjam that has kept

legislatures from acting” on data-driven investigation

and surveillance.

Barry Friedman, Lawless

Surveillance, 97 N.Y.U. L. Rev. 1143, 1199 (2022).

Here, the Court should hold that compliance with

appropriate legislation would satisfy the Fourth

Amendment. See Friedman, Constitutionality, supra,

at 338-41; Friedman, Lawless Surveillance, supra, at

1169-71. Such legislation could take the following

shape:

Predicates. A statute could establish calibrated

predicates matched to the degree of intrusiveness of

particular types of data searches. See Christopher

Slobogin, Virtual Searches: Regulating the Covert

World of Technological Policing 41, 61-67 (2022)

(suggesting four levels of predicates proportional to

intrusiveness). Not every step in a multi-stage

process necessarily requires probable cause. See, e.g.,

18 U.S.C. § 2703(a)-(d) (Stored Communications Act)

(establishing different predicates for obtaining

certain “content” and “noncontent” information).

Predicates should progress “from the lowest, such as

relevant to an ongoing investigation, to the more

traditional probable cause[] depending on the nature

and quantity of the information being accessed.”

Friedman, Lawless Surveillance, supra, at 1197.

Proportionality. Legislation could establish

rules around the types of crimes for which officers

may employ data surveillance. See Murphy, supra, at

541. Some states have set such limits for the use of

certain technologies, such as facial recognition

technology, permitting its use only for serious

offenses like a “crime of violence” or a “human

trafficking offense.” Md. Code Ann., Crim. Proc.

§ 2-503(a)(i); see, e.g., Mont. Code Ann. § 44-15106(2)(a); Utah Code Ann. § 77-23e-103(2)(c)(i).

Distinctions among kinds of data. Legislation

could draw categorical distinctions among types of

data. Location data, browsing history, and the like

may warrant protection not presently afforded to

bank records, pen registers, or IP addresses. Other

limits or stronger predicates could be required when

requested data risks exposing movements into

residences, medical facilities, schools, houses of

worship, or other core protected spaces. See Murphy,

supra, at 544.

Safeguards for data accuracy.

Another

component could be data accuracy and integrity

measures to help prevent “all too frequent” errors that

can “lead to encounters with the police.” Friedman,

Constitutionality, supra, at 313. Data providers could

be required to disclose known accuracy limitations

and mandate corroboration before any data

unmasking or attempts at arrest. See Friedman,

Lawless Surveillance, supra, at 1193-97.

Limits on data storage, security, and

retention.

In scrutinizing CSLI, Carpenter

emphasized the danger in “the retrospective quality

of the data” that is subject only to the “retention

polic[i]es of the wireless carriers,” and allows “the

Government [to] travel back in time to retrace a

person’s whereabouts.” 585 U.S. at 312. Legislation

could require use restrictions, retention limits,

encryption, detailed audit logs, and data breach

notifications. See Friedman, Lawless Surveillance,

supra, at 1193-97; see, e.g., Tenn. Code Ann. § 55-10302(b) (generally requiring data deletion after 90

days); Utah Code Ann. § 41-6a-2004 (nine months).

Accountability and oversight.

To ensure

accountability and oversight, legislation also could

require a neutral magistrate to authorize each stage

of a graduated warrant process, require warrant

returns, and establish periodic compliance audits.

See Murphy, supra, at 541-42; Friedman,

Constitutionality, supra, at 342; Friedman, Lawless

Surveillance, supra, at 1180, 1197-98.

Courts ultimately will need to determine whether

any such statutory scheme is constitutionally

adequate.

Yet with proper guidance, such

frameworks will emerge, as they did with Title III.

Supra at 27-28. This Court should foster them.

Unresolved Statutory Questions Could

Impact The Constitutional Analysis In

This Case

The irony in this case is that the search at issue

did implicate two existing statutes—the Stored

Communications Act (“SCA”), 18 U.S.C. § 2703, and a

recently amended state law analog, Va. Code Ann.

§ 19.2-70.3. See JA129 (warrant application invoking

latter statute). But the parties have not addressed,

and the lower courts did not decide, whether those

statutes were complied with—much less whether

compliance would satisfy the Fourth Amendment.

Both the SCA and Virginia’s analog require a

warrant based on probable cause to compel the

disclosure of the “contents” of certain electronic

communications. See 18 U.S.C. § 2703(a); Va. Code

Ann. § 19.2-70.3(C). Throughout this case, Google

has argued that Location History—unlike the CSLI at

issue in Carpenter—is “substantive information.”

JA28-31. For that reason, it might qualify as

“contents” under these laws, subjecting geofence

warrants to the highest tier of statutory protection.

Id. If that’s correct, the lack of individualized

suspicion at Step One and the magistrate’s absence at

Steps Two and Three of the warrant process likely

violated both statutes, which in turn cuts against

Fourth Amendment reasonableness. Even if it is not

correct and Location History does not qualify as

“contents,” the question still remains whether the

magistrate’s degree of involvement satisfied both

laws.

Answers to those threshold statutory

compliance questions could inform whether either

legislative scheme provided a “constitutionally

adequate substitute for a warrant” in this case. Patel,

576 U.S. at 426. At a minimum, they would help

inform resolution of the Fourth Amendment question.

However the Court rules, it should leave room for

compliance with an appropriate statutory scheme to

inform the Fourth Amendment analysis in this

rapidly evolving context. Encouraging legislation in

this way could help stave off the “very unfortunate”

status quo, where “privacy protection in the 21st

century” has been “left primarily to the federal courts

using the blunt instrument of the Fourth

Amendment.” Riley, 573 U.S. at 408 (Alito, J.,

concurring in part and concurring in the judgment).

And it would serve the Fourth Amendment’s core

purpose of preventing arbitrary governmental

intrusions, while preserving space for legislative

action and effective policing.

CONCLUSION

For the foregoing reasons, this Court should hold

that a search occurred and that compliance with an

adequate statutory scheme may render it reasonable.

Respectfully submitted,

BARRY FRIEDMAN

MARIA PONOMARENKO

MAX ISAACS

KATIE KINSEY

POLICING PROJECT AT

NYU SCHOOL OF LAW

40 Washington Sq. S.

New York, NY 10012

NICHOLAS ROSELLINI

Counsel of Record

LATHAM & WATKINS LLP

500 Montgomery Street

Suite 2000

San Francisco, CA 94111

(415) 395-8165

nick.rosellini@lw.com

SUMER GHAZALA

MAHSHAD BADII

LATHAM & WATKINS LLP

555 11th Street, NW

Suite 1000

Washington, DC 20004

Counsel for Amicus Curiae

March 9, 2026

This is a copy of a public record, reproduced as it was published. It is not legal advice, and it may not be the version a court would rely on. Check the official source before you cite it.