No. _______

d
IN THE

Supreme Court of the United States
TIMOTHY IVORY CARPENTER,
Petitioner,

—v.—

UNITED STATES

OF

AMERICA,
Respondent.

ON PETITION FOR A WRIT OF CERTIORARI TO THE UNITED STATES
COURT OF APPEALS FOR THE SIXTH CIRCUIT

PETITION FOR A WRIT OF CERTIORARI

Daniel S. Korobkin
Michael J. Steinberg
Kary L. Moss
AMERICAN CIVIL LIBERTIES
UNION FUND OF MICHIGAN
2966 Woodward Ave.
Detroit, MI 48201

Nathan Freed Wessler
Counsel of Record
Ben Wizner
Steven R. Shapiro
AMERICAN CIVIL LIBERTIES
UNION FOUNDATION
125 Broad Street
New York, NY 10004
(212) 549-2500
nwessler@aclu.org
Harold Gurewitz
GUREWITZ & RABEN, PLC
333 W. Fort Street, Suite 1400
Detroit, MI 48226

 QUESTION PRESENTED
In this case, as in thousands of cases each
year, the government sought and obtained the
historical cell phone location data of a private
individual pursuant to a disclosure order under the
Stored Communications Act (SCA) rather than by
securing a warrant. Under the SCA, a disclosure
order does not require a finding of probable cause.
Instead, the SCA authorizes the issuance of a
disclosure order whenever the government “offers
specific and articulable facts showing that there are
reasonable grounds to believe” that the records
sought “are relevant and material to an ongoing
criminal investigation.” 18 U.S.C. § 2703(d).
As a result, the district court never made a
probable cause finding before ordering Petitioner’s
service provider to disclose months’ worth of
Petitioner’s cell phone location records. A divided
panel of the Sixth Circuit held that there is no
reasonable expectation of privacy in these location
records, relying in large part on four-decade-old
decisions of this Court.
The Question Presented is:
Whether the warrantless seizure and search of
historical cell phone records revealing the location
and movements of a cell phone user over the course
of 127 days is permitted by the Fourth Amendment.

i

 PARTIES TO THE PROCEEDINGS
In addition to the parties named in the
caption, Timothy Michael Sanders was a defendantappellant below, and was represented by separate
counsel.

ii

 TABLE OF CONTENTS
QUESTION PRESENTED .......................................... i
PARTIES TO THE PROCEEDINGS ......................... ii
TABLE OF AUTHORITIES ...................................... vi
PETITION FOR A WRIT OF CERTIORARI ............. 1
OPINIONS BELOW ................................................... 1
JURISDICTION.......................................................... 1
RELEVANT CONSTITUTIONAL AND
STATUTORY PROVISIONS ...................................... 1
STATEMENT OF THE CASE.................................... 3
REASONS FOR GRANTING THE WRIT ............... 10
I.

THIS CASE PRESENTS AN IMPORTANT
AND RECURRING QUESTION ON THE
SCOPE OF CONSTITUTIONAL PRIVACY
RIGHTS IN THE DIGITAL AGE. .................... 10
A.

The Lower Courts Have Expressly and
Repeatedly Sought This Court’s Guidance
in Addressing the Question Presented. ... 10

B.

This Court’s Recent Decisions Have
Properly Recognized a Need to Reexamine
Traditional Understandings of Privacy
in the Digital Age. ..................................... 16

C.

The Volume and Frequency of Warrantless
Law Enforcement Requests for CSLI
Highlights the Importance of the Question
Presented. ................................................. 18

iii

 II.

FEDERAL COURTS OF APPEALS AND
STATE HIGH COURTS ARE DIVIDED. ........ 21
A.

The Circuits Are Split Over Whether
the Third-Party Doctrine Eliminates
People’s Reasonable Expectation of
Privacy in Their Historical CSLI. ............ 21

B.

The Circuits Are Split Over Whether There
is a Reasonable Expectation of Privacy in
Longer-Term Location Information
Collected by Electronic Means. ................ 24

III. THE SIXTH CIRCUIT ERRED IN HOLDING
THAT THE CONDUCT HERE WAS NOT A
SEARCH............................................................ 26
A.

The Sixth Circuit Erred in Holding That
There Is No Reasonable Expectation of
Privacy in Historical CSLI. ...................... 26

B.

The Sixth Circuit Erred In Deferring to
Congress’s 30-Year-Old Legislative
Scheme. ..................................................... 32

CONCLUSION.......................................................... 35
APPENDIX................................................................ 1a
Opinion, United States Court of Appeals for the
Sixth Circuit (April 13, 2016) ................................ 1a
Order, United States Court of Appeals for the Sixth
Circuit (June 29, 2016) ........................................ 33a
Opinion & Order, United States District Court,
Eastern District Of Michigan, Southern Division
(Dec. 6, 2013) ........................................................ 34a

iv

 Application, United States District Court, Eastern
District Of Michigan, Southern Division
(May 2, 2011) ........................................................ 49a
Order, United States District Court, Eastern
District of Michigan, Southern Division
(May 2, 2011) ........................................................ 56a
Application, United States District Court, Eastern
District of Michigan, Southern Division
(June 7, 2011) ....................................................... 62a
Order, United States District Court, Eastern
District of Michigan, Southern Division
(June 7, 2011) ....................................................... 69a
Government Trial Exhibit 57, Federal Bureau Of
Investigation Cellular Analysis (Nov. 5, 2013) ... 74a

v

 TABLE OF AUTHORITIES
CASES
Bond v. United States, 529 U.S. 334 (2000) ............. 27
Chapman v. United States, 365 U.S. 610 (1961) ..... 27
Commonwealth v. Augustine,
4 N.E.3d 846 (Mass. 2014) .................................... 23
Ferguson v. City of Charleston, 532 U.S. 67 (2001) . 27
Florida v. Jardines, 133 S. Ct. 1409 (2013) ............. 26
In re Application for Tel. Info. Needed for a Criminal
Investigation, 119 F. Supp. 3d 1011 (N.D. Cal.
2015), appeal dismissed, No. 15-16760 (9th Cir.
Feb. 5, 2016) .......................................................... 29
In re Application of the U.S. for Historical Cell Site
Data, 724 F.3d 600 (5th Cir. 2013) ........... 14, 22, 34
In re Application of U.S. for an Order Directing
a Provider of Elec. Commc'n Serv. to Disclose
Records to Gov't, 620 F.3d 304 (3d Cir.
2010) .................................................... 14, 22, 23, 28
Katz v. United States, 389 U.S. 347 (1967) ....... passim
Kyllo v. United States,
533 U.S. 27 (2001) ............................... 17, 26, 28, 30
Minnesota v. Olson, 495 U.S. 91 (1990) ................... 27
New York v. Belton, 453 U.S. 454 (1981) ................. 16
Riley v. California, 134 S. Ct. 2473 (2014) ....... passim
Smith v. Maryland, 442 U.S. 735 (1979) .......... passim
State v. Earls, 70 A.3d 630 (N.J. 2013) .................... 24
Stoner v. California, 376 U.S. 483 (1964) ................ 27

vi

 Tracey v. State, 152 So. 3d 504 (Fla. 2014) ........ 24, 32
United States v. Davis, 754 F.3d 1205 (11th Cir.
2014), rev’d en banc, 785 F.3d 498 (11th Cir.
2015 ) ............................................................... 14, 29
United States v. Davis, 785 F.3d 498 (11th Cir. 2015),
cert. denied, 136 S. Ct. 479 (2015) ................. passim
United States v. Garcia,
474 F.3d 994 (7th Cir. 2007) ................................. 25
United States v. Graham, 796 F.3d 332 (4th Cir.
2015), rev'd en banc, 824 F.3d 421 (4th Cir.
2016) ...................................................................... 14
United States v. Graham, 824 F.3d 421 (4th Cir.
2016) ............................................................... passim
United States v. Guerrero,
768 F.3d 351 (5th Cir. 2014) ................................. 22
United States v. Jacobsen, 466 U.S. 109 (1984)....... 27
United States v. Jones, 132 S. Ct. 945 (2012) ... passim
United States v. Karo, 468 U.S. 705 (1984) ............. 29
United States v. Marquez,
605 F.3d 604 (8th Cir. 2010) ................................. 25
United States v. Maynard,
615 F.3d 544 (D.C. Cir. 2010) ......................... 24, 25
United States v. Miller, 425 U.S. 435 (1976) .... passim
United States v. Pineda-Moreno,
617 F.3d 1120 (9th Cir. 2010) ......................... 20, 25
United States v. Skinner,
690 F.3d 772 (6th Cir. 2012) ................................... 8
United States v. Knotts, 460 U.S. 276 (1983) ........... 20

vii

 Zanders v. State, No. 15A01–1509–CR–1519, __
N.E.3d __, 2016 WL 4140998 (Ind. Ct. App. Aug. 4,
2016), pet. to transfer jurisdiction to Indiana
Supreme Court filed (Sept. 6, 2016)................ 14, 23
CONSTITUTION & STATUTES
U.S. Const. amend. IV ....................................... passim
Communications Assistance for Law Enforcement
Act, Pub. L. No. 103-414, § 207, 108 Stat. 4279
(1994) ..................................................................... 33
Electronic Communications Privacy Act of 1986,
Pub. L. No. 99-508, § 201, 100 Stat. 1848 ............ 33
Hobbs Act, 18 U.S.C. § 1951(a) .................................. 9
Stored Communications Act,
18 U.S.C. § 2703 et seq. .................................. passim
18 U.S.C. § 2703(c)(1)(A) ...................................... 34
18 U.S.C. § 2703(d) ........................................ i, 3, 22
18 U.S.C. § 924(c) ........................................................ 9
28 U.S.C. § 1254(1) ..................................................... 1
725 Ill. Comp. Stat. 168/10 ....................................... 24
Colo. Rev. Stat. § 16-3-303.5(2) ................................ 23
Ind. Code 35-33-5-12 ................................................. 24
Md. Code Ann. Crim. Proc. § 1-203.1(b)................... 24
Me. Rev. Stat. tit. 16, § 648 ...................................... 23
Minn. Stat. §§ 626A.28(3)(d), 626A.42(2)................. 23
Mont. Code Ann. § 46-5-110(1)(a) ............................ 23
N.H. Rev. Stat. Ann. § 644-A:2................................. 23
Utah Code Ann. § 77-23c-102(1)(a) .......................... 23
viii

 Va. Code Ann. § 19.2-70.3(C).................................... 24
Vt. Stat. Ann. tit. 13, § 8102(b) ................................ 23
OTHER AUTHORITIES
American Civil Liberties Union, Cell Phone Location
Tracking Public Records Request
(Mar. 25, 2013) ...................................................... 20
Andrea Meyer, 30th Anniversary of the First
Commercial Cell Phone Call, Verizon
(Oct. 11, 2013) ................................................. 33, 34
Arvind Thiagarajan et al., Accurate, Low-Energy
Trajectory Mapping for Mobile Devices,
8 USENIX Conf. on Networked Syss. Design &
Implementation 20 (2011)..................................... 31
AT&T, Transparency Report (2015) ......................... 19
Background on CTIA’s Wireless Industry Survey,
CTIA-The Wireless Association (2014) ................. 33
CTIA – The Wireless Association, Annual Wireless
Industry Survey (2014) ................................ 7, 18, 33
Daniel Solove, Conceptualizing Privacy,
90 Calif. L. Rev. 1087 (2002) ................................. 15
Pew Research Ctr., Public Perceptions of Privacy
and Security in the Post-Snowden Era
(Nov. 12, 2014) ....................................................... 32
Sherry F. Colb, What Is a Search? Two Conceptual
Flaws in Fourth Amendment Doctrine and
Some Hints of a Remedy,
55 Stan. L. Rev. 119 (2002) ................................... 15

ix

 Stephen J. Blumberg & Julian V. Luke, Ctr. For
Disease Control & Prevention, Wireless
Substitution: Early Release of Estimates from the
National Health Interview Survey, January–June
2014 (Dec. 2014) .................................................... 18
T-Mobile, Transparency Report for 2013 & 2014
(2015) ..................................................................... 19
Will Baude, Further Thoughts on the Precedential
Status of Decisions Affirmed on Alternate Grounds,
The Volokh Conspiracy (Dec. 3, 2013, 7:27 PM),
http://volokh.com/2013/12/03/thoughtsprecedential-status-decisions-affirmed-alternategrounds/ ................................................................. 25

x

 PETITION FOR A WRIT OF CERTIORARI
Petitioner Timothy Carpenter respectfully
petitions for a writ of certiorari to review the
judgment of the United States Court of Appeals for
the Sixth Circuit.
OPINIONS BELOW
The opinion of the Sixth Circuit (Pet. App. 1a–
32a) is reported at 819 F.3d 880. The district court
opinion (Pet. App. 34a–48a) is unpublished, but is
available at 2013 WL 6385838.
JURISDICTION
The Sixth Circuit issued its opinion on April
13, 2016, and denied rehearing en banc on June 29,
2016. (Pet. App. 33a). This Court has jurisdiction
pursuant to 28 U.S.C. § 1254(1).
RELEVANT CONSTITUTIONAL AND
STATUTORY PROVISIONS
The Fourth Amendment
Constitution provides:

to

the

The right of the people to be secure in
their persons, houses, papers, and
effects, against unreasonable searches
and seizures, shall not be violated, and
no Warrants shall issue, but upon
probable cause, supported by Oath or
affirmation, and particularly describing
the place to be searched, and the
persons or things to be seized.

1

U.S.

 The Stored Communications Act, 18 U.S.C. §
2703, provides in relevant part:
(c) Records concerning electronic
communication service or remote
computing service.--(1) A governmental entity may require a provider of
electronic communication service or
remote computing service to disclose a
record or other information pertaining
to a subscriber to or customer of such
service (not including the contents of
communications)
only
when
the
governmental entity—
(A) obtains a warrant issued
using the procedures described in
the Federal Rules of Criminal
Procedure (or, in the case of a
State court, issued using State
warrant procedures) by a court of
competent jurisdiction; [or]
(B) obtains a court order for such
disclosure under subsection (d) of
this section; * * *
(d) Requirements for court order.-A court order for disclosure under
subsection (b) or (c) may be issued by
any court that is a court of competent
jurisdiction and shall issue only if the
governmental entity offers specific and
articulable facts showing that there are
reasonable grounds to believe that the
contents of a wire or electronic
communication, or the records or other

2

 information sought, are relevant and
material to an ongoing criminal
investigation. * * *
STATEMENT OF THE CASE
This case presents the pressing question of
whether the Fourth Amendment protects against the
government’s warrantless acquisition of cell phone
records revealing an individual’s location and
movements over extended periods of time.
1. During the course of an investigation into a
series of armed robberies that occurred in
southeastern Michigan and northwestern Ohio in
2010 and 2011, an Assistant United States Attorney
submitted to different magistrate judges three
applications for orders to access more than five
months of historical cell phone location records for
Petitioner Timothy Carpenter and several other
suspects. Pet. App. 3a, 49a–55a, 62a–68a. The
applications, which were unsworn, did not seek
warrants based on probable cause, but rather orders
under the Stored Communications Act, 18 U.S.C. §
2703(d). Such an order may issue when the
government “offers specific and articulable facts
showing that there are reasonable grounds to believe
that” the records sought “are relevant and material
to an ongoing criminal investigation.” Id.
The applications sought “[a]ll subscriber
information, toll records and call detail records
including listed and unlisted numbers dialed or
otherwise transmitted to and from [the] target
telephones from December 1, 2010 to present[,]” as
well as “cell site information for the target
telephones at call origination and at call termination
3

 for incoming and outgoing calls[.]” Pet. App. 4a
(alterations in original); see also id. at 52a. The
applications stated that “a cooperating defendant
was interviewed about his involvement in [several]
armed robberies and admitted he had a role in eight
different robberies that started in December of 2010
and lasted through March of 2011 at Radio Shack
and T-Mobile stores in Michigan and Ohio.” Pet. App.
53a. The applications further asserted that “the
requested telecommunications records should yield
information that is relevant and material to
corroborate surveillance information and may
identify potential witnesses and/or targets. The
requested information will . . . provide evidence that .
. . Timothy Carpenter and other known and unknown
individuals are violating provisions of Title 18,
United States Code, §1951.” Pet. App. 54a. Rather
than restricting the request to only the days on
which the robberies occurred, however, the primary
application at issue here, which was submitted on
May 2, 2011, sought records “from December 1, 2010
to present.” Pet. App. 52a. That constituted a request
for 152 days of data.
Orders granting the applications were issued
on May 2 and June 7, 2011. Pet. App. 56a–61a, 69a–
73a. The May 2 order directed MetroPCS,
Carpenter’s cellular service provider, to “provide the
locations of cell/site sector (physical addresses) for
the target telephones at call origination and at call
termination for incoming and outgoing calls” from
“December 1, 2010 to present.” Pet. App. 59a–60a.
MetroPCS complied, providing 186 pages of

4

 Carpenter’s cell phone records to the government.1
Those records show each of Carpenter’s incoming and
outgoing calls over the course of 127 days,2 along
with the cell tower (“cell site”) and directional sector
of the tower that Carpenter’s phone connected to at
the start and end of most of the calls.3 Pet. App. 5a–
7a.
A separate order, issued on June 7, 2011,
directed Sprint to produce cell site location
information for Carpenter’s phone while it was
“roaming on Sprint’s cellular tower network” from
March 1 to March 7, 2011. Pet. App. 72a. “Metro PCS
does not have coverage in the Warren, Ohio area,”
where one of the charged robberies took place, and
A sample page from Carpenter’s records was entered into
evidence at trial. Defendant’s Trial Ex. 3. The full records were
provided by the government to the defense in pre-trial discovery
and were discussed by a prosecution’s witness at trial, Trial Tr.
46, Dec. 13, 2013, ECF No. 332, but were not made part of the
record before the district court. They were filed as an appendix
to the Amicus Brief of the American Civil Liberties Union, et
al., at the Sixth Circuit. See Doc. No. 33-1 The parties
stipulated at trial that the cell site location records from “Metro
PCS and Sprint utilized by [government witness] FBI Special
Agent Christopher Hess to formulate his analysis and opinion
are authentic and accurate business records of these
companies.” Gov’t Trial Ex. 58; Trial Tr. 47, Dec. 13, 2013, ECF
No. 332.

1

Although the government’s application and resulting court
order sought 152 days of records (December 1, 2010 through
May 2, 2011), MetroPCS produced 127 days of records
(December 1, 2010 through April 6, 2011).
2

Cell sites, which are the transmitting towers through which
cell phones communicate with the telephone network, consist of
antennas facing different directions that cover distinct wedgeshaped “sectors.”

3

5

 has a “roaming agreement . . . with Sprint, which
does cover that area.” Trial Tr. 59, Dec. 13, 2013,
ECF No. 332.4 Therefore, Sprint, not MetroPCS,
possessed Carpenter’s cell site location information
for calls made and received while he was in Ohio.
Sprint produced two pages of call detail records with
cell site location information for March 3 and 4, 2011.
MetroPCS and Sprint also produced lists of
their cell sites in southern Michigan and
northwestern Ohio, respectively, providing the
longitude, latitude, and physical address of each cell
site, along with the directional orientation of each
sector antenna. See id. at 74. By cross-referencing
the information in Carpenter’s call detail records
with these cell-site lists, the government could
identify the area in which Carpenter’s phone was
located and could thereby deduce Carpenter’s
location and movements at multiple points each day.
2. The precision of a cell phone user’s location
reflected in cell site location information (“CSLI”)
records depends on the size of the cell site sectors in
the area. Most cell sites consist of multiple
directional antennas that divide the cell site into
“sectors.” Pet. App. 5a. The coverage area of cell site
sectors is smaller in areas with greater density of cell
towers, with urban areas having the greatest density
and thus the smallest coverage areas. Id.; see also
Pet. App. 88a (Gov’t Trial Ex. 57, at 13) (providing
maps of MetroPCS and Sprint cell sites).

As explained at trial, “[i]n a roaming situation, if [a service
provider] doesn’t have coverage in a particular area of the
country, they would have an agreement with another company
to be able to utilize their infrastructure.” Id. at 39–40.

4

6

 The density of cell sites continues to increase
as data usage from smartphones grows. Because each
cell site can carry only a fixed volume of data
required for text messages, emails, web browsing,
streaming video, and other uses, as smartphone data
usage increases carriers must erect additional cell
sites, each covering smaller geographic areas. See
CTIA – The Wireless Association, Annual Wireless
Industry Survey (2016)5 (showing that the number of
cell sites in the United States increased from 183,689
to 307,626 from 2005 to 2015); id. (annual wireless
data usage increased from 388 billion megabytes to
9.65 trillion megabytes between 2010 and 2015). This
means that in urban and dense suburban areas like
Detroit, many sectors cover small geographic areas
and therefore can provide relatively precise
information about the location of a phone. Pet. App.
5a.
Although in this case MetroPCS provided only
information identifying Carpenter’s cell site and
sector at the start and end of his calls, service
providers increasingly retain more granular
historical location data, including for text messages
and data connections. United States v. Davis, 785
F.3d 498, 542 (11th Cir. 2015) (en banc) (Martin, J.,
dissenting). Location precision is also increasing as
service providers deploy millions of “small cells,”
“which cover a very specific area, such as one floor of
a building, the waiting room of an office, or a single
home.” United States v. Graham, 824 F.3d 421, 448
(4th Cir. 2016) (en banc) (Wynn, J., dissenting in

Available at http://www.ctia.org/your-wireless-life/howwireless-works/annual-wireless-industry-survey.

5

7

 part and concurring in the judgment) (citation
omitted).
3. Before trial, Carpenter joined his
codefendant’s motion to suppress the CSLI records
on the basis that their acquisition pursuant to the
“‘reasonable grounds standard’ in the Stored
Communications Act . . . is unconstitutional.” Pet.
App. 36a; see also id. at 4a. Relying on United States
v. Skinner, 690 F.3d 772 (6th Cir. 2012), a case
holding that no warrant is required for short-term
real-time tracking of a suspect’s cell phone, the
district court denied the motion on the basis that
acquisition of the cell-site records was not a Fourth
Amendment search. Pet. App. 38a–39a.
At
trial,
the
government
introduced
information about Carpenter’s CSLI records and
relied on them to establish Carpenter’s location on
the days of the charged robberies. FBI Special Agent
Christopher Hess testified that Carpenter’s CSLI
records placed him near the sites of four of the
robberies. Pet. App. 5a–6a. Hess also produced maps
showing the location of Carpenter’s phone relative to
the locations of the robberies, which the government
introduced into evidence. Pet. App. 6a; Id. at 86a–89a
(Gov’t Trial Ex. 57). The government relied on the
records to show Carpenter’s proximity to “the
robberies around the time the robberies happened.”
Pet. App. 6a. The prosecutor argued to the jury, for
example, that Mr. Carpenter was “right where the
first robbery was at the exact time of the robbery, the
exact sector,” Trial Tr. 56, Dec. 16, 2013, ECF No.
333, and that he was “right in the right sector before
the Radio Shack in Highland Park,” id. See also Trial

8

 Tr. 49–62, Dec. 13, 2013, ECF No. 332 (testimony of
Special Agent Hess).
The jury convicted Carpenter of six robberies
in violation of the Hobbs Act, 18 U.S.C. § 1951(a),
and five separate violations of 18 U.S.C. § 924(c) for
using or carrying a firearm in connection with a
federal crime of violence and aiding and abetting. All
but the first of the § 924(c) convictions carried
mandatory consecutive minimum sentences of 25
years each. As a result, the court sentenced
Carpenter to nearly 116 years’ imprisonment (1,395
months).
5. On appeal, a divided three-judge panel of
the Sixth Circuit held that no search occurred under
the Fourth Amendment because Carpenter had no
reasonable expectation of privacy in cell phone
location records held by his service provider. Pet.
App. 17a. Writing for the majority, Judge Kethledge
concluded that people do not have a reasonable
expectation of privacy in CSLI because it is a
business record of the service provider that reveals
routing information rather than the contents of
communications.
Pet.
App.
10a–11a.
Judge
Kethledge relied in part on this Court’s 1979 decision
in Smith v. Maryland, 442 U.S. 735 (1979), reasoning
that like the dialed phone numbers conveyed to the
phone company in Smith, people knowingly expose
their location information to their service provider
and therefore lack an expectation of privacy in it.
Pet. App. 11a–12a.
Judge Stranch disagreed. Concurring in the
judgment only, she explained that “the sheer
quantity of sensitive information procured without a
warrant in this case raises Fourth Amendment
9

 concerns of the type the Supreme Court . . .
acknowledged in United States v. Jones, 132 S. Ct.
945, 964 (2012) (Alito, J., concurring).” Pet. App. 24a.
“I do not think that treating the CSLI obtained as a
‘business record’ and applying that test addresses
our circuit’s stated concern regarding long-term,
comprehensive tracking of an individual’s location
without a warrant.” Id. at 29a. Judge Stranch
concluded, however, that suppression was not
warranted under the good-faith exception to the
exclusionary rule, a question that the majority did
not address. Id. at 29a–31a. On that alternative
basis, she concurred in the judgment.
REASONS FOR GRANTING THE WRIT
I.

THIS CASE PRESENTS AN IMPORTANT
AND RECURRING QUESTION ON THE
SCOPE OF CONSTITUTIONAL PRIVACY
RIGHTS IN THE DIGITAL AGE.
A.

The Lower Courts Have Expressly
and Repeatedly Sought This Court’s
Guidance in Addressing the Question
Presented.

The question at the center of this case—
whether there is a reasonable expectation of privacy
under the Fourth Amendment in a person’s cell site
location information held by their cellular service
provider—requires definitive resolution by this
Court. Numerous lower court judges addressing the
issue have explained that they feel bound by this
Court’s third-party–doctrine cases from the 1970s,
but that they are discomfited by the result they
believe those cases require them to reach. Only this
Court can provide the guidance they seek about
10

 whether and how a doctrine developed long before
the digital age applies to the voluminous and
sensitive digital records at issue here. More
specifically, only this Court can determine whether
Smith v. Maryland, 442 U.S. 735 (1979), and United
States v. Miller, 425 U.S. 435 (1976), render the
Fourth Amendment irrelevant when the government
seeks detailed records from a cell phone provider
cataloging the location and movements of a cell
phone user over many months.
In Smith, this Court ruled that the short-term
use of a pen register to capture the telephone
numbers a person dials is not a search under the
Fourth Amendment. 442 U.S. at 742. The Court
relied heavily on the fact that when dialing a phone
number, the caller “voluntarily convey[s] numerical
information to the telephone company.” Id. at 744.
The Court also assessed the degree of invasiveness of
the surveillance to determine whether the user had a
reasonable expectation of privacy. The Court noted
the “pen register’s limited capabilities,” id. at 742,
explaining that “a law enforcement official could not
even determine from the use of a pen register
whether a communication existed.” Id. at 741
(citation omitted). Similarly, in Miller, the Court
concluded that bank customers do not have any
Fourth Amendment interest in their bank records
because all the information in those records has been
voluntarily conveyed to the bank. 425 U.S. 435, 440–
42 (1976). The principle sometimes discerned from
these cases, that certain records or information
shared with third parties deserve no Fourth
Amendment protection, is known as the “third-party
doctrine.”

11

 Lacking further guidance from this Court,
lower courts have been struggling to apply the predigital holdings in Smith and Miller to newer forms
of pervasive digital data.
In United States v. Davis, 785 F.3d 498 (11th
Cir. 2015) (en banc), cert. denied, 136 S. Ct. 479
(2015), for example, a majority of the en banc
Eleventh Circuit held that this Court’s decisions in
Smith and Miller require the conclusion that there is
no Fourth Amendment protection for CSLI records.
But while the Eleventh Circuit believed it “remains
bound by Smith and Miller,” 785 F.3d at 514, two
separate concurrences called on this Court to clarify
the scope of those decisions, evincing discomfort with
their application to the records at issue. As Judge
Rosenbaum wrote:
In our time, unless a person is willing to
live “off the grid,” it is nearly impossible
to avoid disclosing the most personal of
information to third-party service
providers on a constant basis, just to
navigate daily life. And the thought that
the government should be able to access
such information without the basic
protection that a warrant offers is
nothing less than chilling. . . . Since we
are not the Supreme Court and the
third-party doctrine continues to exist
and to be good law at this time, though,
we must apply the third-party doctrine
where appropriate.
Id. at 525 (Rosenbaum, J., concurring); see also id. at
519, 521 (William Pryor, J., concurring) (“[W]e must
leave to the Supreme Court the task of developing
12

 exceptions to the rules it has required us to
apply. . . . As judges of an inferior court, we have no
business in anticipating future decisions of the
Supreme Court. If the third-party doctrine results in
an unacceptable ‘slippery slope,’ the Supreme Court
can tell us as much. That is, if ‘the Supreme Court
has given reasons to doubt the rule's breadth,’ it
alone must decide the exceptions to its rule.”
(citations omitted)).
Likewise, the en banc majority of the Fourth
Circuit wrote that “[t]he Supreme Court may in the
future limit, or even eliminate, the third-party
doctrine. . . . But without a change in controlling law,
we cannot conclude that the Government violated the
Fourth Amendment in this case.” United States v.
Graham, 824 F.3d 421, 425 (4th Cir. 2016) (en banc).
And in this case, Judge Stranch discussed her
“concern[] about the applicability of a test that
appears to admit to no limitation on the quantity of
records or the length of time for which such records
may be compelled,” concluding that there is a “need
to develop a new test to determine when a warrant
may be necessary under these or comparable
circumstances.” Pet. App. 29a (Stranch, J.,
concurring).
All told, the five courts of appeals to consider
the Fourth Amendment status of historical CSLI
have generated 18 separate majority, concurring, and
dissenting opinions, highlighting the need for this
Court to act. See Pet. App. 1a (majority opinion); id.
at 24a (Stranch, J., concurring); United States v.
Graham, 824 F.3d 421, 424 (4th Cir. 2016) (en banc)
(majority opinion); id. at 438 (Wilkinson, J.,
concurring); id. at 441 (Wynn, J., dissenting in part

13

 and concurring in the judgment); United States v.
Graham, 796 F.3d 332, 338 (4th Cir. 2015) (majority
opinion), vacated, reh'g en banc granted, 624 F. App’x
75 (4th Cir. 2015); id. at 377 (Thacker, J.,
concurring); id. at 378 (Motz, J., dissenting in part
and concurring in the judgment); United States v.
Davis, 785 F.3d 498, 500 (11th Cir. 2015) (en banc)
(majority opinion); id. at 519 (William Pryor, J.,
concurring); id. at 521 (Jordan, J., concurring); id. at
524 (Rosenbaum, J., concurring); id. at 533 (Martin,
J., dissenting); United States v. Davis, 754 F.3d 1205,
1208 (11th Cir. 2014) (unanimous), vacated, reh'g en
banc granted, 573 F. App’x 925 (11th Cir. 2014); In re
Application of the U.S. for Historical Cell Site Data,
724 F.3d 600, 602 (5th Cir. 2013) [“Fifth Circuit
CSLI Opinion”] (majority opinion); id. at 615
(Dennis, J., dissenting); In re Application of U.S. for
an Order Directing a Provider of Elec. Commc'n Serv.
to Disclose Records to Gov't, 620 F.3d 304, 305 (3d
Cir. 2010) [“Third Circuit CSLI Opinion”] (majority
opinion); id. at 319 (Tashima, J., concurring).
As reflected in these 18 opinions attempting to
grapple with the same basic issue, lower courts are
divided over how to apply the third-party doctrine to
CSLI records. Compare Graham, 824 F.3d at 424–25
(no expectation of privacy in CSLI under Smith),
Davis, 785 F.3d at 511–13 (same), and Fifth Circuit
CSLI Opinion, 724 F.3d at 612–13 (same), with
Third Circuit CSLI Opinion, 620 F.3d at 317
(distinguishing Smith and holding that cell phone
users may retain a reasonable expectation of privacy
in CSLI); Zanders v. State, No. 15A01–1509–CR–
1519, __ N.E.3d __, 2016 WL 4140998, at *8–10 (Ind.
Ct. App. Aug. 4, 2016) (distinguishing Smith and
Miller and holding that “the third-party doctrine
14

 does not dictate the outcome of this case”), pet. to
transfer jurisdiction to Indiana Supreme Court filed
(Sept. 6, 2016).
This struggle to define the scope of Fourth
Amendment protection for newer forms of sensitive
digital data reflects, at least in part, scholarly
criticism of the expansive application of the thirdparty doctrine beyond the kinds of records at issue in
Smith and Miller. See, e.g., Sherry F. Colb, What Is a
Search? Two Conceptual Flaws in Fourth
Amendment Doctrine and Some Hints of a Remedy,
55 Stan. L. Rev. 119 (2002); Daniel J. Solove,
Conceptualizing Privacy, 90 Calif. L. Rev. 1087,
1151–52 (2002). These scholars have joined the lower
courts in calling on this Court to ensure that the
Fourth Amendment keeps pace with the rapid
advance of technology.
In sum, there is a substantial question of how
the protections of the Fourth Amendment should
apply to sensitive and private data in the hands of
trusted third parties. As Justice Sotomayor noted in
United States v. Jones,
it may be necessary to reconsider the
premise that an individual has no
reasonable expectation of privacy in
information voluntarily disclosed to
third parties. This approach is ill suited
to the digital age, in which people reveal
a great deal of information about
themselves to third parties in the course
of carrying out mundane tasks.
132 S. Ct.
concurring).

945,

957

15

(2012)

(Sotomayor,

J.,

 It is not necessary in this case to reassess the
continued validity of the third-party doctrine in every
possible context. But it is critically important to
clarify the scope of analog-age precedents to digital
surveillance techniques. Without guidance from
this Court, a cell phone user “cannot know the
scope of his constitutional protection, nor can a
policeman know the scope of his authority.” New
York v. Belton, 453 U.S. 454, 459–60 (1981). As law
enforcement seeks ever greater quantities of location
data and other sensitive digital records, the need for
this Court to speak grows daily more urgent.
B.

This Court’s Recent Decisions
Have Properly Recognized a Need
to Reexamine Traditional Understandings of Privacy in the Digital
Age.

Twice in recent terms this Court has
confronted
crucial
questions
regarding
the
application of the Fourth Amendment in the digital
age. See Riley v. California, 134 S. Ct. 2473 (2014)
(warrant required for search of cell phone seized
incident to lawful arrest); United States v. Jones, 132
S. Ct. 945 (2012) (tracking car with GPS device is a
Fourth Amendment search). This case presents an
important next step in the ongoing effort to reconcile
enduring Fourth Amendment principles with the
reality of a new digital world.
In United States v. Jones, this Court addressed
the pervasive location monitoring made possible by
GPS tracking technology surreptitiously and
warrantlessly attached to a vehicle. All members of
the Court agreed that attaching a GPS device to a
vehicle and tracking its movements constitutes a
16

 search under the Fourth Amendment. In so holding,
the Court made clear that the government’s use of
novel digital surveillance technologies not in
existence at the framing of the Fourth Amendment
does not escape the Fourth Amendment’s reach. 132
S. Ct. at 950–51 (“[W]e must ‘assur[e] preservation of
that degree of privacy against government that
existed when the Fourth Amendment was adopted.’”
(quoting Kyllo v. United States, 533 U.S. 27, 34
(2001))); id. at 963–64 (Alito, J., concurring in the
judgment) (“[S]ociety’s expectation has been that law
enforcement agents and others would not—and
indeed, in the main, simply could not—secretly
monitor and catalogue every single movement of an
individual’s car for a very long period.”).
In Riley v. California, the Court addressed
Americans’ privacy rights in the contents of their cell
phones, unanimously holding that warrantless
search of the contents of a cell phone incident to a
lawful arrest violates the Fourth Amendment. In so
doing, the Court rejected the government’s inapt
analogy to other physical objects that have
historically been subject to warrantless search
incident to an arrest. 134 S. Ct. at 2489 (“Cell phones
differ in both a quantitative and a qualitative sense
from other objects that might be kept on an
arrestee’s person.”).
Monitoring an individual’s location and
movements over an extended period of time by
collecting and analyzing cell phone records can and
frequently will expose extraordinarily sensitive
details of a person’s life including, potentially, “a
wealth of detail about . . . familial, political,
professional, religious, and sexual associations.”

17

 Jones, 132 S. Ct. at 955 (Sotomayor, J., concurring).
Without disputing that premise, the court of appeals
nonetheless
held
that
this
voluminous
documentation of a person’s movements in public
and private spaces is unprotected by the Fourth
Amendment by analogizing to the kinds of limited
analog data at issue in Smith and Miller. Pet. App.
11a–14a. As this Court recently cautioned, however,
unexamined reliance on “pre-digital analogue[s]”
risks causing “a significant diminution of privacy.”
Riley, 134 S.Ct. at 2493. Accordingly, “any extension
of . . . reasoning [from decisions concerning analog
searches] to digital data has to rest on its own
bottom.” Id. at 2489. Only this Court can make that
ultimate constitutional judgment.
C.

The Volume and Frequency of
Warrantless
Law
Enforcement
Requests for CSLI Highlights the
Importance
of
the
Question
Presented.

“[M]ore than 90% of American adults . . . own
a cell phone.” Riley, 134 S. Ct. at 2490. As of
December 2015, there were more than 377 million
wireless subscriber accounts in the United States.6
Forty-four percent of U.S. households have only cell
phones.7 When “nearly three-quarters of smart phone
CTIA – The Wireless Association, Annual Wireless Industry
Survey
(2016),
http://www.ctia.org/your-wireless-life/howwireless-works/annual-wireless-industry-survey.
6

7 Stephen J. Blumberg & Julian V. Luke, Ctr. For Disease
Control & Prevention, Wireless Substitution: Early Release of
Estimates from the National Health Interview Survey, January–
June 2014 1 (Dec. 2014), http://www.cdc.gov/nchs/data/nhis/
earlyrelease/wireless201412.pdf.

18

 users report being within five feet of their phones
most of the time, with 12% admitting that they even
use their phones in the shower,” Riley, 134 S. Ct. at
2490, the privacy implications of warrantless law
enforcement access to cell phone location data are
difficult to overstate.
This is not an isolated or occasional concern.
Law enforcement is requesting staggering volumes
of CSLI from service providers. From July 2015 to
June 2016, for example, AT&T received 75,302
requests for cell phone location information.8 Verizon
received approximately 18,935 requests for cell
phone location data in just the first half of 2016.9
The government often obtains large volumes of
CSLI pursuant to such requests. In this case the
government requested five months’ and obtained
nearly four months’ (127 days’) worth of Carpenter’s
location data comprising thousands of location data
points. A request for months of data is no aberration:
according to T-Mobile, which now owns Carpenter’s
service provider, MetroPCS, the average law
enforcement request “asks for approximately fiftyfive days of records.”10 Other recent and pending
cases involve comparable or even greater quantities

8 AT&T, Transparency Report, at 4 (2016), http://about.att.com/
content/dam/csr/Transparency%20Reports/ATT_TransparencyR
eport_July2016.pdf .

Verizon, Transparency Report 1H 2016, at 5 (2016),
https://www.verizon.com/about/portal/transparency-report/wpcontent/uploads/2016/07/Transparency-Report-US-1H-2016.pdf.

9

10 T-Mobile, Transparency Report for 2013 & 2014, at 5 (2015),
http://newsroom.t-mobile.com/content/1020/files/NewTrans
parencyReport.pdf.

19

 of sensitive location information obtained without a
warrant. In one case, the government obtained 221
days (more than seven months) of cell site location
information, revealing 29,659 location points for one
defendant. See Graham, 824 F.3d at 446–47 (Wynn,
J., dissenting in part and concurring in the
judgment).
In Jones, Justice Alito recognized that of the
“many new devices that permit the monitoring of a
person’s movements,” cell phones are “[p]erhaps most
significant.” 132 S. Ct. at 963 (Alito, J., concurring in
the judgment). Yet most law enforcement agencies
are obtaining these large quantities of historical
CSLI without a probable cause warrant. See
American Civil Liberties Union, Cell Phone Location
Tracking Public Records Request (Mar. 25, 2013)11
(responses to public records requests sent to roughly
250 local law enforcement agencies show that “few
agencies consistently obtain warrants” for CSLI). The
volume of warrantless requests for CSLI and the
ubiquity of cell phones make the question presented
one of compelling national importance.
Judge Kozinski has summarized the situation
well. In an opinion written six years ago, he began by
noting that this Court’s decision in United States v.
Knotts, 460 U.S. 276, 283–84 (1983), expressly left
open the question whether “‘twenty-four hour
surveillance of any citizen of this country’ by means
of ‘dragnet-type law enforcement practices’ violates
the Fourth Amendment’s guarantee of personal
privacy.” United States v. Pineda-Moreno, 617 F.3d
11 https://www.aclu.org/cases/cell-phone-location-tracking-public
-records-request.

20

 1120, 1126 (9th Cir. 2010) (Kozinski, C.J., dissenting
from denial of rehearing en banc). He then cogently
observed, “[w]hen requests for cell phone location
information have become so numerous that the
telephone company must develop a self-service
website so that law enforcement agents can retrieve
user data from the comfort of their desks, we can
safely say that ‘such dragnet-type law enforcement
practices’ are already in use.” Id. What was true six
years ago is even more true today. This Court’s
intervention is needed now to ensure that the Fourth
Amendment does not become a dead letter as police
accelerate their warrantless access to rich troves of
sensitive personal location data.
II.

FEDERAL COURTS OF APPEALS AND
STATE HIGH COURTS ARE DIVIDED.

The Sixth Circuit’s decision in this case widens
the conflict over whether, or in what circumstances,
sensitive cell phone location data held in trust by a
service provider is protected by a warrant
requirement.
A.

The Circuits Are Split Over
Whether the Third-Party Doctrine
Eliminates People’s Reasonable
Expectation of Privacy in Their
Historical CSLI.

The Sixth Circuit joins the Fourth, Fifth, and
Eleventh Circuits in holding that there is no
reasonable expectation of privacy in historical cell
site location information under the Fourth
Amendment, and therefore that no warrant is
required. In the first of these decisions, In re
Application of the U.S. for Historical Cell Site Data,
21

 724 F.3d 600 (5th Cir. 2013), a magistrate judge
rejected a government application for an order
pursuant to the Stored Communications Act, 18
U.S.C. § 2703(d), seeking historical CSLI, holding
that a warrant is required under the Fourth
Amendment. On appeal, a divided panel of the Fifth
Circuit held that any expectation of privacy in CSLI
is vitiated by the cell service provider’s creation and
possession of the records. 724 F.3d at 613. The court
rejected the argument that cell phone users retain an
expectation of privacy in the data because they do
not voluntarily convey their location information to
the service provider. Id. at 613–14; see also United
States v. Guerrero, 768 F.3d 351, 358–59 (5th Cir.
2014) (applying In re Application in the context of a
suppression motion). The Fourth and Eleventh
Circuits have subsequently agreed with this position.
Graham, 824 F.3d at 424–25; Davis, 785 F.3d at
511–13.
The Third Circuit takes the contrary position.
See Fifth Circuit CSLI Opinion, 724 F.3d at 616
(Dennis, J., dissenting) (recognizing split between
Third and Fifth Circuits). In a decision issued more
than a year before this Court’s opinion in Jones, the
Third Circuit held that magistrate judges have
discretion to require a warrant for historical CSLI if
they determine that the location information sought
will implicate the suspect’s Fourth Amendment
privacy rights by showing, for example, when a
person is inside a constitutionally protected space.
Third Circuit CSLI Opinion, 620 F.3d at 319. In
reaching that conclusion, the court rejected the
argument that a cell phone user’s expectation of
privacy is eliminated by the service provider’s ability
to access that information:
22

 A cell phone customer has not
“voluntarily”
shared
his
location
information with a cellular provider in
any meaningful way. . . . [I]t is unlikely
that cell phone customers are aware
that their cell phone providers collect
and
store
historical
location
information. Therefore, “[w]hen a cell
phone user makes a call, the only
information that is voluntarily and
knowingly conveyed to the phone
company is the number that is dialed
and there is no indication to the user
that making that call will also locate the
caller; when a cell phone user receives a
call, he hasn’t voluntarily exposed
anything at all.”
Id. at 317–18 (last alteration in original). Therefore,
the court held, the third-party doctrine does not
apply to historical CSLI records. Id.
This split in the circuits is accentuated by the
growing number of states that require a warrant for
historical CSLI by statute or pursuant to judicial
opinion. See Zanders v. State, No. 15A01–1509–CR–
1519, __ N.E.3d __, 2016 WL 4140998 (Ind. Ct. App.
Aug. 4, 2016); Commonwealth v. Augustine, 4 N.E.3d
846 (Mass. 2014); Colo. Rev. Stat. § 16-3-303.5(2);
Me. Rev. Stat. tit. 16, § 648; Minn. Stat. §§
626A.28(3)(d), 626A.42(2); Mont. Code Ann. § 46-5110(1)(a); Utah Code Ann. § 77-23c-102(1)(a); N.H.
Rev. Stat. Ann. § 644-A:2; 2016 Vt. Laws No. 169 (S.
155) (to be codified at Vt. Stat. Ann. tit. 13, §
8102(b)). Additional states require a warrant for realtime cell phone location data. See, e.g., Tracey v.

23

 State, 152 So. 3d 504 (Fla. 2014); State v. Earls, 70
A.3d 630 (N.J. 2013); 725 Ill. Comp. Stat. 168/10;
Ind. Code 35-33-5-12; Md. Code Ann. Crim. Proc. § 1203.1(b); Va. Code Ann. § 19.2-70.3(C). Requiring a
warrant for CSLI would harmonize the protections
available to people throughout the United States.
B.

The Circuits Are Split Over
Whether There is a Reasonable
Expectation of Privacy in LongerTerm
Location
Information
Collected by Electronic Means.

In United States v. Maynard, 615 F.3d 544
(D.C. Cir. 2010), aff’d on other grounds sub nom.
Jones, 132 S. Ct. 945, the D.C. Circuit held that
using a GPS device to surreptitiously track a car over
the course of 28 days violates reasonable
expectations of privacy and is therefore a Fourth
Amendment search. Id. at 563. The court explained
that “[p]rolonged surveillance reveals types of
information not revealed by short-term surveillance,
such as what a person does repeatedly, what he does
not do, and what he does ensemble. These types of
information can each reveal more about a person
than does any individual trip viewed in isolation.” Id.
at 562. Therefore, people have a reasonable
expectation of privacy in the intimate and private
information revealed by “prolonged GPS monitoring.”
Id. at 563.
Although this Court affirmed on other
grounds, relying on a trespass-based rationale, the
D.C. Circuit’s approach under the Katz reasonableexpectation-of-privacy test remains controlling law in

24

 that circuit.12 And that holding does not depend on
the nature of the tracking technology at issue:
prolonged electronic surveillance of the location of a
person’s cell phone is at least as invasive as
prolonged electronic surveillance of the location of
her car. See Jones, 132 S. Ct. at 963 (Alito, J.,
concurring in the judgment) (explaining that law
enforcement access to cell phone location information
is “[p]erhaps most significant” of the “many new
devices that permit the monitoring of a person’s
movements.”).
The Sixth Circuit rejected this reasoning when
it held that the information contained in CSLI
records is categorically unprotected by the Fourth
Amendment, regardless of what it reveals and over
what period of time. Pet. App. 13a–14a. In doing so,
the court of appeals widened the circuit split over
whether people have a reasonable expectation of
privacy in their longer-term location information—a
split that existed prior to Jones and continues today.
Compare Maynard, 615 F.3d at 563 (prolonged
electronic location tracking is a search under the
Fourth Amendment), with Pineda-Moreno, 591 F.3d
at 1216–1217 (prolonged electronic location tracking
is not a search under the Fourth Amendment),
United States v. Garcia, 474 F.3d 994, 996–99 (7th
Cir. 2007) (same), and United States v. Marquez, 605
F.3d 604, 609 (8th Cir. 2010) (“A person traveling via
automobile on public streets has no reasonable
12 See Will Baude, Further Thoughts on the Precedential Status
of Decisions Affirmed on Alternate Grounds, The Volokh
Conspiracy (Dec. 3, 2013, 7:27 PM), http://volokh.com/2013/
12/03/thoughts-precedential-status-decisions-affirmedalternate-grounds/.

25

 expectation of privacy in his movements from one
locale to another.”).
III.

THE SIXTH CIRCUIT ERRED IN
HOLDING THAT THE CONDUCT HERE
WAS NOT A SEARCH.
A.

The Sixth Circuit Erred in Holding
That There Is No Reasonable
Expectation of Privacy in Historical
CSLI.

The Sixth Circuit majority held that the mere
fact that the government obtained the CSLI records
from Petitioner’s service provider, rather than from
Petitioner himself, dooms his Fourth Amendment
claim in light of United States v. Miller and Smith v.
Maryland. Neither Miller nor Smith compels that
conclusion and this Court should reject that
understanding of its prior precedent. The mere fact
that another person or entity has access to or control
over private records does not in itself—and without
regard to any other circumstance—destroy an
otherwise reasonable expectation of privacy. Though
third-party access to records may be one factor
weighing on the Katz reasonable-expectation-ofprivacy analysis, the third-party doctrine elucidated
in Miller and Smith is not and never has been an onoff switch. See Florida v. Jardines, 133 S. Ct. 1409,
1418–19 (2013) (Kagan, J., concurring) (expectation
of privacy in odors detectable by a police dog that
emanate from a home); Jones, 132 S. Ct. at 964
(Alito, J., concurring in the judgment) (information
about location and movement in public, even though
exposed to public view); Kyllo, 533 U.S. 27 (thermal
signatures emanating from a home); Ferguson v. City

26

 of Charleston, 532 U.S. 67, 78 (2001) (“The
reasonable expectation of privacy enjoyed by the
typical patient undergoing diagnostic tests in a
hospital is that the results of those tests will not be
shared with nonmedical personnel without her
consent.”); Bond v. United States, 529 U.S. 334, 336
(2000) (bag exposed to the public on luggage rack of
bus); Minnesota v. Olson, 495 U.S. 91, 98–99 (1990)
(“an overnight guest has a legitimate expectation of
privacy in his host’s home” even though his
possessions may be disturbed by “his host and those
his host allows inside”); United States v. Jacobsen,
466 U.S. 109, 115 (1984) (reasonable expectation of
privacy in letters and sealed packages entrusted to
private freight carrier); Katz v. United States, 389
U.S. 347 (1967) (reasonable expectation of privacy in
contents of phone call even though call is conducted
over private companies’ networks); Stoner v.
California, 376 U.S. 483, 487–90 (1964) (implicit
consent to janitorial personnel to enter motel room
does not amount to consent for police to search room);
Chapman v. United States, 365 U.S. 610, 616–17
(1961) (search of a house invaded tenant’s Fourth
Amendment rights even though landlord had
authority to enter house for some purposes).
The Sixth Circuit erred in treating the fact of
third party access to the records as dispositive. Pet.
App. 14a. This Court should make clear that the
reasonable-expectation-of-privacy test relies on a
totality-of-the-circumstances
analysis.
Avoiding
mechanical applications of holdings from the analog
age is of paramount importance when dealing with
highly sensitive and voluminous digitized records.
See Riley, 134 S. Ct. at 2489. It is virtually
impossible to participate fully in modern life without
27

 leaving a trail of digital breadcrumbs that create a
pervasive record of the most sensitive aspects of our
lives. Ensuring that technological advances do not
“erode the privacy guaranteed by the Fourth
Amendment,” Kyllo, 533 U.S. at 34, requires nuanced
applications of analog-age precedents.
This is not to say that proper resolution of this
case requires wholesale rejection of Smith and
Miller’s holdings. Even on the plain terms of those
decisions, Petitioner retains a reasonable expectation
of privacy in his CSLI.
To assess an individual’s expectation of
privacy in records held by a third party this Court
has looked to, among other factors, whether the
records were “voluntarily conveyed” to that entity,
Miller, 425 U.S. at 442; Smith, 442 U.S. at 744, and
what privacy interest a person has in the information
the records reveal, Miller, 425 U.S. at 442; Smith,
442 U.S. at 741–42. Unlike the dialed phone
numbers and limited bank records at issue in Smith
and Miller, “[a] cell phone customer has not
‘voluntarily’ shared his location information with a
cellular provider in any meaningful way.” Third
Circuit CSLI Opinion, 620 F.3d at 317. Location
information is not entered by the user into the phone,
nor otherwise affirmatively transmitted to the
service provider. This is doubly true when a person
receives a call, thereby taking no action that would
knowingly or voluntarily reveal location. Id. at 317–
18. It is also particularly clearly the case when that
person’s cell phone is roaming on another carrier’s
network, as was Carpenter’s here, because
“[t]ypically, a cell phone user does not know when
her phone is roaming onto another provider’s

28

 network, much less the name of the other provider on
whose network her phone is roaming.” In re
Application for Tel. Info. Needed for a Criminal
Investigation, 119 F. Supp. 3d 1011, 1028–29 (N.D.
Cal. 2015), appeal dismissed, No. 15-16760 (9th Cir.
Feb. 5, 2016). “As a result, cell phone users, unlike a
bank depositor or telephone dialer, will often not
know the identity of the third party to which they are
supposedly conveying information.” Id. at 1029.
Moreover, the documentation of a person’s
movements, locations, and activities over the course
of time contained in CSLI records is exceedingly
sensitive and private in ways that were not at issue
in Smith or Miller. This is so for at least two reasons.
First, because people carry their phones with them
virtually everywhere they go, including inside their
homes and other constitutionally protected spaces,
cell phone location records can reveal information
about presence, location, and activity in those spaces.
See United States v. Davis, 754 F.3d 1205, 1215–16
(11th Cir. 2014) (Sentelle, J.), rev’d en banc, 785 F.3d
498 (11th Cir. 2015). In United States v. Karo, 468
U.S. 705 (1984), this Court held that location
tracking implicates Fourth Amendment privacy
interests when it may reveal information about
individuals in areas where they have reasonable
expectations of privacy. The Court explained that
using an electronic device—there, a beeper—to infer
facts about “location[s] not open to visual
surveillance,” like whether “a particular article is
actually located at a particular time in the private
residence,” or to later confirm that the article
remains on the premises, was just as unreasonable
as physically searching the location without a
warrant. Id. at 714–16. Such location tracking “falls
29

 within the ambit of the Fourth Amendment when it
reveals information that could not have been
obtained through visual surveillance” from a public
place. Id. at 707; see also Kyllo, 533 U.S. at 36 (use of
thermal imaging device to learn information about
interior of home constitutes a search).
Second, CSLI reveals a great sum of sensitive
and private information about a person’s movements
and activities in public and private spaces that, at
least over the longer term, violates expectations of
privacy. In Jones, although the majority opinion
relied on a trespass-based rationale to determine
that a search had taken place, 132 S. Ct. at 949, it
specified that “[s]ituations involving merely the
transmission of electronic signals without trespass
would remain subject to Katz [reasonableexpectation-of-privacy] analysis.” Id. at 953. Five
Justices conducted a Katz analysis, and concluded
that at least longer-term location tracking violates
reasonable expectations of privacy. Id. at 960, 964
(Alito, J., concurring in the judgment); id. at 955
(Sotomayor, J., concurring).
This conclusion did not depend on the
particular type of tracking technology at issue in
Jones. As Justice Sotomayor explained, electronic
location tracking implicates the Fourth Amendment
because it “generates a precise, comprehensive record
of a person’s public movements that reflects a wealth
of detail about her familial, political, professional,
religious, and sexual associations.” Id. at 955. This
Court subsequently amplified that point when it
explained that cell phone location data raises
particularly acute privacy concerns because it “can
reconstruct someone’s specific movements down to

30

 the minute, not only around town but also within a
particular building.” Riley, 134 S. Ct. at 2490 (citing
Jones, 132 S. Ct. at 955 (Sotomayor, J., concurring)).
The records obtained by the government in
this case implicate both the expectation of privacy in
private spaces and the expectation of privacy in
longer-term location information. They allow the
government to know or infer when a person slept at
home and when he didn’t. Davis, 785 F.3d at 540–41
(Martin, J., dissenting). They show a person’s
movements around town, nearly down to the
minute.13 Id. They even allow the government to
learn who a person associated with and when. See,
e.g., Pet. App. 81a–82a (concluding that codefendants were at the same location based on their
CSLI records); Trial Tr. 107, Dec. 16, 2013, ECF No.
333 (same).
It is not surprising, therefore, that polling data
shows that more than 80 percent of people consider

Even knowing only periodic information about which
cell sites a phone connects to over time can be used to
interpolate the path the phone user traveled, thus revealing
information beyond just where the phone was located
at discrete points. See, e.g., Arvind Thiagarajan et
al., Accurate, Low-Energy Trajectory Mapping for Mobile
Devices, 8 USENIX Conf. on Networked Syss. Design
& Implementation 20 (2011), https://www.usenix.org/legacy/
events/nsdi11/tech/full_papers/Thiagarajan.pdf?CFID=2305506
85&CFTOKEN=76524860 (describing one algorithm for
accurate trajectory interpolation using cell site information).
Law enforcement routinely uses cell site data for this purpose;
in this case, the government presented testimony explaining
that cell site data points revealed Carpenter’s trajectories
placing him at the businesses in question at the relevant times.
See Trial Tr. 55, 57, 62, Dec. 13, 2013, ECF No. 332.
13

31

 “[d]etails of [their] physical location over time” to be
“sensitive”—evincing greater concern over this
information than over the contents of their text
messages, a list of websites they have visited, or
their relationship history.14 Historical CSLI enables
the government to “monitor and track our cell
phones, and thus ourselves, with minimal
expenditure of funds and manpower, [which] is just
the type of gradual and silent encroachment into the
very details of our lives that we as a society must be
vigilant to prevent.” Tracey, 152 So. 3d at 522
(internal quotation marks omitted).
B.

The
Sixth
Circuit
Erred
In
Deferring to Congress’s 30-Year-Old
Legislative Scheme.

In concluding that the Fourth Amendment
does not protect people’s cell site location records
from warrantless search, the Sixth Circuit majority
explained that “Congress has specifically legislated
on the question before us today, and in doing so has
struck the balance reflected in the Stored
Communications Act.” Pet. App. 15a. Thus, “society
itself—in the form of its elected representatives in
Congress—has already struck a balance that it
thinks reasonable.” Id. at 16a. Therefore, the
majority wrote, “[t]here is considerable irony in [a]
request” to “declare that balance unconstitutional.”
Id. at 15a.

14 Pew Research Ctr., Public Perceptions of Privacy and Security
in the Post-Snowden Era, 32, 34 (Nov. 12, 2014),
http://www.pewinternet.org/files/2014/11/PI_PublicPerception
sofPrivacy_111214.pdf.

32

 The supposed balance to which the majority
refers is decades old, and is a relic of legislation
passed before the proliferation of cell phones and the
availability of large volumes of increasingly precise
cell site location information. When Congress passed
the Stored Communications Act in 1986,15 there were
a mere 1,000 cell sites in the United States16
(compared to more than 300,000 today)17 and less
than one half of one percent of Americans had a cell
phone.18 Congress gave no indication that it even
considered the existence of historical CSLI, not to
mention the possibility that law enforcement might
want to access it. When Congress amended the
Stored Communications Act in 1994,19 cellular
networks were still fragmented and rudimentary,
with less than 18,000 cell sites across the country.20
Congress simply did not contemplate the
contemporary ubiquity of cell phones and the volume
Electronic Communications Privacy Act of 1986, Pub. L. No.
99-508, § 201, 100 Stat. 1848.
15

16 Andrea Meyer, 30th Anniversary of the First Commercial Cell
Phone Call, Verizon (Oct. 11, 2013), https://www.verizon
wireless.com/news/article/2013/10/30th-anniversary-cell-phone.
html and https://www.slideshare.net/slideshow/embed_code/
27105077?rel=0

CTIA – The Wireless Association, Annual Wireless Industry
Survey.

17

Meyer, 30th Anniversary of the First Commercial Cell Phone
Call.

18

Communications Assistance for Law Enforcement Act, Pub.
L. No. 103-414, § 207, 108 Stat. 4279 (1994).
19

20 Background on CTIA’s Wireless Industry Survey 2, CTIA-The
Wireless Association (2014), http://www.ctia.org/docs/defaultsource/Facts-Stats/ctia_survey_ye_2013_graphics-final.pdf.

33

 and precision of CSLI when crafting the SCA. Courts
should not give undue weight to this outdated
legislative scheme in evaluating people’s reasonable
expectation of privacy under the Fourth Amendment.
Moreover, in concluding that acquisition of
historical CSLI is a Fourth Amendment search, a
court need not hold the Stored Communications Act
unconstitutional. The SCA contains a mechanism for
law enforcement to obtain a warrant for CSLI. See 18
U.S.C. § 2703(c)(1)(A). “Section 2703(c) may be fairly
construed to provide for ‘warrant procedures’ to be
followed when the government seeks customer
records that may be protected under the Fourth
Amendment, including historical cell site location
information.” Fifth Circuit CSLI Opinion, 724 F.3d
at 617 (Dennis, J., dissenting). The determination
that “one proposed interpretation or use of the SCA
as applied did not comply with the Fourth
Amendment’s requirement for a warrant based on
probable cause” is firmly within the purview of the
judiciary. Pet. App. 32a (Stranch, J., concurring).
Indeed, “[t]he question before [the court] is one that
courts routinely answer: did the search at issue
require a warrant?” Id. at 31a–32a. This Court
should provide a “simple” answer—“get a warrant.”
Riley, 134 S. Ct. at 2495.

34

 CONCLUSION
For the foregoing reasons, the petition for a
writ of certiorari should be granted.
Respectfully Submitted,
Nathan Freed Wessler
Counsel of Record
Ben Wizner
Steven R. Shapiro
AMERICAN CIVIL LIBERTIES
UNION FOUNDATION
125 Broad Street
New York, NY 10004
(212) 549-2500
nwessler@aclu.org
Harold Gurewitz
GUREWITZ & RABEN, PLC
333 W. Fort Street,
Suite 1400
Detroit, MI 48226
Daniel S. Korobkin
Michael J. Steinberg
Kary L. Moss
AMERICAN CIVIL LIBERTIES
UNION FUND OF
MICHIGAN
2966 Woodward Ave.
Detroit, MI 48201
Dated: September 26, 2016

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