United States v. Terrance Baker ( 2023 )


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  •                      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.