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

No. 25-112

In the Supreme Court of the United States

_________

O KELLO T. CHATRIE ,

v.

Petitioner,

U NITED S TATES OF A MERICA,

Respondent.

_________

On Petition For A Writ Of Certiorari

To The United States Court Of Appeals

For The Fourth Circuit

_________

BRIEF OF X CORP. AS AMICUS CURIAE

IN SUPPORT OF PETITIONER

_________

AMY P EIKOFF

Pacific Legal Foundation

3100 Clarendon Blvd.,

Suite 1000

Arlington, VA 22201

(202) 888-6881

apeikoff@pacificlegal.org

MARK MILLER

Counsel of Record

Pacific Legal Foundation

4440 PGA Blvd.,

Suite 307

Palm Beach Gardens, FL

33410

(561) 691-5000

mark@pacificlegal.org

Counsel for Amicus Curiae X Corp.

QUESTIONS PRESENTED

This case concerns the constitutionality of geofence

warrants. For cell phone users to use certain services,

their cell phones must continuously transmit their exact locations to their service providers. A geofence

warrant allows law enforcement to obtain, from the

service provider, the identities of users who were in

the vicinity of a particular location at a particular

time.

In this case, law enforcement obtained, and served

on Google, a geofence warrant seeking anonymized location data for every device within 150 meters of the

location of a bank robbery within one hour of the robbery. After Google returned an initial list, law enforcement sought—without seeking an additional

warrant—information about the movements of certain devices for a longer, two-hour period, and Google

complied with that request as well. Then—again

without seeking an additional warrant—law enforcement requested de-anonymized subscriber information for three devices. One of those devices belonged to Petitioner Okello Chatrie. Based on the evidence derived from the geofence warrant, Petitioner

was convicted of armed robbery.

The questions presented are:

1. Whether the execution of the geofence warrant

violated the Fourth Amendment.

2. Whether the exclusionary rule should apply to

the evidence derived from the geofence warrant.

ii

TABLE OF CONTENTS

Identity and Interest of Amicus Curiae ..................... 1

Introduction and Summary of the Argument ............ 2

Argument .................................................................... 7

I. The Third-Party Doctrine Originated In

“Secret Agent Cases,” Which The Common

Law Would Address Under The Doctrine Of

Illegal Contract. This Explains Why There

Was No “Reasonable Expectation Of Privacy”

In Those Cases................................................... 7

II. The Common Law Of Contract Traditionally

Protected Privacy, And So Is A Proper Lens

Through Which To Analyze The Third-Party

Doctrine ........................................................... 12

III. This Approach Makes It Possible To Limit The

Third-Party Doctrine’s Application Without

Resorting To “Balancing . . . Weighty Or

Incommensurable Principles” ......................... 15

Conclusion ................................................................. 18

iii

TABLE OF AUTHORITIES

Cases

Byrd v. United States,

584 U.S. 395 (2018) ............................................... 6

Carpenter v. United States,

585 U.S. 296 (2018) ........... 2-7, 9, 11, 13-14, 16, 18

Hanover Nat’l Bank of City of New York

v. First Nat’l Bank of Burlingame,

109 F. 421 (8th Cir. 1901) ................................... 11

Katz v. United States,

389 U.S. 347, 361 (1967) ...... 3, 5-6, 9-10, 13, 15-17

Lange v. California,

594 U.S. 295 (2021) ......................................... 7, 15

Leaders of a Beautiful Struggle v.

Balt. Police Dep’t,

2 F.4th 330 (4th Cir. 2021) ................................. 3-4

Smith v. Maryland,

442 U.S. 735 (1979) ................. 2, 4, 8-10, 15, 17-18

United States v. Chatrie,

136 F.4th 100 (4th Cir. 2025) ................... 2-4, 7, 10

United States v. Jones,

565 U.S. 400 (2012) ........................... 1, 4, 6, 13, 16

United States v. Miller,

425 U.S. 435 (1976) ................. 2, 4, 8-10, 15, 17-18

United States v. Smith,

110 F.4th 817 (5th Cir. 2024) ............................. 3-4

U.S. Constitution

U.S. Const. amend. IV .................. 1-3, 5-7, 9-15, 17-18

Rules

Sup. Ct. R. 37.2 ........................................................... 1

iv

Sup. Ct. R. 37.6 ........................................................... 1

Other Authorities

5 Williston, Samuel & Lord, Richard A.,

A Treatise on the Law of Contracts

§ 12:1 (4th ed. 2009) ............................................ 10

Amar, Akhil Reed, Fourth Amendment

First Principles,

107 Harv. L. Rev. 757 (1994) ................................ 6

Brandeis, Louis D. & Warren,

Samuel D., The Right to Privacy,

4 Harv. L. Rev. 193 (1890) ............................. 12-13

Cuddihy, William J., The Fourth

Amendment: Origins and Original

Meanings 602-1791

(Oxford Univ. Press 2009) ..................................... 5

Del Rosso, Christina & Bast, Carol M.,

Protecting Online Privacy in the

Digital Age: Carpenter v. United

States and the Fourth Amendment’s

Third-Party Doctrine,

28 Cath. U. J. L. & Tech. 89 (2020) ............... 11-12

Greenwald, Glenn, NSA collecting

phone records of millions of Verizon

customers daily, The Guardian

(June 6, 2013),

https://tinyurl.com/3rehu775 ................................ 9

If These Walls Could Talk: The Smart

Home and the Fourth Amendment

Limits of the Third-Party Doctrine,

130 Harv. L. Rev. 1924 (2017) .............................. 8

Kerr, Orin S., The Case for the

Third-Party Doctrine,

107 Mich. L. Rev. 561 (2009)................................. 8

v

Logan, Wayne A. & Linford, Jake

Contracting for Fourth Amendment

Privacy Online,

104 Minn. L. Rev. 101 (2020) .............................. 15

Peikoff, Amy L., Of Third-Party

Bathwater: How to Throw Out the

Third-Party Doctrine While

Preserving Government’s Ability to

Use Secret Agents,

88 St. John’s L. Rev. 349 (2014) .......................... 15

Wade, John W., et al., Prosser,

Wade and Schwartz’s Cases and

Materials on Torts

(The Foundation Press 1994) .............................. 12

Whitwam, Ryan, Oops: Google says it

might have deleted your Maps

Timeline data, Ars Technica

(Mar. 24, 2025),

https://tinyurl.com/46snw6sa ................................ 5

IDENTITY AND INTEREST OF

AMICUS CURIAE 1

“Awareness that the government may be watching

chills associational and expressive freedoms.” United

States v. Jones, 565 U.S. 400, 416 (2012) (Sotomayor,

J., concurring). X Corp., an American technology company headquartered in Bastrop, Texas, strives to protect the associational and expressive freedoms of users of its real-time information-sharing app and associated services. X understands that this means also

ensuring its users’ Fourth Amendment rights are respected regarding the data X collects and processes.

While providing services to users, X necessarily collects, processes, and stores multiple classes of sensitive user data which could be the subject of “reverse

searches” by law enforcement or other government

agencies, including location information. 2 X believes

contractual promises, like those it makes to its users

in its Terms of Service, should be recognized as relevant to the protection their data receives under the

Fourth Amendment.

1 Pursuant to Rule 37.2, Amicus Curiae provided timely notice

to all parties. Pursuant to Rule 37.6, Amicus Curiae affirms that

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

and no counsel or party made a monetary contribution intended

to fund the preparation or submission of this brief. No person

other than Amicus Curiae, their members, or their counsel made

a monetary contribution to its preparation or submission.

2 X may infer the location of its users using multiple signals,

including the user-specified location, the user’s IP address, and—

for the subset of users who consent—device-provided location

data like that at issue in this case. X routinely resists overbroad

or otherwise invalid government demands for user data,

including through litigation.

2

INTRODUCTION AND

SUMMARY OF ARGUMENT

As Judge Gregory noted below, while a majority of

the en banc Fourth Circuit agreed “to affirm the district court’s opinion,” that is the only thing about

which it agreed; “its reasoning is fractured.” United

States v. Chatrie, 136 F.4th 100, 157 (4th Cir. 2025)

(Gregory, J., dissenting). The set of opinions exemplifies the division and confusion that exists, not only

about geofence warrants, but more generally about

the application of the third-party doctrine after this

Court’s ruling in Carpenter v. United States, 585 U.S.

296 (2018). By granting Okello Chatrie’s petition, this

Court can clear up the confusion about both issues,

helping ensure uniform Fourth Amendment protection for sensitive data belonging to users of services

which have become integral to our specialized, technologically advanced economy.

At one extreme was Judge Wilkinson, who saw this

case as involving a “straightforward application” of

this Court’s rulings in Smith v. Maryland, 442 U.S.

735 (1979), and United States v. Miller, 425 U.S. 435

(1976). Chatrie, 136 F.4th at 109 (Wilkinson, J., concurring). At the other extreme was Judge Wynn, who,

after applying the Carpenter majority’s “two amorphous balancing tests,” comprised of “a series of

weighty and incommensurable principles,” Carpenter,

585 U.S. at 397 (Gorsuch, J., dissenting), concluded,

first, “when the Government accessed Location History data that was traceable to Chatrie, it invaded his

reasonable expectation of privacy,” Chatrie, 136 F.4th

at 125 (Wynn, J., concurring), and second, Chatrie’s

sharing of his Location History with Google was not

3

“meaningfully voluntary,” and so did not undermine

that expectation. Id. at 127.

Disagreements about the application of multi-factor balancing tests are not surprising. This balancingtest approach in Fourth Amendment jurisprudence

stems from the infamous Katz “reasonable expectation

of privacy” test. Katz v. United States, 389 U.S. 347,

361 (1967) (Harlan, J., concurring). Judge Berner’s

suggestion below, that a search occurs when government obtains data that is non-anonymous or “likely to

be traceable to a particular individual,” Chatrie, 136

F.4th at 156 (Berner, J., concurring), can be added to

the parade of considerations courts must attempt to

weigh post-Carpenter, including:

• How long is the period of time to which the data

corresponds? See, e.g., Leaders of a Beautiful

Struggle v. Balt. Police Dep’t, 2 F.4th 330, 341

(4th Cir. 2021) (interpreting Carpenter as “solidif[ying] the line between short-term tracking

of public movements—akin to what law enforcement could do ‘[p]rior to the digital age’—

and prolonged tracking that can reveal intimate details through habits and patterns.”);

• How “sensitive” is the data? See, e.g., United

States v. Smith, 110 F.4th 817, 832 (5th Cir.

2024) (noting location data provides “an intimate window into a person’s life, revealing not

only his particular movements, but through

them his ‘familial, political, professional, religious, and sexual associations.’ ”) (citations

omitted);

• How “intrusive[]” is the invasion? See, e.g.,

Smith, 110 F. 4th at 833 (“While it is true that

4

•

•

•

geofences tend to be limited temporally, the potential intrusiveness of even a snapshot of precise location data should not be understated.”)

(citations and quotations omitted);

Does the data facilitate retrospective tracking?

See, e.g., Chatrie, 136 F.4th at 121 (Wynn, J.,

concurring) (noting that the CSLI at issue in

Carpenter “allowed police to ‘travel back in

time’ to ‘reconstruct a person’s movements,’ unlocking ‘a category of information otherwise unknowable.’ ”) (quoting Carpenter, 585 U.S. at

312);

Should courts focus on “capabilities” of the relevant technology, or “results,” that is, the data

obtained by government in a given case? See

Chatrie, 136 F.4th at 126 (Wynn, J., dissenting)

(noting that Location History has the capacity

to “track a person’s ‘physical presence,’ ” and

therefore “ ‘implicates privacy concerns far beyond those considered in Smith and Miller.’ ”)

Cf. id. at 139 (Richardson, J., concurring) (noting that “the two hours’ worth of Location History data that law enforcement obtained from

Google at Step Two” was “far less revealing

than that obtained in Jones, Carpenter, or

Beautiful Struggle”); and

Was the sharing “meaningfully voluntary”? See

Chatrie, 136 F.4th at 141 (Richardson, J., concurring) (noting that “unlike CSLI, Location

History data is obtained by a user’s affirmative

act.”). Cf. Smith, 110 F.4th at 835 (“As anyone

with a smartphone can attest, electronic opt-in

5

processes are hardly informed and, in many instances, may not even be voluntary.”) (citations

omitted).

And so on. This miasma is, as Justice Gorsuch

noted, “where Katz inevitably leads.” Carpenter, 585

U.S. at 397 (Gorsuch, J., dissenting).

Besides causing judicial headaches, the third-party

doctrine enables government to gather broad swaths

of information without first obtaining a warrant based

on probable cause and particularized suspicion. This

undermines property rights and privacy—necessary

for enjoyment of associational and expressive freedoms—and contradicts the Founders’ understanding

of our Fourth Amendment protections. See William J.

Cuddihy, The Fourth Amendment: Origins and Original Meanings 602-1791 776 (Oxford Univ. Press

2009) (“[Particularized warrants were] the orthodox

protocol of search and seizure in 1791. . . . [W]arrants

enjoyed the overriding mandate of established usage”

by 1800.) (citation omitted).

Moreover, it prevents “third parties” like Google

and X Corp. from acting according to their own judgment in relation to both government and their users.

Google recently made a major change to its product

architecture by no longer collecting Location History

in Sensorvault, which was used to store the data at

issue in this case; location data is now stored on the

user’s device, where it is less available to Google to retrieve in response to legal process. Ryan Whitwam,

Oops: Google says it might have deleted your Maps

Timeline data, Ars Technica (Mar. 24, 2025). 3 Was

this a decision Google made to avoid being coerced into

3 https://tinyurl.com/46snw6sa.

6

helping governments undermine its users’ property

rights and privacy through an end run around the

Fourth Amendment?

Amicus X Corp. urges this Court to grant Petitioner

Chatrie’s Petition for a Writ of Certiorari. This case

presents an opportunity to clarify this area of constitutional law by tethering a decision to the Fourth

Amendment’s original meaning: all searches of private property require warrants based on particularized probable cause, Jones, 565 U.S. at 404-10 (holding a search occurred when government obtained information by means of trespass on a constitutionally

protected “effect”), and a search occurs when government gains access to “houses, papers, [or] effects,” U.S.

Const. amend. IV, that belong to a person under the

law. Byrd v. United States, 584 U.S. 395, 403-04

(2018) (“[Katz] supplements, rather than displaces,

the traditional property-based understanding of the

Fourth Amendment.”) (internal citation and quotation

omitted).

On this view—and even on an alternative originalist view centering on the Amendment’s promise that

all searches and seizures be “reasonable” 4—this tethering is achieved by recourse to the common law. See

4 See Akhil Reed Amar, Fourth Amendment First Principles,

107 Harv. L. Rev. 757, 761 (1994) (presenting and arguing for a

“[r]efurbished” Fourth Amendment, through analysis of both the

amendment’s text and the common law). But see Carpenter, 585

U.S. at 355-58 (Thomas, J., dissenting) (comparing “reasonable”

as used in the Fourth Amendment’s text to the term’s

significance in the Katz test). “Suffice it to say, the Founders

would be confused by this Court’s transformation of their

common-law protection of property into a ‘warrant requirement’

and a vague inquiry into ‘reasonable expectations of privacy.’ ”

Id. at 356-57.

7

Lange v. California, 594 U.S. 295, 309 (2021) (noting

the common law may be instructive regarding what

searches the Founders would have considered reasonable, and the Fourth Amendment must be interpreted

to “provide at a minimum the degree of protection it

afforded when it was adopted”) (internal citations and

quotations omitted).

Amicus X Corp. agrees that, for Fourth

Amendment purposes, Petitioner Chatrie has property rights in his Location History as recognized in

Google’s terms of service, Chatrie, No. 25-112, Brief of

Petitioner 31-32, and therefore his Fourth Amendment rights were violated when government obtained

his data without a warrant based on particularized

probable cause. This case and others involving reverse searches of sensitive data held by third parties

should be viewed through the lens of the common law

of contract as understood by our Founders. This approach will provide a clear, bright-line rationale for

limiting the third-party doctrine’s scope in a manner

both consistent with the Carpenter result and appropriate for our technological age.

ARGUMENT

I.

The Third-Party Doctrine Originated In

“Secret Agent Cases,” Which The Common

Law Would Address Under The Doctrine Of

Illegal Contract. This Explains Why There

Was No “Reasonable Expectation Of

Privacy” In Those Cases

The third-party doctrine in its pre-Carpenter form

is what Judge Wynn referred to as a “mechanical

appl[ication]” of the doctrine. Chatrie, 136 F.4th at

8

125 (Wynn, J., concurring). It says the Fourth Amendment is not implicated when: (1) you share information with a third party—for example, your bank,

your phone company, Google, or X Corp.—even for a

limited purpose; and (2) the third party then shares

the information with the government. See Orin S.

Kerr, The Case for the Third-Party Doctrine, 107 Mich.

L. Rev. 561, 563 (2009). The doctrine’s history, however, is key to understanding its appropriate scope.

The genesis of the doctrine is a series of mid-twentieth

century “secret agent” cases involving criminals or

criminal organizations. Id. at 567-68 (discussing “secret agent” cases heard by this Court between 1952

and 1971). Think of Tony Soprano divulging information about his illegal businesses to a “business associate” turned government informant, and a prosecutor using the informant’s disclosures to indict and convict Soprano. But then, in the 1970s, in Smith and

Miller, the scope of the doctrine was dramatically expanded to apply, not only to mafia dons, but also to

ordinary, innocent citizens who share information

with third parties, whether while doing business, or

simply enjoying life.

Alarm bells did not ring immediately. Back then

we shared exponentially less information with third

parties than we do today. See Note If These Walls

Could Talk: The Smart Home and the Fourth Amendment Limits of the Third-Party Doctrine, 130 Harv. L.

Rev. 1924, 1925 (2017) (“Our daily activities increasingly involve turning over information to third parties

in order to undertake basic transactions[.]”). But the

digital age brought about a new set of pernicious consequences this Court could never have anticipated. In

2013, the world learned, for example, that the National Security Agency had continuously collected

9

phone record metadata of all Verizon customers for

several years. See Glenn Greenwald, NSA collecting

phone records of millions of Verizon customers daily,

The Guardian (June 6, 2013). 5 Attempts to chisel

away at the third-party doctrine followed, but without

overturning Smith and Miller outright.

Carpenter, with its additional balancing test, is a

prime example. Yes, Carpenter’s result is consistent

with the original meaning and protections of the

Fourth Amendment. Further, a court that properly

applied Carpenter’s complex rubric should hold that

the government violated the rights of Chatrie and

other Google users in this case. But the law in this

area is, to be blunt, a mess. Amicus X Corp. believes

this Court should grant Petitioner Chatrie a writ of

certiorari to finish what it started in Carpenter. This

Court, with the benefit of decades of hindsight on the

effects of its post-Katz expansion of the third-party

doctrine, should clarify the law in this area and at the

very least continue to narrow or distinguish Smith

and Miller, as both failed to justify the third-party doctrine in its pre-Carpenter form. 6

5 https://tinyurl.com/3rehu775.

6 The only justification offered by this Court in Miller for

extending the doctrine beyond the context of the secret agent

cases was that Congress had “assumed” the “lack of any

legitimate expectation of privacy concerning the information

kept in bank records” in enacting the Bank Secrecy Act, which

had “a high degree of usefulness in criminal, tax, and regulatory

investigations and proceedings.” Miller, 425 U.S. at 442-43

(citations omitted). Later this Court, in Smith, merely applied

the Katz-mediated extension of the doctrine from Miller, without

overt reference to the Miller Court’s question-begging rationale.

The closest the Smith majority got to acknowledging the issue

was this footnote:

10

Justification is due because, although few would

expect to retain a legitimate expectation of privacy

when they entrust information to confederates in

criminal activity, the same cannot be said of ordinary

individuals sharing information with service providers in their daily lives. See, e.g., Chatrie, 136 F.4th at

127 (Wynn, J., concurring) (“[I]t would be a grave misjudgment to conflate an individual’s limited disclosure

to Google with an open invitation to the state.”). The

distinction lies in the common-law doctrine of illegal

contract, which deems unenforceable any agreement

made intentionally to achieve an illegal end. See 5

Samuel Williston & Richard A. Lord, A Treatise on the

Law of Contracts § 12:1 (4th ed. 2009).

Situations can be imagined, of course, in which

Katz’ two-pronged inquiry would provide an

inadequate index of Fourth Amendment

protection. For example, if the Government were

suddenly to announce on nationwide television

that all homes henceforth would be subject to

warrantless entry, individuals thereafter might

not in fact entertain any actual expectation of

privacy regarding their homes, papers, and

effects. . . . In determining whether a “legitimate

expectation of privacy” existed in such cases, a

normative inquiry would be proper.

Smith, 442 U.S. at 740 n.5.

The mere existence of a statute, even one that is useful in

“criminal, tax, and regulatory investigations,” Miller, 425 U.S. at

442-43 (citations omitted), does not extinguish a “legitimate

expectation of privacy”—much less a property right protected by

the Fourth Amendment. Especially considering arguments

raised against the third-party doctrine since Smith and Miller,

reconsideration of this Court’s rulings in those cases is

appropriate.

11

If Tony Soprano makes an “arrangement” with a

“business associate,” any collateral promises are unenforceable, including promises to keep it a secret.

But terms of service agreements between users and

Google or X Corp. would not be deemed illegal contracts, merely because some users happened to have

also committed crimes or are otherwise properly subject to government investigation. See, e.g., Hanover

Nat’l Bank of City of New York v. First Nat’l Bank of

Burlingame, 109 F. 421, 425 (8th Cir. 1901) (“The

mere fact that a contract the consideration and performance of which are lawful incidentally assists one in

evading a law is no bar to its enforcement.”). A fortiori, that one user breaks the law does not entitle the

government to trample on the rights of other, lawabiding users who might be ensnared by constitutionally insufficient, dragnet warrants or similarly unreasonable searches. Accordingly, promises made to users by these companies to, e.g., safeguard user data

and disclose it in only limited, enumerated circumstances are enforceable under common law according

to their terms, just as (to use a pertinent common law

analogy) records entrusted to a bailee still belong to

the bailor. Carpenter, 585 U.S. at 399 (Gorsuch, J.,

dissenting). 7 Both users and bailors retain privacy

and property interests entitled to Fourth Amendment

protection. Nothing less is “reasonable.” 8

7 Justice Gorsuch dissented in Carpenter on the narrow ground

that Carpenter did not invoke contract- or property-based

arguments. While he noted such arguments could justify Fourth

Amendment protection of Carpenter’s cell-site location information (“CSLI”), the Carpenter majority did not reach the issue.

8 See Christina Del Rosso & Carol M. Bast, Protecting Online

Privacy in the Digital Age: Carpenter v. United States and the

12

II. The Common Law Of Contract Traditionally

Protected Privacy, And So Is A Proper Lens

Through Which To Analyze The Third-Party

Doctrine

“The Right to Privacy,” Louis D. Brandeis & Samuel D. Warren, The Right to Privacy, 4 Harv. L. Rev.

193 (1890), written by future Supreme Court justice

Louis Brandeis and partner Samuel Warren, has been

credited with giving rise to a distinct “right of privacy.” See John W. Wade et al., Prosser, Wade and

Schwartz’s Cases and Materials on Torts 947 (The

Foundation Press 1994). Their core thesis was that

this right of privacy was necessary to prevent or redress the publication, without the subject’s permission, of private facts, surreptitiously taken photographs, and the like. Brandeis & Warren, supra, at

195-96. Notably, the authors did not argue that the

common law left privacy without protection. Rather,

they argued, the laws protecting rights to property

and contract, or defending against breaches of trust or

confidence, did not adequately protect privacy when

new technologies made possible invasions of another’s

privacy, without committing physical trespass, without privity of contract, and without any relationship

of trust or confidence. Id. at 213.

Once courts began recognizing a “right to privacy,”

however, traditional legal protections for privacy

seemed to be gradually eroded or forgotten. This is

unfortunate because, unlike common-law rights to

Fourth Amendment’s Third-Party Doctrine, 28 Cath. U. J. L. &

Tech. 89, 95-96 (2020) (“[T]he third-party doctrine enables

the . . . government to engage in surveillance and monitoring of

one’s daily life, similar to the general warrants that the Fourth

Amendment ultimately intended to prevent.”) (citation omitted).

13

property or contract, or against breaches of trust or

confidence, this “right to privacy” came packaged with

an “amorphous balancing test,” see Carpenter, 585

U.S. at 397 (Gorsuch, J., dissenting) (using this language), from its very inception. In their article,

Brandeis and Warren envisioned this new “right” as

one subject to “limitations” to be determined by balancing “the dignity and convenience of the individual”

against “the demands of the public welfare or of private justice.” Brandeis & Warren, supra, at 214. Not

surprisingly, by the late 1960s, an individual’s enjoyment of privacy vis-à-vis government was determined

in Katz to depend on a judge’s pitting the actual privacy expectations of an individual against various and

sundry demands of society, to divine whether one had

a “reasonable expectation of privacy.” Katz, 389 U.S.

at 361 (Harlan, J., concurring).

Decades later Justice Antonin Scalia helped reverse this trend, explaining in United States v. Jones,

565 U.S. at 400, that the Katz privacy test was “added

to, not substituted for, the common-law trespassory

test.” Id. at 409. We unfortunately cannot know how

he would have ruled in Carpenter. And while some

Justices searched in Carpenter for an interest to justify finding the relevant data was Carpenter’s,

whether a contract might be sufficient did not arise on

the facts of that case. Even so, each of the dissenting

Justices who believed Carpenter presented no winning Fourth Amendment argument further inquired

into whether he possessed a property interest in the

data at issue.

Justice Kennedy found Carpenter did not own, create, or control the records at issue and therefore a subpoena sufficed. Carpenter, 585 U.S. at 329-30 (Kennedy, J., dissenting). Justice Thomas said the issue

14

was not “ ‘whether’ a search occurred,” but rather

“whose property was searched.” Id. at 342 (Thomas,

J., dissenting). However, he continued, “[n]either the

terms of his contracts nor any provision of law makes

the records [Carpenter’s].” Ibid. Thomas noted Carpenter argued based on statute, not “property, tort or

contract law[.]” Id. at 354. Justice Alito wrote, “Carpenter indisputably lacks any meaningful propertybased connection to the cell-site records. . . .” Id. at

384 (Alito, J., dissenting).

Justice Gorsuch found a statutory basis for Carpenter’s cell-site records to “qualify as his papers or effects

under existing law.” Id. at 405 (Gorsuch, J., dissenting). “Those interests[,]” he continued, “might even

rise to the level of a property right.” Id. at 406. Nonetheless, Gorsuch dissented because Carpenter failed

to “invoke the law of property, or any analogies to the

common law.” Ibid.; see also id. at 399 (“Entrusting

your stuff to others is a bailment [a type of contract]. . . . A bailee normally owes a legal duty [to the

bailor] to keep [your stuff] safe, according to the terms

of the contract.”). Fourth Amendment rights are not

automatically extinguished when entrusting your documents to a third party; rather, “[t]hese ancient principles” protect your interests, even in digital records.

Id. at 400.

This Court should grant certiorari to determine

whether Petitioner Chatrie’s rights under his contract

with Google are relevant to the Fourth Amendment

protection his Location History deserves consistent

with both Justices Thomas’s and Gorsuch’s opinions

in Carpenter. Were this Court to address the relevance of the doctrine of illegal contract to understanding the third-party doctrine’s origins and proper

scope, it could clarify this area of law for the benefit of

15

lower courts and litigants—i.e., service providers and

users—alike. Moreover, doing so would restore and

reinforce the baseline of protection that the Fourth

Amendment should and was intended to provide,

something sorely needed in our increasingly digital

world. Lange, 594 U.S. at 309. Cf. Wayne A. Logan &

Jake Linford, Contracting for Fourth Amendment Privacy Online, 104 Minn. L. Rev. 101, 108 (2020)

(“[I]mporting contract tools of interpretation [into

data privacy] holds significant promise for . . . resolving . . . privacy questions in the Internet Age.”).

III. This Approach Makes It Possible To Limit

The Third-Party Doctrine’s Application

Without Resorting To “Balancing . . .

Weighty Or Incommensurable Principles”

When viewed through the lens of this traditional

“contract” approach, the third-party doctrine is arguably superfluous, because an illegal contract cannot

create an enforceable expectation of privacy, whether

via recognition of a property interest, or otherwise.

See Amy L. Peikoff, Of Third-Party Bathwater: How to

Throw Out the Third-Party Doctrine While Preserving

Government’s Ability to Use Secret Agents, 88 St.

John’s L. Rev. 349, 374-76 (2014). This approach also

calls into question the amorphous, pragmatic Katz

test. For it is seeing the third-party doctrine in the

context of Katz which invited this Court, in Smith and

Miller, to set aside the doctrine’s origins and dramatically expand its scope, without justification and with

detrimental consequences for law-abiding individuals.

As Justice Thomas noted, “[a]fter 50 years, it is still

unclear what question the Katz test is even asking.

This Court has steadfastly declined to elaborate the

relevant considerations or identify any meaningful

16

constraints.” Carpenter, 585 U.S. at 358 (Thomas, J.,

dissenting) (quotations and citations omitted). “Katz

has yielded an often unpredictable—and sometimes

unbelievable—jurisprudence.” Id. at 394 (Gorsuch, J.,

dissenting) (quotations and citations omitted). But to

achieve justice for Petitioner Chatrie and others who

suffer unreasonable searches of their “persons,

houses, papers, and effects,” and to do so in a way

which provides clarity for judges deciding such cases

in the future, this Court need only recognize that the

common law of contract provides a principled reason,

rooted in our legal traditions, to return the third-party

doctrine to its original scope.

Standard contracts between users and companies

like Google and X Corp. are enforceable under common law. When their terms include a company’s

promise to protect a user’s data and keep it confidential, or to allow a user to control or delete it, that promise should be heeded and should not be terminable by

government fiat. Such contracts should be recognized

as legitimate means for preserving one’s property and

privacy. As Justice Sotomayor wrote regarding one

“weighty or incommensurable principle[]” courts must

“balance” post-Carpenter, “it may be necessary to reconsider the premise that an individual has no reasonable expectation of privacy in information voluntarily

disclosed to third parties.” Jones, 565 U.S. at 417 (Sotomayor, J., concurring). 9 What should matter for

Justice Sotomayor inspired many to reconsider the thirdparty doctrine, including her future colleague, Justice Gorsuch,

who in his Carpenter dissent expressed willingness to either

abandon the doctrine altogether, or alternatively limit its scope

to that for which this brief argues. See Carpenter, 585 U.S. at

387-91 (Gorsuch, J., dissenting) (examining various explanations

9

17

Fourth Amendment purposes is not solely whether information is shared with a third party and the sharing

is voluntary, but also how the common law views the

context in which the voluntary sharing occurs—including whether, as in the case before this Court, the

parties’ agreement protects the user’s right to the information at issue.

for the third-party doctrine as expanded by Smith and Miller and

concluding, “[i]n the end, what do Smith and Miller add up to? A

doubtful application of Katz that lets the government search

almost whatever it wants whenever it wants.”); and id. at 390

(alluding to a “secret-agent-case” scenario, and agreeing that one

could be seen as consenting to having one’s papers searched by

the government if the third party to whom one had granted

access happened to be an undercover government agent).

18

CONCLUSION

The Government violated Petitioner Chatrie’s

Fourth Amendment rights—along with those of other

Google users—when it obtained their Location Histories by means of a geofence warrant devoid of individualized suspicion. That a majority of the Fourth Circuit failed to reach this conclusion demonstrates how

muddled the law in this area is in the wake of

Carpenter.

This Court should grant Chatrie a writ of certiorari

and then consider whether the third-party doctrine, as

expanded in Smith and Miller, can withstand the

scrutiny made possible by decades of experience with

this Court-created doctrine.

Respectfully submitted,

AMY P EIKOFF

Pacific Legal Foundation

3100 Clarendon Blvd.,

Suite 1000

Arlington, VA 22201

(202) 888-6881

apeikoff@pacificlegal.org

MARK MILLER

Counsel of Record

Pacific Legal Foundation

4440 PGA Blvd.,

Suite 307

Palm Beach Gardens, FL

33410

(561) 691-5000

mark@pacificlegal.org

Counsel for Amicus Curiae X Corp.

AUGUST 2025