                      FOR PUBLICATION

    UNITED STATES COURT OF APPEALS
         FOR THE NINTH CIRCUIT


 UNITED STATES OF AMERICA,                    No. 17-50151
           Plaintiff-Appellee,
                                               D.C. No.
                 v.                      3:16-cr-01770-BTM-1

 MIGUEL ANGEL CANO,
        Defendant-Appellant.                    OPINION


       Appeal from the United States District Court
          for the Southern District of California
      Barry Ted Moskowitz, District Judge, Presiding

            Argued and Submitted April 10, 2019
                   Pasadena, California

                       Filed August 16, 2019

Before: Susan P. Graber and Jay S. Bybee, Circuit Judges,
        and M. Douglas Harpool,* District Judge.

                      Opinion by Judge Bybee




     *
       The Honorable M. Douglas Harpool, United States District Judge
for the Western District of Missouri, sitting by designation
2                    UNITED STATES V. CANO

                            SUMMARY**


                            Criminal Law

    The panel reversed the district court’s order denying the
defendant’s motion to suppress evidence obtained from
warrantless searches of his cell phone by Customs and Border
Protection officials, and vacated his conviction for importing
cocaine.

    Applying United States v. Cotterman, 709 F.3d 952 (9th
Cir. 2013) (en banc), the panel held that manual cell phone
searches may be conducted by border officials without
reasonable suspicion but that forensic cell phone searches
require reasonable suspicion. The panel clarified Cotterman
by holding that “reasonable suspicion” in this context means
that officials must reasonably suspect that the cell phone
contains digital contraband. The panel further concluded that
cell phone searches at the border, whether manual or forensic,
must be limited in scope to whether the phone contains digital
contraband; and that a broader search for evidence of a crime
cannot be justified by the purposes of the border search
exception to the Fourth Amendment warrant requirement.

    The panel held that to the extent that a Border Patrol
agent’s search of the defendant’s phone – which included the
recording of phone numbers and text messages for further
processing – went beyond a verification that the phone lacked
digital contraband, the search exceeded the proper scope of a
border search and was unreasonable as a border search under

    **
       This summary constitutes no part of the opinion of the court. It has
been prepared by court staff for the convenience of the reader.
                  UNITED STATES V. CANO                       3

the Fourth Amendment. The panel held that although the
agents had reason to suspect the defendant’s phone would
contain evidence leading to additional drugs, the record does
not give rise to an objectively reasonable suspicion that the
digital data in the phone contained contraband, and the border
search exception therefore did not authorize the agents to
conduct a warrantless forensic search of the defendant’s
phone. The panel held that the good faith exception to the
exclusionary rule does not apply because the border officials
did not rely on binding appellate precedent specifically
authorizing the cell phone searches at issue here.

    Rejecting the defendant’s contention that the government
violated his rights under Brady v, Maryland, 373 U.S. 83
(1963), and Fed. R. Crim. P. 16, by failing to turn over certain
information he requested from the FBI and DEA in pursuit of
this third-party defense, the panel found no evidence that the
prosecution had knowledge or possession of evidence
showing that the defendant’s cousin or his cousin’s gang were
involved in drug trafficking at the Mexico-California border,
and held that the prosecutor should not be held to have
“access” to any information that an agency not involved in
the investigation or prosecution of the case refuses to turn
over.
4                 UNITED STATES V. CANO

                        COUNSEL

Harini P. Raghupathi (argued), Federal Defenders of San
Diego, Inc., San Diego, California, for Defendant-Appellant.

Mark R. Rehe (argued), Assistant United States Attorney;
Helen H. Hong, Assistant United States Attorney, Chief,
Appellate Section, Criminal Division; Adam L. Braverman,
United States Attorney; United States Attorney’s Office, San
Diego, California; for Plaintiff-Appellee.

Sophia Cope and Adam Schwartz, Electronic Frontier
Foundation, San Francisco, California, for Amicus Curiae
Electronic Frontier Foundation.


                         OPINION

BYBEE, Circuit Judge:

    Defendant-Appellant Miguel Cano was arrested for
carrying cocaine as he attempted to cross into the United
States from Mexico at the San Ysidro Port of Entry.
Following his arrest, a Customs and Border Protection
official seized Cano’s cell phone and searched it, first
manually and then using software that accesses all text
messages, contacts, call logs, media, and application data.
When Cano moved to suppress the evidence obtained from
the warrantless searches of his cell phone, the district court
held that the searches were valid under the border search
exception to the Fourth Amendment’s warrant requirement.

    Applying United States v. Cotterman, 709 F.3d 952 (9th
Cir. 2013) (en banc), we conclude that manual cell phone
                  UNITED STATES V. CANO                     5

searches may be conducted by border officials without
reasonable suspicion but that forensic cell phone searches
require reasonable suspicion. We clarify Cotterman by
holding that “reasonable suspicion” in this context means that
officials must reasonably suspect that the cell phone contains
digital contraband. We further conclude that cell phone
searches at the border, whether manual or forensic, must be
limited in scope to a search for digital contraband. In this
case, the officials violated the Fourth Amendment when their
warrantless searches exceeded the permissible scope of a
border search. Accordingly, we hold that most of the
evidence from the searches of Cano’s cell phone should have
been suppressed. We also conclude that Cano’s Brady claims
are unpersuasive. Because we vacate Cano’s conviction, we
do not reach his claim of prosecutorial misconduct.

   We reverse the district court’s order denying Cano’s
motion to suppress and vacate Cano’s conviction.

                 I. THE BACKGROUND

A. The Facts

    Defendant-Appellant Miguel Cano worked in the flooring
and carpet installation trade and lived with his wife and
children in the Mission Hills community north of Los
Angeles. In the summer of 2016, however, Cano moved from
Los Angeles to Tijuana, Mexico, where he stayed with his
cousin Jose Medina. While staying with Medina, Cano
crossed the border into the United States six times, sometimes
remaining in the United States for less than thirty minutes.
On two of those trips, Cano was referred to secondary
inspection, but no contraband was found.
6                 UNITED STATES V. CANO

    On July 25, 2016, Cano arrived at the San Ysidro Port of
Entry from Tijuana. In primary inspection, Cano stated that
“he was living in Mexico, working in San Diego, but going to
LA on that day.” Pursuant to a random Customs and Border
Protection (CBP) computer referral, Cano was referred to
secondary inspection, where a narcotic-detecting dog alerted
to the vehicle’s spare tire. A CBP official removed the spare
tire from the undercarriage of the truck and discovered 14
vacuum-sealed packages inside, containing 14.03 kilograms
(30.93 pounds) of cocaine.

    Cano was arrested, and a CBP official administratively
seized his cell phone. The CBP officials called Homeland
Security Investigations (HSI), which dispatched Agents
Petonak and Medrano to investigate. After arriving, Agent
Petonak “briefly” and manually reviewed Cano’s cell phone,
noticing a “lengthy call log” but no text messages. Agent
Petonak later stated that the purpose of this manual search
was “two-pronged”: “to find some brief investigative leads in
the current case,” and “to see if there’s evidence of other
things coming across the border.”

    Agent Petonak proceeded to question Cano, who waived
his Miranda rights and agreed to talk. During that interview,
Cano denied any knowledge of the cocaine. Cano stated that
he had moved to Tijuana to look for work in nearby San
Diego, because work was slow in Los Angeles. He also said
he had crossed the border every day for the previous three
weeks looking for work. He told Agent Petonak that he was
headed to a carpet store in Chula Vista that day to seek work.
When pressed, Cano was not able to provide the name or
address of the store, claiming that he intended to look it up on
Google after crossing the border. Cano also explained that he
did not have his flooring tools with him in his pickup truck so
                  UNITED STATES V. CANO                      7

as to avoid problems with border crossings; Cano intended to
drive to Los Angeles to retrieve his tools if he located work
in San Diego.

    During the interrogation, Agent Petonak specifically
asked Cano about the lack of text messages on his cell phone.
Cano responded that his cousin had advised him to delete his
text messages “just in case” he got pulled over in Mexico and
police were to check his cell phone. Cano stated that he
erased his messages to avoid “any problems” with the
Mexican police.

    While Agent Petonak questioned Cano, Agent Medrano
conducted a second manual search of the cell phone. Agent
Medrano browsed the call log and wrote down some of the
phone numbers on a piece of paper. He also noticed two
messages that arrived after Cano had reached the border, and
he took a photograph of the messages. The first message
stated, “Good morning,” and the second message stated,
“Primo, are you coming to the house?” Agent Medrano gave
all of this information—the recorded list of calls and the
photograph—to Agent Petonak.

    Finally, Agent Medrano conducted a “logical download”
of the phone using Cellebrite software. A Cellebrite search
enables the user to access text messages, contacts, call logs,
media, and application data on a cell phone and to select
which types of data to download. It does not, however, allow
the user to access data stored within third-party applications.
Agent Medrano typically does not select the option to
download photographs.

    After Agent Petonak interviewed Cano, he reviewed the
results of the Cellebrite download of Cano’s phone by Agent
8                    UNITED STATES V. CANO

Medrano. The Cellebrite results revealed that Cano had sent
no text messages, and it listed all the calls made by Cano.
Agent Petonak later concluded that none of the phone
numbers in the call log corresponded to carpeting stores in
San Diego.

B. The Proceedings

     Cano was indicted for importing cocaine. Before trial,
Cano moved to suppress any evidence obtained from Agents
Petonak and Medrano’s warrantless searches of his cell phone
at the border. The district court denied Cano’s motion, ruling
that the manual searches and the Cellebrite search of Cano’s
phone were valid border searches. During trial, the
government introduced evidence that resulted from the
manual searches of the phone and from Agent Medrano’s
Cellebrite download of the phone.1

    In preparation for trial, Cano indicated his intent to
present a third-party culpability defense claiming that his
cousin, Jose Medina, was responsible for placing the drugs in
Cano’s spare tire without Cano’s knowledge. Cano proffered
evidence that Medina had a key to Cano’s car and had driven
it shortly before Cano’s attempted border crossing, that


    1
         Some—but not all—of the evidence was available through
alternative channels. For example, the government introduced a call log,
unchallenged by Cano, that the government received from Cano’s phone
company. Similarly, the government later obtained a warrant to search the
phone, and an agent conducted further searches. Because the government
introduced at trial much evidence pre-dating those events, and because the
government has not argued that any Fourth Amendment error was
harmless, those later events do not affect our Fourth Amendment analysis
of the warrantless searches. United States v. Rodriguez, 880 F.3d 1151,
1163 (9th Cir. 2018)
                  UNITED STATES V. CANO                      9

Medina had a criminal record including a conviction for
cocaine possession, that Medina was a member of a Chicago-
based gang called the Latin Kings, and that the Latin Kings
sold cocaine within the United States and were involved with
a cartel that trafficked drugs across the border.

     Following Cano’s implication of Medina, the government
contacted Medina and promised him immunity and
immigration papers in exchange for his cooperation. Medina
initially denied being involved with drugs, but later contacted
the government on his own and offered to help them with the
“biggest RICO case” and “drug seizures of 20 to 25
kilograms at a time.” All of this information was made
available to Cano.

    As part of his defense, Cano sought additional discovery
from HSI, the Federal Bureau of Investigation (FBI), and the
Drug Enforcement Agency (DEA) regarding: (1) records
linking Medina to drug sales, distribution, or trafficking; and
(2) records linking the Latin Kings to drug trafficking from
Mexico to Southern California. The government opposed
Cano’s discovery motion, arguing that the evidence was not
material under Federal Rule of Criminal Procedure
16(a)(1)(E)(i) and that discovery should be limited to HSI, as
neither the DEA nor the FBI had participated in the
investigation of Cano. The district court originally overruled
both objections, finding the evidence material under Rule 16
and exculpatory under Brady v. Maryland, 373 U.S. 83
(1963). The court also reasoned that, because HSI could
inquire of the DEA and FBI if it sought inculpatory evidence,
HSI had access to the files and was required to provide any
exculpatory evidence held by the DEA or FBI.
10                   UNITED STATES V. CANO

    In response to the court’s discovery order, HSI produced
Medina’s immigration file and his Bureau of Prisons record.
Agent Petonak also searched for Medina’s name in two
different police clearinghouses, but neither returned any hits.2
Both Agent Petonak and the United States Attorney’s Office
(USAO) subsequently requested information showing a link
between the Latin Kings and drug trafficking from Mexico
from the legal counsel of both the FBI and DEA. Both
agencies denied the requests without providing any
explanation or any indication as to whether the requested
information existed.

    Following these attempts, the government moved for the
district court to reconsider its discovery order and excuse it
from discovery relating to files held by the FBI and DEA.
The district court granted the motion to reconsider, finding
that the prosecutor did not have access to the evidence when
he was “rebuffed” by agencies over which he had no control.

    The case proceeded to trial and Cano presented his third-
party culpability defense. The first trial resulted in a hung
jury and a mistrial. On retrial, Cano again relied on his third-
party culpability defense. The second trial resulted in Cano’s
conviction. This appeal followed, in which Cano raises three
issues: (1) whether the warrantless searches of his cell phone
violated the Fourth Amendment and whether the resulting
evidence should be suppressed; (2) whether the government’s
non-disclosure of materials that may have been held by the
DEA and FBI violated his right to due process under Brady


     2
       A police clearinghouse works for the purpose of “deconfliction” by
notifying an agency if another agency has an investigation pending against
the same person or item. The DEA and FBI participate in the two
clearinghouses searched by Agent Petonak.
                    UNITED STATES V. CANO                         11

and Federal Rule of Criminal Procedure 16; and (3) whether
the government raised an improper propensity inference in its
closing argument. We address Cano’s first two arguments in
turn. Because we conclude that the district court erred in
denying Cano’s motion to suppress, we vacate Cano’s
conviction and do not reach his claim of prosecutorial
misconduct.

    II. THE WARRANTLESS SEARCH OF CANO’S
                 CELL PHONE

    The Fourth Amendment protects “[t]he right of the people
to be secure in their persons, houses, papers, and effects,
against unreasonable searches and seizures.” U.S. Const.
amend. IV.3 Ordinarily, before conducting a search, police
must obtain a warrant issued by a judicial officer based “upon
probable cause, supported by Oath or affirmation, and
particularly describing the place to be searched, and the
persons or things to be seized.” Id. Warrants are generally
required “unless ‘the exigencies of the situation’ make the
needs of law enforcement so compelling that the warrantless
search is objectively reasonable under the Fourth
Amendment.” Mincey v. Arizona, 437 U.S. 385, 393–94
(1978) (citation omitted). Consequently, “searches conducted
outside the judicial process, without prior approval by judge
or magistrate, are per se unreasonable under the Fourth
Amendment—subject only to a few specifically established
and well-delineated exceptions.” Katz v. United States, 389
U.S. 347, 357 (1967) (footnote omitted). Such “specifically
established and well-delineated exceptions” include exigent


    3
       We review de novo “the district court’s determination that [a]
warrantless search . . . was a valid border search.” United States v.
Cardona, 769 F.2d 625, 628 (9th Cir. 1985).
12                UNITED STATES V. CANO

circumstances, searches incident to arrest, vehicle searches,
and border searches. See Arizona v. Gant, 556 U.S. 332, 343
(2009) (vehicle searches); Brigham City v. Stuart, 547 U.S.
398, 403 (2006) (exigent circumstances; listing other
exceptions, including warrantless entry to fight a fire, to
prevent the imminent destruction of evidence, or in “hot
pursuit” of a fleeing suspect); United States v. Ramsey, 431
U.S. 606, 616 (1977) (border searches); Weeks v. United
States, 232 U.S. 383, 392 (1914) (searches incident to arrest),
overruled in part on other grounds by Mapp v. Ohio, 367
U.S. 643 (1961).

    Exceptions to the warrant requirement are subject to two
important constraints. First, any search conducted under an
exception must be within the scope of the exception. Second,
some searches, even when conducted within the scope of the
exception, are so intrusive that they require additional
justification, up to and including probable cause and a
warrant.

    The first constraint is illustrated by the Supreme Court’s
decision in Riley v. California, 573 U.S. 373 (2014), a case
involving the search incident to arrest exception. In Riley, the
Court addressed “whether the police may, without a warrant,
search digital information on a cell phone seized from an
individual who has been arrested”; in other words, whether
cell phones fell within the scope of the search incident to
arrest exception. Id. at 378. The Court began by recognizing
the increasing role in our lives of “minicomputers that also
happen to have the capacity to be used as a telephone”;
“[m]odern cell phones, as a category, implicate privacy
concerns far beyond those implicated by the search of a
cigarette pack, a wallet, or a purse.”            Id. at 393.
Acknowledging that “it has been well accepted that [a search
                  UNITED STATES V. CANO                      13

incident to lawful arrest] constitutes an exception to the
warrant requirement,” id. at 382, the Court pointed out that
such searches serve two purposes: (1) to secure “the officer’s
safety” and (2) to “prevent . . . concealment or destruction [of
evidence],” id. at 383 (citation omitted). The Court then
considered whether a cell phone search qualified as a search
incident to arrest by considering “whether application of the
search incident to arrest doctrine to [cell phones] would
‘untether the rule from the justifications underlying the . . .
exception.’” Id. at 386 (quoting Gant, 556 U.S. at 343).

     The Court concluded that neither purpose for the search
incident to arrest exception justified the search of a cell
phone. The Court rejected the government’s argument that
searching a cell phone incident to arrest would “help ensure
officer safety in . . . indirect ways, for example by alerting
officers that confederates of the arrestee are headed to the
scene.” Id. at 387. The Court reasoned that the government’s
position “would . . . represent a broadening” of the
exception’s foundational concern that “an arrestee himself
might grab a weapon and use it against an officer.” Id. at
387–88. The Court observed that “once law enforcement
officers have secured a cell phone, there is no longer any risk
that the arrestee himself will be able to delete incriminating
data from the phone,” id. at 388, and police have means to
ensure that data cannot be wiped from the phone remotely,
id. at 390. The Court concluded “not that the information on
a cell phone is immune from search; [but rather] that a
warrant is generally required before such a search, even when
a cell phone is seized incident to arrest.” Id. at 401.

    The second constraint on warrantless searches is
illustrated by the Court’s decision in United States v.
Montoya de Hernandez, 473 U.S. 531 (1985). Montoya was
14                UNITED STATES V. CANO

stopped at Los Angeles International Airport and referred to
secondary inspection. Id. at 533. She had arrived from
Bogota and was carrying $5,000 in cash. Id. She had no
credit cards and no hotel reservations. Id. at 533–34.
Because border officials suspected that Montoya may have
swallowed cocaine-filled balloons, Montoya was held in the
customs office and, after a magistrate judge issued an order,
taken to a hospital for a rectal examination. Id. at 534–35.
Over the next four days, she passed 88 balloons containing
cocaine. Id. at 536. Montoya argued that the search she was
subjected to, though a border search, was so intrusive that it
could not be conducted without a high level of particularized
suspicion. Id. at 536–37, 540. The Court balanced her
privacy interests against the interests of the government at the
border and concluded that, while routine searches may be
conducted at the border without any showing of suspicion, a
more intrusive, nonroutine search must be supported by
“reasonable suspicion.” Id. at 537–41; see also United States
v. Flores-Montano, 541 U.S. 149, 152 (2004) (suggesting that
nonroutine searches are limited to “highly intrusive searches
of the person” involving “dignity and privacy interests”).

    Cano recognizes that he was subject to search at the
border, but Cano and amicus Electronic Frontier Foundation
(“EFF”) raise two categorical challenges and one as-applied
challenge to the searches conducted here. First, EFF argues
that any warrantless search of a cell phone falls outside the
scope of the border search exception. Second, EFF argues
that even if the search is within the scope of the border search
exception, a warrantless cell phone search is so intrusive that
it requires probable cause. We address these categorical
challenges in Part II.A. Third, Cano asserts that, even if cell
phones are generally subject to search at the border, the
manual and forensic searches of his cell phone exceeded the
                  UNITED STATES V. CANO                    15

“well delineated” scope of the border search. We address this
as-applied question in Part II.B. Finally, the government
argues that even if the border search exceeded the limits of
the Fourth Amendment, the search was conducted in good
faith, and the evidence is admissible. We consider the good
faith exception in Part II.C.

A. Border Searches and Cell Phones

    “[B]order searches constitute a ‘historically recognized
exception to the Fourth Amendment’s general principle that
a warrant be obtained.’” Cotterman, 709 F.3d at 957 (quoting
Ramsey, 431 U.S. at 621). Indeed, border searches typically
do not require any particularized suspicion, so long as they
are “routine inspections and searches of individuals or
conveyances seeking to cross our borders.” Almeida-Sanchez
v. United States, 413 U.S. 266, 272 (1973); see United States
v. Seljan, 547 F.3d 993, 999 (9th Cir. 2008) (en banc). Such
searches are “reasonable simply by virtue of the fact they
occur at the border.” Ramsey, 431 U.S. at 616. The
exception is “rooted in ‘the long-standing right of the
sovereign to protect itself by stopping and examining persons
and property crossing into this country,’” Cotterman, 709
F.3d at 960 (quoting Ramsey, 431 U.S. at 616), to “prevent[]
the entry of unwanted persons and effects,” id. (quoting
Flores-Montano, 541 U.S. at 152).

    The sovereign’s right to conduct suspicionless searches at
the border “does not mean, however, that at the border
‘anything goes.’” Id. (quoting Seljan, 547 F.3d at 1000).
Rather, the border search exception is a “narrow exception”
that is limited in two important ways. Id. (citation omitted).
First, “[t]he authorizing statute limits the persons who may
legally conduct a ‘border search’ to ‘persons authorized to
16                    UNITED STATES V. CANO

board or search vessels.’” United States v. Soto-Soto, 598
F.2d 545, 549 (9th Cir. 1979) (citing 19 U.S.C. § 482).4 This
includes customs and immigration officials, but not general
law enforcement officers such as FBI agents. Id.; see United
States v. Diamond, 471 F.2d 771, 773 (9th Cir. 1973) (stating
that “customs agents are not general guardians of the public
peace”). Second, a border search must be conducted “in
enforcement of customs laws.” Soto-Soto, 598 F.2d at 549.
A border search must be conducted to “enforce importation
laws,” and not for “general law enforcement purposes.” Id.


     4
         Section 482 now reads in relevant part:

               Any of the officers or persons authorized to board
          or search vessels may stop, search, and examine . . . any
          vehicle, beast, or person, on which or whom he or they
          shall suspect there is merchandise which is subject to
          duty, or shall have been introduced into the United
          States in any manner contrary to law . . . . [and may]
          seize and secure the same for trial.

19 U.S.C. § 482(a); see id. § 1467 (“[T]he appropriate customs officer for
[a] port or place of arrival may . . . enforce, cause inspection, examination,
and search to be made of the persons, baggage, and merchandise
discharged or unladen from [an arriving] vessel . . . .”); id. § 1496 (“The
appropriate customs officer may cause an examination to be made of the
baggage of any persons arriving in the United States in order to ascertain
what articles are contained therein and whether subject to duty, free of
duty, or prohibited . . . .”); id. § 1582 (“[A]ll persons coming into the
United States from foreign countries shall be liable to detention and search
by authorized officers or agents . . . .”).

     The Court has described § 482 as granting the executive “plenary
authority to conduct routine searches and seizures at the border, without
probable cause or a warrant.” Montoya de Hernandez, 473 U.S. at 537.
We have held that the “outer limits of authority delegated by [§ 482 are]
available only in border searches.” Corngold v. United States, 367 F.2d
1, 3 (9th Cir. 1966) (en banc).
                  UNITED STATES V. CANO                       17

A general search cannot be “justif[ied] . . . on the mere basis
that it occurred at the border.” Id. (affirming the suppression
of evidence where an FBI agent stopped and searched the
vehicle of an alien to determine whether the car had been
stolen).

    1. Cell Phone Data as Contraband

    As we discussed briefly above, the Supreme Court has
identified two principal purposes behind warrantless border
searches: First, to identify “[t]ravellers . . . entitled to come
in” and, second, to verify their “belongings as effects which
may be lawfully brought in.” Carroll v. United States, 267
U.S. 132, 154 (1925); see Ramsey, 431 U.S. at 620 (“The
border-search exception is grounded in the recognized right
of the sovereign to control . . . who and what may enter the
country.”).

    EFF argues that applying the border search exception to
a cell phone’s data would “untether” the exception from the
purposes underlying it. EFF contends that a border search
encompasses only a search for illegal persons and physical
contraband located on the body of the applicant for
admission or among his effects. Because digital data on a cell
phone cannot conceal objects such as drugs, guns, or
smuggled persons, EFF asserts that digital cell phone
searches are always beyond the scope of the border search
exception.

    We agree with EFF that the purpose of the border search
is to interdict contraband, but we disagree with its premise
that cell phones cannot contain contraband. Although cell
18                   UNITED STATES V. CANO

phone data cannot hide physical objects,5 the data can contain
digital contraband. The best example is child pornography.
See United States v. Molina-Isidoro, 884 F.3d 287, 295 n.3
(5th Cir. 2018) (Costa, J., specially concurring) (“One type of
contraband that can be stored within the data of a cell
phone . . . is child pornography.”). And because cell phones
may ultimately be released into the interior, even if the owner
has been detained, the United States has a strong interest in
preventing the entry of such material. See, e.g., United States
v. Vergara, 884 F.3d 1309, 1311 (11th Cir.) (describing how
agents returned one of the defendant’s phones to a family
member after defendant had been arrested for possessing
child pornography on his other two phones), cert. denied, 139
S. Ct. 70 (2018). We find no basis for the proposition that the
border search exception is limited to searching for physical
contraband. At the very least, a cell phone that has photos
stored on it is the equivalent of photographs, magazines, and
books.6 See Riley, 573 U.S. at 394; Cotterman, 709 F.3d at
964. The contents may be digital when they are on the phone,
but the physicality of the phone itself and the possibility that


     5
        No one contests that a border official could, consistent with the
Fourth Amendment, examine the physical body of a cell phone to see if
the phone itself is contraband—because, for example, it is a pirated copy
of a patented U.S. phone—or if the phone itself presents a physical threat
to officers. See Riley, 573 U.S. at 387 (“Law enforcement officers remain
free to examine the physical aspects of a phone to ensure that it will not
be used as a weapon—say, to determine whether there is a razor blade
hidden between the phone and its case.”). The dispute here concerns only
whether border officials may search the digital data contained within the
phone.
     6
     We need not address here questions surrounding the use of “cloud
computing,” where the phone gives access to, but does not contain in its
own memory, digital data stored in the cloud. See Riley, 573 U.S. at
397–98; Cotterman, 709 F.3d at 965 & n.12.
                    UNITED STATES V. CANO                            19

the phone’s contents can be printed or shared electronically
gives border officials sufficient reason to inspect it at the
border. We conclude that cell phones—including the phones’
data—are subject to search at the border.

    2. Forensic Cell Phone Searches as an Intrusive Search

    The second question we must address in response to
amicus EFF is whether forensic searches of a cell phone are
so intrusive that they require reasonable suspicion or even
probable cause. We answered this question in our en banc
decision in Cotterman, but with respect to laptop computers.7
Cotterman, 709 F.3d at 962–68. Cotterman was a United
States citizen returning to the United States from Mexico. Id.
at 957. When he reached the port of entry, border officials
noted that Cotterman had various convictions for sexual
conduct with children. Id. Concerned that Cotterman might
be involved in child sex tourism, officials conducted a brief
search of his laptop computers and digital cameras and noted
that the laptops had password-protected files. Id. at 958. The
officials detained the computers for several days in order to
run a comprehensive forensic search of the hard drive, which
revealed hundreds of images of child pornography. Id. at
958–59. For us, “the legitimacy of the initial search of
Cotterman’s electronic devices at the border [was] not in
doubt,” id. at 960, “[t]he difficult question . . . [was] the
reasonableness, without a warrant, of the forensic



    7
      Although Cotterman referred to “electronic devices” generally, see
709 F.3d at 962–68, our holding was limited to the “examination of
Cotterman’s computer,” id. at 968, and did not address cell phones. We
mentioned cell phones only once—in the first paragraph of the
introduction describing the modern “digital world.” Id. at 956.
20                UNITED STATES V. CANO

examination that comprehensively analyzed the hard drive of
the computer,” id. at 961.

    We acknowledged the “substantial personal privacy
interests” in “[e]lectronic devices . . . capable of storing
warehouses full of information.” Id. at 964. At the same
time, we recognized “the important security concerns that
prevail at the border” and the legitimacy of “[t]he effort to
interdict child pornography.” Id. at 966. We held that a
routine, manual search of files on a laptop computer—“a
quick look and unintrusive search”—is reasonable “even
without particularized suspicion,” but that officials must
“possess a particularized and objective basis for suspecting
the person stopped of criminal activity” to engage in a
forensic examination, which is “essentially a computer strip
search.” Id. at 960–61, 966, 967 (citation omitted). We
concluded that reasonable suspicion was “a modest, workable
standard that is already applied in the extended border search,
Terry stop, and other contexts.” Id. at 966; see id. at 968
(defining reasonable suspicion as “a particularized and
objective basis for suspecting the particular person stopped of
criminal activity” (quoting United States v. Cortez, 449 U.S.
411, 417–18 (1981))).

    We think that Cotterman’s reasoning applies equally to
cell phones. In large measure, we anticipated the Supreme
Court’s reasoning in Riley, 573 U.S. at 393–97, when we
recognized in Cotterman that digital devices “contain the
most intimate details of our lives” and “the uniquely sensitive
nature of data on electronic devices carries with it a
significant expectation of privacy,” Cotterman, 709 F.3d at
965–66; see Riley, 573 U.S. at 385, 393 (describing cell
phones as “a pervasive and insistent part of daily life” that,
“as a category, implicate privacy concerns far beyond those
                      UNITED STATES V. CANO                               21

implicated by the search of a cigarette pack, a wallet, or a
purse”). The Court’s view of cell phones in Riley so closely
resembles our own analysis of laptop computers in Cotterman
that we find no basis to distinguish a forensic cell phone
search from a forensic laptop search.8

    Nor do we believe that Riley renders the Cotterman
standard insufficiently protective. Riley, of course, held that
“a warrant is generally required” before searching a cell
phone, “even when a cell phone is seized incident to arrest.”
573 U.S. at 401. But here we deal with the border search
exception—not the search incident to arrest exception—and
the difference in context is critical. In light of the
government’s enhanced interest in protecting the “integrity of
the border” and the individual’s decreased expectation of
privacy, the Court has emphasized that “the Fourth
Amendment’s balance of reasonableness is qualitatively
different at the international border than in the interior” and
is “struck much more favorably to the Government.”
Montoya de Hernandez, 473 U.S. at 538–40. As a result,
post-Riley, no court has required more than reasonable
suspicion to justify even an intrusive border search. See
United States v. Wanjiku, 919 F.3d 472, 485 (7th Cir. 2019)
(“[N]o circuit court, before or after Riley, has required more
than reasonable suspicion for a border search of cell phones
or electronically-stored data.”); Touset, 890 F.3d at 1234

    8
        We note that the Eleventh Circuit disagreed with Cotterman in
United States v. Touset, 890 F.3d 1227, 1234 (11th Cir. 2018). The court
held that no level of suspicion was required to conduct a forensic search
of a cell phone. Id. at 1234–35. Nevertheless, the Touset court held, in
the alternative, that the forensic search of various electronic devices seized
at the border were supported by reasonable suspicion. Id. at 1237. As
with most cell phone search cases, in Touset border agents were looking
for child pornography.
22                UNITED STATES V. CANO

(“Riley, which involved the search-incident-to-arrest
exception, does not apply to searches at the border.”);
Molina-Isidoro, 884 F.3d at 291 (“For border searches both
routine and not, no case has required a warrant.”); id. at 293
(“The bottom line is that only two of the many federal cases
addressing border searches of electronic devices have ever
required any level of suspicion. They both required only
reasonable suspicion and that was for the more intrusive
forensic search.”); see also Kolsuz, 890 F.3d 133, 137 (4th
Cir. 2018) (concluding that a “forensic examination of
Kolsuz’s phone must be considered a nonroutine border
search, requiring some measure of individualized suspicion”
but declining to decide whether the standard should be
reasonable suspicion or probable cause).

     Accordingly, we hold that manual searches of cell phones
at the border are reasonable without individualized suspicion,
whereas the forensic examination of a cell phone requires a
showing of reasonable suspicion. See Cotterman, 709 F.3d
at 968.

B. The Searches of Cano’s Cell Phone and the Scope of the
   Border Search Exception

    Having concluded that border officials may conduct
suspicionless manual searches of cell phones, but must have
reasonable suspicion before they conduct a forensic search,
we still must address the core of Cano’s argument: whether
the manual and forensic searches of his cell phone were not
searches for digital contraband, but searches for evidence of
a crime, and thus exceeded the proper scope of a border
search.
                     UNITED STATES V. CANO                             23

    1. The Border Exception and the Search for Contraband

    As a threshold matter, Cano argues that border searches
are limited in both purpose and scope to searches for
contraband.9 In response, the government argues that
searches for evidence that would aid in prosecuting past and
preventing future border-related crimes are tethered to the
purpose of the border search exception—namely, interdicting
foreign contraband—and thus fall within its scope.




    9
       Cano emphasizes that the officials who arrested him were looking
for evidence of a crime, not contraband that could be seized at the border,
and this renders the search unconstitutional. He points to Officers Petonak
and Medrano, who searched Cano’s cell phone, and who testified that their
searches had a dual purpose: “to find some brief investigative leads in the
current case” and “to see if there[] [was] evidence of other things coming
across the border.” Because the agents acknowledged that they sought
evidence to use against Cano in building a criminal case, Cano argues that
the court should treat the search as one conducted for “general law
enforcement purposes” rather than a border search.

     Cano’s focus on the officials’ subjective motivations is misplaced,
however. As the district court recognized, “courts have repeatedly held
that the Fourth Amendment’s reasonableness analysis is ‘predominantly
an objective inquiry.’” See Whren v. United States, 517 U.S. 806, 813
(1996) (upholding a “pretextual” stop because “[s]ubjective intentions
play no role in ordinary . . . Fourth Amendment analysis”). We have
upheld border searches of persons seeking entry even when those searches
were conducted “at the behest” of DEA agents seeking criminal evidence.
See United States v. Schoor, 597 F.2d 1303, 1305–06 (9th Cir. 1979)
(holding a border search reasonable where it was conducted “at the
behest” of DEA agents and included a search for certain items of evidence
in addition to a search for contraband). Thus, the mere fact that Officers
Petonak and Medrano subjectively hoped to find “investigative leads”
pertaining to the seized shipment of cocaine does not render their searches
of Cano’s phone beyond the border search exception.
24                UNITED STATES V. CANO

    This is a close question, but we think Cano has the better
of the argument. There is a difference between a search for
contraband and a search for evidence of border-related
crimes, although the distinction may not be apparent.
Cotterman helps us focus on the difference. There, border
officials had been alerted that Cotterman had a criminal
record of sex abuse of minors and might be involved in “child
sex tourism.” Cotterman, 709 F.3d at 957. The officials
seized his laptop and subjected it to searches for child
pornography, which they found. In Cotterman, the child
pornography was contraband subject to seizure at the border.
As contraband, the child pornography is also evidence of
various crimes, including possession of child pornography,
18 U.S.C. § 2252A(a)(5)(B), and importation of obscene
material, 18 U.S.C. § 1462(a). But nothing in Cotterman
authorized border officials to conduct a search for evidence
that Cotterman was involved in sex-related crimes generally.

    Border officials are authorized to seize “merchandise
which . . . shall have been introduced into the United States
in any manner contrary to law.” 19 U.S.C. § 482(a)
(emphasis added). The photos on Cotterman’s laptop
computer were such merchandise. 18 U.S.C. § 2252(a). But
border officials have no general authority to search for crime.
This is true even if there is a possibility that such crimes may
be perpetrated at the border in the future. So, for example, if
U.S. officials reasonably suspect that a person who has
presented himself at the border may be engaged in price
fixing, see 15 U.S.C. § 1, they may not conduct a forensic
search of his phone or laptop. Evidence of price fixing—
texts or emails, for example—is not itself contraband whose
importation is prohibited by law. Such emails may be
evidence of a crime, but they are not contraband, and there is
no law prohibiting the importation of mere evidence of crime.
                      UNITED STATES V. CANO                               25

    We recognize that our analysis is in tension with the
Fourth Circuit’s decision in Kolsuz. Kolsuz was detained at
Washington Dulles International Airport when customs
agents discovered firearm parts in his luggage. Kolsuz, 890
F.3d at 138–39. Kolsuz was arrested and his cell phone
seized. Id. at 139. The agents subjected the phone to a
month-long forensic search, producing a 896-page report. Id.
Kolsuz challenged the search, which the district court upheld
and the Fourth Circuit affirmed. Id. at 139–42. The court
approved the forensic search because the agents had “reason
to believe . . . that Kolsuz was attempting to export firearms
illegally” and that “their search would reveal not only
evidence of the export violation they already had detected,
but also ‘information related to other ongoing attempts to
export illegally various firearm parts.’” Id. at 143 (quoting
the district court; citation omitted). According to the Fourth
Circuit, “[t]he justification behind the border search
exception is broad enough to accommodate not only the
direct interception of contraband as it crosses the border, but
also the prevention and disruption of ongoing efforts to
export contraband illegally.” Id. (emphasis added).10

    We agree with much of the Fourth Circuit’s discussion of
foundational principles, but we respectfully disagree with the
final step approving the search for further evidence that


     10
        As support for this proposition, the Fourth Circuit cited two district
court cases originating within our circuit. Both of those cases addressed
fact-patterns almost identical to Cano’s, and in each case the district court
held that the border-search exception was not limited to searching for
contraband directly. See United States v. Mendez, 240 F. Supp. 3d 1005,
1007–08 (D. Ariz. 2017); United States v. Ramos, 190 F. Supp. 3d 992,
999 (S.D. Cal. 2016). In neither case was the issue appealed to our circuit.
Thus, Cano’s case presents the first opportunity for us to consider the
matter.
26                UNITED STATES V. CANO

Kolsuz was smuggling weapons. Our disagreement focuses
precisely on the critical question that we previously
identified: Does the proper scope of a border search include
the power to search for evidence of contraband that is not
present at the border? Or, put differently, can border agents
conduct a warrantless search for evidence of past or future
border-related crimes? We think that the answer must be
“no.” The “[d]etection of . . . contraband is the strongest
historic rationale for the border-search exception.” Molina-
Isidoro, 884 F.3d at 295 (Costa, J., specially concurring).
Indeed, “every border-search case the Supreme Court has
decided involved searches to locate items being smuggled”
rather than evidence. Id. (emphasis added); see Montoya de
Hernandez, 473 U.S. at 537 (the border search is “to prevent
the introduction of contraband into this country”); United
States v. 12 200-Foot Reels of Super 8mm. Film, 413 U.S.
123, 125 (1973) (border searches are “necessary to prevent
smuggling and to prevent prohibited articles from entry”);
United States v. Thirty-Seven Photographs, 402 U.S. 363, 376
(1971) (“Customs officers characteristically inspect luggage
and their power to do so is not questioned in this case; it is an
old practice and is intimately associated with excluding
illegal articles from the country”). In fact, the Court has long
“draw[n] a sharp distinction between searches for contraband
and those for evidence that may reveal the importation of
contraband.” Molina-Isidoro, 884 F.3d at 296 (Costa, J.,
specially concurring).       The classic statement on the
distinction between seizing goods at the border because their
importation is prohibited and seizing goods at the border
because they may be useful in prosecuting crimes is found in
Boyd v. United States:

        Is a search and seizure, or, what is equivalent
        thereto, a compulsory production of a man’s
                  UNITED STATES V. CANO                       27

        private papers, to be used in evidence against
        him in a proceeding to forfeit his property for
        alleged fraud against the revenue laws—is
        such a proceeding for such a purpose an
        “unreasonable search and seizure” within the
        meaning of the fourth amendment of the
        constitution? . . . . The search for and seizure
        of stolen or forfeited goods, or goods liable to
        duties and concealed to avoid the payment
        thereof, are totally different things from a
        search for and seizure of a man’s private
        books and papers for the purpose of obtaining
        information therein contained, or of using
        them as evidence against him. The two things
        differ toto coelo.

116 U.S. 616, 622–23 (1886), overruled in part on other
grounds by Warden, Md. Penitentiary v. Hayden, 387 U.S.
294 (1967); see also id. at 633 (stating that compelling a man
to produce the evidence against himself not only violates the
Fifth Amendment, but makes the seizure of his “books and
papers” unreasonable under the Fourth Amendment).

     Although we continue to acknowledge that “[t]he
Government’s interest in preventing the entry of unwanted
persons and effects is at its zenith at the international border”
and that “the expectation of privacy is less at the border than
it is in the interior,” Flores-Montano, 541 U.S. at 152, 154,
we hold that the border search exception authorizes
warrantless searches of a cell phone only to determine
whether the phone contains contraband. A broader search
cannot be “justified by the particular purposes served by the
exception.” Florida v. Royer, 460 U.S. 491, 500 (1983).
28                UNITED STATES V. CANO

     2. The Impact of a Limited Scope for Border Searches

    Our conclusion that the border search exception is
restricted in scope to searches for contraband implicates two
practical limitations on warrantless border searches. First,
border officials are limited to searching for contraband only;
they may not search in a manner untethered to the search for
contraband. The Supreme Court has repeatedly emphasized
that “[t]he scope of the search must be ‘strictly tied to and
justified by’ the circumstances which rendered its initiation
permissible.” Terry v. Ohio, 392 U.S. 1, 19 (1968).

    The validity of the manual searches conducted by Agents
Petonak and Medrano at their inception is beyond dispute.
Manual searches of a cell phone at the border can be
conducted without any suspicion whatsoever, see Cotterman,
709 F.3d at 960, and both agents were officers of HSI and
thus had authority to conduct border searches, Soto-Soto, 598
F.2d at 548–49. As the Supreme Court explained in Terry,
however, “a search which is reasonable at its inception may
violate the Fourth Amendment by virtue of its intolerable
intensity and scope.” 392 U.S. at 18.

    Once Cano was arrested, Agent Petonak briefly searched
Cano’s phone and observed that there were no text messages.
The observation that the phone contained no text messages
falls comfortably within the scope of a search for digital
contraband. Child pornography may be sent via text
message, so the officers acted within the scope of a
permissible border search in accessing the phone’s text
messages.

   Agent Medrano conducted a second manual search of the
phone log and text messages on Cano’s phone. Medrano,
                     UNITED STATES V. CANO                            29

however, did more than thumb through the phone consistent
with a search for contraband. He also recorded phone
numbers found in the call log, and he photographed two
messages received after Cano had reached the border. Those
actions have no connection whatsoever to digital contraband.
Criminals may hide contraband in unexpected places, so it
was reasonable for the two HSI officers to open the phone’s
call log to verify that the log contained a list of phone
numbers and not surreptitious images or videos. But the
border search exception does not justify Agent Medrano’s
recording of the phone numbers and text messages for further
processing, because that action has no connection to ensuring
that the phone lacks digital contraband. Accordingly, to the
extent that Agent Medrano’s search of Cano’s phone went
beyond a verification that the phone lacked digital
contraband, the search exceeded the proper scope of a border
search and was unreasonable as a border search under the
Fourth Amendment.11


     11
        The fact of Cano’s arrest does not affect our analysis. The border
search does not lose its identity as such once Cano was arrested. The
United States retains a strong interest in preventing contraband from
entering the United States, whether it is brought in inadvertently,
smuggled, or admitted into the United States once its owner is arrested.
See United States v. Ickes, 393 F.3d 501, 503–05 (4th Cir. 2005)
(upholding the post-arrest search of a laptop computer at the border where
the officials had reason to suspect the computer carried child
pornography); see also United States v. Bates, 526 F.2d 966, 967–68 (5th
Cir. 1976) (per curiam) (upholding a search of the defendant’s vehicle
after he had been arrested at the border for violating his bond in
connection with a previous drug crime under both the search incident to
arrest and the border search exception).

    The government has not argued that the forensic search of Cano’s
phone can be justified as a search incident to lawful arrest. Such an
argument is foreclosed by Riley. See Riley, 573 U.S. at 388–91. Nor has
30                  UNITED STATES V. CANO

    Second, because the border search exception is limited in
scope to searches for contraband, border officials may
conduct a forensic cell phone search only when they
reasonably suspect that the cell phone contains contraband.
We have held that a “highly intrusive” search—such as a
forensic cell phone search—requires some level of
particularized suspicion. Cotterman, 709 F.3d at 963, 968;
see Flores-Montano, 541 U.S. at 152. But that just begs the
question: Particularized suspicion of what? Contraband? Or
evidence of future border-related crimes? Having concluded
above that border searches are limited in scope to searches for
contraband and do not encompass searches for evidence of
past or future border-related crimes, we think the answer here
is clear: to conduct a more intrusive, forensic cell phone
search border officials must reasonably suspect that the cell
phone to be searched itself contains contraband.

    Were we to rule otherwise, the government could conduct
a full forensic search of every electronic device of anyone
arrested at the border, for the probable cause required to
justify an arrest at the border will always satisfy the lesser
reasonable suspicion standard needed to justify a forensic
search. As the Court pointed out in Riley, modern cell phones
are “minicomputers” with “immense storage capacity.” 573
U.S. at 393. Such phones “carry a cache of sensitive personal
information”—“[t]he sum of an individual’s private life”—
such that a search of a cell phone may give the government


the government argued that once Medrano saw the phone numbers in the
call log and the text messages that he could record them consistent with
the plain view exception. See United States v. Comprehensive Drug
Testing, 621 F.3d 1162, 1175–77 (9th Cir. 2010) (en banc) (per curiam),
overruled in part on other grounds as recognized by Demaree v.
Pederson, 887 F.3d 870, 876 (9th Cir. 2018) (per curiam).
                  UNITED STATES V. CANO                     31

not only “sensitive records previously found in the home,”
but a “broad array of private information never found in a
home in any form—unless the phone is.” Id. at 393–97.
Were we to give the government unfettered access to cell
phones, we would enable the government to evade the
protections laid out in Riley “on the mere basis that [the
searches] occurred at the border.” Soto-Soto, 598 F.2d at 549.

     Moreover, in cases such as this, where the individual
suspected of committing the border-related crime has already
been arrested, there is no reason why border officials cannot
obtain a warrant before conducting their forensic search. This
“is particularly true in light of ‘advances’ in technology that
now permit ‘the more expeditious processing of warrant
applications.’” Birchfield v. North Dakota, 136 S. Ct. 2160,
2192 (2016) (quoting Missouri v. McNeely, 569 U.S. 141, 154
(2013)); see Riley, 573 U.S. at 401. Indeed, in most cases the
time required to obtain a warrant would seem trivial
compared to the hours, days, and weeks needed to complete
a forensic electronic search. See, e.g., Wanjiku, 919 F.3d at
477 (noting that a forensic “preview” takes one to three
hours; the full examination “could take months”); Kolsuz, 890
F.3d at 139 (describing how the forensic search “lasted for a
full month, and yielded an 896-page report”); Cotterman, 709
F.3d at 959 (describing how the first forensic search was
conducted over five days; additional evidence was found
“[o]ver the next few months”). We therefore conclude that
border officials may conduct a forensic cell phone search
only when they reasonably suspect that the cell phone to be
searched itself contains contraband.

   Applied here, if the Cellebrite search of Cano’s cell phone
qualifies as a forensic search, the entire search was
32                    UNITED STATES V. CANO

unreasonable under the Fourth Amendment.12 Although
Agents Petonak and Medrano had reason to suspect that
Cano’s phone would contain evidence leading to additional
drugs, the record does not give rise to any objectively
reasonable suspicion that the digital data in the phone
contained contraband.13 Absent reasonable suspicion, the
border search exception did not authorize the agents to
conduct a warrantless forensic search of Cano’s phone, and
evidence obtained through a forensic search should be
suppressed.

     C. Good Faith Exception

    We next consider whether the evidence uncovered by the
searches is nevertheless allowed by the good faith exception.
Having held that the manual searches partially violated the
Fourth Amendment and having held that, if the Cellebrite

     12
         Whether the Cellebrite search constitutes a forensic search is
disputed. Because the district court passed on the issue without deciding
it, because neither party has briefed the question to us, and because we are
vacating Defendant’s conviction, we decline to reach the merits of the
parties’ dispute. See ASSE Int’l, Inc. v. Kerry, 803 F.3d 1059, 1079 (9th
Cir. 2015).
     13
       Indeed, the detection-of-contraband justification would rarely seem
to apply to an electronic search of a cell phone outside the context of child
pornography. The courts of appeals have just begun to confront the
difficult questions attending cell phone searches at the border. Most of the
cases have involved child pornography. See, e.g., Wanjiku, 919 F.3d 472;
Touset, 890 F.3d 1227; Molina-Isidoro, 884 F.3d 287; Vergara, 884 F.3d
1309; Cotterman, 709 F.3d 952. Among the courts of appeals, only the
Fourth Circuit has addressed the question outside the context of
pornography. Kolsuz, 890 F.3d 133 (exportation of firearms parts); see
also United States v. Kim, 103 F. Supp. 3d 32 (D.D.C. 2015) (exports in
violation of Iranian trade embargo); United States v. Saboonchi, 990 F.
Supp. 2d 536 (D. Md. 2014) (same).
                   UNITED STATES V. CANO                       33

search of Cano’s phone was a forensic search, it violated the
Fourth Amendment, we must determine whether the
appropriate remedy is suppression of the evidence. The
exclusionary rule is “a ‘prudential’ doctrine”; it is “‘not a
personal constitutional right,’ nor is it designed to ‘redress the
injury’ occasioned by an unconstitutional search.” Davis v.
United States, 564 U.S. 229, 236 (2011) (quoting Stone v.
Powell, 428 U.S. 465, 486 (1976)). Because “[e]xclusion
exacts a heavy toll on both the judicial system and society at
large,” we invoke the rule when we are confident that it will
“deter future Fourth Amendment violations.” Id. at 236–37.
The exclusionary rule does not deter such violations “when
the police conduct a search in objectively reasonable reliance
on binding judicial precedent.” Id. at 239. We have said that
the good faith exception applies only to searches where
“binding appellate precedent . . . ‘specifically authorizes’ the
police’s search.” United States v. Lara, 815 F.3d 605, 613
(9th Cir. 2016) (quoting Davis, 564 U.S. at 232). It is not
sufficient for the question to be “unclear” or for the
government’s position to be “plausibly . . . permissible.” Id.
at 613–14. At the same time, the “precedent [does not have]
to constitute a factual match with the circumstances of the
search in question for the good-faith exception to apply” so
as not to “make the good-faith exception a nullity.” United
States v. Lustig, 830 F.3d 1075, 1082 (9th Cir. 2016).

    The government points to Cotterman as support for the
good faith of the officials. We fail to see how border officials
could believe that Cotterman was “binding appellate
precedent” authorizing their search. Although we have
concluded that Cotterman is still good law after Riley, the
officials could not rely on Cotterman to justify a search for
evidence; Cotterman was a search for contraband that the
government has a right to seize at the border. Here, the
34                UNITED STATES V. CANO

officials’ search was objectively tied only to proving their
case against Cano and finding evidence of future crimes.
Searching for evidence and searching for contraband are not
the same thing.

    We understand that border officials might have thought
that their actions were reasonable, and we recognize that
border officials have to make in-the-moment decisions about
how to conduct their business—whether or not they have
written guidance from the courts. But as we understand the
Davis rule, the good faith exception to the exclusionary rule
applies only when the officials have relied on “binding
appellate precedent.” See Lara, 815 F.3d at 613; see also
Wanjiku, 919 F.3d at 485–86 (finding that agents had
reasonable suspicion to search the defendant’s cell phone,
laptop, and portable hard drive for child pornography;
holding that, if probable cause was required, the officials
acted in good faith). This is a rapidly developing area, not an
area of settled law. Even if our decision in Cotterman
rendered the searches “plausibly . . . permissible,” it did not
“specifically authorize” the cell phone searches at issue here.
Lara, 815 F.3d at 613–14.

                            ***

    In sum, the manual searches and the Cellebrite search of
Cano’s cell phone exceeded the scope of a valid border
search. Because the good faith exception does not apply,
most of the evidence obtained from the searches of Cano’s
cell phone should have been suppressed. We thus reverse the
district court’s order denying Cano’s motion to suppress, and
we vacate Cano’s conviction. On any retrial, the district court
should determine whether any additional evidence from the
warrantless searches of Cano’s cell phone should be
                  UNITED STATES V. CANO                       35

suppressed, either because the Cellebrite search qualifies as
a forensic search, which the government lacked reasonable
suspicion to conduct, or because the evidence exceeds the
proper scope of a border search.

                 III. DISCOVERY ISSUES

    Cano has also alleged that the government violated his
rights under both Brady and Federal Rule of Criminal
Procedure 16 when it failed to turn over certain information
that Cano requested from the FBI and DEA. We address
Cano’s discovery claims, as the issues may be relevant on any
retrial.

    Under Brady, the prosecution has an obligation, imposed
by the Due Process Clause, to produce “evidence favorable to
an accused upon request . . . where the evidence is material
either to guilt or to punishment.” 373 U.S. at 87.
“[E]vidence is material only if there is a reasonable
probability that, had the evidence been disclosed to the
defense, the result of the proceeding would have been
different.” United States v. Bagley, 473 U.S. 667, 682
(1985).14

    Under Rule 16, the government must, upon request, turn
over any documents “within the government’s possession,
custody, or control” that are “material to preparing the
defense.” Fed. R. Crim. P. 16(a)(1)(E)(i). The defendant
“must make a threshold showing of materiality, which
requires a presentation of facts which would tend to show that
the Government is in possession of information helpful to the

    14
        We review de novo whether a Brady violation has occurred.
United States v. Stever, 603 F.3d 747, 752 (9th Cir. 2010).
36                  UNITED STATES V. CANO

defense.” United States v. Muniz-Jaquez, 718 F.3d 1180,
1183–84 (9th Cir. 2013) (quoting United States v. Stever, 603
F.3d 747, 752 (9th Cir. 2010)). Because “[i]nformation that
is not exculpatory or impeaching may still be relevant to
developing a possible defense,” Rule 16 is “broader than
Brady.” Id. at 1183.15

    Under both Brady and Rule 16, the government “has no
obligation to produce information which it does not possess
or of which it is unaware.” Sanchez v. United States, 50 F.3d
1448, 1453 (9th Cir. 1995). It has an obligation to turn over
only material, exculpatory or otherwise helpful to the defense,
that it has in its possession.16 “Possession” is not limited to
what the prosecutor personally knows. Browning v. Baker,
875 F.3d 444, 460 (9th Cir. 2017), cert. denied, 138 S. Ct.
2608 (2018); United States v. Bryan, 868 F.2d 1032, 1036
(9th Cir. 1989). Because prosecutors are in a “unique
position to obtain information known to other agents of the
government,” they have an obligation to “disclos[e] what
[they] do[] not know but could have learned.” Carriger v.
Stewart, 132 F.3d 463, 480 (9th Cir. 1997) (en banc); see also
Kyles v. Whitley, 514 U.S. 419, 437 (1995) (describing how


     15
        Although discovery rulings are generally reviewed for abuse of
discretion, Stever, 603 F.3d at 752, we review a district court’s
interpretation of the discovery rules de novo, United States v. Cedano-
Arellano, 332 F.3d 568, 570–71 (9th Cir. 2003).
     16
        The “possession” element of Brady is treated as coextensive with
that of Rule 16. See, e.g., United States v. Bryan, 868 F.2d 1032, 1037
(9th Cir. 1989) (using the same “knowledge and access” test to determine
“possession” for both Rule 16 and Brady); United States v. Grace, 401 F.
Supp. 2d 1069, 1076 (D. Mont. 2005) (“Whether exculpatory information
is in the government’s possession for Brady purposes is measured by the
same . . . test used under Rule 16(a)(1)(E) for discovery.”).
                  UNITED STATES V. CANO                       37

the “individual prosecutor has a duty to learn of any favorable
evidence known to [those] acting on the government’s
behalf”); Youngblood v. West Virginia, 547 U.S. 867, 869–70
(2006) (per curiam). This includes information held by
subordinates such as investigating police officers, see Kyles,
514 U.S. at 438; United States v. Price, 566 F.3d 900, 908–09
(9th Cir. 2009), and sometimes extends to information held
by other executive branch agencies, see United States v.
Santiago, 46 F.3d 885, 893 (9th Cir. 1995); United States v.
Jennings, 960 F.2d 1488, 1490–91 (9th Cir. 1992).

    Documents held by another executive branch agency are
deemed to be “in the possession of the government” if the
prosecutor has “knowledge of and access to” the documents.
Bryan, 868 F.2d at 1036. Knowledge and access are
presumed if the agency participates in the investigation of the
defendant. Id. (“The prosecutor will be deemed to have
knowledge of and access to anything in the possession,
custody or control of any federal agency participating in the
same investigation of the defendant.”). However, “a federal
prosecutor need not comb the files of every federal agency
which might have documents regarding the defendant in order
to fulfill his or her obligations under [Rule 16].” Id.; see also
Kyles, 514 U.S. at 437 (“We have never held that the
Constitution demands an open file policy . . . .”).

    Here, Cano asserted a third-party defense theory: he was
staying in Tijuana with his cousin, Jose Medina; Medina was
a member of the Latin Kings gang which was involved in the
drug trade; and Medina had access to Cano’s car before Cano
was stopped at the border. Cano requested that the U.S.
Attorney’s Office turn over any material held by HSI, the
FBI, and the DEA relating to: (1) records linking his cousin
Jose Medina to drug sales, distribution, and trafficking; and
38                UNITED STATES V. CANO

(2) documentation showing a link between the Latin Kings
and drug trafficking through the United States-Mexico
border. The district court found that both requests might
produce evidence that was exculpatory under Brady and
material under Rule 16, but limited Cano’s discovery to only
material held by HSI. The court concluded that the
prosecutor did not have access to evidence held by the FBI
and DEA, and thus had no obligation to provide such
evidence, because both agencies had “rebuffed” the
prosecutor’s attempts to obtain information. Thus, the only
issue raised on appeal is whether any material held by the
DEA and FBI should be deemed “within the government’s
possession.”

    We find no evidence that the prosecution had knowledge
or possession of evidence showing that Medina or the Latin
Kings were involved in drug trafficking at the Mexico-
California border. Medina had one drug-related conviction,
and it was for simple possession of cocaine, not trafficking.
Before trial, however, the prosecution team reached out to
Medina and promised him immunity and immigration
documents in exchange for cooperation and information
concerning drug importation. Although Medina originally
rebuffed the government, he eventually offered to work with
the government and “stated that he would be able to assist the
Government with the . . . biggest RICO . . . case and drug
seizures of 20 to 25 kilograms at a time.” The district court
found that Medina’s statements “spawn[ed] an inference that
[he] is closely connected to the drug-traffickers in Tijuana.”
Based on this inference, Cano argues that the government had
sufficient knowledge of a possible connection between
Medina and drug trafficking to trigger the government’s
discovery obligations.
                     UNITED STATES V. CANO                            39

    Cano’s argument, however, misstates the test we first set
out in Bryan. Cano has argued only that the prosecutor had
knowledge that certain facts might exist. However, we have
said that the prosecutor’s disclosure obligations turn on “the
extent to which the prosecutor has knowledge of and access
to the documents sought by the defendant.” Bryan, 868 F.2d
at 1036 (emphasis added); see also Santiago, 46 F.3d at 894
(analyzing whether the prosecutor had knowledge of and
access to certain inmate files). We have required disclosure
only of documents that the prosecutor knew existed. Bryan,
868 F.2d at 1034–37.

    Here, although Cano has presented evidence alleging a
plausible connection between Medina and drug trafficking,
Cano has failed to adduce any evidence showing that
prosecutors or investigators knew that the FBI or the DEA
possessed documents showing that connection. In fact, the
record established the opposite. One of the HSI agents ran
Medina’s name through two different law enforcement
clearinghouses—in which the FBI and DEA both
participate—and neither search returned any hits.

    Moreover, the prosecutor did not have access to FBI or
DEA files and thus was under no obligation to “comb the
files” of the FBI and DEA for documents relating to
Medina.17 We have occasionally presumed that a prosecutor

    17
        Cano sought to introduce a 2015 report from the FBI’s National
Gang Intelligence Center listing the Latin Kings as one of the top gangs
involved in cross border crime, and including drug importation in its list
of cross-border crimes. (The evidence was not ultimately presented at
trial.) Cano also proffered information concerning two government
informants working within the Latin Kings. Although these reports may
suggest that the FBI may have had further information regarding a
connection between the Latin Kings and drug importation, Cano has not
40                   UNITED STATES V. CANO

has access to an agency’s files where the prosecutor actually
obtained inculpatory information from the agency, even if the
agency was not involved in the investigation or prosecution.
See Santiago, 46 F.3d at 894 (concluding that the prosecutor
had access to other inmates’ prison files where the prosecutor
was able to obtain the defendant’s prison file from the Bureau
of Prisons). Here, however, the U.S. Attorney’s Office
advised the district court that it did not obtain any evidence—
inculpatory or exculpatory—from the FBI or the DEA.
Following the district court’s initial discovery order, HSI’s
agent—Agent Petonak—made a formal request to the legal
counsel for the FBI and the DEA for any “materials related to
the Latin Kings importing cocaine from Mexico to the United
States,” but both agencies “declined to provide [him] with
any such information.” Neither agency revealed whether any
such information existed or provided a reason for its refusal.
The U.S. Attorney’s Office also reached out to the FBI and
the DEA for Latin Kings-related discovery. That request was
also denied.

    Cano argues that the FBI and DEA’s refusal to turn over
information in this particular case should not be
determinative and that the test for access under Bryan and
Santiago requires only that the U.S. Attorney’s Office or
investigating agency generally have access to this type of
information. Cano points to evidence from both prosecution
and defense witnesses that HSI regularly works with the FBI
and the DEA; that “interagency cooperation has been
emphasized” after September 11, 2001; that agents from the
different agencies regularly access information for one
another; that a DEA representative worked in Agent
Petonak’s office; and that agents are often cross-listed


established that the prosecutor had access to the FBI’s or the DEA’s files.
                  UNITED STATES V. CANO                      41

between agencies. From this, Cano argues that HSI generally
has access to FBI and DEA files for inculpatory purposes,
and thus asserts that the refusal of the FBI and DEA to
provide information in this particular case should not relieve
HSI of its discovery obligations. To rule otherwise, Cano
contends, would allow these withholding agencies “to
effectively wall off exculpatory information from the
government in a particular defendant’s case, all the while
providing the government free-flowing access to information
in its overall investigations.”

    Although we are sympathetic to Cano’s concerns
regarding strategic withholding, the rule Cano urges us to
adopt is much too broad. Brady and Rule 16 obligations are
case specific. In Bryan we stated that the test for
“possession” turns on the prosecutor’s “knowledge of and
access to the documents sought by the defendant in each
case” and that “[t]he prosecutor will be deemed to have
knowledge of and access to anything in the possession,
custody or control of any federal agency participating in the
same investigation of the defendant.” 868 F.2d at 1036
(emphases added). Such a case-by-case approach makes
sense, as the FBI and DEA may have valid concerns over
revealing sensitive information in cases wholly unrelated to
the agencies’ own workload; the agencies may be reluctant to
cooperate in a particular investigation if it means opening
their files in other investigations. If Cano thinks that the FBI
or the DEA have other information, not known to the U.S.
Attorney’s Office or the investigating officers, he may file a
request under the Freedom of Information Act, subject to that
Act’s own restrictions on releasing “records or information
compiled for law enforcement purposes.” 5 U.S.C.
§ 552(b)(7). Brady and Rule 16 are not a means for a
defendant to require the prosecutor to do this work for him.
42                UNITED STATES V. CANO

See generally Roth v. U.S. Dep’t of Justice, 642 F.3d 1161,
1175–76 (D.C. Cir. 2011); Boyd v. Crim. Div. of U.S. Dep’t
of Justice, 475 F.3d 381, 386–89 (D.C. Cir. 2007).

    Cano is unable to identify any case in which the
prosecutor was required to obtain discovery from an agency
wholly unrelated to the investigation of the defendant in spite
of that agency’s refusal to comply; all of the cases cited by
Cano imposing a “duty to learn” on the prosecutor involve
independent federal agencies that had participated in the
investigation of the defendant. See Price, 566 F.3d at
908–09; Carriger, 132 F.3d at 479–80; United States v.
Perdomo, 929 F.2d 967, 971 (3d Cir. 1991); United States v.
Osorio, 929 F.2d 753, 762 (1st Cir. 1991). Indeed, the Third
Circuit has held that a Brady obligation is not triggered where
the agency did not participate in the investigation in any way,
did not share any information with the prosecuting team, and
where the prosecutor had no authority or control over the
agency’s members. United States v. Pelullo, 399 F.3d 197,
218 (3d Cir. 2005); see also United States v. Salyer, 271
F.R.D. 148, 156 (E.D. Cal. 2010) (concluding that “[t]he need
for formal process in the acquisition of documents [from
another agency] is the antithesis of ‘access’”). We similarly
now hold that the prosecutor should not be held to have
“access” to any information that an agency not involved in
the investigation or prosecution of the case refuses to turn
over.

    Because the HSI agents and prosecutors in Cano’s case
neither knew of nor had access to any additional files relating
to Medina and the Latin Kings, we conclude that the
government has satisfied its discovery obligations under
Brady and Rule 16.
                UNITED STATES V. CANO               43

                  IV. CONCLUSION

   We REVERSE the district court’s order denying Cano’s
motion to suppress and VACATE Cano’s conviction.
