                 FOR PUBLICATION
 UNITED STATES COURT OF APPEALS
      FOR THE NINTH CIRCUIT

UNITED STATES OF AMERICA,                   No. 08-10351
                Plaintiff-Appellee,             D.C. No.
               v.                        2:07-cr-00118-PMP-
BRANDON DEMARLO MONGHUR,                          LRL
             Defendant-Appellant.
                                              OPINION

       Appeal from the United States District Court
                for the District of Nevada
         Philip M. Pro, District Judge, Presiding

                  Argued and Submitted
          May 4, 2009—San Francisco, California

                   Filed August 11, 2009

    Before: Procter Hug, Jr., Michael Daly Hawkins, and
            Richard C. Tallman, Circuit Judges.

                Opinion by Judge Tallman




                           10875
                UNITED STATES v. MONGHUR            10877




                       COUNSEL

Jason F. Carr (argued), Assistant Federal Public Defender,
Franny A. Forsman, Federal Public Defender, Las Vegas,
Nevada, for defendant-appellant Brandon Monghur.
10878               UNITED STATES v. MONGHUR
Robert L. Ellman (argued), Assistant United States Attorney,
Gregory A. Brower, United States Attorney, Las Vegas,
Nevada, for plaintiff-appellee United States of America


                             OPINION

TALLMAN, Circuit Judge:

   Brandon Monghur appeals the district court’s denial of his
suppression motion, following which he entered a conditional
guilty plea to being a felon in possession of a firearm in viola-
tion of 18 U.S.C. §§ 922(g)(1) and 924(a)(2). In denying the
motion, the district court concluded that Monghur waived his
expectation of privacy in the closed container within which
federal law enforcement discovered the revolver in question.
We must decide whether the container search, conducted
without a warrant, violated the Fourth Amendment’s prohibi-
tion of unreasonable searches and seizures.

   We have jurisdiction pursuant to 28 U.S.C. § 1291 and con-
clude that the search was unlawful. We therefore vacate the
conviction and the order denying suppression and remand for
further proceedings.

                                  I

   On May 9, 2007, Brandon Monghur, a previously con-
victed felon, was arrested pursuant to a state warrant for
attempted murder and the battery of Antoinette Wilson.1
Monghur was detained in a segregated cell at Nevada’s Clark
County Detention Center (“CCDC”). The CCDC has a tele-
phone system that allows inmates to make outbound calls.
Next to each telephone is a placard instructing them how to
place calls and cautioning that inmate calls are subject to
  1
   Wilson is the mother of Monghur’s children, all of whom live in Wil-
son’s apartment, which is the residence where the search was conducted.
                     UNITED STATES v. MONGHUR                      10879
monitoring and recording. A similar auditory warning is also
issued to the recipient of each outbound call.

   On the day of his arrest, Monghur made several telephone
calls from the jail, including three calls to a person named
Prince Bousley. In the first call, Bousley asked Monghur if he
had been caught with “the thing.” Monghur confirmed that he
had not, and that “the thing” was hidden in Wilson’s apart-
ment, where he stayed “on and off for several months.” In the
second call, Bousley inquired whether Monghur wanted him
to retrieve “the thing” from Wilson’s residence. Monghur
agreed and told Bousley to come to the CCDC and pick up the
key to Wilson’s apartment. During the third and final tele-
phone call, Monghur told Bousley that he had put “the thing”
in the closet in his room and that it was located “in the green.”

   FBI Special Agent Gary McCamey, who knew Monghur
through an investigation into local gang activity, reviewed the
telephone recordings on May 10, 2007. Although neither
speaker specifically identified “the thing,” Agent McCamey
correctly surmised based on his experience and familiarity
with “street vernacular” that Bousley and Monghur were
referring to a firearm. At least six law enforcement officers
immediately proceeded to Wilson’s apartment and informed
her that they had credible information that there was a hand-
gun in her residence. Wilson, as she had done on a previous
visit by officers, expressed no knowledge of any gun on the
premises. She readily consented to a search and requested that
any firearm found in the apartment be immediately removed
out of concern for the safety of her five young children who
lived there and were present at the time.2 She led agents to her
son’s bedroom, which was the room in which Monghur slept
when he stayed with Wilson.
  2
    Wilson’s eldest child was eight or nine years old at the time in ques-
tion.
10880                UNITED STATES v. MONGHUR
   The agents proceeded to the bedroom closet, which con-
tained clothing, shoes, and other items belonging to an adult
male. On the shelf was an opaque green plastic storage con-
tainer.3 They removed the lid and found a .38 caliber revolver.
The agents seized the handgun and removed it from the prem-
ises, as Wilson requested. At no point did the agents obtain,
or attempt to obtain, a search warrant.

   A federal grand jury returned an indictment charging
Monghur with one count of being a felon in possession of a
firearm, in violation of 18 U.S.C. §§ 922(g)(1) and 924(a)(2),
and a related forfeiture count. Monghur moved to suppress the
weapon. He argued that the warrantless search of the closed
container violated his Fourth Amendment rights, requiring
suppression of the fruits of the unlawful search. In response,
the Government argued that (1) Wilson had authority to con-
sent to the container search, (2) exigent circumstances justi-
fied the warrantless search, and (3) Monghur had no
expectation of privacy in the container.

   After holding an evidentiary hearing, a magistrate judge
recommended denial of Monghur’s motion. The magistrate
rejected the Government’s first two theories, finding that Wil-
son lacked both express and apparent authority to consent to
the search of the container, and that exigent circumstances did
not exist to excuse the warrant requirement. The Government
does not challenge these rulings on appeal. The magistrate
concluded, however, that Monghur relinquished any expecta-
tion of privacy with respect to the container, reasoning:

      During a phone call that he had reason to believe law
      enforcement officials were listening to, Monghur
      told Bousley he had hidden a handgun inside a green
      storage container in his bedroom closet. By his own
      voluntary act he knowingly assumed the risk that the
  3
    The container had the name “Aaron” written on the side, but the record
is unclear whether agents on the scene noticed this at the time.
                  UNITED STATES v. MONGHUR                 10881
    police would learn where he was hiding his gun. By
    doing so, Monghur extinguished any reasonable
    expectation of privacy he might otherwise have had
    in the contents of the container.

The district court adopted the magistrate’s findings in full
over Monghur’s objections and denied Monghur’s suppres-
sion motion.

   Monghur then pled guilty but, with the Government’s con-
sent, conditionally reserved the right to appeal the suppression
order. He was sentenced to 96 months imprisonment, to be
followed by three years of supervised release. Monghur
timely appealed.

                               II

   We review de novo the district court’s denial of a motion
to suppress evidence. United States v. Nance, 962 F.2d 860,
862 (9th Cir. 1992). Factual findings are reviewed for clear
error. Id.

                               A

   [1] “The Fourth Amendment is a vital safeguard of the right
of the citizen to be free from unreasonable governmental
intrusions into any area in which he has a reasonable expecta-
tion of privacy.” Winston v. Lee, 470 U.S. 753, 767 (1985).
As the parties agree, Monghur, at least initially, held a reason-
able expectation of privacy in the closed container that he
stored in the closet in Wilson’s apartment. See United States
v. Davis, 332 F.3d 1163, 1167 (9th Cir. 2003) (“’A person has
an expectation of privacy in his or her private, closed contain-
ers’ and ‘does not forfeit that expectation of privacy merely
because the container is located in a place that is not con-
trolled exclusively by the container’s owner.’ ” (quoting
United States v. Fultz, 146 F.3d 1102, 1105 (9th Cir. 1998))).
The only question raised by this appeal is whether Monghur
10882                UNITED STATES v. MONGHUR
relinquished, abandoned, or otherwise waived that expectation
of privacy by disclosing the handgun’s existence and location
in jail telephone conversations that he knew were monitored
by law enforcement.4

   Relying on the general principle that “[w]hat a person
knowingly exposes to the public . . . is not a subject of Fourth
Amendment protection,” Katz v. United States, 389 U.S. 347,
351 (1967), the Government contends that “[b]y making state-
ments to [Bousley], knowing that jailors were listening,
[Monghur] disavowed his expectation of privacy in the con-
tainer, not merely the words he uttered over the telephone.”
Br. of Appellee at 15. The district court seems to have
accepted the Government’s analysis. We disagree.

   [2] The Government’s position on appeal, to a large extent,
conflates two separate inquiries. Much of its briefing focuses
on the reasonableness of Monghur’s expectation of privacy in
his jail telephone conversations. But Monghur concedes, as he
must, that he had no expectation of privacy in those calls. See
United States v. Van Poyck, 77 F.3d 285, 291 (9th Cir. 1996)
(“[A]ny expectation of privacy in outbound calls from prison
is not objectively reasonable and . . . the Fourth Amendment
is therefore not triggered by the routine taping of such calls.”).
The Government attempts to extrapolate from the undisputed
lack of an expectation of privacy in the jail telephone calls to
equally apply to the closed container. We are not persuaded.
Whether Monghur had a constitutionally protected expecta-
tion of privacy in a closed container stored in Wilson’s
apartment—given his admissions made during telephone con-
versations with Bousley—is a distinct constitutional question.

  [3] We have not squarely addressed what effect, if any, a
  4
   The Government’s only argument on appeal relates to Monghur’s
expectation of privacy in the closed container. Therefore, we do not
address the exigency or consent arguments presented to, and rejected by,
the district court.
                  UNITED STATES v. MONGHUR               10883
voluntary disclosure might have on a Fourth Amendment
analysis in this context. See United States v. Gust, 405 F.3d
797, 804 n.14 (9th Cir. 2005) (“We express no opinion
whether Gust’s pre-search admissions to the police that the
cases contained guns should be relevant to determining
whether Gust retained any expectation of privacy in the gun
case, as neither party raised this issue on appeal.”). The Sev-
enth Circuit addressed a similar question in United States v.
Cardona-Rivera, 904 F.2d 1149 (7th Cir. 1990). Officers
arrested a defendant in possession of two conspicuously
wrapped packages that they believed were bricks of cocaine.
The officers inquired as to the contents, to which the defen-
dant responded, “coke.” Id. at 1152. The officers then took the
packages to the federal building where, without a warrant,
they opened them and found cocaine. Id.

   [4] On appeal from the denial of a suppression motion the
Seventh Circuit held that officers were not required to obtain
a warrant before searching the packages, despite ample time
to do so, because the defendant had voluntarily and contem-
poraneously disclosed to the officers that they contained con-
traband. Id. at 1156. The court concluded that the defendant
had waived any expectation of privacy in the packages’ con-
tents, thus obviating the warrant requirement:

    [H]ere the waiver of privacy was direct and explicit.
    Asked what the packages contained, Luna said
    “coke” (he denied this at the suppression hearing,
    but the judge disbelieved him). He stripped the cloak
    of secrecy from the package. It was as if he had
    unwrapped it and pointed. Once Luna admitted that
    his package contained a contraband substance, no
    lawful interest of his could be invaded by the offi-
    cers’ opening the packages, whether on the spot or
    later in their office. No purpose would be served by
    insisting on a warrant in such a case or by setting
    aside the conviction because of the absence of a war-
    rant.
10884                 UNITED STATES v. MONGHUR
Id.; see also Wayne R. LaFave, Search & Seizure: A Treatise
on the Fourth Amendment § 5.5 (4th ed. 2004) (“[T]he act of
stating to police the contents of the container is much like
revealing the contents by using a transparent container.”).5

   [5] We think the Seventh Circuit’s reasoning in Cardona-
Rivera makes perfect sense. When made to a law enforcement
officer, an unequivocal, contemporaneous, and voluntary dis-
closure that a package or container contains contraband
waives any reasonable expectation of privacy in the contents.
See Pennsylvania v. Mimms, 434 U.S. 106, 108-09 (1977)
(recognizing that “reasonableness” remains the touchstone
under the Fourth Amendment). The Constitution does not
require the formality of a warrant in such circumstances.

   [6] The facts of this case are, however, sufficiently distin-
guishable from Cardona-Rivera that the logical underpinnings
of the principle announced there find no parallel in the instant
case. Cognizant that jail personnel might be listening,
Monghur attempted to disguise the subject matter by using
ambiguous, generic language to describe the handgun and its
whereabouts: “the thing” was in a closet, “in the green.” It is
relevant that Monghur never explicitly identified the contra-
band at issue. Although Agent McCamey had his reasoned
suspicions, “the thing,” viewed in context, could have been a
number of things, including contraband.6 Nor did Monghur
  5
     Some state courts have adopted similar holdings. See Commonwealth
v. Kondash, 808 A.2d 943, 949 (Pa. Super. Ct. 2002) (holding that the
defendant’s admission revealing that his closed pouch contained needles
was a relinquishment of any expectation of privacy he had therein and,
therefore, no constitutional violation associated with its warrantless search
occurred); People v. Carper, 876 P.2d 582, 584-85 (Colo. 1994) (holding
that, by disclosing to an agent that he was carrying a bindle inside his
pocket that contained cocaine, the defendant “did not manifest a subjective
privacy interest in the contents of his pocket or of the bindle”); State v.
Ludtke, 306 N.W.2d 111, 114 (Minn. 1981) (“[The] defendant, by volun-
teering what the contents were, had implicitly signaled that he no longer
had any expectation of privacy in the satchel.”).
   6
     We do not suggest that police officers cannot rely on their training,
experience, or familiarity with street jargon to interpret coded phrases. But
                     UNITED STATES v. MONGHUR                       10885
specifically identify the container itself. Indeed, at the sup-
pression hearing, Agent McCamey testified that based on the
conversations he did not know that he was looking for a green
plastic container when agents went to Wilson’s apartment.
Perhaps most significantly, coded language aside, Monghur
never made a voluntary disclosure directly to law enforce-
ment. He was informing an associate where to find his gun in
the hope that it could be removed before its discovery. That
Monghur acted covertly knowing that calls were monitored or
recorded—and that law enforcement might review the
conversations—is materially different from directly and inten-
tionally admitting to a police officer the contraband contents
of a specific package or closed container.

   Nothing about his jailhouse conversations with Bousley,
which law enforcement later overheard, operates as a “direct
and explicit” waiver of an expectation of privacy in a con-
tainer hidden elsewhere. Cardona-Rivera, 904 F.2d at 1156.
Monghur’s efforts to conceal the subject matter based on what
he said on the phone demonstrate both an objective and sub-
jective intention to preserve privacy—not to relinquish it. We
therefore reject the Government’s position that Monghur
waived his expectation of privacy in the closed container
through his statements on the telephone.

   [7] To be clear, we think based on his admissions in the jail
telephone conversations, coupled with Monghur’s criminal
record for violence and what officers discovered when Wilson
invited them to look around, Agent McCamey had probable
cause to believe Monghur had a firearm stashed inside Wil-
son’s apartment. Exigency was not established here and is
unchallenged on appeal. Therefore, we must presume that,

the fact that a coded phrase was used in the monitored telephone conversa-
tions is relevant in assessing whether Monghur, through his actions, relin-
quished his expectation of privacy in the contents of a closed container
located elsewhere.
10886             UNITED STATES v. MONGHUR
after discovering Monghur’s possessions in the closet and
identifying the green plastic container (i.e., what they reason-
ably believed was “the green”), agents could have sealed the
apartment and presented their observations from the investi-
gation, Monghur’s known criminal history, and Monghur’s
conversations with Bousley to a neutral and detached magis-
trate to support a warrant application. But, we find no basis
to conclude that Monghur waived his expectation of privacy
in the closed container because he made an encrypted, incrim-
inating disclosure that he was warned would be reviewed by
law enforcement. Accordingly, the agents’ search of his
closed container without a warrant violated Monghur’s Fourth
Amendment rights.

                               B

   The application of the exclusionary rule deserves brief
mention. While this appeal was pending, the Supreme Court
decided Herring v. United States, 129 S. Ct. 695 (2009),
which confirmed that “suppression is not an automatic conse-
quence of a Fourth Amendment violation.” Id. at 698; see also
Hudson v. Michigan, 547 U.S. 586, 591 (2006) (“Suppression
of evidence . . . has always been our last resort, not our first
impulse.”). The Court reaffirmed that, before applying the
exclusionary rule, courts should examine whether the benefits
of deterring police misconduct outweigh the “substantial
social costs” of applying the rule, which include the principal
concern of “letting guilty and possibly dangerous defendants
go free—something that ‘offends basic concepts of the crimi-
nal justice system.’ ” Herring, 129 S. Ct. at 701 (quoting
United States v. Leon, 468 U.S. 897, 908 (1984)). Chief Jus-
tice Roberts, writing for the majority, explained:

    To trigger the exclusionary rule, police conduct must
    be sufficiently deliberate that exclusion can mean-
    ingfully deter it, and sufficiently culpable that such
    deterrence is worth the price paid by the justice sys-
    tem. As laid out in our cases, the exclusionary rule
                   UNITED STATES v. MONGHUR                 10887
    serves to deter deliberate, reckless, or grossly negli-
    gent conduct, or in some circumstances recurring or
    systemic negligence.

Id. at 702. By contrast, because “[a]n error that arises from
nonrecurring and attenuated negligence is . . . far removed
from the core concerns that led us to adopt the rule in the first
place,” id., “when police mistakes are the result of negligence
such as that described here, rather than systemic error or reck-
less disregard of constitutional requirements, any marginal
deterrence does not ‘pay its way,’ ” id. at 704 (quoting Leon,
468 U.S. at 907-08). See also United States v. Noster, No. 07-
50391, 2009 WL 2032347, at *3-4 (9th Cir. July 15, 2009);
United States v. Al Nasser, 555 F.3d 722, 726 (9th Cir. 2009).

   [8] Here, having concluded that the warrantless search was
lawful, the district court never reached the question of sup-
pression. In light of “the general rule . . . that a federal appel-
late court does not consider an issue not passed upon below,”
remand is appropriate to allow the district court, which is in
a superior position to assess the deliberateness and culpability
of the officers’ conduct, to apply Herring in the first instance.
See Singleton v. Wuff, 428 U.S. 106, 120 (1976).

                               III

   The warrantless search of the closed container stored in
Wilson’s apartment, though supported by probable cause, was
unlawful and violated Monghur’s Fourth Amendment protec-
tion against unreasonable searches and seizures. For the fore-
going reasons, we VACATE the conviction and the order
denying Monghur’s suppression motion and REMAND to the
district court to consider whether suppression is the appropri-
ate remedy in light of Herring.

  VACATED AND REMANDED.
