Court Opinion

ID: 9367031
Source: CourtListenerOpinion
Date Created: 2023-01-30 19:00:35.55887+00
Date Added: 2024-06-11T17:15:56.889162
License: Public Domain

FOR PUBLICATION

     UNITED STATES COURT OF APPEALS
          FOR THE NINTH CIRCUIT

UNITED STATES OF AMERICA,                         No. 20-50314

                 Plaintiff-Appellee,            D.C. No. 2:18-cr-
                                                  00779-PA-2
    v.

TERRANCE DOUGLAS BAKER,                             OPINION

                 Defendant-Appellant.

         Appeal from the United States District Court
            for the Central District of California
          Percy Anderson, District Judge, Presiding

           Argued and Submitted October 4, 2022
                   Pasadena, California

                     Filed January 30, 2023

Before: Danielle J. Forrest and Gabriel P. Sanchez, Circuit
   Judges, and Nancy D. Freudenthal, * District Judge.

                   Opinion by Judge Sanchez

*
  The Honorable Nancy D. Freudenthal, United States District Judge for
the District of Wyoming, sitting by designation.
2                     UNITED STATES V. BAKER

                          SUMMARY **

                          Criminal Law

    The panel affirmed Terrance Baker’s convictions for
Hobbs Act robbery and conspiracy to commit robbery in
violation of 18 U.S.C. § 1951(a) and a sentence enhancement
under U.S.S.G. § 3C1.1, reversed his conviction for
brandishing a firearm in violation of 18 U.S.C. §
924(c)(1)(A)(ii), and remanded for a reduction of sentence
or retrial on the § 924(c) count.
    One week after an armed robbery of a Sprint store, Baker
was stopped and frisked by the Los Angeles Police
Department. Although no weapons or contraband were
found on Baker, an officer removed a car key from his belt
loop without his consent and walked to a nearby parking lot
in search of the car associated with the key. Baker denied
having a car. When officers located a red Buick whose
flashing headlights responded to the key fob, Baker fled and
was apprehended a short distance away. A handgun was
recovered from the car and later introduced at Baker's trial
as the weapon used in the Sprint store robbery.
    Baker contended that the evidence of the handgun
resulted from an illegal search and seizure and should have
been suppressed at trial. The panel held that even if officers
had reasonable grounds to stop Baker, the search and seizure
exceeded constitutional limits. The panel noted that the
Government is unable to explain how the officers’ post-
patdown detention and search for the car was intended to

**
  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. BAKER                    3

confirm or dispel their suspicions about a crime being
committed or to secure the safety of anyone on the
scene. The panel explained that had officers limited their
Terry stop to a brief detention and protective patdown search
of Baker, they would have had no occasion to search for a
car in an adjoining parking lot that matched the key fob
hanging from Baker’s belt loop. The Government argued
that by stating he did not have a car, Baker abandoned the
car key, eliminating his possessory interest in it and leaving
him without standing to challenge its seizure or the resulting
search of the car. Based on the totality of the circumstances,
the panel concluded that Baker did not objectively
demonstrate his intent to abandon the car key. The panel
concluded that the discovery of the handgun was the product
of illegal police conduct, whether that conduct is framed as
exceeding the permissible scope of a Terry stop or as the
warrantless seizure of the car key.
    The panel wrote that the exclusionary rule required
suppression of the handgun evidence at Baker’s trial unless
an exception to the rule applies. The Government argued
that the attenuation doctrine applies based on Baker’s flight
from officers. Rejecting this argument, the panel noted that
where this court has found flight to satisfy the attenuation
doctrine, the circumstances of that flight have provided
independent grounds for discovering the challenged
evidence such that the officer's prior illegal conduct was not
the sole reason for the discovery of the evidence. The panel
explained that here the officers’ illegal seizure of the key was
the sole reason for the discovery of the car—Baker’s flight
played no role in the identification of the red Buick or its
eventual search, and therefore could not purge the taint of
the illegal conduct.
4                  UNITED STATES V. BAKER

    The panel concluded that the Government demonstrated
beyond a reasonable doubt that the jury would have
convicted Baker of robbery and conspiracy to commit
robbery in violation of § 1951(a) based on substantial
independent evidence establishing Baker's involvement in
the robbery. The panel concluded that there is, however,
reasonable doubt whether the jury would have convicted
Baker of brandishing a firearm in violation of § 924(c)
absent the admission of the handgun. The panel therefore
vacated Baker’s conviction on the § 924(c) count.
    The panel held that because the jury was adequately
informed of the limitations of cell site location information,
the district court’s decision to admit the testimony of the
Government’s cell data mapping expert was not erroneous
under any standard of review. The panel held that the district
court did not abuse its discretion in denying admission of a
report by the Department of Commerce’s National Institute
of Standards and Technology (NIST) on guidelines for
mobile device forensics. Because none of the report’s stated
purposes describes the activities of the NIST, the panel
rejected Baker’s argument that public records exception to
the hearsay rule applies.
    Baker contended that the trial testimony of Baker’s co-
defendant was insufficient to support the factual finding that
Baker threatened the co-defendant, and that the district court
therefore erred in applying an obstruction of justice
sentencing enhancement under § 3C1.1. Rejecting this
contention, the panel held that the district court’s
determination that Baker committed obstructive conduct
was not clearly erroneous.
                   UNITED STATES V. BAKER                  5

                        COUNSEL

Gail Ivens (argued), Gail Ivens Attorney at Law, Monterey,
California, for Defendant-Appellant.
Bram M. Alden (argued), Assistant United States Attorney,
Criminal Appeals Section Chief; Tracy L. Wilkison, United
States Attorney; Joseph D. Axelrad; Jeffrey M.
Chemerinsky, Department of Justice Office of the United
States Attorney, Los Angeles, California; Charles E. Fowler
Jr., Department of Justice United States Attorney’s Office,
Austin, Texas; Plaintiff-Appellee.

                        OPINION

SANCHEZ, Circuit Judge:

    One week after an armed robbery of a Sprint store in Los
Angeles, Terrance Baker was stopped and frisked by the Los
Angeles Police Department (LAPD). Although no weapons
or contraband were found on Baker, an officer removed a car
key from his belt loop without his consent and walked to a
nearby parking lot in search of the car associated with the
key. Baker denied having a car. When officers located a red
Buick whose flashing headlights responded to the key fob,
Baker fled and was apprehended a short distance away. A
handgun was recovered from the car and later introduced at
Baker’s trial as the weapon used in the Sprint store robbery.
Baker was convicted of Hobbs Act robbery and conspiracy
to commit robbery in violation of 18 U.S.C. § 1951(a), and
brandishing a firearm in violation of 18 U.S.C. §
924(c)(1)(A)(ii).
6                  UNITED STATES V. BAKER

    This appeal presents two principal questions: whether
officers violated Baker’s Fourth Amendment right to be free
from unreasonable searches and seizures by exceeding the
scope of their patdown search and seizing the car key, and,
if a constitutional violation occurred, whether the handgun
evidence was nevertheless admissible because Baker’s flight
from officers attenuated the discovery of the handgun. We
conclude that the handgun evidence was illegally obtained
and should have been excluded at trial, and that this error
prejudiced Baker as to the brandishing conviction but was
harmless as to the convictions for Hobbs Act robbery and
conspiracy. We reject Baker’s claims of error concerning
the district court’s evidentiary rulings at trial and its
imposition of an obstruction of justice sentencing
enhancement. Accordingly, we affirm in part, reverse in
part, and remand for further proceedings.
                             I.
    One week after the robbery of a Sprint store in Los
Angeles, LAPD Officers Byun and Salas observed a group
of individuals congregating at the Nickerson Gardens
housing complex. Baker stood among them in front of the
complex. According to Officer Byun, officers were aware
that Baker was a gang member who did not reside at
Nickerson Gardens and Officer Byun suspected that Baker
was trespassing.
    As the officers approached Baker, he lifted his shirt to
demonstrate he was unarmed. Officer Byun conducted a
patdown search of Baker that revealed no weapons or
contraband. Officer Byun then observed a car key attached
to Baker’s belt loop, which Officer Byun removed. He
directed Baker to hand over his driver’s license. Officer
Byun walked away with the car key and Baker’s driver’s
                   UNITED STATES V. BAKER                   7

license to an adjacent parking lot, where he paused at various
parked cars to identify which car matched the key. Officer
Salas directed Baker to walk toward the parking lot, then
commanded him to stop and put his hands behind his back
as Officer Byun continued his search for the car. Officer
Salas asked Baker if he had driven a car to the location, and
Baker responded “I don’t have a car.”
     When Officer Byun pressed the car lock on the key, he
observed flashing headlights from a red Buick parked on the
street. “You don’t have a car? That’s your car right there,
it’s blinking, man,” Officer Byun said to Baker. Officer
Byun signaled to Officer Salas to handcuff Baker. Baker
took off running. After a brief foot chase during which
Officer Byun lost the car key, Baker was apprehended a
short distance away. He told police the car belonged to his
mother and that “he had run because he was scared.”
    While Baker was in custody, additional officers arrived
to investigate the red Buick identified by Officer Byun.
LAPD Officer Ceballos testified at trial that when he peered
inside the car, he “was able to see underneath the front seat
what appeared to be the butt of a handgun.” Another officer
used a baton to open the car door, setting off the car alarm,
and officers recovered a handgun with a black frame and
silver slide. The gun was admitted at trial along with
surveillance video of the robbery. Government expert
witnesses testified that the gun recovered from the red Buick
was a real firearm and that its distinctive black-and-silver
color scheme matched the gun used by the robber in the
surveillance video.
   At trial, the prosecution also introduced testimony by
Baker’s co-defendant Walter Collin Beatty, who described
in detail how he and Baker planned and committed the
8                   UNITED STATES V. BAKER

robbery of the Sprint store where Beatty worked. Another
store employee testified that a handgun was pointed at his
head and he was forced on the ground and held in the back
room while Beatty took iPhones from the Sprint safe. The
jury was shown Facebook photos of Baker in clothing
appearing to match the clothing worn by the robber in the
surveillance video of the robbery. Cell phone evidence
introduced against Baker included toll records showing
seven calls between Baker and Beatty on the evening of the
robbery, as well as cell site location information (“CSLI”)
admitted to show Baker’s movement toward the Sprint store
before the robbery and away from the store afterward.
    The district court denied Baker’s motions to suppress the
evidence of the handgun and to exclude the testimony of
Jeffrey Bennett, the Government’s cell data mapping expert.
The district court also sustained the Government’s objection
to the introduction of a 2014 publication by the United States
Department of Commerce, which defense counsel sought to
introduce during Bennett’s cross-examination.
    The jury found Baker guilty of the three counts arising
from the Sprint store robbery. Based on Beatty’s testimony
that Baker had threatened him prior to Beatty’s trial
testimony, the district court applied an obstruction of justice
sentencing enhancement. Baker was sentenced to 125
months on each of the two Hobbs Act counts, to be served
concurrently, and a consecutive 84-month term for the §
924(c) count. He timely appealed.
                              II.
   Baker contends that the evidence of the handgun resulted
from an illegal search and seizure and should have been
suppressed at trial. We review the denial of a motion to
suppress de novo and the district court’s underlying factual
                       UNITED STATES V. BAKER                           9

findings for clear error, including the finding that property
has been abandoned for purposes of the Fourth Amendment.
United States v. Magdirila, 962 F.3d 1152, 1156 (9th Cir.
2020); United States v. Stephens, 206 F.3d 914, 916–17 (9th
Cir. 2000).
                                   A.
    The Fourth Amendment guarantees “[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. A “search” involves governmental
infringement on “an expectation of privacy that society is
prepared to consider reasonable,” while a “seizure” of
property involves “some meaningful interference [by the
government] with an individual’s possessory interests in that
property.” United States v. Jacobsen, 466 U.S. 109, 113
(1984). Fourth Amendment rights are personal rights that
“may not be vicariously asserted.” Alderman v. United
States, 394 U.S. 165, 174 (1969). To establish standing to
challenge governmental intrusions under the Fourth
Amendment, an individual must demonstrate their
reasonable expectation of privacy in a place searched, or
meaningful interference with their possessory interest in
property seized. See United States v. Singleton, 987 F.2d
1444, 1447 (9th Cir. 1993) (citing United States v. Salvucci,
448 U.S. 83, 95 (1980)); Lavan v. City of Los Angeles, 693
F.3d 1022, 1027–29 (9th Cir. 2012). 1 “Because warrantless
searches or seizures of abandoned property do not violate the

1
  The question of who may challenge a given instance of conduct under
the Fourth Amendment has been described both as a question of
“standing” and as “within the purview of substantive Fourth Amendment
law.” See United States v. $40,955.00 in U.S. Currency, 554 F.3d 752,
756 (9th Cir. 2009) (quoting Rakas v. Illinois, 439 U.S. 128, 140 (1978)).
10                 UNITED STATES V. BAKER

[F]ourth [A]mendment, persons who voluntarily abandon
property lack standing to complain of its search or seizure.”
United States v. Nordling, 804 F.2d 1466, 1469 (9th Cir.
1986).
    We begin with the bedrock principle that warrantless
searches and seizures “are per se unreasonable under the
Fourth Amendment—subject only to a few specifically
established and well delineated exceptions.” Minnesota v.
Dickerson, 508 U.S. 366, 372 (1993) (quoting Thompson v.
Louisiana, 469 U.S. 17, 19–20 (1984)). One of these
exceptions is the Terry stop, which permits an officer with
reasonable suspicion that an individual is engaged in a crime
to briefly detain the individual and make “‘reasonable
inquiries’ aimed at confirming or dispelling [the officer’s]
suspicions.” Dickerson, 508 U.S. at 373 (quoting Terry v.
Ohio, 392 U.S. 1, 30 (1968)). If the officer has reasonable
suspicion that the detained individual is “armed and
presently dangerous,” the officer may conduct a frisk, a
protective patdown search of the individual for weapons.
Terry, 392 U.S. at 30.
    The Government contends that the stop-and-frisk was
lawful because it was supported by the officers’ reasonable
suspicion that Baker was trespassing in front of the
Nickerson Gardens housing complex. Baker disputes that
the officers had reasonable grounds to initiate a stop-and-
frisk and argues that he was effectively arrested without
probable cause. We need not resolve this dispute because
even if officers had reasonable grounds to stop Baker, the
search and seizure conducted in this case exceeded
constitutional limits.
    A Terry stop must be “confined in scope” to a “carefully
limited search of the outer clothing … in an attempt to
                   UNITED STATES V. BAKER                  11

discover weapons.” Id. at 29, 30. If weapons are discovered,
they “may properly be introduced in evidence against the
person from whom they were taken.” Id. at 31. Police
officers may also seize “nonthreatening contraband detected
during a protective patdown search … so long as the
officers’ search stays within the bounds marked by Terry.”
Dickerson, 508 U.S. at 373.            As the Government
acknowledges, Baker has standing to challenge the legality
of the Terry stop-and-frisk initiated against him, including
whether officers exceeded the permissible scope of the stop.
It is well established that a Terry stop is a seizure of an
individual and a frisk is a search of the individual’s person
within the meaning of the Fourth Amendment. See Terry,
392 U.S. at 16–20. Assuming officers reasonably suspected
that Baker was trespassing and armed, they were authorized
to briefly detain him to ask questions related to trespassing
and to pat him down for weapons. But after officers
confirmed that Baker did not possess weapons or
contraband, they turned to other purposes. Officer Byun
removed a key visibly hanging from Baker’s belt loop and
searched for a car that corresponded to it. Officers continued
to detain Baker, not for the purpose of inquiring about
trespass, but to ask him questions about whether he owned a
car. Officer Byun made no claim that he suspected the car
key was a weapon or contraband. See Dickerson, 508 U.S.
at 377–78.
    The Government is unable to explain how the officers’
post-patdown detention and search for the car was intended
to confirm or dispel their suspicions about a crime being
committed or to secure the safety of anyone on the scene.
Baker has shown that the handgun was discovered as a result
of police conduct that violated his Fourth Amendment rights.
Id. at 373; Terry, 392 U.S. at 30–31. Had officers limited
12                     UNITED STATES V. BAKER

their Terry stop to a brief detention and protective patdown
search of Baker, they would have had no occasion to search
for a car in an adjoining parking lot that matched the key fob
hanging from Baker’s belt loop.
    Our holding in United States v. Brown, 996 F.3d 998 (9th
Cir. 2021), is instructive. We considered whether an officer
conducting a Terry stop could lawfully reach into the
detainee’s pocket as the initial means of conducting a
patdown search. Id. at 1009. Noting that the Government
cited no case from the Supreme Court upholding such a
search, we held that even if the officer “was authorized to
conduct a protective frisk, his search of [the defendant’s]
right pocket exceeded what Terry and its progeny allow.” Id.
at 1008. Here, the Government has similarly failed to
identify any caselaw showing that the removal of a key from
a defendant’s belt loop qualifies as part of a lawful Terry
frisk. Where a “protective search goes beyond what is
necessary to determine if the suspect is armed, it is no longer
valid under Terry and its fruits will be suppressed.”
Dickerson, 508 U.S. at 373 (citing Sibron v. New York, 392
U.S. 40, 65–66 (1968)).
    The Government conceded at oral argument that the
officers should not have seized the key from Baker during
the Terry stop. However, the Government argues that by
stating he did not have a car, Baker abandoned the car key,
eliminating his possessory interest in it and leaving him
without standing to challenge its seizure or the resulting
search of the car. 2 See Nordling, 804 F.2d at 1469. The

2
 In addition to advising police that the red Buick belonged to his mother,
Baker did not assert a possessory or ownership interest in the car after
his arrest or in his suppression motion. The Government speculates that
                     UNITED STATES V. BAKER                       13

district court accepted the premise that Baker lacked
standing to challenge seizure of the key “because of his
statements that he did not have a possessory or any interest
in the car prior to the seizure.”
    The Government’s standing argument fails to persuade
because Baker’s statements concerning the car did not
constitute abandonment of a possessory interest in the key
hanging from his belt. Because abandonment is “a question
of intent,” we must consider the totality of the circumstances
to determine whether an individual, by their words, actions,
or other objective circumstances, so relinquished their
interest in the property that they no longer retain a reasonable
expectation of privacy in it at the time of its search or seizure.
Id.; Lavan, 693 F.3d at 1027–28. Our caselaw recognizes
two important factors in this inquiry: the denial of ownership
and the physical relinquishment of the property. Nordling,
804 F.2d at 1469; see also United States v. Lopez-Cruz, 730
F.3d 803, 809 (9th Cir. 2013) (“[N]one of our
‘abandonment’ cases has held that mere disavowal of
ownership, without more, constitutes abandonment of a
person’s reasonable expectation of privacy in that
property.”).
    Based on the totality of the circumstances, we conclude
that Baker did not objectively demonstrate his intent to
abandon the car key. Baker never disclaimed any ownership
or possessory interest in the key itself, nor did he voluntarily

Baker “could have taken the car and its key without his mother’s
permission, in which case he would not have standing to object to the
seizure of the key,” but no evidence in the record supports this
conjecture.
14                    UNITED STATES V. BAKER

relinquish possession or control over the key. 3 Instead,
Officer Byun removed the key from Baker’s belt loop
without his consent. That the key was hanging from Baker’s
belt manifests an objective intent to maintain possession of
it. According to the Government, Baker’s assertion that he
had no car operated to deny any ownership interest in the car
key. The Government identifies no precedent in support of
the proposition that a person abandons an item in his
possession by stating he does not own a different, related
item. Even if such a claim had a basis in law, an individual
does not relinquish a possessory interest in an item merely
by stating he does not own the item. See Lopez-Cruz, 730
F.3d at 808–09 (concluding the defendant did not abandon
cell phones in his possession when he told police the phones
belonged to a friend because the defendant “did not disclaim
use of them or otherwise disassociate himself from them”).
No evidence in the record suggests that Baker disassociated
himself from the car key even if the key belonged to
someone else.
    The discovery of the handgun was the product of illegal
police conduct, whether that conduct is framed as exceeding
the permissible scope of a Terry stop or as the warrantless
seizure of the car key. Where evidence is obtained from an
unlawful search or seizure, the exclusionary rule renders
inadmissible both “primary evidence obtained as a direct
result of an illegal search or seizure” and “evidence later

3
 These circumstances differ from examples in which abandonment was
found where the defendant discarded property in a hotel wastebin before
checking out, Abel v. United States, 362 U.S. 217, 241 (1960), threw
property out of a moving vehicle, United States v. McLaughlin, 525 F.2d
517, 519–20 (9th Cir. 1975), released control over it to a third party,
United States v. Mendia, 731 F.2d 1412, 1414 (9th Cir. 1984), or
deliberately left it on an airplane, Nordling, 804 F.2d at 1469–70.
                   UNITED STATES V. BAKER                  15

discovered and found to be derivative of an illegality,”
known as “fruit of the poisonous tree.” Utah v. Strieff, 579
U.S. 232, 237 (2016) (quoting Segura v. United States, 468
U.S. 796, 804 (1984)); Wong Sun v. United States, 371 U.S.
471, 488 (1963). The exclusionary rule required suppression
of the handgun evidence at Baker’s trial unless an exception
to the rule applies. Strieff, 579 U.S. at 237–38. We address
next the Government’s contention that the handgun evidence
was admissible under the attenuation doctrine based on
Baker’s flight from officers.
                             B.
    The Supreme Court has adopted several exceptions to the
exclusionary rule, observing that the “significant costs” of
excluding evidence from a criminal trial “have led us to
deem it applicable only where its deterrence benefits
outweigh its substantial social costs.” Id. at 237 (quoting
Hudson v. Michigan, 547 U.S. 586, 591 (2006)) (internal
quotation marks and ellipsis omitted). The exception
relevant to this case is the attenuation doctrine. Id. at 238.
    Under the attenuation doctrine, “[e]vidence is admissible
when the connection between unconstitutional police
conduct and the evidence is remote or has been interrupted
by some intervening circumstance, so that ‘the interest
protected by the constitutional guarantee that has been
violated would not be served by suppression of the evidence
obtained.’” Id. (quoting Hudson, 547 U.S. at 593). Courts
determining whether attenuation applies consider the three
factors set forth in Brown v. Illinois, 422 U.S. 590, 603–04
(1975): first, the “temporal proximity” between the conduct
and the discovery of the evidence; second, the “presence of
intervening circumstances”; and third, “the purpose and
16                  UNITED STATES V. BAKER

flagrancy of the official misconduct.” The Government
bears the burden of demonstrating admissibility. Id. at 604.
    In Utah v. Strieff, for example, an officer unlawfully
stopped the defendant and discovered during the detention
that the defendant had an outstanding arrest warrant. 579
U.S. at 235, 240. The officer arrested the defendant and
conducted a search incident to arrest that led to the discovery
of drug-related evidence, the admission of which the
defendant challenged. Id. at 235–36. Applying the Brown
factors, the Court held that the discovery of the evidence
“only minutes after the illegal stop” favored suppression. Id.
at 239–40. However, the valid arrest warrant—one that
predated and was “entirely unconnected” to the illegal
stop—constituted an intervening circumstance that favored
a finding of attenuation. Id. at 240. The Court reasoned that
the arrest warrant obligated the officer to arrest the defendant
and the arrest itself established the officer’s authority to
search the defendant’s person. Id. at 240–41. As to the third
factor, the officer’s decision to initiate the stop rested on
“good-faith mistakes” rather than a purposeful or flagrant
disregard for the law. Id. at 241. The Court thus deemed the
drug-related evidence admissible because “the unlawful stop
was sufficiently attenuated by the pre-existing arrest
warrant.” Id. at 242.
    Here, the first and third Brown factors favor suppression
of the evidence. See Brown, 422 U.S. at 603–604. The
parties agree that very little time elapsed between the seizure
of the key and the discovery of the gun in the car. And while
we do not view the officers as acting with flagrant disregard
for the law, we also cannot conclude that they acted on a
reasonable but mistaken belief that Baker had consented to
their actions. See, e.g., Strieff, 579 U.S. at 241–42
(concluding exclusion of evidence would not serve deterrent
                    UNITED STATES V. BAKER                  17

purpose where officer’s detention arose out of “good-faith
mistakes”); United States v. Boone, 62 F.3d 323, 325 (10th
Cir. 1995) (officer’s “mistaken belief” that the defendant had
consented to a search did not qualify as “flagrant
misconduct”). No reasonable interpretation of the record
suggests that Baker consented to, or even was equivocal
about, the officers taking the car key off his belt. The record
clearly demonstrates that Officer Byun removed the car key
from Baker’s belt loop during the patdown without asking
for permission or consent. We have held that suppression is
favored where an officer violates the law “with the purpose
of extracting evidence against the defendant.” United States
v. Washington, 387 F.3d 1060, 1075 (9th Cir. 2004). The
officers’ conduct following the patdown of Baker was
plainly “investigatory,” an “expedition for evidence in the
hope that something might turn up.” See Brown, 422 U.S. at
605. The record contains no other explanation for their
actions, and the Government has identified none.
    The Government instead emphasizes the second Brown
factor, arguing that Baker’s flight as officers attempted to
handcuff him was an intervening circumstance that
attenuated the taint of any illegal misconduct. Citing our
decisions in United States v. Garcia, 516 F.2d 318, 319–20
(9th Cir. 1975), and United States v. McClendon, 713 F.3d
1211, 1214 (9th Cir. 2013), the Government urges that
“flight, on its own, triggers attenuation.” The district court
relied on the same cases to conclude Baker’s flight was an
intervening circumstance that attenuated the connection
between the officers’ conduct and the discovery of the gun.
The district court found “there was reasonable suspicion to
detain [Baker] which ripened [into] probable cause when he
fled, and that permitted the officers to observe the gun in the
18                  UNITED STATES V. BAKER

car.” These arguments misapprehend the attenuation
doctrine.
    Baker’s flight from police does not qualify as an
intervening circumstance because the red Buick was
discovered as a consequence of the officers’ misconduct
before Baker fled from officers. The relevant inquiry for
attenuation is not whether illegal police conduct was “part of
a series of facts” culminating in the discovery of challenged
evidence, but whether the evidence was obtained “by
exploitation of that illegality or instead by means sufficiently
distinguishable to be purged of the primary taint.” Garcia,
516 F.2d at 319 (quoting Wong Sun, 371 U.S. at 488). The
officers’ means of discovering the handgun cannot be
distinguished from their illegal conduct: they discovered the
handgun by seizing the car key from Baker, using the key to
identify the Buick parked nearby, and then searching that
Buick, in clear causal succession. See United States v.
Chamberlin, 644 F.2d 1262, 1269 (9th Cir. 1980) (evidence
is excludable where officers’ “illegal activity tends to
significantly direct the investigation to the evidence in
question”).
    We have never held that a defendant's flight from law
enforcement always attenuates the taint of an officer’s prior
illegal conduct regardless of the circumstances. Rather,
where we have found flight to satisfy the attenuation
doctrine, the circumstances of that flight have provided
independent grounds for discovering the challenged
evidence such that the officer's prior illegal conduct was not
the sole reason for the discovery of the evidence. In Garcia,
an officer directed a driver to stop at a checkpoint. 516 F.2d
at 319. Instead of complying, the driver sped off. Id.
Following a high-speed chase, officers stopped the driver
and arrested him, finding contraband in the car in a search
                       UNITED STATES V. BAKER                           19

incident to his arrest. Id. We affirmed the denial of the
driver’s motion to suppress, concluding that even if the
initial checkpoint stop had been illegal, the driver’s flight
and ensuing high-speed chase supplied officers with the
requisite “probable cause to arrest [the driver] and then to
search his car.” Id. at 320.
    The flight in Garcia, along with other untainted evidence
about the defendant’s suspicious behavior, gave the officers
a basis independent from the illegal checkpoint stop to
effectuate an arrest and search the defendant’s car. Id. In
other words, the illegal stop in Garcia proved to be no more
than “part of a series of facts” leading up to the discovery of
contraband in the car. Id. Here, however, the officers’
illegal seizure of the key was the sole reason for the
discovery of the car. Baker’s flight played no role in the
identification of the red Buick or its eventual search and
therefore could not purge the taint of the prior illegal
conduct. 4 The car was located by officers before Baker fled.
It was after Baker was taken into custody that a different
officer observed what appeared to be the butt of a handgun
protruding from underneath the front car seat. Because the
key had been lost during the foot pursuit, officers opened the
car with a baton and recovered the handgun. To the extent
the district court found that Baker’s flight gave officers
grounds to identify the Buick or to search it, it is unsupported
by the record.

4
  Garcia does not suggest that if the arrestee had been on foot, his flight
would have supplied officers with justification to search for evidence
against him in a car—or, for that matter, in any place other than the
location of his arrest. See Preston v. United States, 376 U.S. 364, 367
(1964) (“Once an accused is under arrest and in custody, then a search
made at another place, without a warrant, is simply not incident to the
arrest.”).
20                  UNITED STATES V. BAKER

    For similar reasons, McClendon does not support the
Government’s position. There, officers found a backpack in
a parked car belonging to the defendant and searched it,
discovering a firearm and ammunition. 713 F.3d at 1213.
Officers then located a man matching McClendon’s
description and ordered him to stop. Id. McClendon
continued walking away and discarded an object from his
waistband. Id. at 1213–14. Police arrested McClendon and
found a loaded handgun a few feet away. Id. at 1214. We
affirmed the denial of a motion to suppress the handgun
evidence. Id. at 1218. Assuming the search of the backpack
had been illegal, we concluded the search was not the but-
for cause of the discovery of the handgun because police
would have searched for McClendon for other reasons. Id.
at 1217–18. Even if police were motivated to search for
McClendon based on the illegal search of the backpack, we
also concluded that McClendon’s decision to flee was an
intervening event that purged the taint from the original
search. Id. at 1218 (citing Garcia, 516 F.2d at 319–20).
Stated another way, even if the backpack search was a but-
for cause of the officers’ discovery of the handgun, the flight
during which McClendon discarded the gun moments before
his arrest interrupted the chain of events leading to the gun’s
discovery. See id. Baker’s flight, by contrast, did not alter
the sequence of events in which the officers illegally seized
the key, identified the red Buick, and searched it. See id.
Simply put, the handgun evidence was obtained “by
exploitation of that illegality.” Garcia, 516 F.2d at 319
(quoting Wong Sun, 371 U.S. at 488).
    The Government has not met its burden to show
attenuation between the illegal search and seizure and the
discovery of the handgun evidence.
                   UNITED STATES V. BAKER                  21

                             C.
    The Government contends that even if admission of the
handgun was in error, the error was harmless. Before we can
hold a constitutional error harmless as to a particular
conviction, we must determine whether the Government has
met its burden of showing beyond a reasonable doubt that
the error did not contribute to the conviction. Chapman v.
California, 386 U.S. 18, 24 (1967). Where the trial court
errs in admitting evidence obtained in violation of the Fourth
Amendment, we “review[] the remainder of the evidence
against the defendant” to determine whether there is any
reasonable doubt that the jury would have convicted the
defendant absent the erroneously admitted evidence.
Arizona v. Fulminante, 499 U.S. 279, 310 (1991). That is a
demanding standard but does not erect “a barrier so high that
it could never be surmounted.” Neder v. United States, 527
U.S. 1, 18 (1999).
    We conclude the Government has demonstrated beyond
a reasonable doubt that the jury would have convicted Baker
of robbery and conspiracy to commit robbery in violation of
18 U.S.C. § 1951(a) based on substantial independent
evidence establishing Baker’s involvement in the robbery.
However, there is reasonable doubt whether the jury would
have convicted Baker of brandishing a firearm in violation
of 18 U.S.C. § 924(c) absent the admission of the handgun,
and we accordingly vacate his conviction of this count.
    The Hobbs Act provides for the punishment of
“[w]hoever in any way or degree obstructs, delays, or affects
commerce or the movement of any article or commodity in
commerce, by robbery or extortion or attempts or conspires
so to do.” 18 U.S.C. § 1951(a). In relevant part, the Act
defines robbery as “the unlawful taking or obtaining of
22                  UNITED STATES V. BAKER

personal property from the person or in the presence of
another, against his will, by means of actual or threatened
force, or violence, or fear of injury, immediate or future.” Id.
§ 1951(b)(1).
    The evidence that Baker committed robbery and
conspiracy in violation of the Hobbs Act was substantial. A
Sprint employee testified at trial that the robber took phones
with a total value of approximately $30,000 and that the
robbed store was closed for the remainder of the day,
establishing that the robbery affected interstate commerce.
Surveillance video and testimony of the non-involved Sprint
employee established that a gunman entered the store,
directed co-defendant Beatty to fill a duffle bag with phones,
and held the other employee at gunpoint as Beatty did so,
establishing the unlawful taking of personal property by
force. See 18 U.S.C. § 1951(b)(1).
    Beatty testified that Baker was the gunman who
committed this robbery. Beatty described their conspiracy
in detail, explaining that Baker came up with the idea to rob
the store while Beatty pretended to be a victim, that the two
men spoke four or five times in the two weeks before the
robbery to finalize their plan, and that they met following the
robbery to divvy up the stolen iPhones, which they went on
to sell. In addition to Beatty’s testimony, Baker’s phone
records showed a series of phone calls between Baker and
Beatty the evening of the robbery, including one call an hour
and five minutes before the robbery, another call sixteen
minutes before the robbery, and five calls in the three hours
after the robbery. CSLI was admitted to show Baker’s
movement toward the Sprint store before the robbery and
away from the store afterward, and the surveillance video of
the robbery showed the robber wearing clothing that
appeared to match clothing worn by Baker in Facebook
                   UNITED STATES V. BAKER                  23

photos. In view of the remaining evidence in the record, we
conclude there is no reasonable doubt the jury would have
found Baker guilty of Hobbs Act robbery and conspiracy
even without the handgun evidence. See Chapman, 386 U.S.
at 24.
    The brandishing conviction is a different matter. In
relevant part, 18 U.S.C. § 924(c)(1)(A)(i) provides for a
sentence of “not less than 5 years” for “any person who,
during and in relation to any crime of violence … uses or
carries a firearm.” “[I]f the firearm is brandished,” such
person shall “be sentenced to a term of imprisonment of not
less than 7 years.” 18 U.S.C. § 924(c)(1)(A)(ii). To convict
under § 924(c), the Government was required to prove the
firearm Baker used was real. See United States v. Garrido,
596 F.3d 613, 617 (9th Cir. 2010). As the district court
instructed, a “real firearm” under § 924(c) is a weapon that
“expel[s] a projectile by the action of an explosive,” and
“[t]oys, replicas, antiques,” and “blank firing prop gun[s]”
do not qualify. The jury returned a guilty verdict on the §
924(c) count, finding that Baker knowingly possessed a
firearm in furtherance of the robbery and knowingly used,
carried, and brandished a firearm during and in relation to
the crime.
    There is reasonable doubt whether the jury would have
convicted Baker under § 924(c) had the district court
excluded the gun recovered from the car. Evidence at trial
suggested that the gun Baker used in the robbery was not
real. Beatty testified that before the robbery, Baker told him
“he was going to use a fake firearm.” Beatty further testified
that he could not verify whether the gun Baker used during
the robbery was real because Beatty never touched it.
Surveillance video of the robbery could not independently
establish whether the gun used was real or a replica. The
24                  UNITED STATES V. BAKER

Government contends that the gun in the video did not
“appear[] fake,” but that is precisely the purpose of replicas.
    In addition, the handgun evidence was central to the
Government’s case that Baker violated § 924(c). During
opening argument, the prosecution stressed that the “silver
and black semi-automatic handgun” recovered from “inside
the vehicle the defendant was using” matched the gun used
in the Sprint store robbery. A special agent testified that he
examined the gun recovered by police and confirmed it was
real, and an LAPD detective commented for the jury on the
similarities between the recovered gun and the gun featured
in the surveillance video. The prosecution’s closing
argument repeatedly emphasized that the real gun admitted
into evidence and the gun used in the robbery were one and
the same, urging the jury to find that Baker “was found in
possession of that very real gun, that unique, very real gun
that was used during the Sprint store robbery.” On this
record, it cannot be said that the admission of the gun was
“harmless beyond a reasonable doubt” as to Baker’s
conviction under § 924(c). See Chapman, 386 U.S. at 24;
Fulminante, 499 U.S. at 310.
                             III.
    Finally, Baker raises several claims of error concerning
the admissibility of other evidence at trial and the district
court’s imposition of an obstruction of justice sentencing
enhancement.      We review preserved challenges to
evidentiary rulings for abuse of discretion and unpreserved
challenges to evidentiary rulings for plain error. United
States v. Orm Hieng, 679 F.3d 1131, 1135 (9th Cir. 2012).
We find no error in these determinations.
                   UNITED STATES V. BAKER                  25

                             A.
    Baker contends that the district court erred in admitting
the testimony of the Government’s cell data mapping expert.
Federal Rule of Evidence 702 “assign[s] to the trial judge the
task of ensuring that an expert’s testimony both rests on a
reliable foundation and is relevant to the task at hand.”
Daubert v. Merrell Dow Pharms., 509 U.S. 579, 597 (1993).
In evaluating the admissibility of expert testimony, the
district court considers whether the witness’s “theory or
technique … can be (and has been) tested”; whether it “has
been subjected to peer review and publication”; its “known
or potential rate of error”; “the existence and maintenance of
standards controlling the technique’s operation”; and
whether it has attracted “[w]idespread acceptance” within a
relevant scientific community. Id. at 593–94.
     At trial, the Government proffered the testimony of CSLI
expert Bennett, who explained how information about the
cell towers to which Baker’s phone connected on the
evening of the robbery allowed him to discern the phone’s
movement toward the Sprint store before the robbery and
away from it afterward. Baker concedes that expert
testimony about CSLI “has been admitted in district court[s]
across the country.” He argues, however, that the district
court abused its discretion in admitting such testimony on
the ground that “[n]either the court nor the government
appropriately circumscribed the import of the historical cell
tower data” by explaining that CSLI shows a phone’s
location within a range rather than pinpointing it exactly.
The Government argues that Baker failed to object to
Bennett’s testimony on this ground at trial and his challenge
is therefore subject to plain error review. We conclude that
Baker’s challenge fails under either abuse of discretion or
plain error review.
26                 UNITED STATES V. BAKER

    Baker relies on the Seventh Circuit case United States v.
Hill, 818 F.3d 289, 299 (7th Cir. 2016), which “caution[ed]
the government not to present historical cell-site evidence
without clearly indicating the level of precision—or
imprecision—with which that particular evidence pinpoints
a person’s location at a given time.” Hill concluded that the
challenged expert testimony in the case “made the jury
aware … of the relative imprecision” of CSLI, and that its
admission “was therefore not an abuse of the district court’s
considerable discretion.” Id. at 299. So too here. Bennett
explained that CSLI can show “where a phone was in a
general sense at [a given] time,” and he described how he
used this data to conclude that “the defendant’s phone
move[d] from one area of Los Angeles to the area, general
area of the crime scene at the approximate time the crime
happened and then move[d] away.” He confirmed the
limitations of CSLI on cross-examination. Because the jury
was adequately informed of the limitations of CSLI, the
district court’s decision to admit Bennett’s testimony was
not erroneous under any standard. See Orm Hieng, 679 F.3d
at 1135.
                             B.
    Baker challenges the exclusion of a report by the
Department of Commerce’s National Institute of Standards
and Technology (“NIST”) on guidelines for mobile device
forensics, which defense counsel sought to introduce while
cross-examining the Government’s CSLI expert. The
prosecution objected to the introduction of the report on
grounds that it lacked foundation and is hearsay, objections
                       UNITED STATES V. BAKER                         27

the court sustained. 5      We review Baker’s preserved
challenge to the district court’s evidentiary ruling for abuse
of discretion. See Orm Hieng, 679 F.3d at 1135.
    Baker concedes that the NIST report is hearsay but
argues it was admissible under the public records exception
to hearsay. “As a general rule, a party is prohibited from
introducing a statement made by an out-of-court declarant
when it is offered at trial to prove the truth of the matter
asserted.” United States v. Torres, 794 F.3d 1053, 1059 (9th
Cir. 2015) (citing Fed. R. Evid. 801(c), 802)). Under the
public records exception, “[a] record or statement of a public
office” is admissible if it sets forth “the office’s activities”;
is “a matter observed while under a legal duty to report, but
not including, in a criminal case, a matter observed by law-
enforcement personnel”; or, “in a civil case or against the
government in a criminal case, [pertains to] factual findings
from a legally authorized investigation.” Fed. R. Evid.
803(8)(A)(i), (ii), (iii).
     The only potentially applicable public records exception
is a record or statement that sets forth an “office’s activities,”
but that is not the function of the NIST report in question.
Its stated purpose is to “provid[e] an in-depth look into
mobile devices and explain[] technologies involved and their
relationship to forensic procedures,” and to “discuss[]
procedures for the validation, preservation, acquisition,
examination, analysis, and reporting of digital information.”
None of these purposes describes the activities of the

5
 On appeal, Baker argues that the NIST report was self-authenticating
under Federal Rule of Evidence 902(5). The Government concedes as
much for purposes of this appeal, but correctly points out that
authenticity does not establish admissibility. See Orr v. Bank of Am., NT
& SA, 285 F.3d 764, 776 (9th Cir. 2002).
28                 UNITED STATES V. BAKER

National Institute of Standards and Technology. The district
court did not abuse its discretion in denying admission of
this report.
                             C.
    Baker contends that the trial testimony of Baker’s co-
defendant Beatty was insufficient to support the factual
finding that Baker threatened Beatty, and that the district
court therefore erred in applying an obstruction of justice
sentencing enhancement. We review the district court’s
application of the Sentencing Guidelines to the facts of a
case for abuse of discretion. United States v. Gasca-Ruiz,
852 F.3d 1167, 1170 (9th Cir. 2017) (en banc). “A factual
finding that a defendant obstructed justice is reviewed for
clear error.” United States v. Garro, 517 F.3d 1163, 1171
(9th Cir. 2008) (citing United States v. Jimenez, 300 F.3d
1166, 1170 (9th Cir. 2002)).           The district court’s
determination that Baker committed obstructive conduct
was not clearly erroneous.
    The Sentencing Guidelines direct district courts to apply
a two-level sentencing enhancement if “the defendant
willfully obstructed or impeded, or attempted to obstruct or
impede, the administration of justice with respect to the
investigation, prosecution, or sentencing of the instant
offense of conviction,” including by “threatening,
intimidating, or otherwise unlawfully influencing a co-
defendant, witness, or juror, directly or indirectly, or
attempting to do so.” U.S.S.G. § 3C1.1; U.S.S.G. § 3C1.1
app. n.4.
    Beatty testified that while the two men were in custody
at the same detention center, Baker told Beatty that Baker
“better not find out [Beatty was] testifying because [Baker]
knows where [Beatty’s] family stays.” Beatty also testified
                    UNITED STATES V. BAKER                    29

that he and Baker could not “get face-to-face” at the time of
the alleged threat, as they were not housed in the same dorm.
On appeal, Baker argues that Beatty was impeached by his
statement that he was not “face-to-face” with Baker when
the alleged threat was made, and that the district court’s
factual finding that Baker threatened Beatty was therefore
clearly erroneous.
    Beatty’s statement that Baker threatened him is not
irreconcilable with his statement that they did not come face-
to-face. See Anderson v. City of Bessemer City, N.C., 470
U.S. 564, 573–74 (1985) (a district court’s account of the
evidence is not clearly erroneous if it “is plausible in light of
the record viewed in its entirety”). A witness who was
housed in Beatty’s dorm at the detention center testified that
the witness and Baker had multiple conversations from
opposite sides of a door rather than face-to-face, indicating
that real-time communication with those housed in other
dorms was possible. Baker alternatively might have
threatened Beatty in writing. Although the manner of the
threat was not fully articulated at trial, the district court did
not commit clear error in choosing between permissible
views of the evidence to conclude Baker committed
obstructive conduct. See United States v. Barbosa, 906 F.2d
1366, 1370 (9th Cir. 1990) (“[A] court reviewing the
imposition of a sentence under the Guidelines should give
‘due regard to the opportunity of the district court to judge
the credibility of the witnesses.’” (quoting 18 U.S.C. §
3742(e))).
                              IV.
     Evidence of the handgun should have been suppressed at
trial as fruit of an illegal search and seizure by the LAPD.
We hold that this error was prejudicial as to Baker’s firearm
30                 UNITED STATES V. BAKER

brandishing conviction under 18 U.S.C. § 924(c), but was
harmless as to his convictions for Hobbs Act robbery and
conspiracy under 18 U.S.C. § 1951(a). We reject the other
claims of error and affirm the convictions under 18 U.S.C. §
1951(a) and sentencing enhancement under U.S.S.G. §
3C1.1, reverse the conviction under 18 U.S.C. § 924(c), and
remand for a reduction in sentence or retrial on that count.
  AFFIRMED in part, REVERSED in part, and
REMANDED.