                 FOR PUBLICATION

  UNITED STATES COURT OF APPEALS
       FOR THE NINTH CIRCUIT

UNITED STATES OF AMERICA,                  No. 12-30007
                Plaintiff-Appellee,
                                             D.C. No.
                  v.                      4:11-cr-00010-
                                              RRB-4
ANTHONY GADSON, AKA Anthony
Gadsen,
           Defendant-Appellant.


UNITED STATES OF AMERICA,                  No. 12-30047
                Plaintiff-Appellee,
                                             D.C. No.
                  v.                      4:11-cr-00010-
                                              RRB-2
WILLIE WILSON,
             Defendant-Appellant.            OPINION

      Appeal from the United States District Court
                for the District of Alaska
    Ralph R. Beistline, Chief District Judge, Presiding

                 Argued and Submitted
          August 13, 2013—Anchorage, Alaska

                  Filed August 19, 2014

Before: Alex Kozinski, Chief Judge, and Marsha S. Berzon
           and Sandra S. Ikuta, Circuit Judges.

                Opinion by Judge Ikuta;
        Concurrence and Dissent by Judge Berzon
2                  UNITED STATES V. GADSON

                           SUMMARY*


                          Criminal Law

    The panel affirmed (1) Anthony Gadson’s conviction and
sentence for conspiracy to distribute more than 500 grams of
cocaine, possession with intent to distribute controlled
substances, possession of firearms in furtherance of the
conspiracy, and possession of controlled substances; and (2)
Willie Wilson’s conviction and sentence for the same
offenses as well as for retaliation against a witness.

    The panel held that the district court did not misinterpret
the hearsay rules and did not abuse its discretion in declining
to admit, as statements against interest under Fed. R. Evid.
804(b)(3), out-of-court statements by Gadson’s brother. The
panel held that the exclusion of the statements did not deprive
Gadson of his constitutional right to present a defense.

    The panel held that the district court did not abuse its
discretion in admitting the government’s dog sniff expert
testimony without holding a Daubert hearing, where there
was adequate evidence regarding the reliability of the dog’s
alert.

     The panel held that the district court did not plainly err by
failing to raise sua sponte the question of the authenticity of
the recordings of prison phone calls made by Gadson and
Wilson to third parties, and that the district court did not
abuse its discretion in concluding that the government had

  *
    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. GADSON                       3

carried its burden of making a prima facie case that the voices
on the tapes were those of Gadson and Wilson.

    The panel rejected Wilson’s multiple arguments regarding
the district court’s admission of an officer’s testimony
regarding the recorded phone calls. The panel held that the
district court did not plainly err in not considering sua sponte
whether sufficient steps were taken to ensure the statements’
accuracy, and that Wilson did not establish that the district
court plainly erred in admitting the tapes on audibility
grounds. The panel rejected Wilson’s contention that the
district court erred in allowing the officer to testify
concerning the content of the telephone calls. Applying Fed.
R. Evid. 701, the panel observed that a lay witness’s opinion
testimony necessarily draws on the witness’s own
understanding, including a wealth of personal information,
experience, and education, that cannot be placed before the
jury.

    The panel held that the district court did not err in
declining to strike a portion of the officer’s testimony as
impermissible vouching, or as an improper opinion on the
ultimate issue of guilt or innocence under Fed. R. Evid.
704(b). The panel wrote that there is no basis for applying
Rule 704(b) to a lay witness.

    The panel held that the district court did not plainly err in
formulating its jury instruction on Pinkerton liability, and that
a rational jury could have concluded that it was reasonably
foreseeable to Gadson that one of his co-conspirators would
use a firearm in furtherance of the drug trafficking offenses.

    Reviewing for plain error, the panel held that there was
sufficient evidence to support Wilson’s conviction under 18
4               UNITED STATES V. GADSON

U.S.C. § 1513(b)(2) for assaulting an informant with the
intent to retaliate for providing information to the
government.     The panel explained that unlike with
confessions to the police, corroboration is not required for
Wilson’s private statements, intercepted by the police, made
to his cousin.

   The panel held that the district court did not commit
reversible error at sentencing in calculating the quantity of
drugs attributable to Gadson, in applying to Gadson a
managerial role enhancement pursuant to U.S.S.G.
§ 3B1.1(b), or in denying Wilson a minor role reduction
pursuant to U.S.S.G. § 3B1.2.

    Judge Berzon concurred and dissented. She concurred
with the majority opinion except for the part concerning the
officer’s testimony as to the content of the defendants’
recorded telephone conversations. She wrote that United
States v. Freeman, 498 F.3d 893 (9th Cir. 2007), upon which
the majority’s holdings rest, goes much too far in allowing
lay officer testimony concerning recorded conversations, and
should be revisited en banc. Even accepting Freeman as
binding precedent, she would hold the trial court plainly erred
in admitting some of the officer’s testimony and that the error
was prejudicial.
                 UNITED STATES V. GADSON                      5

                         COUNSEL

John Balazs, Sacramento, California, for Defendant-
Appellant Anthony Gadson.

Krista Hart, Sacramento, California, for Defendant-Appellant
Willie Wilson.

Kirby A. Heller (argued), Mythili Raman, Acting Assistant
Attorney General, Denis J. McInerney, Acting Deputy
Assistant Attorney General, Criminal Division, United States
Department of Justice, Washington, D.C.; Karen L. Loeffler,
United States Attorney, Elizabeth F. Crail, Special Assistant
United States Attorney, Stephen Cooper, Assistant United
States Attorney, Anchorage, Alaska, for Plaintiff-Appellee.


                          OPINION

IKUTA, Circuit Judge:

    Anthony Gadson and Willie Wilson appeal their
convictions for conspiracy to distribute more than 500 grams
of cocaine, possession with intent to distribute controlled
substances, and possession of firearms in furtherance of their
conspiracy and possession of controlled substances. Wilson
also appeals his conviction for retaliation against a witness.
On appeal, they challenge various evidentiary rulings, the
correctness of certain jury instructions, the sufficiency of the
evidence as to two counts, and sentencing determinations.
We affirm the convictions.
6                 UNITED STATES V. GADSON

                                 I

    During the period from March 2009 through February
2010, a residence at 5260 Fouts Avenue in Fairbanks, Alaska,
was the hub of a drug trafficking operation. Two brothers,
Brandon and Joshua Haynes, along with Donte Edwards,
lived at the Fouts house.1 Gadson, a brother of Brandon and
Joshua Haynes, visited the house from time to time, though
he lived in Anchorage. Wilson, a cousin of the Haynes
brothers and Gadson, joined the group in November 2009.
Joe Powell was also involved with the group and would
sometimes complete transactions on behalf of Brandon
Haynes.

    According to testimony at trial, Joshua Haynes regularly
sold crack cocaine at or near the Fouts house. Joshua made
ten sales of cocaine to Joshua Voaklander during the spring
and summer of 2009, half of which were witnessed by
Gadson. During one of the transactions at which Gadson was
present, Joshua displayed an assault rifle hidden under his
couch cushions to Voaklander, which Joshua said was “for
when somebody comes in through the front door.”

   One of the sources for the cocaine was a person with the
code name “Transporter” who brought drugs up from
Anchorage to the Fouts house in Fairbanks. On the two
occasions that Gadson’s trips to the Fouts house coincided
with Transporter’s trips, Gadson picked up bags containing
$40,000 to $50,000 in cash from Brandon Haynes. At one
point, Transporter was arrested for driving without a license,



  1
    We refer to Brandon and Joshua Haynes by their first names where
necessary to avoid confusion.
                UNITED STATES V. GADSON                      7

and Gadson complained that his arrest could have “messed
everything up,” meaning “everybody go to jail.”

    Officer Avery Thompson, a member of the Alaska
Statewide Drug Enforcement Unit, began investigating this
drug conspiracy in early 2010. By February 2010, he
suspected that the Fouts house was at the center of a drug
operation. A confidential informant working with the
investigation executed two controlled buys of cocaine from
Edwards, one of which took place in the driveway of the
Fouts house. Following the buy, Officer Thompson and other
members of the Fairbanks police department obtained a
search warrant for the Fouts house. Although no one was in
the house at the time of the search, they saw footprints in the
new snow leading away from the open kitchen window.
Subsequent investigation revealed that these footprints
belonged to Wilson, and that when the police arrived, Wilson
escaped out the window in his bare feet and scrambled over
to a friend’s house.

    Inside, Officer Thompson and the other police
investigators found a shoe box on top of the living room
couch containing approximately a kilogram of cocaine,
another shoe box containing another kilogram of cocaine and
some $29,000 in cash behind the drugs. Gadson’s
fingerprints were identified on the second living room shoe
box. A loaded shotgun and ballistic vests were found near the
shoe boxes. Powder cocaine, crack cocaine, ecstasy,
marijuana, drug paraphernalia, and more cash and money
orders were found in various locations in the kitchen and
dining room. The bedrooms contained more drugs. In one
bedroom, the police found Wilson’s possessions, including
prescription pill bottles in Wilson’s name and a ring with
Wilson’s initials. Inside that room, the officers found powder
8               UNITED STATES V. GADSON

cocaine, crack, marijuana, heroin, 156 tabs of ecstasy, and
approximately $13,000 in cash. A loaded handgun was
nearby on the floor.

    While the police were searching the Fouts house, Wilson
had reached his friend’s house, and informed Edwards (who
was also at the friend’s house) about the raid. Edwards and
Wilson drove to Gadson’s house in Anchorage and decided
to stay there until things cooled off in Fairbanks. Brandon
Haynes was also in Anchorage at the time. After about two
weeks, Edwards returned to Fairbanks, and began buying
drugs from Gadson for sale. But when Brandon Haynes
returned to Fairbanks at the end of May, and resumed drug
activities in a new location, Edwards switched back to
Haynes as a supplier.

    At some point in November 2010, the police used a
confidential informant named Donny Pitka to make a
controlled buy from Brandon Haynes. Pitka asked Brandon
to deliver the drugs to undercover police in a vehicle near
Brandon’s new apartment on Adams Drive. Brandon had
Powell deliver the cocaine, and the police arrested Powell
when he approached the vehicle. The police then closed in on
the Adams Drive apartment, arrested Brandon, and
discovered cocaine, marijuana, ecstasy, oxycontin, and
$14,000 in cash inside the apartment.

    With Brandon Haynes in police custody, Edwards began
buying again from Gadson. In January 2011, Gadson sold
Edwards seven or more ounces of cocaine. By March 2011,
Gadson moved up from Anchorage to 2805 Gillam Way in
Fairbanks. On April 20, a federal grand jury indicted
Gadson, Wilson, Brandon Haynes, Edwards, Powell, and
others. Arrest warrants were issued for the defendants.
                UNITED STATES V. GADSON                     9

    Officer Thompson picked up Gadson’s trail at the end of
April. After conducting several days of surveillance at
Gadson’s Gillam Way house and observing a good deal of
“short-term traffic” indicative of drug dealing, he obtained a
search warrant for the residence and garage. Officers
executed the warrant at the beginning of May and found a
ballistic vest and around $3,950 cash in the house. They
discovered another $38,430 in a bag in the unlocked garage.
The officers did not recover any firearms or an appreciable
amount of cocaine from the Gillam Way house. Later that
day, Gadson was arrested in his vehicle with another $1,300
on his person. Wilson turned himself in a few days later after
learning of the outstanding warrant. Further investigation of
the items obtained from the Gillam Way house suggested
they had been used in drug transactions. A drug dog named
Marley gave positive alerts for the presence of narcotics when
presented with cash found at Gadson’s house and on his
person.

    Following their arrests, Gadson, Edwards, Wilson, and
Powell were all detained in the same wing of the Fairbanks
Correctional Center. Pitka, who had been involved in the
controlled buy that led to Brandon Haynes’s arrest, was in the
same prison on unrelated charges. After Powell learned about
Pitka’s role from his attorney, word spread to the other co-
conspirators. In a series of recorded phone calls between
Wilson and his cousin, Gabriella Haynes, Wilson discussed
the police reports mentioning Pitka and told Gabriella Haynes
that “the CI’s here,” using the standard abbreviation for a
confidential informant. A few days later, Wilson told
Gabriella that “[s]nitches can’t go into the hallways.” On
May 21, soon after the call to Gabriella Haynes, Wilson
assaulted Pitka as he was walking down the hallway. The
assault lasted two minutes and was captured on video.
10              UNITED STATES V. GADSON

Although the details of the fight are disputed, the video
recording shows Wilson punching Pitka, who suffered a
number of abrasions, scratches, and bites from the encounter.
The day after the assault, Wilson called Gabriella Haynes
again and told her that he hit “Donny,” who had “started this
shit,” and referenced the earlier controlled buy between Pitka
and Brandon Haynes.

    On June 23, 2011, the government charged Gadson,
Wilson, and others with five crimes: conspiracy to distribute,
and possession with intent to distribute, more than 500 grams
of cocaine and other controlled substances, in violation of
21 U.S.C. §§ 846, 841(a)(1), (b)(1)(B), (b)(1)(C), (b)(1)(D)
(Count 1); possession with intent to distribute controlled
substances, in violation of 21 U.S.C. § 841(a)(1), (b)(1)(B),
(b)(1)(C), (b)(1)(D) (Count 2); possession of firearms in
furtherance of Counts 1 and 2, in violation of 18 U.S.C.
§ 924(c)(1)(A)(i) (Count 3); and conspiracy to retaliate
against a witness, in violation of 18 U.S.C. § 1513(e) (Count
5). The government also charged Wilson with attempting to
kill a witness, in violation of 18 U.S.C. § 1513(a)(1)(B),
(a)(2)(B) (Count 6), and retaliation against a witness, in
violation of 18 U.S.C. § 1513(b)(2) (Count 7).

    On October 11, 2011, a jury found Gadson and Wilson
guilty of conspiracy to distribute, possession of drugs with
intent to distribute, and possession of three firearms in
furtherance of the conspiracy (Counts 1, 2 and 3). Wilson
was also found guilty of retaliation against a witness (Count
7). Neither was found guilty of conspiring to retaliate against
a witness (Count 5), and Wilson was acquitted of attempting
to kill a witness (Count 6).
                 UNITED STATES V. GADSON                     11

    On December 29, 2011, Gadson received a below-
Guidelines sentence of 300 months of imprisonment and eight
years of supervised release. The court attributed 10,521,103
grams of drugs to Gadson on the basis of his involvement in
the conspiracy, and the sentence included, among other
things, a three-level enhancement for having a managerial
role. On January 27, 2012, the court sentenced Wilson to 168
months of imprisonment and five years of supervised release,
a sentence that also fell below the Guideline range. The court
declined to give Wilson a minor role adjustment, noting that
he had been entrusted to guard the drugs and cash in the Fouts
house, and that he had sold drugs to Pitka and later assaulted
him.

    On appeal, Gadson and Wilson challenge certain of the
district court’s evidentiary rulings and jury instructions. They
also contest the sufficiency of the evidence as to two counts.
Finally, they challenge the district court’s sentencing
determinations. We consider each of these challenges in turn.

                               II

    We begin by addressing Gadson and Wilson’s challenges
to the district court’s evidentiary rulings. Where those
challenges have been preserved, we review the district court’s
rulings for an abuse of discretion, and uphold them unless
they are “illogical, implausible, or without support in
inferences that may be drawn from the facts in the record.”
United States v. Hinkson, 585 F.3d 1247, 1263 (9th Cir. 2009)
(en banc). We review de novo the district court’s
interpretations of the legal standard for its decision. United
States v. Waters, 627 F.3d 345, 351–52 (9th Cir. 2010).
12               UNITED STATES V. GADSON

                               A

   First, we consider Gadson’s argument that the district
court abused its discretion by not admitting certain out-of-
court statements by his brother, Brandon Haynes.

     In preparing for trial, Gadson learned that Brandon had
made two statements to the police that were helpful to
Gadson. Specifically, Brandon said that it was he who had
put the $38,000 in cash into Gadson’s garage at the Gillam
Way house. Brandon also denied that he had given Gadson
bags of $40,000 to $50,000, which contradicted Edwards’s
testimony that he had witnessed those transactions. In
addition, Brandon told Wilson in a jail conversation that
“[y]ou and I both know [Gadson] should not be in it,”
possibly referring to the case arising out of the drug operation
at the Fouts house.

     Gadson subpoenaed Brandon to testify at his trial, but
Brandon invoked his Fifth Amendment right not to testify.
At trial, Gadson moved to admit Brandon’s statements under
Rule 804(b)(3) of the Federal Rules of Evidence. The district
court denied the motion, ruling that Brandon had given
inconsistent testimony, and that this evidence was “so
suspect” that “it would be a miscarriage of justice to permit
it.”

    Gadson argues that the district court erroneously
interpreted the hearsay rules and that the district court thereby
abused its discretion in disallowing the evidence. According
to Gadson, although Brandon’s statements were hearsay, they
were admissible as statements against interest under Rule
804(b)(3) of the Federal Rules of Evidence. Even if those
statements did not qualify as statements against interest,
                      UNITED STATES V. GADSON                            13

Gadson contends that their exclusion robbed him of his
constitutional right to present a complete defense.

    Rule 804(b)(3) provides that out-of-court statements are
not excluded by the rule against hearsay if the declarant is
unavailable as a witness, and the statement (1) is “truly self-
inculpatory,” meaning it was “sufficiently against the
declarant’s penal interest that a reasonable person in the
declarant’s position would not have made the statement
unless believing it to be true,” Williamson v. United States,
512 U.S. 594, 603–04 (1994) (internal quotation marks
omitted), and (2) “is supported by corroborating
circumstances that clearly indicate its trustworthiness,” Fed.
R. Evid. 804(b)(3)(B).2




 2
     Rule 804(b)(3) states in full:

           (b) The Exceptions. The following are not excluded by
           the rule against hearsay if the declarant is unavailable
           as a witness:

           (3) Statement Against Interest. A statement that:

           (A) a reasonable person in the declarant’s position
           would have made only if the person believed it to be
           true because, when made, it was so contrary to the
           declarant’s proprietary or pecuniary interest or had so
           great a tendency to invalidate the declarant’s claim
           against someone else or to expose the declarant to civil
           or criminal liability; and

           (B) is supported by corroborating circumstances that
           clearly indicate its trustworthiness, if it is offered in a
           criminal case as one that tends to expose the declarant
           to criminal liability.
14              UNITED STATES V. GADSON

    The district court did not misinterpret the hearsay rules
and did not abuse its discretion in declining to admit
Brandon’s statements under Rule 804(b)(3). As an initial
matter, the parties agree that Brandon was unavailable within
the meaning of Rule 804(b) due to his invocation of his
Fifth Amendment privilege against self-incrimination.
Nevertheless, Brandon’s statements that Gadson “should not
be in it,” and that Brandon had not given Gadson two bags of
cash, are not “truly self-inculpatory” for purposes of Rule
804(b)(3)(A) because they do not expose Brandon himself to
criminal liability. Statements that “curry favor or deflect (or
share) blame” do not fall within the scope of Rule
804(b)(3)(A). Hernandez v. Small, 282 F.3d 1132, 1141 n.8
(9th Cir. 2002).

    Further, while Brandon’s statement that he was the person
who had put money in the garage at the Gillam Way house
might have been self-inculpatory, the district court could have
reasonably concluded that it was not supported by
corroborating circumstances indicating its trustworthiness. In
general, the exculpatory statements of family members “are
not considered to be highly reliable,” LaGrand v. Stewart,
133 F.3d 1253, 1268 (9th Cir. 1998); see also United States
v. Paguio, 114 F.3d 928, 933 (9th Cir. 1997), and therefore
the close family relationship between Brandon and Gadson
supports the district court’s determination that Brandon’s
statements were not trustworthy. Further, the district court’s
determination that Brandon’s testimony was “suspect” or
unreliable was supported by testimony that he had made
contradictory statements to the police and his co-conspirators.

    Gadson argues that there was sufficient evidence
corroborating Brandon’s statement that he had put the
$38,000 in the Gillam Way garage. Specifically, he cites the
                UNITED STATES V. GADSON                     15

testimony from a downstairs tenant to the effect that someone
named “Brandon” had previously lived in the apartment, and
that the garage was usually unlocked. This slight evidence
does not make the district court’s decision to disallow
Brandon’s statement “illogical, implausible, or without
support in inferences that may be drawn from facts in the
record,” Hinkson, 585 F.3d at 1251. Accordingly, the district
court’s decision not to admit the three statements at issue was
not an abuse of discretion.

    Nor did the exclusion of Brandon’s statements deprive
Gadson of his constitutional right to present a defense. The
Supreme Court has held that “[a] defendant’s right to present
relevant evidence is not unlimited, but rather is subject to
reasonable restrictions,” and the exclusion of evidence is
unconstitutional “only where it has infringed upon a weighty
interest of the accused.” United States v. Scheffer, 523 U.S.
303, 308 (1998). When the excluded evidence does not bear
“persuasive assurances of trustworthiness” and is not “critical
to the defense,” Chia v. Cambra, 360 F.3d 997, 1003 (9th
Cir. 2004), its exclusion does not violate a defendant’s due
process rights, see United States v. Fowlie, 24 F.3d 1059,
1069 (9th Cir. 1994) (rejecting a due process challenge to
evidence excluded under Fed. R. Evid. 804(b)(3) because the
statement lacked any “significant indicia of reliability” and
was “tangential at best”); cf. Chambers v. Mississippi,
410 U.S. 284, 302 (1973) (holding unconstitutional an
application of evidentiary rule that precluded the admission
of a confession of guilt by a third party, where the testimony
was directly exculpatory and bore “persuasive assurances of
trustworthiness”).

   In this case, Brandon’s three statements do not have any
“persuasive assurances of trustworthiness” and do not
16                  UNITED STATES V. GADSON

constitute critical exculpatory evidence, such as “someone
else’s admissions of guilt.” Fowlie, 24 F.3d at 1069. Given
Brandon Haynes’s unreliability and the substantial evidence
establishing that Gadson was involved in the drug
transactions at the Fouts and Gillam Way houses, exclusion
of Brandon’s three statements did not violate Gadson’s due
process rights.

                                    B

    We next turn to Gadson’s argument that the district court
erred in admitting the government’s dog sniff expert
testimony without holding a Daubert hearing.3

    At trial, the government sought to introduce testimony
from Investigator Joshua Moore, whose dog Marley gave
positive alerts for the presence of narcotics when presented
with several bundles of cash found at Gadson’s house and on
his person.

    Before testifying to the jury, Investigator Moore testified
extensively during voir dire about his experience and his
dog’s training and reliability in the field. Investigator Moore
and Marley were certified as a K-9 team in June 2010.
Investigator Moore testified that he had been a canine handler
since May 2010 and had received four-and-a-half weeks of
training. Marley had been trained by another officer to detect
marijuana, heroin, cocaine, and methamphetamine.


     3
     Although Gadson did not join Wilson’s objection at trial to the
admission of this testimony without a Daubert hearing, we review
Gadson’s claim for abuse of discretion rather than plain error “because the
matter was sufficiently brought to the attention of the district court.”
United States v. Hieng, 679 F.3d 1131, 1141 (9th Cir. 2012).
                UNITED STATES V. GADSON                    17

According to Investigator Moore, Marley had practiced in a
variety of training scenarios to ensure that he was reliably
detecting the presence of various odors rather than simply
associating them with one specific set of circumstances. The
police department logs showed that Marley had a reliability
rating of 100 percent in the field and had made only one
potential false positive alert. Investigator Moore also noted
the limits to Marley’s abilities: while he could detect the
presence of four different drugs, he was unable to distinguish
between individual drugs, and so an alert as to a pile of cash
would indicate only that it had at some point been near one or
more of those four drugs.

    At the conclusion of the voir dire, the court ruled that
Investigator Moore and Marley were “adequately trained and
experienced to testify, to give an opinion that possibly could
assist the jury in some way” and overruled Wilson’s objection
that the canine evidence was inadmissible without a Daubert
hearing.

    On appeal, Gadson claims that dog sniff evidence is
inherently unreliable and based on junk science. In making
this argument, Gadson relies on various studies and reports
indicating that dog sniff errors may be caused by handler
cueing and errors, or may arise because drug dogs alert to
residual odors and to compounds that are not unique to
contraband. See, e.g., Richard E. Myers II, Detector Dogs
and Probable Cause, 14 Geo. Mason L. Rev. 1, 14–16, 21–24
(2006); Lisa Lit, Julie B. Schweitzer, and Anita Oberbauer,
Handler Beliefs Affect Scent Detection Dog Outcomes,
14 Animal Cognition 387 (2011). According to one expert
cited by Gadson, a dog alert is insufficient to establish
probable cause in a criminal case due to a high error rate.
Myers, supra, at 14–16. In light of this evidence, Gadson
18               UNITED STATES V. GADSON

argues that Investigator Moore’s testimony was not enough
to demonstrate reliability, and the district court should have
conducted a full hearing (as opposed to a voir dire) on the
reliability of the dog sniff evidence.

    We review the district court’s decision to admit expert
testimony for abuse of discretion. Mukhtar v. Cal. State
Univ., Hayward, 299 F.3d 1053, 1063 (9th Cir. 2002), as
amended 319 F.3d 1073 (9th Cir. 2003), overruled in
nonrelevant part by Estate of Barabin v. AstenJohnson, Inc.,
740 F.3d 457, 467 (9th Cir. 2014) (en banc). Under Rule 702
of the Federal Rules of Evidence, “[a] witness who is
qualified as an expert by knowledge, skill, experience,
training, or education may testify in the form of an opinion,”
provided the testimony meets certain criteria. Rule 702 also
requires “the trial judge [to] ensure that any and all scientific
testimony or evidence admitted is not only relevant, but
reliable.” Daubert v. Merrell Dow Pharms., Inc., 509 U.S.
579, 589 (1993).

    Although the district court must perform a gatekeeping
function, a trial court “not only has broad latitude in
determining whether an expert’s testimony is reliable, but
also in deciding how to determine the testimony’s reliability.”
Mukhtar, 299 F.3d at 1064. The inquiry into whether the
testimony is sufficiently reliable is “a flexible one.” United
States v. Alatorre, 222 F.3d 1098, 1102 (9th Cir. 2000). A
separate pretrial hearing on reliability is not required, and a
voir dire procedure can be sufficient. Id. at 1102–05

   The Supreme Court has largely disposed of Gadson’s
argument that dog sniff evidence is inherently unreliable. In
Florida v. Harris, the Supreme Court held that the Florida
Supreme Court erred by imposing an unnecessarily strict
                UNITED STATES V. GADSON                     19

standard for evaluating whether the alert of a drug detection
dog provided probable cause to search a vehicle. 133 S. Ct.
1050, 1056–57 (2013). According to Harris, a court can
conclude that a “dog performs reliably in detecting drugs”
based on the dog’s training, test results, field history, and
other case-specific facts. Id. at 1057–58. For example,
“evidence of a dog’s satisfactory performance in a
certification or training program can itself provide sufficient
reason to trust his alert,” although a defendant must be given
the “opportunity to challenge such evidence of a dog’s
reliability.” Id. at 1057. This conclusion disposes of
Gadson’s claim that dog sniff evidence is per se unreliable
because it is based on “junk science.”

    Moreover, Harris did not suggest that a district court had
to perform a full-fledged Daubert hearing to determine
whether the dog sniff testimony was sufficiently reliable to
establish probable cause. Id. at 1056–58. Rather, the Court
held that both the state and the defendant can proffer evidence
relating to the dog’s reliability, and the court can “then
evaluate the proffered evidence to decide what all the
circumstances demonstrate. If the State has produced proof
from controlled settings that a dog performs reliably in
detecting drugs, and the defendant has not contested that
showing, then the court should find probable cause.” Id. at
1058. A district court considering whether evidence of a dog
alert is admissible under Rule 702 can undertake a similar
evaluation. Here, Gadson had ample opportunity to cross-
examine Moore, “contest the adequacy of a certification or
training program,” or raise “circumstances surrounding a
particular alert” that undercut Marley’s reliability. Id. at
1057. This was sufficient to satisfy the district court’s
gatekeeping function, and the court did not abuse its
discretion in declining to do more.
20               UNITED STATES V. GADSON

    Given Harris’s determination that a dog’s alert that meets
certain reliability requirements may be sufficient to “make a
reasonably prudent person think that a search would reveal
contraband or evidence of a crime,” id. at 1058, we conclude
that a dog’s alert that meets such requirements is also
sufficiently reliable to be admissible under Rule 702. Under
the standard enunciated in Harris, the evidence regarding the
reliability of Marley’s alert was more than adequate.
Investigator Moore gave extensive testimony regarding his
and Marley’s training and certification. He also testified
regarding Marley’s reliability rating of 100 percent in the
field. The defendants did not proffer evidence to the
contrary. Accordingly, the district court did not abuse its
discretion in admitting evidence of Marley’s alert.

                               C

    We now consider Wilson’s claim that the district court
erred by admitting the recordings of the prison phone calls
made by Gadson and Wilson to third parties because the tapes
had not been properly authenticated in violation of Rule 901
of the Federal Rules of Evidence. Wilson further claims that
Officer Thompson’s testimony was insufficient to support a
finding that the voices on the tapes belonged to the
defendants.

    Because neither Gadson nor Wilson challenged the
authentication of the tapes themselves at trial, we review this
claim for plain error. See United States v. Lindsey, 634 F.3d
541, 550–51 (9th Cir. 2011). Plain error is “(1) error, (2) that
is plain, (3) that affect[s] substantial rights,” and “(4) the
error seriously affect[s] the fairness, integrity, or public
reputation of judicial proceedings.” United States v. Cotton,
535 U.S. 625, 631 (2002) (alteration in original, internal
                UNITED STATES V. GADSON                     21

citations and quotations marks omitted). Wilson did
challenge the district court’s decision that the government put
forth sufficient evidence that the voices on the tapes belonged
to Gadson and Wilson, and so we review that determination
for abuse of discretion. See United States v. Yin, 935 F.2d
990, 994 (9th Cir. 1991).

    Under Rule 901(a) of the Federal Rules of Evidence, in
order “[t]o satisfy the requirement of authenticating or
identifying an item of evidence, the proponent must produce
evidence sufficient to support a finding that the item is what
the proponent claims it is.” In other words, the party offering
the evidence must make a prima facie showing of authenticity
“so that a reasonable juror could find in favor of authenticity
or identification.” Yin, 935 F.2d at 996 (internal quotation
marks omitted). The item may be authenticated by extrinsic
evidence, id. at 995, such as through testimony of a
knowledgeable witness, Fed. R. Evid. 901(b)(1). Thus, where
the government offers an audiotape, a witness with
knowledge may testify that the recording is what it purports
to be, or is a true and accurate copy of the original. See
United States v. Panaro, 266 F.3d 939, 951 (9th Cir. 2001);
United States v. Mouton, 617 F.2d 1379, 1383–84 (9th Cir.
1980). Where the government offers a tape recording of the
defendant’s voice, it must also make a prima facie case that
the voice on the tape is in fact the defendant’s, whether by
means of a witness who recognizes the voice or by other
extrinsic evidence. United States v. Torres, 908 F.2d 1417,
1425 (9th Cir. 1990). Once the offering party meets this
burden, “the probative value of the evidence is a matter for
the jury.” United States v. Workinger, 90 F.3d 1409, 1415
(9th Cir. 1996). The district court does not abuse its
discretion in admitting evidence that meets the minimum
requirements for authentication. Id. at 1416.
22               UNITED STATES V. GADSON

     Here, Officer Thompson testified that he was familiar
with the prison telephone system and gave detailed testimony
regarding how the system recorded all calls, how the jail call
log could be searched based on date, phone bank, and
telephone number, and how he had run such searches many
times. He testified that he reviewed more than 100 hours of
prison phone calls relating to Gadson and Wilson. Although
Officer Thompson did not testify that the calls introduced at
trial were accurate copies of the prison recordings, neither
defendant challenged the recordings on this basis. Officer
Thompson’s testimony was “sufficient to support a finding
that the item is what the proponent claims it is,” Fed. R. Evid.
901(a), and the district court did not err in failing to raise this
issue sua sponte.

     Nor did the district court abuse its discretion in
concluding that the government had carried its burden of
making a prima facie case that the voices on the tapes were
those of Gadson and Wilson. Officer Thompson testified as
to the methodology he had used to identify the speakers. He
first listened to recordings of all phone calls made from the
cell wing in the prison where the defendants were held during
the applicable time period and scanned those calls for context
clues suggesting the identity of the speaker. Officer
Thompson identified Gadson’s voice on the recording based
on several factors: he had met Gadson and was familiar with
his “very unique” voice, he determined that almost all of
Gadson’s calls were to Gabriella Haynes, and in at least one
conversation, Officer Thompson heard Gadson talking about
a list of items which had been seized from his house during
the search, information accessible to only a handful of people
at that time.
                 UNITED STATES V. GADSON                     23

    Officer Thompson identified Wilson’s voice in the
recording based on other extrinsic evidence. First, Officer
Thompson heard the voice of a different prisoner calling
Gabriella Haynes shortly after Wilson was admitted. Because
the other defendants had previously been detained, Officer
Thompson reasonably inferred that this new voice belonged
to Wilson, the last member of the drug operation to be
arrested. Second, during the time Wilson was in the
segregation unit, he had to make written requests to use the
telephone, and the timing of Wilson’s requests corresponded
with the new voice’s calls to Gabriella Haynes. Finally, the
caller discussed facts particular to Wilson’s case.

    Officer Thompson sufficiently narrowed the universe of
possible callers so as to support an inference that the speakers
in these calls were Gadson and Wilson. Cf. Yin, 935 F.2d at
996; Torres, 908 F.2d at 1425. Because the district court’s
admission of this testimony was not “illogical, implausible,
or without support in inferences that may be drawn from facts
in the record,” Hinkson, 585 F.3d at 1251, it did not abuse its
discretion in admitting it.

                              III

    We next consider Wilson’s multiple arguments regarding
the district court’s admission of Officer Thompson’s
testimony regarding the recorded phone calls.

                               A

   Because the sound quality of the tape recordings was
poor, Wilson claims that Officer Thompson was acting as a
government-produced transcript of the recordings, and the
court did not take the necessary steps to ensure the accuracy
24               UNITED STATES V. GADSON

of the transcript or interpretation. Because neither defendant
raised this claim at trial, we review it for plain error. See
Lindsey, 634 F.3d at 550–51. Applying this standard, we
conclude the district court did not plainly err. Officer
Thompson’s testimony regarding the context of the phone
calls and interpretation of ambiguous or vague statements was
not akin to a verbatim transcript of the calls, and thus the
district court did not commit plain error in not considering
sua sponte whether sufficient steps were taken to ensure the
statements’ accuracy. Cf. United States v. Armijo, 5 F.3d
1229, 1234 (9th Cir. 1993) (considering various factors
regarding the accuracy of a transcription translating recorded
telephone calls from Spanish to English). Moreover, even
under the standard applied to written transcripts, there were
ample indicia of accuracy, given that defense counsel had the
opportunity to challenge the accuracy of Officer Thompson’s
testimony and to introduce alternative versions, and the
district court informed the jury on at least three occasions that
the calls, not Officer Thompson’s testimony, were the
evidence. See id.

     Nor did Wilson establish that the district court plainly
erred in admitting the tapes on audibility grounds. “A
recorded conversation is generally admissible unless the
unintelligible portions are so substantial that the recording as
a whole is untrustworthy.” United States v. Lane, 514 F.2d
22, 27 (9th Cir. 1975). Wilson has not shown that the tapes
were so uniformly unintelligible that the recordings should
not have been presented to the jury. No objection was made
at trial on this basis. Nor was there evidence “that persons in
the courtroom were unable to hear substantial portions of the
conversations recorded on the tapes, or that the words were
unintelligible.” United States v. Tisor, 96 F.3d 370, 377 (9th
Cir. 1996). Further, Wilson waived or forfeited this argument
                    UNITED STATES V. GADSON                              25

by opposing efforts to provide the original recordings to the
jury during their deliberations. When the jury requested the
original telephone recordings (rather than the courtroom
recordings of the clips as they were played during the trial),
Wilson objected to giving the jury the original clips.
Although the government proposed to give the jury “the
clearest possible version” of the clips played at trial, Wilson
argued against various approaches suggested by the
government that would have enabled the jury to hear the
originals, and contended that the jury should be limited to the
recording of what was played in court.4 Consequently, the
district court’s failure to sua sponte exclude the tapes was not
plain error.

                                     B

     Second, Wilson asserts that the district court erred in
allowing Officer Thompson to testify concerning the content
of the telephone calls. Wilson claims this type of testimony
is inadmissible because it does not meet the criteria for lay
opinion testimony under Rule 701 of the Federal Rules of
Evidence. According to Wilson, Officer Thompson’s
testimony was inadmissible under this rule because Officer
Thompson was not a percipient witness to the conversations,
his testimony was based on the investigation as a whole, his
interpretation of vague testimony usurped the jury’s role as
trier of fact, and his interpretation of one phone call relied on
hearsay.




 4
   Accordingly, the dissent errs in asserting that in response to the jury’s
request for the tapes, defendants merely “consent[ed] to the district court’s
chosen solution” to the jury’s request for the tapes. Dissent at 75 & n.3.
26              UNITED STATES V. GADSON

    Our consideration of Wilson’s arguments requires us to
examine the scope of Rule 701. Rule 701 allows a lay
witness to offer opinions that are (a) “rationally based on the
witness’s perception,” (b) “helpful” to the jury, and (c) “not
based on scientific, technical, or other specialized knowledge
within the scope of” expert testimony. When promulgated in
1975, this rule represented a departure from the then-
prevailing evidentiary principles governing lay witness
testimony, which generally required witnesses “to limit their
testimony just to the facts they perceived and avoid opinions
or inferences based on those facts.” 29 Charles Alan Wright
& Victor James Gold, Federal Practice & Procedure § 6251,
at 105 (1997). Courts justified this approach on the grounds
that “lay-witness opinion usurps the role of the jury, whose
job it is to draw conclusions as to the meaning of the
evidence,” and because “testimony limited to perceived facts
was considered more reliable than mere opinion, which could
be misleading.” Id. § 6252, at 109.

    The drafters of Rule 701 rejected both these distinctions.
First, the distinction between “fact” and “opinion” proved to
be unworkable in practice. See Fed. R. Evid. 701 advisory
committee’s note (noting “the practical impossibility of
determining by rule what is a ‘fact’” and that “[w]itnesses
often find difficulty in expressing themselves in language
which is not that of an opinion or conclusion”); see also
United States v. Pierson, 503 F.2d 173, 176 (D.C. Cir. 1974)
(stating that the “so-called opinion rule” was “not strictly
followed—due in large part to the difficulty of drawing a fine
distinction between fact and opinion”). Indeed, as the D.C.
Circuit explained, “[t]here is no conceivable statement
however specific, detailed and ‘factual,’ that is not in some
measure the product of inference and reflection as well as
observation and memory.” Pierson, 503 F.2d at 176 (quoting
                    UNITED STATES V. GADSON                             27

McCormick on Evidence § 11 (1972)). The drafters of Rule
701 also rejected the concern that lay opinion testimony
would mislead juries. Rule 701 assumes instead that “the
natural characteristics of the adversary system will generally
lead to an acceptable result,” and weaknesses in the lay
witness’s testimony can be emphasized through “cross-
examination and argument.” Fed. R. Evid. 701 advisory
committee’s notes; see also United States v. Beck, 418 F.3d
1008, 1015 (9th Cir. 2005) (noting that “direct and
cross-examination of a lay witness testifying as to his or her
opinion is relied upon to verify the accuracy of the
testimony”).

    In applying Rule 701 to the lay opinion testimony of law
enforcement officers, we have held that an officer’s
interpretation of intercepted phone calls may meet Rule 701’s
“perception” requirement when it is an interpretation “of
ambiguous conversations based upon [the officer’s] direct
knowledge of the investigation.” United States v. Freeman
(Kevin Freeman), 498 F.3d 893, 904–05 (9th Cir. 2007); see
also United States v. Simas, 937 F.2d 459, 464–65 (9th Cir.
1991) (finding no abuse of discretion in admitting officers’
lay testimony “concerning their understanding of what
[defendant] meant to convey by his vague and ambiguous
statements”).5 In Kevin Freeman, for instance, we held that
once the government established a foundation, a police

 5
   The majority of the circuits allow officers to provide interpretations of
recorded conversations based on their knowledge of the investigation,
subject to various safeguards. See United States v. Albertelli, 687 F.3d
439, 444–48 (1st Cir. 2012); United States v. El-Mezain, 664 F.3d 467,
513–14 (5th Cir. 2011); United States v. Jayyousi, 657 F.3d 1085,
1102–03 (11th Cir. 2011); United States v. Rollins, 544 F.3d 820, 830–33
(7th Cir. 2008); United States v. Garcia, 994 F.2d 1499, 1506–07 (10th
Cir. 1993); United States v. De Peri, 778 F.2d 963, 977–78 (3d Cir. 1985).
28              UNITED STATES V. GADSON

officer could provide lay witness opinion testimony regarding
the meaning of statements in the defendant’s intercepted
phone calls because the testimony was based on the officer’s
“direct perception of several hours of intercepted
conversations—in some instances coupled with direct
observation of [the defendants]—and other facts he learned
during the investigation.” 498 F.3d at 904–05; see also
United States v. El-Mezain, 664 F.3d 467, 513–14 (5th Cir.
2011) (allowing lay opinion testimony interpreting telephone
calls when “the agents’ opinions were limited to their
personal perceptions from their investigation of this case”);
United States v. Rollins, 544 F.3d 820, 830–33 (7th Cir.
2008) (finding no error in the district court’s decision to
allow the agent’s testimony regarding his “impressions” of
recorded conversations when the testimony was “based on the
agent’s perceptions derived from the investigation of this
particular conspiracy”). Such testimony is admissible even
if the testifying officer was not a participant in the recorded
conversation. Kevin Freeman, 498 F.3d at 904; see also
United States v. Jayyousi, 657 F.3d 1085, 1102 (11th Cir.
2011) (holding that a lay witness’s testimony was admissible
even though “he did not personally observe or participate in
the defendants’ conversations”); United States v. Garcia,
994 F.2d 1499, 1507 (10th Cir. 1993) (admitting an officer’s
opinion based only “on listening to the conversations between
coconspirators”).

    Lay witness testimony regarding the meaning of
ambiguous conversations based on the witness’s direct
perceptions and experience may also prove “helpful to the
jury” for purposes of Rule 701. See Kevin Freeman, 498 F.3d
at 904–05 (agent’s “understanding of ambiguous phrases”
based on the “direct perception of several hours of intercepted
conversations” along with “direct observation” of defendants
                 UNITED STATES V. GADSON                     29

and “other facts he learned during the investigation” resulted
in testimony that “proved helpful to the jury in determining
what the [co-conspirators] were communicating during the
recorded telephone calls”); see also Rollins, 544 F.3d at
832–33 (agent’s testimony based on listening to every
intercepted conversation, and other “personal observations
and perceptions” related to the specific case at issue “assisted
the jury in determining several facts in issue”).

    On the other hand, an officer’s testimony interpreting
recorded conversations may fall outside the scope of Rule
701 if it is not based on the witness’s perception (for
example, if it is based on speculation or hearsay) or is not
helpful to the jury. Kevin Freeman, 498 F.3d at 905. Lay
testimony is not helpful to the jury if it merely provides
“‘interpretation of clear statements’” that are within the
common knowledge of the jury. Id. (quoting United States v.
Dicker, 853 F.2d 1103, 1109 (3d Cir. 1988)). In Dicker, for
instance, a government agent testified about the meaning of
recorded conversations, and explained that the parties to the
conversation were discussing means for obtaining “phony
paperwork.” 853 F.2d at 1106. But the recorded
conversations themselves did not include any discussion of
phony paperwork, and there was no indication “that the
documents to be obtained were not to be genuine.” Id. at
1105. Under these circumstances, Dicker held that the
officer’s mischaracterization of the plain words used in the
conversation was not helpful to the jury, and thus barred by
Rule 701. Id. at 1108–10; see also United States v. Freeman
(Marcus Freeman), 730 F.3d 590, 597 (6th Cir. 2013)
(holding that Rule 701 barred an officer’s testimony which
essentially “spoon-fed his interpretations of the phone calls
and the government’s theory of the case to the jury,
interpreting even ordinary English language”); Rollins,
30               UNITED STATES V. GADSON

544 F.3d at 833 (admitting an agent’s “impressions”
regarding an intercepted conversation because the agent “was
not merely telling the jury what result to reach as to the
defendants’ culpability”). As the drafters of Rule 701 noted,
“meaningless assertions which amount to little more than
choosing up sides” should be excluded for lack of
helpfulness. Fed. R. Evid. 701 advisory committee’s note.
In addition, testimony that relies on or conveys hearsay
evidence, such as when an officer relies on the truth of a third
party’s statement as the basis for an interpretation of a
statement in an intercepted phone call, is also inadmissible,
both because it would not be based on the officer’s own
perceptions, and would not be helpful. Kevin Freeman,
498 F.3d at 905. Any error in admitting lay opinion testimony
under Rule 701, however, could be harmless if in light of the
evidence as a whole, there was a “fair assurance that the jury
was not substantially swayed by the error.” Id. (internal
quotation marks omitted).

    A minority of circuits have construed Rule 701 much
more narrowly and barred officers from interpreting
intercepted communications based on their review of the
recordings and personal involvement in an investigation.
Thus in United States v. Hampton, 718 F.3d 978 (D.C. Cir.
2013), the D.C. Circuit determined that a district court had
violated Rule 701 by allowing an FBI agent to testify
regarding intercepted conversations, even though the
government established that the FBI agent had been in charge
of the investigation, monitored wiretaps, performed physical
surveillance, supervised other agents who monitored the
wiretaps, and had reviewed each of the 20,000 conversations
intercepted by the wiretaps. Id. at 981–83. According to the
D.C. Circuit, such testimony raised a risk that the agent “was
testifying based upon information not before the jury” and the
                 UNITED STATES V. GADSON                     31

jury “had no way of verifying his inferences or of
independently reaching its own interpretations.” Id. at 983
(internal quotation marks omitted); see also United States v.
Grinage, 390 F.3d 746, 750–51 (2d Cir. 2004) (same).

     We disagree with this approach, which harkens back to
the evidentiary policies that were rejected by the drafters of
Rule 701. A lay witness’s opinion testimony necessarily
draws on the witness’s own understanding, including a wealth
of personal information, experience, and education, that
cannot be placed before the jury. If witnesses cannot draw on
their experience and knowledge, they are effectively limited
to presenting factual information. Such an approach echoes
the now-abandoned distinction between allowing testimony
regarding “facts” but not “opinions,” and revives the
historical policy that admitting lay opinion testimony usurps
the role of the jury, a view that was rejected by the Rule 701
drafters. See Hampton, 718 F.3d at 983; id. at 986 (Brown,
J., concurring); Grinage, 390 F.3d at 749–51.

    Rule 701 does not impose such a limitation. Under Rule
701, while the district court must exercise its discretion
wisely to minimize problems that may arise in admitting lay
opinion testimony, see Albertelli, 687 F.3d at 447 (listing
dangers and safeguards), the guiding policy of the Rule is to
trust the jury to identify unreliable opinion testimony with the
help of the adversary process, see Fed. R. Evid. 701 advisory
committee’s note. Courts regularly admit lay opinion
testimony regarding the identity of a person in a photograph,
see, e.g., Beck, 418 F.3d at 1014–15, and voice identification
testimony, see, e.g., United States v. Thomas, 586 F.2d 123,
133 n.23 (9th Cir. 1978), even though the witness provides
such identification based on past contacts with the pertinent
individual that are outside the jury’s knowledge. Similarly,
32                  UNITED STATES V. GADSON

an investigator who has accumulated months or even years of
experience with the events, places, and individuals involved
in an investigation necessarily draws on that knowledge when
testifying; indeed, it is those out-of-court experiences that
make the witness’s testimony helpful to the jury. Contrary to
the rationale of Hampton and Grinage, “the application of
Rule 701 should not be influenced by concern that opinion
testimony usurps the role of the jury or that factual testimony
is more reliable than opinion testimony.”6 Wright, supra,
§ 6252, at 112.

    We now consider Wilson’s arguments in light of these
principles. “The admissibility of lay opinion testimony under
Rule 701 is committed to the sound discretion of the trial
judge and his decision will be overturned only if it constitutes
a clear abuse of discretion.” Nationwide Transp. Fin. v. Cass
Info. Sys., Inc., 523 F.3d 1051 (9th Cir. 2008) (quoting United
States v. Yazzie, 976 F.2d 1252, 1255 (9th Cir. 1992)).
Because Wilson did not challenge Officer Thompson’s
testimony under Rule 701 at trial, we review for plain error.
See Lindsey, 634 F.3d at 550–51.

                                     1

    First, Wilson argues that Officer Thompson could not
offer his interpretations of the recorded phone conversations
under Rule 701, because lay opinion testimony is admissible


 6
    We therefore decline the dissent’s invitation to adopt a rule that a lay
witness (or at least an officer) cannot provide lay opinion testimony based
on information and experiences that are within the lay witness’s
knowledge, but have not been put before the jury. Dissent at 65, 70. Such
a rule would not be consistent with the plain language of Rule 701 or our
decision in Kevin Freeman.
                UNITED STATES V. GADSON                   33

only when a witness was a party to the conversation himself
or was a percipient witness. Because we rejected this precise
argument in Kevin Freeman, 498 F.3d at 904–05, the district
court did not plainly err in not striking Officer Thompson’s
testimony on this ground.

                             2

     Next, Wilson claims that Officer Thompson’s
interpretation was inadmissible because it was based on the
investigation as a whole, including the police report and
information contributed by other officers, rather than merely
his personal observations. The district court did not plainly
err in failing to strike Officer Thompson’s testimony on this
ground. According to his testimony, Officer Thompson had
been involved in the investigation of the drug conspiracy
since early 2010. His involvement spanned the searches of
the Fouts house, the multi-day surveillance of the Gillam
Way house, the search of the Gillam Way house, and the
review of around 100 hours of prison phone calls. In light of
our decision in Kevin Freeman, where we admitted testimony
based on similar experiences, the district court had ample
grounds to conclude that Officer Thompson based his
interpretations on his personal knowledge of facts he learned
during the investigation.

    In arguing against this conclusion, Wilson relies on
Marcus Freeman, in which the Sixth Circuit held that an
agent’s testimony was not admissible under Rule 701 because
it was based solely on the agent’s review of 23,000 phone
conversations, rather than on the agent’s involvement in the
investigation. 730 F.3d at 596–99. The facts of Marcus
Freeman are quite different from our case, however. In
Marcus Freeman, the government conceded that the
34              UNITED STATES V. GADSON

testifying agent “lacked the first-hand knowledge required to
lay a sufficient foundation for his testimony under Rule
701(a).” Id. at 597. Because the agent had not been involved
in the surveillance of the defendant, and had not observed
“any activity relevant to interpreting the calls,” the agent
relied solely on “the general knowledge of the FBI and the
investigation as a whole.” Id. at 596. Nor did the agent shed
light on the meaning of ambiguous statements based on
personal knowledge regarding the investigation; rather the
agent essentially “spoon-fed his interpretations of the phone
calls and the government’s theory of the case to the jury,
interpreting even ordinary English language.” Id. at 597.
Under these circumstances, the agent’s testimony was not
“rationally based” on his own concrete perceptions regarding
the investigation and was not helpful to the jury, as required
by Rule 701. Here, by contrast, Officer Thompson had the
requisite personal experience and knowledge of the
investigation, had reviewed the phone calls in the context of
that knowledge, and did not merely regurgitate the
government’s theory of the case. Because the government
established a foundation for Officer Thompson’s testimony,
while such a foundation was fatally lacking in Marcus
Freeman, Marcus Freeman has little bearing on Wilson’s
claims.

                              3

    Along the same lines, Wilson argues that the district court
erred in not sua sponte striking Officer Thompson’s
interpretation of Wilson’s reference to “Powell” to mean “Joe
Powell,” and his interpretation of Wilson’s references to
“Donte” and “they have him on tape” to mean the police had
Donte Edwards on tape.            Wilson argues that this
interpretation of vague testimony usurps the jury’s function.
                 UNITED STATES V. GADSON                     35

We disagree. Officer Thompson’s testimony was based on
his knowledge of the investigation and the persons involved,
evidence that was also before the jury. Because a jury may
become confused by vague pronouns such as “who,” “him,”
and “that,” Officer Thompson’s testimony would provide
helpful context. See Kevin Freeman, 498 F.3d at 900, 902
(holding that an officer’s interpretation of “ambiguous
statements consisting of ordinary terms,” like “that” was
admissible as lay opinion testimony).

    The dissent highlights a particular conversation, where
Wilson stated “‘You know, he’s the one’”—referring to the
informant Pitka—“‘that started this shit.’ . . . ‘That time with
Batman, that was him.’” Dissent at 78. At trial, Officer
Thompson explained that “Batman” refers to Brandon
Haynes, and Wilson’s statement “that time” refers back to the
November 2010 incident (in which Officer Thompson was
involved) where Pitka executed a controlled buy from
Brandon which led to Brandon’s eventual arrest. As the
dissent recognizes, id., Officer Thompson’s testimony that
“Batman” was Brandon’s nickname is precisely the type of
investigation-specific opinion testimony that Kevin Freeman
authorizes. But contrary to the dissent, id., Officer
Thompson’s explanation of “that time” is likewise
admissible, because Kevin Freeman permits “interpretations
of ambiguous conversations based upon [the officer’s] direct
knowledge of the investigation,” 498 F.3d at 904–05. For
instance, Kevin Freeman approved of the officer’s
interpretation of the statement, “Man, it’s done already” to
mean “he’s given the cocaine to Kevin Freeman and that he’s
received his money for it.” Id. at 902. According to Kevin
Freeman, such interpretations “did nothing more than
offer one possible framework for understanding the
conversation.” Id. Officer Thompson’s testimony regarding
36                  UNITED STATES V. GADSON

his interpretation of “that time” falls comfortably within the
same range of interpretive testimony. At the very least, it was
not plain error for the district court to allow the testimony.
Indeed, the dissent advances no reason why the district
court’s failure to cut off Officer Thompson’s testimony sua
sponte was “clear” or “obvious” error, United States v. Olano,
507 U.S. 725, 734 (1993) (internal quotation marks omitted),
in light of our settled law allowing this type of testimony.7

                                      4

    We next turn to Gadson’s hearsay challenge to the
admissibility of Officer Thompson’s testimony characterizing
statements made by Brandon Haynes.8 As we have
explained, lay opinion testimony may not convey or rely on
hearsay, because it is not helpful to the jury. Kevin Freeman,
498 F.3d at 905.

    During Officer Thompson’s testimony about one of the
prison phone calls, he noted that Wilson was



     7
      We have carefully considered—and rejected—each of Wilson’s
challenges to specific statements by Officer Thompson. The dissent,
however, points to several additional parts of the trial transcript, where the
dissent claims Officer Thompson repeated clear words or speculated as to
their meaning. Dissent at 77–78. Wilson himself did not cite these
statements, let alone argue that the district court erred in failing to strike
them or that the admission of such testimony was prejudicial. Because
Wilson never raised such arguments, and the government has not had an
opportunity to respond, we decline to address them here. See Greenwood
v. FAA, 28 F.3d 971, 977 (9th Cir. 1994) (stating that we “will not
manufacture arguments for an appellant”).
 8
   In his brief, Wilson states that he joins this argument. Fed. R. App. P.
28(i).
                 UNITED STATES V. GADSON                      37

        reading off of a portion of the [police] report
        that we made after interviewing Brandon
        Haynes. You hear Brandon Haynes . . . in the
        background . . . [say] ‘Hell, no.’ One thing
        we learned throughout this investigation is
        that in different phone calls [Brandon Haynes]
        made numerous denials to everyone, even
        though we had a video-recorded, audio-
        recorded interview with Mr. Haynes where he
        made these admissions to us.

Gadson’s counsel made a hearsay objection to “the purported
admissions of Brandon Haynes,” but the district court
implicitly denied the objection.

    According to Gadson, Officer Thompson’s statement that
Brandon “made these admissions to us” is hearsay that is not
admissible under any exception. We disagree. Officer
Thompson’s statement that Brandon “made these admissions
to us” does not meet the definition of hearsay: a statement
that is offered “to prove the truth of the matter asserted in the
statement.” Fed. R. Evid. 801(c)(2). Officer Thompson did
not testify as to the nature of “these admissions,” repeat any
assertion made by Brandon, or suggest that the jury should
consider any admission made by Brandon to be truthful.
Rather, Officer Thompson mentioned Brandon’s admissions
to the police as context for the recorded phone call, and to
explain why the jurors would hear Brandon state “Hell, no”
in the background. A witness making statements to provide
clarification and context for other statements is not offering
evidence for the truth of the matter asserted, and such
testimony does not run afoul of any hearsay prohibition. See
United States v. Collicott, 92 F.3d 973, 981 n.7 (9th Cir.
1996); see also United States v. Whitman, 771 F.2d 1348,
38                  UNITED STATES V. GADSON

1352 (9th Cir. 1985) (no error where informant’s recorded
statements were only offered “to show that they were made,”
and to put the statements in context, rather than for their
truth). Accordingly, the district court did not abuse its
discretion in declining to strike this testimony.

                                     5

     Finally, Wilson argues that the district court erred in
allowing Officer Thompson to provide his interpretation of
drug jargon such as “nine of leaded” (crack cocaine), or “a
strap” (firearm), because he had not been qualified as an
expert witness.9 Because neither Gadson nor Wilson objected
at trial to the drug jargon testimony as impermissible expert
testimony, we review this claim for plain error. See United
States v. Pino-Noriega, 189 F.3d 1089, 1097 (9th Cir. 1999).

    “[L]aw enforcement testimony about the meaning of drug
jargon may be both expert and lay testimony, depending on
the circumstances.” United States v. Reed, 575 F.3d 900, 922
(9th Cir. 2009). Unlike a lay witness, a witness who is an
expert on drug jargon may interpret encoded drug terms even
if the witness had not been involved in that particular
investigation. See id. And so police officers’ testimony
regarding drug terms related to an investigation may be
expert opinion testimony, lay opinion testimony, or both.
Although we have noted the difficulties that may arise when
an agent qualified as an expert also provided lay testimony,


 9
   The dissent suggests that Officer Thompson should have been qualified
as an expert before offering any of his opinions because he used
“specialized equipment” to listen the phone calls. Dissent at 70. None of
the parties objected to Officer Thompson’s testimony on this basis at trial,
and Wilson has not raised this argument on appeal.
                 UNITED STATES V. GADSON                     39

see Kevin Freeman, 498 F.3d at 903–04, we have
nevertheless held that such dual use of “case agents as both
expert and lay witnesses is not so inherently suspect that it
should be categorically prohibited.” Id. at 904.

    Our concerns regarding a witness who qualifies as an
expert giving lay opinion testimony are not directly
applicable when an agent who is providing lay testimony also
interprets a few drug terms in the context of discussing
personal observations. While witnesses who testify as an
expert may receive “unmerited credibility” for their lay
testimony, because expert testimony is “likely to carry special
weight with the jury,” id. at 903 (internal quotation marks
omitted), the converse is not true: a lay witness’s testimony
carries no special weight, even if at points the lay witness has
recourse to relevant background and training. Similarly, there
is no special risk that lay testimony regarding firsthand
observations would be merely speculative. Cf. id. at 904. We
have also expressed concern that because expert witnesses
may opine on matters about which they have no personal
knowledge, they may also rely on inadmissible hearsay when
providing lay testimony. Id. Such a danger does not
necessarily arise when lay witnesses are testifying about
matters in which they were involved.

    Here, Officer Thompson testified primarily as a lay
witness providing his firsthand knowledge of the case; he
referenced his reliance on training and police experience (as
opposed to familiarity with the individuals through the
specific investigation) only when defining the single term
“nine of leaded.” This isolated instance does not raise the
concerns identified in Kevin Freeman. Further, the district
court could reasonably conclude that Officer Thompson
encountered the two terms at issue in the context of his
40                 UNITED STATES V. GADSON

investigation as well as through his training and experience.
See Reed, 575 F.3d at 922. “Because the distinction between
lay and expert testimony in this context is a fine one, we do
not fault the district court for failing to intervene sua
sponte.”10 Kevin Freeman, 498 F.3d at 904.

    We also reject Wilson’s argument that Officer
Thompson’s reference to police reports, or to his use of
special equipment to review the tapes, gave him an
unwarranted aura of special knowledge. Wilson did not raise
this argument at trial, and the district court did not plainly err
in not addressing sua sponte this concern.

                                   C

    Both defendants object to a specific portion of Officer
Thompson’s testimony in response to questioning by
Wilson’s attorney. After Officer Thompson had testified
regarding the recorded prison phone calls, Wilson’s attorney
engaged him in the following colloquy:

         [Wilson’s attorney]: [N]onetheless, when we
         come into the life or come into the courtroom,



  10
     Further, the admission of Officer Thompson’s definition of these
terms did not affect the defendants’ substantial rights, because the
evidence regarding Officer Thompson’s background and experience (he
had been assigned to the statewide drug enforcement unit for the previous
three and a half years and had received several hundred hours of training
in drug-related investigations) would have qualified him to give expert
testimony on this subject. See United States v. Figueroa-Lopez, 125 F.3d
1241, 1247 (9th Cir. 1997) (holding that the admission of lay testimony
about countersurveillance operations was harmless because witness was
indeed qualified to give expert opinion testimony on that subject).
                 UNITED STATES V. GADSON                     41

       wherever we go, we bring our own position
       and biases with us.

       [Officer Thompson]: I would agree.

       [Wilson’s Attorney]: Right. So you would
       have a tendency to project a police officer’s
       interpretation onto things?

       [Officer Thompson]: I would—I would state
       yes, that I think I put a— a— good case
       together, and I’m confident of the people
       charged in the case are guilty of the crimes.

Gadson’s counsel objected to Officer Thompson’s answer on
the ground that it constituted vouching. The district court did
not strike the answer, but stated before the jury: “[u]ltimately
it’s up to the jury to determine guilt or innocence, and so the
jury should consider all the evidence presented in that
regard.”

    On appeal, Gadson renews his argument that Officer
Thompson’s statement constituted impermissible vouching
because it was Officer Thompson’s personal opinion of the
defendants’ guilt. Wilson joins this argument, and also
argues that Officer Thompson’s opinion was improper
because it went to the ultimate issue of the defendants’ guilt,
in violation of Rule 704(b) of the Federal Rules of Evidence.

    Prosecutors may not place “the prestige of the
government behind a witness through personal assurances of
the witness’s veracity, or suggesting that information not
presented to the jury supports the witness’s testimony.”
United States v. Necoechea, 986 F.2d 1273, 1276 (9th Cir.
42              UNITED STATES V. GADSON

1993). By putting an unwarranted imprimatur of credibility
or authority on the testifying witness, a prosecutor may
“jeopardize the defendant’s right to be tried solely on the
basis of the evidence presented to the jury.” United States v.
Weatherspoon, 410 F.3d 1142, 1146–48 (9th Cir. 2005)
(internal citations omitted). In this case, however, the
government did not elicit Officer Thompson’s testimony, nor
did it vouch for his credibility “either by putting its own
prestige behind the witness, or by indicating that extrinsic
information not presented in court supports the witness’[s]
testimony.” United States v. Garcia-Guizar, 160 F.3d 511,
520 (9th Cir. 1998) (internal quotation marks omitted).
Rather, Officer Thompson testified only that he was confident
about his own testimony after defense counsel attacked his
credibility. The defendants have not pointed to any case
suggesting that such testimony constitutes impermissible
vouching. Accordingly, the district court did not err in
declining to strike the testimony on that ground.

    Wilson argues that the district court erred in not striking
Officer Thompson’s response because it was an opinion on
the ultimate issue of guilt or innocence. Under Rule 704(b),
an expert witness in a criminal case “must not state an
opinion about whether the defendant did or did not have a
mental state or condition that constitutes an element of the
crime charged or of a defense.” We have interpreted this rule
as precluding an expert witness from offering “a direct
opinion on the defendant’s guilt or innocence.” Kevin
Freeman, 498 F.3d at 906. But Rule 704(b) is inapplicable
by its terms. Officer Thompson was not testifying as an
expert witness here. The defendants have cited no cases
applying Rule 704(b) to a lay witness, and there is no basis
for doing so under the text of the rule. Accordingly, the
                    UNITED STATES V. GADSON                              43

district court did not err in not striking the testimony on Rule
704(b) grounds.11

                                    IV

     Gadson raises two challenges relating to the government’s
reliance on Pinkerton v. United States, 328 U.S. 640 (1946),
to obtain his conviction for possessing firearms in furtherance
of drug trafficking offenses under 18 U.S.C. § 924(c)(1).12 At
trial, the government relied on Pinkerton, which “renders all
co-conspirators criminally liable for reasonably foreseeable
overt acts committed by others in furtherance of the
conspiracy they have joined, whether they were aware of
them or not.” United States v. Hernandez-Orellana, 539 F.3d
994, 1007 (9th Cir. 2008). The jury found Gadson guilty with
respect to a shotgun and handgun found inside the Fouts
house, but not guilty with respect to a rifle found outside.



  11
    Indeed, even if Officer Thompson had testified as an expert witness,
any error in failing to strike his remark would have been harmless. In
analogous circumstances, we have held that a failure to strike a single
comment over the course of a lengthy trial was not plain error when the
government did not rely on the comment in its arguments to the jury. Cf.
United States v. Gomez-Osorio, 957 F.2d 636, 642 (9th Cir. 1992). The
government did not cite Officer Thompson’s comment at all. Moreover,
the court gave an immediate curative instruction to the jury, stating that:
“[u]ltimately it’s up to the jury to determine guilt or innocence, and so the
jury should consider all the evidence presented in that regard.”
  12
     The statute provides that “any person who, during and in relation to
any crime of violence or drug trafficking crime . . . uses or carries a
firearm, or who, in furtherance of any such crime, possesses a firearm,
shall, in addition to the punishment provided for such crime of violence
or drug trafficking crime—(i) be sentenced to a term of imprisonment of
not less than 5 years.” 18 U.S.C. § 924(c)(1)(A).
44              UNITED STATES V. GADSON

    Gadson challenges the instruction on Pinkerton liability
given to the jury, arguing that it allowed him to be convicted
without a showing that the coconspirators’ use of the firearms
was reasonably foreseeable to him. He also challenges the
sufficiency of the evidence to convict him under a Pinkerton
theory.

                              A

   We begin by considering the district court’s instruction on
Pinkerton liability:

       [Y]ou may find the defendant guilty of . . .
       possession of a firearm in furtherance of . . .
       drug trafficking, Count 3, if the government
       has proved each of the following elements
       beyond a reasonable doubt:

       First, a person named in the respective count
       of the first superseding indictment committed
       the crime as alleged in the count. Second, the
       person was a member of the conspiracy
       charged in Count 1 of the superseding
       indictment. Third, the person committed the
       crime in furtherance of the conspiracy . . . .
       Fourth, the defendant was a member of the
       same conspiracy at the time the offense was
       committed. And, fifth, the offense fell within
       the scope of the unlawful agreement and
       could reasonably have been foreseen to be a
       necessary or natural consequence of the
       unlawful agreement.
                 UNITED STATES V. GADSON                      45

    Gadson claims that this instruction misstated the law. He
focuses on the portion of the court’s instruction which stated
that the jury could find Gadson guilty of the firearm offense
committed by a coconspirator only if the government proved
beyond reasonable doubt that the offense “could reasonably
have been foreseen to be a necessary or natural consequence
of the unlawful agreement.” According to Gadson, the
instruction failed to convey to the jury that it had to find that
the offense was reasonably foreseeable to Gadson, not just
objectively reasonably foreseeable to a coconspirator.

    Neither Gadson nor Wilson raised this particular
objection to the Pinkerton instruction, and so our review is
for plain error. See United States v. Kessi, 868 F.2d 1097,
1102 (9th Cir. 1989) (one type of objection to an instruction
does not necessarily preserve another objection if there was
no reason to believe the district court was fully aware of that
objection). We conclude that the district court did not plainly
err in formulating its Pinkerton instruction. The instruction
directly tracks the language of Pinkerton, which held that
coconspirator liability would not extend to a case where

        the substantive offense committed by one of
        the conspirators was not in fact done in
        furtherance of the conspiracy, did not fall
        within the scope of the unlawful project, or
        was merely a part of the ramifications of the
        plan which could not be reasonably foreseen
        as a necessary or natural consequence of the
        unlawful agreement.

328 U.S. at 647–48. Moreover, we have upheld an
identical instruction as “an accurate statement of the
applicable law.” United States v. Alvarez-Valenzuela, 231
46                   UNITED STATES V. GADSON

F.3d 1198, 1202–03 (9th Cir. 2000).13 Indeed, the Ninth
Circuit Model Criminal Jury Instruction 8.25 requires only
that “the offense fell within the scope of the unlawful
agreement and could reasonably have been foreseen to be a


 13
      The instruction upheld in Alvarez-Valenzuela was as follows:

          Each member of a conspiracy is responsible for the
          actions of the other members performed during the
          course and in furtherance of the conspiracy. If one
          member of the conspiracy commits a crime in
          furtherance of the conspiracy, the other members have
          also, under the law, committed that crime. Therefore,
          you may find a defendant guilty of possession of a
          firearm during and in relation to a drug trafficking
          crime, as charged in Count 1 or in Count 3 of the
          Indictment, if the government has proven each of the
          following elements beyond a reasonable doubt:

          First, a person involved in the conspiracy in Count 1 or
          Count 3 knowingly possessed a firearm during and in
          relation to a drug trafficking crime;

          Second, the person was a member of the conspiracy
          charged in Count 1 or Count 3;

          Third, the person possessed the firearm in furtherance
          of the conspiracy;

          Fourth, the defendant was a member of the same
          conspiracy at the time that the offense charged in either
          Count 1 or Count 3 was committed; and

          Fifth, the offense fell within the scope of the unlawful
          agreement and could reasonably have been foreseen to
          be a necessary or natural consequence of the unlawful
          agreement.

231 F.3d at 1202–03.
                UNITED STATES V. GADSON                    47

necessary or natural consequence of the unlawful agreement.”
In light of this authority, we cannot say that the district
court’s formulation of the jury instruction was error that is
plain, or that the instructions, read as a whole, were
“misleading or inadequate to guide the jury’s deliberation,”
United States v. Frega, 179 F.3d 793, 806 n.16 (9th Cir.
1999).

    In arguing otherwise, Gadson relies on United States v.
Castaneda, 9 F.3d 761 (9th Cir. 1993), overruled in
nonrelevant part by United States v. Nordby, 225 F.3d 1053,
1059 (9th Cir. 2000), which identified a due process
limitation on the scope of Pinkerton liability in certain
circumstances. Id. at 766. In Castaneda, the wife of a major
drug trafficker was charged with a violation of § 924(c) under
a Pinkerton theory. The only evidence linking the wife to the
conspiracy was her marital relationship to her husband and a
few phone calls in which the wife relayed information to
members of the conspiracy at her husband’s request. Id. at
767–68. We held that “due process constrains the application
of Pinkerton where the relationship between the defendant
and the substantive offense is slight,” id. at 766, and
concluded that a Pinkerton instruction would violate due
process on the facts of that case, given the slight connection
between the wife and the conspiracy, id. at 768. We
emphasized, however, the narrowness of this holding. Id.

    The due process concerns identified in Castaneda are not
present here. There was substantial evidence of Gadson’s
participation in the drug conspiracy, and a reasonable jury
could conclude that Gadson could have foreseen the use of
firearms in connection with the drug trafficking.
Accordingly, the application of a Pinkerton theory in this
48               UNITED STATES V. GADSON

context does not violate “fundamental precepts of due
process.” Id.

    Gadson’s reliance on United States v. Green, 592 F.3d
1057 (9th Cir. 2010), is likewise misplaced. Green analyzed
the elements of vicarious liability for mail and wire fraud, and
determined as a matter of first impression that the fraudulent
acts committed by third parties in furtherance of the scheme
must be reasonably foreseeable to the defendant for liability
to attach. Id. at 1069–71. Based on this analysis, we struck
down a jury instruction that required the government to prove
only that “defendant or a co-schemer knew or could have
reasonably foreseen” that a fraudulent communication would
be emailed or faxed as part of the scheme. Id. Given that
Gadson was not charged with the specific crime at issue in
Green, it does not affect our plain error analysis.

                               B

    Gadson also challenges the sufficiency of the evidence
introduced at trial to support his conviction under Pinkerton
for possession of two firearms in furtherance of drug
trafficking pursuant to 18 U.S.C. § 924(c)(1).

    To establish Gadson’s liability under a Pinkerton theory,
the government had to prove that it could be “reasonably
foreseen as a necessary or natural consequence of the
unlawful agreement” that one of Gadson’s “coconspirators
would use a firearm” in furtherance of the drug trafficking
offenses. United States v. Carter, 560 F.3d 1107, 1113 (9th
Cir. 2009) (internal quotation marks omitted).           The
government need not prove that Gadson had “actual
knowledge that guns would be used,” only that he was
involved in the plan and such use would be reasonably
                UNITED STATES V. GADSON                    49

foreseeable “from the nature of the plan.” Id. (internal
quotation marks omitted).

    Gadson does not challenge the jury’s finding that one of
the co-conspirators used a gun in furtherance of drug
trafficking. Rather, he argues that the evidence was
insufficient to prove that he could have reasonably foreseen
that a co-conspirator at the Fouts house possessed the shotgun
and handgun in furtherance of the drug conspiracy.

    In reviewing the constitutional sufficiency of evidence to
support a criminal conviction, we must determine whether
“after viewing the evidence in the light most favorable to the
prosecution, any rational trier of fact could have found the
essential elements of the crime beyond a reasonable doubt.”
Jackson v. Virginia, 443 U.S. 307, 319 (1979). Although
Gadson moved for a judgment of acquittal under Rule 29 of
the Federal Rules of Criminal Procedure after the close of the
government’s case, he did not renew his motion after the
close of all the evidence. Accordingly, we review his
challenge for plain error, see United States v. Phillips, 704
F.3d 754, 762 (9th Cir. 2012), cert. denied, 133 S. Ct. 2796
(2013), although we are mindful that plain error review of a
sufficiency claim is only “theoretically more stringent than
the standard for a preserved claim,” United States v. Flyer,
633 F.3d 911, 917 (9th Cir. 2011) (internal quotation marks
omitted).

    Under this standard of review, the evidence was sufficient
to sustain Gadson’s conviction for possession of the two
firearms in furtherance of the charged drug crimes. The
evidence at trial showed that Gadson frequented the Fouts
house, was a core member of the conspiracy, and was a
primary supplier of cocaine sold out of the Fouts house. The
50                   UNITED STATES V. GADSON

jury heard expert testimony that drug dealers commonly keep
guns at locations with large quantities of drugs or money
because they are concerned about raids by police or
competitors, and the government introduced evidence
regarding the drugs, cash, and firearms found at the Fouts
house. There was also the more specific testimony at trial
that Gadson was present when Joshua Haynes showed
Voaklander an assault rifle hidden under the couch cushions
and explained that it was to be used in case “somebody comes
in through the front door.” Taking this evidence in the light
most favorable to the prosecution, Jackson, 443 U.S. at 319,
a rational jury could have concluded that it was reasonably
foreseeable to Gadson that one of his co-conspirators would
use a firearm in furtherance of the drug trafficking offenses.

                                     V

    Wilson challenges the sufficiency of the evidence at trial
as well. His claim is that the evidence introduced at trial was
insufficient to support a finding that he assaulted Pitka in
retaliation for providing information to a federal official in
violation of 18 U.S.C. § 1513(b)(2).14 Wilson did not move

 14
      The statute provides:

           (b) Whoever knowingly engages in any conduct and
           thereby causes bodily injury to another person or
           damages the tangible property of another person, or
           threatens to do so, with intent to retaliate against any
           person for—

           (2) any information relating to the commission or
           possible commission of a Federal offense or a violation
           of conditions of probation, supervised release, parole,
           or release pending judicial proceedings given by a
           person to a law enforcement officer;
                  UNITED STATES V. GADSON                          51

for acquittal at the close of trial, and so we review for plain
error.

    To prove a violation of § 1513(b)(2), the government
must show: “(1) knowing engagement in conduct (2) either
causing, or threatening to cause, bodily injury to another
person (3) with the intent to retaliate for, inter alia,”
providing information relating to a federal offense to a law
enforcement officer. United States v. Henderson, 626 F.3d
326, 342 (6th Cir. 2010) (internal quotation marks omitted).
Wilson argues that no rational trier of fact could conclude
that he acted with the requisite intent to retaliate against
Pitka.

     Wilson’s argument fails. Taking the evidence in the light
most favorable to the prosecution, the evidence showed that
Wilson knew that Pitka was a confidential informant who had
implicated Wilson and other coconspirators to the police.
Further, a jury could have concluded that Wilson intended to
harm Pitka because he was a “snitch.” The evidence shows
that Wilson assaulted Pitka in the hallway a few days after
telling Gabriella Haynes that “[s]nitches can’t go into the
hallways,” and later reported to Gabriella that he had hit
“Donny,” and made other statements suggesting he thought
it was Pitka’s involvement in the controlled buy that led to
the unraveling of the drug conspiracy. Wilson offered no
alternative explanation for the assault. Based on this
evidence, a reasonable juror could conclude that Wilson
intended to retaliate because Pitka provided information to


        or attempts to do so, shall be fined under this title or
        imprisoned not more than 20 years, or both.

18 U.S.C. § 1513(b)(2).
52               UNITED STATES V. GADSON

the government. Accordingly, there was sufficient evidence
to support Wilson’s conviction under 18 U.S.C. § 1513(b)(2).

    Because the evidence establishing that Wilson had the
specific intent to retaliate against Pitka was derived primarily
from his recorded telephone calls, Wilson also argues that the
jury could not rely on this evidence because the calls
constituted confessions that had not been adequately
corroborated. See United States v. Lopez-Alvarez, 970 F.2d
583, 589–90 (9th Cir. 1992). We disagree. Lopez-Alvarez
stated the longstanding rule that under most circumstances, a
confession made to the police “requires some independent
corroborating evidence in order to serve as the basis for a
conviction.” Id. at 589. We explained that the purpose of
this rule is to address the “high incidence of false confessions
and the resulting need to prevent errors in convictions based
upon untrue confessions alone.” Id. (internal quotation marks
omitted). A secondary rationale is to preserve a robust
criminal justice system premised on “extrinsic evidence
independently secured through skillful investigation,” rather
than one that relies heavily on confessions. Id. at 589 n.5.
Wilson’s statements to his cousin are not confessions to the
police, but private statements that were intercepted by the
police. Therefore, the corroboration requirement of Lopez-
Alvarez is not applicable. Moreover, the policy rationales
underlying Lopez-Alvarez are not present when police
investigation obtains statements or admissions made by the
defendant to a third person under the circumstances here.

                              VI

    We now address Gadson and Wilson’s claims that the
district court committed procedural errors at sentencing. In
determining whether the district court erred in its calculation
                 UNITED STATES V. GADSON                     53

of a defendant’s sentence, we review the district court’s
interpretation of the Guidelines de novo, its application of the
Guidelines to the facts for abuse of discretion, and its factual
findings, including drug quantity and roles in an offense, for
clear error. United States v. Staten, 466 F.3d 708, 713 (9th
Cir. 2006); see also United States v. Gonzalez, 528 F.3d
1207, 1214 (9th Cir. 2008) (drug quantity); United States v.
Rivera, 527 F.3d 891, 908 (9th Cir. 2008) (roles).

                               A

     The Sentencing Guidelines set forth a procedure for
determining the applicable sentencing range. The district
court must first determine the correct offense guideline
section applicable to the offense of conviction, and then
determine the correct base offense level. United States v.
Rivera-Gomez, 634 F.3d 507, 510–11 (9th Cir. 2011). Here
the guideline for Gadson’s convictions under 21 U.S.C.
§ 841(a)(1) for Counts 1 and 2 (conspiracy to distribute and
possession of a controlled substance with intent to distribute)
is § 2D1.1 of the Sentencing Guidelines. Section 2D1.1(a)(5)
directs the district court to add up the drugs for which the
defendant was responsible and then use the Guidelines’ Drug
Quantity Table to determine the defendant’s base offense
level. In determining the quantity of drugs for which a
defendant is responsible, the district court is to consider all
quantities of contraband with which the defendant was
directly involved, and “all reasonably foreseeable acts and
omissions of others in furtherance of the jointly undertaken
criminal activity.” U.S.S.G. § 1B1.3(a)(1)(B). After
calculating the base offense level, the district court must
determine the specific offense characteristics, id. § 2D1.1(b),
determine any adjustments related to victim, role, and
54               UNITED STATES V. GADSON

obstruction of justice, id. § 1B1.1(a)(3), and determine the
defendant’s criminal history category, id. § 1B1.1(a)(6).

    In making the required calculation of drug quantities,
the district court adopted the Presentence Investigation
Report’s (PSR) findings that Gadson was responsible for
10,521,103 grams of marijuana equivalency, resulting in a
base offense level of 36. See U.S.S.G. § 2D1.1(c)(2). The
district court also adopted a two-level adjustment for
“maintain[ing] a premises for the purpose of manufacturing
or distributing a controlled substance,” id. § 2D1.1(b)(12),
a three-level adjustment for being “a manager or
supervisor (but not an organizer or leader) and the criminal
activity involved five or more participants or was otherwise
extensive,” id. § 3B1.1(b), and a two-level adjustment
for obstruction of justice, id. § 3C1.1. Accordingly, the
district court assigned Gadson a total offense level of 43,
resulting in a Guideline sentencing range of life. U.S.S.G.
Ch. 5, pt. A. The district court ultimately sentenced Gadson
to 300 months of imprisonment and eight years of supervised
release.

    Gadson argues that the district court clearly erred in two
ways in its calculation of the Guidelines range. First, he
argues that the district court erred in calculating the quantity
of drugs attributable to him. Second, he argues that there was
insufficient evidence to support the three-level enhancement
for having a managerial or supervisory role.

                               1

    We start with Gadson’s claim that the district court’s
calculation of the drug quantity attributable to Gadson was
clearly erroneous. In cases involving “jointly undertaken
                UNITED STATES V. GADSON                    55

criminal activity,” the base offense level is determined on
the basis of “all reasonably foreseeable acts and omissions
of others in furtherance” of that activity. U.S.S.G.
§ 1B1.3(a)(1)(B). The government bears the burden of
proving the amount of drugs attributable to a defendant by a
preponderance of the evidence. United States v. Culps,
300 F.3d 1069, 1076 (9th Cir. 2002). A district court may
approximate the amount of drugs attributable to a defendant
where the amount of drugs seized by the officers “does not
reflect the scale of the offense.” U.S.S.G. § 2D1.1 cmt. 5. In
making an estimate, the court may consider, among other
factors, “the price generally obtained for the controlled
substance, financial or other records, [and] similar
transactions in controlled substances by the defendant.” Id.
Thus, a court may convert cash into drug quantities, provided
there is some evidence supporting a connection between the
money seized and the drug transactions. See United States v.
Otis, 127 F.3d 829, 836 (9th Cir. 1997) (citing United States
v. Gonzalez-Sanchez, 953 F.2d 1184 (9th Cir. 1992)).

    In this case, the PSR attributed to Gadson all the drugs
seized from the Fouts house (1,977.4 grams of powder
cocaine, 186 ecstasy pills, 31.5 grams of marijuana, 17.02
grams of crack cocaine, and 4.8 grams of heroin), all the
drugs seized from the Gillam Way house (.4 grams of powder
cocaine and 140.9 grams of marijuana), ten purchases of
nine-ounce units of crack by Voaklander (2,551 grams), and
another 4,623.7 grams of powder cocaine based on trial
testimony. Using the conversion tables found at § 2D1.1(c)
of the Sentencing Guidelines, the PSR converted the quantity
of each drug into an equivalent quantity of marijuana,
totalling 10,521,103 grams of marijuana. The PSR also
converted the cash and money orders seized at the Fouts
($51,455) and Gillam Way ($43,020) houses into an
56              UNITED STATES V. GADSON

equivalent amount of powder cocaine, using a ratio of
$40,000 per kilogram. The total amount of powder cocaine
calculated in this manner was 2.27 kilograms. The district
court expressly adopted the PSR’s factual findings.

    Gadson argues that the district court made three errors in
calculating the drug quantity. First, he contends that the
district court erred in failing to make an express factual
finding that Gadson could reasonably foresee that all the
drugs attributed to him (aside from the drugs seized from his
Gillam Way house) were in furtherance of the jointly
undertaken criminal activity. We disagree. While the
“district court must make an express factual finding regarding
the amount of drugs that the defendant reasonably foresaw as
being part of the conspiracy,” the district court “may satisfy
the requirement that it make factual findings by specifically
adopting the findings of the presentence report,” United
States v. Whitecotton, 142 F.3d 1194, 1198 (9th Cir. 1998), so
long as the PSR includes more than “conclusory statements
unsupported by the facts or the Guidelines,” United States v.
Gamez-Orduño, 235 F.3d 453, 464 (9th Cir. 2000) (internal
quotation marks omitted); see also United States v. Becerra,
992 F.2d 960, 966 (9th Cir. 1993). Gadson’s PSR contained
detailed factual recitations connecting him to the drugs at
issue and establishing that they were part of the conspiracy.
Accordingly, the district court did not err in adopting the PSR
findings as its own.

    Second, Gadson claims that the district court erred by
holding him accountable for 90 ounces (2,551.5 grams) of
crack cocaine that Voaklander testified he had purchased
from Joshua Haynes at the Fouts house over a nine-month
period. These sales accounted for the lion’s share of the
drugs attributable to Gadson. The district court did not
                 UNITED STATES V. GADSON                      57

clearly err in making this finding. First, Voaklander testified
that Gadson had been present and observed approximately
half of the transactions. Gadson claims that the district court
erred in relying on Voaklander’s allegedly uncorroborated
and untrustworthy testimony.           Nevertheless, because
Voaklander testified under oath, and was subject to full cross-
examination by Gadson’s counsel, the district court could
credit Voaklander’s testimony even though it was
uncorroborated and Voaklander would benefit from his
cooperation with the government. See United States v.
Alvarez, 358 F.3d 1194, 1213 (9th Cir. 2004). Moreover,
other evidence introduced at trial established that Gadson was
involved in the transactions at the Fouts house: he was
regularly present at the house, his fingerprints were found on
a box in the house containing nearly a kilo of cocaine, he
received large sums of cash on two occasions from Joshua
Haynes, who lived at the Fouts house and sold the drugs to
Voaklander, and he complained about how the arrest of
Transporter, who ferried drugs from Anchorage to Fairbanks,
could have “messed everything up.” In light of this
testimony, the district court did not clearly err in finding that
Voaklander’s purchases of crack from Joshua Haynes were
within the scope of the joint undertaking and reasonably
foreseeable to Gadson.

    Third, Gadson asserts that it was improper for the district
court to convert the cash found in the Fouts and Gillam Way
houses to marijuana and include the marijuana equivalency
amount in calculating his base offense level. According to
the PSR, the cash seized from the Fouts house was equivalent
to 1.2 kilograms powder cocaine, and the cash seized from
the Gillam Way houses was equivalent to 1.07 kilograms.
Gadson argues that the government failed to prove that all of
the seized currency (converted to 2.27 kilograms of powder
58              UNITED STATES V. GADSON

cocaine) was attributable to him. He also claims that the
currency could have been associated with the sale of drugs
that were already included in his base offense level, leading
to double counting.

     Gadson’s argument is unavailing because any error in
attributing the seized currency (converted to 2.27 kilograms
of powder cocaine) to Gadson would be harmless. First, it is
not clear that the 2.27 kilograms of powder cocaine were
included in the calculation of Gadson’s base offense level. In
calculating the marijuana equivalency of the drugs
attributable to Gadson, the PSR converted 6,601.5 grams of
powder cocaine to 1,320,300 grams of marijuana. The
6,601.5 grams is equivalent to the amount of actual drugs
seized from the Fouts (1,977.4 grams) and Gillam Way (.4
grams) houses, and the drugs described at trial (4,623.7
grams). Gadson does not explain how the 2.27 kilograms of
powder cocaine were included in the calculation of his base
offense level. But even if we assume that the PSR had
converted the 2.27 kilograms of powder cocaine into 472,380
grams of marijuana equivalence (2,361.9 grams of power
cocaine converted at a ratio of 1 : 200), and included that
amount in the total amount of drugs attributable to Gadson,
such inclusion would not affect his sentence. Removing the
472,380 grams would reduce the total quantity of drugs
attributable to Gadson from 10,521,103 grams to 10,048,723
grams of marijuana equivalence. This is still 48,723 grams
greater than the minimum quantity of drugs required to
support the base offense level of 36 found by the district
court. U.S.S.G. § 2D1.1(c)(2). Because the base offense
level would be the same with or without the amounts
attributable to the seized currency, any error was harmless.
United States v. Garcia-Guizar, 234 F.3d 483, 491 (9th Cir.
2000).
                UNITED STATES V. GADSON                     59

                              2

    We now turn to Gadson’s claim that the district court
erred in imposing a three-level sentencing enhancement for
playing a managerial role. See U.S.S.G. § 3B1.1(b). Under
§ 3B1.1(b), an enhancement is required where a defendant
was a “manager or supervisor (but not an organizer or leader)
and the criminal activity involved five or more participants.”
To prove that a defendant played such a role, the government
must demonstrate that the defendant oversaw “one or more
other participants,” meaning persons who are “‘criminally
responsible for the commission of the offense, but [who] need
not have been convicted.’” United States v. Smith, 719 F.3d
1120, 1125 (9th Cir. 2013) (quoting U.S.S.G. § 3B1.1 cmt.
2); see also United States v. Woods, 335 F.3d 993, 1001 (9th
Cir. 2003).

    In making this determination, a district court should
consider “the exercise of decision making authority, the
nature of participation in the commission of the offense, the
recruitment of accomplices, the claimed right to a larger share
of the fruits of the crime, the degree of participation in
planning or organizing the offense, the nature and scope of
the illegal activity, and the degree of control and authority
exercised over others.” Rivera, 527 F.3d at 908 (quoting
U.S.S.G. § 3B1.1 cmt. 4). In particular, “there must be
evidence that the defendant exercised some control over
others involved in commission of the offense [or was]
responsible for organizing others for the purpose of carrying
out the crime.” United States v. Riley, 335 F.3d 919, 929 (9th
Cir. 2003) (alteration in original, internal quotation marks
omitted). The district court need not make any specific
findings as to this issue so long as evidence in the record
supports an inference that the defendant exercised the
60               UNITED STATES V. GADSON

requisite degree of control. United States v. Whitney,
673 F.3d 965, 975 (9th Cir. 2012).

    The district court did not clearly err in finding that
Gadson played a managerial role in the drug conspiracy. The
record supports an inference that Gadson “oversaw” a
participant in the offense by the name of “Transporter.”
Transporter was not named in the indictment, but testimony
at trial established that he transported drugs on several
occasions from Anchorage, where Gadson maintained a
residence, to the Fouts house, that his visits to Fairbanks were
coordinated with Gadson’s, and that Gadson complained that
Transporter could have “messed everything up” if he were
arrested. The district court could conclude, based on this
testimony, that Transporter was a “participant” in the criminal
offense, and that Gadson directed him to deliver drugs to
Fairbanks from Anchorage. Cf. United States v. Egge,
223 F.3d 1128, 1132 (9th Cir. 2000) (finding § 3B1.1(b)
enhancement warranted where participant, among other
things, accompanied defendant on trips to pick up drugs);
United States v. Franco, 136 F.3d 622, 631 (9th Cir. 1998)
(finding § 3B1.1(b) enhancement warranted where defendant
asked participant to run an errand for him and to set up a drug
transaction). On those facts, imposition of the managerial
role enhancement was not an abuse of discretion.

                               B

    We next address Wilson’s sentencing claim. The district
court adopted the PSR’s findings and assigned Wilson a base
offense level of 28 based on the quantity of drugs attributable
to him. Wilson claims that the district court erred in denying
him a downward adjustment under U.S.S.G. § 3B1.2 because
                    UNITED STATES V. GADSON                            61

he was “substantially less culpable” than the other
participants. See id. cmt. 3.

     A two-level downward adjustment for minor role is
warranted when the defendant was “minor participant in any
criminal activity.” Id. § 3B1.2(b).15 The commentary
explains that a “minor participant” must be a defendant who
was “substantially less culpable than the average participant,”
id. § 3B1.2 cmt. 3(A), but “whose role could not be described
as minimal,” id. § 3B1.2 cmt. 5. The defendant bears the
burden of proving that he was a minor participant by a
preponderance of the evidence. United States v. Rosas,
615 F.3d 1058, 1067 (9th Cir. 2010).

    Here, the district court concluded that although Wilson
was clearly not an organizer or leader of the operation, he was
not a minor participant either, citing the fact that Wilson was
one of the group, was trusted enough by Gadson and Haynes
to be left alone at the house with the drugs and the guns, and
was “aligned” with the co-conspirators as demonstrated by
his assault on Pitka. The testimony and evidence discussed
extensively throughout this opinion support the district
court’s conclusion, which means the district court’s
determination that Wilson’s level of involvement was not
minor was not clear error. See United States v. Daychild,
357 F.3d 1082, 1102–03 (9th Cir. 2004) (no clear error where
defendant was directly involved in a central act of the
conspiracy, i.e., the exchange of drugs for money); see also
United States v. Del Toro-Barboza, 673 F.3d 1136, 1155 (9th


 15
    Wilson also maintains that he could be eligible for a 4-level “minimal”
participant adjustment. The analysis is similar for both categories,
although a minimal participant must make a greater showing of his lesser
complicity. U.S.S.G. § 3B1.2.
62              UNITED STATES V. GADSON

Cir. 2012) (no clear error where defendant failed to provide
any evidence explaining his lesser role in the conspiracy).

                             VII

    Finally, defendants claim that the cumulative impact of
the trial errors warrant reversal. Because we find no
error—and certainly not prejudicial error—reversal is
unwarranted.

     AFFIRMED.



BERZON, Circuit Judge, concurring and dissenting:

    I concur in the majority opinion except for Part III (B),
concerning Officer Avery Thompson’s testimony as to the
content of the defendants’ recorded telephone calls. As to
Part III (B), the majority’s holdings rest on United States v.
Freeman (Kevin Freeman), 498 F.3d 893 (9th Cir. 2007).
Kevin Freeman, in my view, goes much too far in allowing
lay officer testimony concerning recorded conversations.
Other circuits are considerably stricter than Kevin Freeman
in this regard. In my view, the other circuits are correct, and
Kevin Freeman is wrong. Kevin Freeman should be revisited
by an en banc court, perhaps in this case.

    Even accepting Kevin Freeman as binding precedent for
the present, I dissent. I would hold the trial court plainly
erred under Kevin Freeman in admitting some of Officer
Thompson’s testimony, and that the error was prejudicial.
                 UNITED STATES V. GADSON                     63

                               I.

    Defendants challenge Officer Thompson’s testimony
under Federal Rule of Evidence 701, which allows a lay
witness to offer an opinion only if it is (a) “rationally based
on the witness’s perception,” (b) “helpful to clearly
understanding the witness’s testimony or to determining a
fact in issue,” and (c) “not based on scientific, technical, or
other specialized knowledge within the scope of” expert
testimony. Fed. R. Evid. 701. This Court broadly permits an
officer to “interpret[] . . . ambiguous conversations based
upon his direct knowledge of the investigation.” Kevin
Freeman, 498 F.3d at 904. That aspect of Kevin Freeman is,
in my view, wrong, and it is, as the majority recognizes,
inconsistent with the case law in several other circuits. See,
e.g., United States v. Freeman (Marcus Freeman), 730 F.3d
590 (6th Cir. 2013); United States v. Hampton, 718 F.3d 978
(D.C. Cir. 2013); United States v. Johnson, 617 F.3d 286 (4th
Cir. 2010); United States v. Grinage, 390 F.3d 746 (2d Cir.
2004); United States v. Peoples, 250 F.3d 630 (8th Cir. 2001);
see also Maj. Op. at 30–31. The holding should be revisited
by an en banc court.

                              A.

    Kevin Freeman addressed whether a police officer may
testify as both an expert witness concerning coded drug terms
and as a lay witness concerning his general knowledge about
the case. The Court expressed concern “that a case agent who
testifies as an expert receives ‘unmerited credibility’ for lay
testimony,” Kevin Freeman, 498 F.3d at 903 (citation
omitted), but held that “the use of case agents as both expert
and lay witnesses is not so inherently suspect that it should be
categorically prohibited,” id. at 904. In so holding, Kevin
64              UNITED STATES V. GADSON

Freeman also discussed the scope of permissible lay opinion
testimony by an officer regarding the content of a defendant’s
recorded conversations. It is that portion of Kevin Freeman
which the majority reaffirms, and on which it relies
repeatedly in rejecting defendants’ challenges to Officer
Thompson’s testimony.

    In Kevin Freeman, the officer “offered interpretations of
ambiguous conversations that did not consist of coded terms
at all.” 498 F.3d at 902. For example,

       [i]n several conversations, [the officer]
       interpreted ambiguous phrases such as “that,”
       “they,” and “one of them,” to refer to either
       money or cocaine. In another conversation,
       [he] interpreted [a co-conspirator]’s statement,
       “Man, it’s done already” to mean “he’s given
       the cocaine to Kevin Freeman and that he’s
       received his money for it.”

Id. Similarly, “during one recorded telephone call, [a co-
conspirator] stated that he ‘touched bases with two of those.’
[The officer] testified, without offering an explanation, that
this meant that [the speaker] was able to obtain two kilograms
of cocaine. Id. at 900. “During another recorded telephone
call, Freeman informed [a co-conspirator] that he wished to
get off of the telephone while driving. . . . [The officer]
testified that Freeman’s desire to get off of the telephone was
motivated by a fear of being pulled over and arrested for the
possession of cocaine.” Id.

    The Court noted that “in these instances [the officer]
ceased to apply his specialized knowledge of drug jargon and
the drug trade and began to interpret ambiguous statements
                UNITED STATES V. GADSON                    65

based on his general knowledge of the investigation.” Id. at
902. Kevin Freeman nonetheless held that most of the
officer’s testimony met the requirements of Rule 701,
because his “understanding of ambiguous phrases was based
on . . . several hours of intercepted conversations . . . and
other facts he learned during the investigation,” and the
testimony “proved helpful to the jury in determining what
[the defendant and his co-conspirators] were communicating
during the recorded telephone calls.” Id. at 904–05. In the
Court’s view, the officer’s testimony “did nothing more than
offer one possible framework for understanding the
conversation.” Id. at 902. The Court did not express any
concern about whether the information that formed the basis
of the officer’s testimony came from evidence that had not
been presented to the jury.

                             B.

    Other circuits have severely restricted the ability of
officers to testify on the basis of information not before the
jury. In Marcus Freeman, the Sixth Circuit held that an FBI
agent’s testimony regarding the meaning of the defendant’s
recorded conversations was improper lay opinion testimony
under Rule 701. 730 F.3d at 596–99. The court noted that
“there is a risk when an agent ‘provides interpretations of
recorded conversations based on his knowledge of the entire
investigation . . . that he [is] testifying based upon
information not before the jury, including hearsay, or at the
least, that the jury [c]ould think he ha[s] knowledge beyond
what [is] before them.’” Id. at 596 (citing First, Second, and
D.C. Circuit opinions).

    The agent in Marcus Freeman “repeatedly substantiated
his responses and inferences with generic information and
66                  UNITED STATES V. GADSON

references to the investigation as a whole.” Id. But he “failed
to explain the basis of his interpretations—what experience
he had that the jurors themselves did not have—and therefore
failed to lay a foundation under Rule 701.” Id. at 597.
Although the agent testified that he had listened to
approximately 23,000 recorded calls, the jury only heard a
small number at trial. Id. at 597–99. The court was
concerned that the jury, “left in the dark regarding the source
of [the agent’s] information,” id. at 596, and with “no way of
verifying his inferences or of independently assessing the
logical steps he had taken,” id. at 597, “likely gave him the
benefit of the doubt in this situation,” id. at 596. Marcus
Freeman held such rootless testimony to be an impermissible
usurpation of the jury’s function. Id.1

    The D.C. Circuit reached a similar conclusion in
Hampton, holding that an FBI agent improperly testified
about his understanding of a defendant’s recorded
conversations, where the jury had no way to “verify[] his
inferences or . . . independently reach[] its own
interpretations.” 718 F.3d at 982–83. In that case, the
government acknowledged during its opening statement that
“the recorded telephone calls were ‘very, very cryptic,’” and
that the jury would need help from the agent “to interpret
them.” Id. at 981. The agent then testified that he had
“reviewed every conversation—some 20,000—captured by
the wiretaps, not just the 100 or so recordings admitted into
evidence,” and as a result he had a better understanding of
what was being said than did the jury. Id. The court noted


 1
   As these quotes show, and contrary to the majority’s account, see Maj.
Op. at 33–34, Marcus Freeman’s primary concern was that the jury was
not provided information as to the source of the officer’s knowledge of the
investigation, not that he did not have the requisite knowledge.
                 UNITED STATES V. GADSON                      67

that under Rule 701, the “[j]urors too must independently
assess the basis of the opinion and scrutinize the witness’s
reasoning. But ‘[w]hen a witness has not identified the
objective bases for his opinion, the proffered opinion . . . does
not help the jury but only tells it in conclusory fashion what
it should find.’” Id. (quoting United States v. Rea, 958 F.2d
1206, 1216 (2d Cir. 1992)).

     In Grinage, the Second Circuit was likewise troubled by
“the risk that [the case agent] was testifying based upon
information not before the jury.” 390 F.3d at 750. As in
Hampton and Marcus Freeman, the agent testified that he had
listened to many more recorded conversations than would be
played for the jury, and “some pertinent calls he listened to
‘upwards of 20 plus times.’” Id. at 748. He also repeatedly
“told the jury that his interpretations were ‘based on [his]
knowledge of the entire investigation.’” Id. at 748–49. In
doing so, the court concluded, he “interpreted both the calls
that the jury heard and the calls that the jury did not hear.”
Id. at 750. Moreover, “the agent was presented to the jury
with an aura of expertise and authority which increased the
risk that the jury would be swayed by his testimony, rather
than rely on its own interpretation of the calls.” Id. at 751.
Accordingly, “his interpretations of the calls went beyond
permissible lay opinion testimony under Rule 701(b) because,
rather than being helpful to the jury, it usurped the jury’s
function.” Id.

    These cases well identify the dangers of allowing a police
officer — who is not an ordinary lay person — to testify
based on masses of information not described in any detail to
the jury. When our circuit held in Kevin Freeman that an
agent’s “interpret[ation of] ambiguous statements based on
his general knowledge of the investigation” was permissible
68              UNITED STATES V. GADSON

lay opinion testimony, it did not address these risks at all.
498 F.3d at 902.

    The majority now reads Kevin Freeman as providing
blanket approval for Officer Thompson’s lay opinion
testimony, even though he failed to explain the basis for his
opinions and often invoked, without any detail as to the
source, his knowledge of evidence not presented at trial. That
understanding — which may well be an accurate reading of
Kevin Freeman — confirms that our case law has sanctioned
a major breakdown in the limits properly placed on lay
opinion testimony. The majority maintains otherwise,
rejecting the holdings in cases such as Hampton, Grinage,
and Marcus Freeman as inconsistent with Rule 701’s
acceptance of lay opinion testimony. Not so.

    For one thing, although the majority opinion professes
confidence in the jury’s ability to “identify unreliable [lay]
opinion testimony,” Maj. Op. at 31, enabling case agents to
opine on the basis of information not before the jury, without
sharing that information, the majority deprives the jury of the
information it would need to perform that critical function.
How can the jury be expected to evaluate the reliability of lay
opinion testimony when the “experience [the agent] ha[s] that
the jurors themselves d[o] not have” is not identified for the
jury? Marcus Freeman, 730 F.3d at 597. Of equal
importance: when a case agent is not required to provide the
factual basis for his testimony, the district court has no way
of assessing whether he is “rely[ing] upon [or] convey[ing]
inadmissible hearsay evidence” or other improper bases for
lay opinion testimony. Kevin Freeman, 498 F.3d at 904. The
majority’s holding thus undermines both the foundational
gatekeeping role played by judge and the factfinding role of
jury. Rule 701 does not contemplate such abdication.
                 UNITED STATES V. GADSON                     69

    Nor, contrary to the majority’s supposition, is what the
majority permits here, relying on Kevin Freeman, in any way
similar to a lay witness identifying a photograph based on
past contacts with the individual, contacts outside the jury’s
knowledge. See Maj. Op. at 31. There are four reasons at
least why this analogy does not work, and why the testimony
in this case went far beyond the intended confines of the lay
opinion rule, Rule 701.

    First, we actually have no idea, nor did the jury or judge,
whether Officer Thompson’s testimony was “rationally based
on [his] perception[s,]” Fed. R. Evid. 701(a), or instead on
what he heard from others — via reports, conversations, and
so on — during the course of the investigation.

    Second, Officer Thompson was not testifying to
something of which he had knowledge that the jury did not.
The jury itself heard the tapes, as well as information about
the events constituting the crimes. Officer Thompson was
instead telling the jury the meaning he ascribed to particular
facts and conversations, rather than leaving that
determination to the jury.

    Third, a police officer is not an ordinary lay witness. He
is associated directly with the prosecution, and is likely to be
regarded as enjoying special authority or expertise, even if
not testifying as an expert witness. His interpretation, when
premised, as here, on asserted vast knowledge beyond the
jury’s ken, is likely to be accorded more weight than that of
the usual percipient witness whose ability to provide coherent
testimony Rule 701 was meant to preserve.

    Finally, Officer Thompson’s statements regarding the
technologically improved means by which he listened to the
70                   UNITED STATES V. GADSON

tapes, see infra pp. 70–73, indicates that his testimony does
not meet the third requirement of Rule 701 — that it “not [be]
based on scientific, technical, or other specialized knowledge
within the scope of Rule 702.” Fed. R. Evid. 701(c); see also
United States v. Finley, 301 F.3d 1000, 1007 (9th Cir. 2002)
(identifying, as a requirement of Rule 702, that “the subject
matter at issue must be beyond the common knowledge of the
average layman”). Perception using specialized equipment is
not the sort of lay opinion at which Rule 701 is directed. A
professional photographer who was able to identify an
individual in a photograph only after amplifying the details
through the use of specialized equipment would not be giving
lay opinion testimony, even though he was in the end
reporting his own (amplified) perceptions.

                                     C.

    This case illustrates the pitfalls of a regime in which
officers are permitted to testify as lay witnesses on the basis
of information derived from the investigation as a whole, not
all of which is before the jury, using specialized equipment
and methodologies not available to the jury.2

   All parties acknowledge the recordings were of poor
quality. Officer Thompson began his testimony by “let[ting]


  2
    It is important to note that unlike in prior cases challenging an officer’s
interpretation of recorded conversations, the parties here have not
provided this Court with any recording or transcript of the telephone calls
at issue. The Court has only a transcript with the notation “(Audio
played)” followed by Officer Thompson’s testimony interpreting that
audio. The majority thus relies entirely on Officer Thompson’s own
testimony in holding that the recorded statements were “vague” and that
Officer Thompson’s opinions “would provide helpful context” for jury.
Maj. Op. at 35.
                 UNITED STATES V. GADSON                      71

the jury know” that “sometimes the jail phone calls are kind
of hard to . . . hear” and “sometimes it might be a little bit
hard to understand.” “[S]ometimes they’re just fuzzy,” and
“the volume’s not so good on them.” The prosecution asked
whether Officer Thompson could “direct us to what [he]
w[as] hearing” “[i]f it’s not a real clear – when we try to play
it over the system.” And throughout the trial, because the
statements were not always “clear on the recording” the
prosecution often asked Officer Thompson what particular
participants were “saying here?”

    Officer Thompson also repeatedly vouched for his
understanding of the recordings because he had “a better way
of listening to” them than the jury. Specifically, Officer
Thompson told the jury that prior to the trial he listened to the
recordings “a lot of the times, . . . pushing the headphones
into my ears, and slowing some of the phone calls down.” In
addition to having been able to “control . . . the phone calls”
by “play[ing] it back three seconds and listen[ing] to it
again,” Officer Thompson was also able to “sit down [in] a
super- — super-quiet room” when listening to the recordings.
As a result, Officer Thompson “was confident [he] was
hearing it correctly” and “in [his] notes,” which he referenced
repeatedly during trial, he “tried as best as possible to write
down accurate statements.” Officer Thompson thus affirmed
his ability to “translate” the calls if the jury was unable to
hear them clearly.

    In light of the poor quality of the recordings, Officer
Thompson’s expressed confidence in his own “translat[ion]”
imbued him “with an aura of expertise and authority which
increased the risk that the jury would be swayed by his
testimony.” Grinage, 390 F.3d at 751. Although the court
instructed the jury that the “[s]tatements made on the phone
72               UNITED STATES V. GADSON

calls are the evidence, not the discussion that counsel and
witnesses have had,” the instruction was an ineffective cure
when the jury was repeatedly reminded that it had a more
limited ability to hear and understand the phone calls than did
the witness. Cf. United States v. Robinson, 707 F.2d 872, 879
(6th Cir. 1983) (holding that it was error to admit tapes
portions of which were entirely inaudible because it caused
the jury to rely too heavily on unreliable transcriptions of the
recorded conversations).

    The risk that the jury would improperly defer to Officer
Thompson’s judgment was compounded by his repeated
testimony that he listened to hundreds of hours of recordings
to which the jury was not privy. He told the jury “just so
everyone knows, there’s about 150 hours or so of jail phone
call recordings.” Of those, he “probably listened to a total of
110, 120 of these . . . tapes” and “tr[ied] to maintain notes of
a lot of them.” The jury was then told that it would
“[c]ertainly not” have to “listen to all . . . 150 hours.” It
would only be hearing a “[l]imited number of calls.”
Throughout the trial, Officer Thompson was asked to provide
his interpretation of the calls on the basis of the
“investigation” as a whole, and he frequently invoked his
knowledge of “all of the conversations[.]”

    Thus, when the quality of a recording was poor, Officer
Thompson told the jury that he could rely on his extensive
knowledge of other recordings to ensure that he was
translating the call properly. For example, when the
prosecution noted that it “was having trouble hearing” a
particular recording, and asked Officer Thompson to “clarify
what we were hearing there[,]” Officer Thompson stated
“I’ve listened to literally probably in excess of 100 hours of
                 UNITED STATES V. GADSON                      73

conversation, so I’ve got a pretty good grasp on being able to
listen to this[,]” before telling the jury what was being said.

     Officer Thompson also directly testified about portions of
the recordings that were not, in fact, played for the jury. For
example, he testified that there is “a very short clip out of the
same phone call,” in which Defendant Willie L. Wilson
“says, ‘Yeah, they got my ring from the house.’” When the
prosecutor attempted to correct Officer Thompson,
suggesting that the clip may have said only “‘They got my
ring[,]’” Officer Thompson responded “I think the clip
actually was cut a little short.” He also testified regarding a
portion of a conversation in which Wilson states that he is
going to “exit[] the line for just a moment” to go and get his
“paperwork,” including a police report. But the prosecutor
decided “to move ahead to where Mr. Wilson is returning
with the paperwork, rather than necessarily listening to him
going and getting the paperwork.” Although the prosecutor’s
decision to skip ahead is understandable to avoid having to
listen to minutes of silence, the jury was asked to trust Officer
Thompson that prior to placing the call on hold, Wilson stated
that he was going to go get his legal paperwork.

    As in Marcus Freeman, Officer Thompson “drew
conclusions from the phone calls the jury heard as well as
from . . . other phone calls and . . . evidence the jury had no
access to. In doing so, he infringed upon the role of the jury
to decide what to infer from the evidence, and instead told
them what conclusions and inferences to draw.” 730 F.3d at
598. In light of Officer Thompson’s repeated invocation of
recordings not in evidence “the jury was left to trust that he
had some information—information unknown to them—that
made him better situated to interpret the words used in the
calls than they were.” Id. at 597.
74              UNITED STATES V. GADSON

    Notably, when questioned on cross-examination whether
a particular phrase frequently used by Wilson “could be
interpreted [in] any number of different ways,” Officer
Thompson stated “I think out of context, it certainly could be.
I think if you placed it in context with the prior statements
and the statements made after that,” not all of which the jury
had access to, “I think it certainly puts it into a better
perspective.” This testimony was similar to that found
troubling in Hampton, where an agent was asked if it was
possible for someone else — the jury, perhaps — to
understand a statement differently, and he responded “‘[i]f
they just had this portion of the conversation and didn’t know
other things about the investigation and other conversations,
maybe. But I think—anybody who has listened to all of the
calls and is aware of all of the conversations would agree
with me.’” 718 F.3d at 982. As in Hampton, Officer
Thompson’s suggestion that no other interpretation of the
telephone calls would be correct when placed in context —
context unavailable to the jury — created a serious “risk that
the jury w[ould] defer to the officer’s superior knowledge of
the case” and the recordings themselves. Id. at 981.

    The recordings’ poor quality, as well as the limited
selection played, left the jury without “the information it
need[ed] to conduct an independent assessment of lay opinion
testimony.” Id. Aside from vague references to “the
investigation” as a whole, Officer Thompson “failed to
explain the basis of his interpretations—what experience he
had that the jurors themselves did not have—and therefore
failed to lay a foundation under Rule 701.” Marcus Freeman,
730 F.3d at 597. In Grinage, all 2,000 recorded calls were
admitted into evidence, even though only thirteen were
played at trial. 390 F.3d at 747–48. When the officer in
Grinage gave his opinion based on having “listened to all of”
                    UNITED STATES V. GADSON                            75

the calls, id. at 748, the jury was at least able to listen to the
recordings that informed the officer’s testimony, if it so
desired. Here, by contrast, none of the calls — not even the
ones played during trial — were directly admitted into
evidence.3 Thus when Officer Thompson “interpreted those
conversations on the basis of his listening to ‘all of the calls,’
the jury had no way of verifying his inferences or of
independently assessing the logical steps he had taken.”
Marcus Freeman, 730 F.3d at 597 (quoting Hampton,
718 F.3d at 983). It is understandable that “the jury, left in
the dark regarding the source of [Officer Thompson]’s
information, [would] likely g[i]ve him the benefit of the
doubt in this situation.” Id. at 596. But to allow the jury to
so do is to sanction an abdication of the jury’s duty.




   3
     It appears that the government failed to preserve excerpts of the
recordings containing only those telephone calls, or portions thereof, that
were actually played at trial. When the jury asked during deliberations to
“review the recordings of all jail phone calls,” the court played only the
audio recording of the trial proceedings in which the telephone calls were
played — essentially, a recording of a recording. The next morning, the
jury asked if it could hear “the original telephone recordings, not the
recordings of the playback?” — presumably because the trial recordings
were even harder to hear than the original tapes. But because the
government had failed to preserve the excerpts, and defense counsel
expressed concern that if allowed access to the full recordings, the jury
might inadvertently hear portions that were never played at the trial, the
court agreed to tell the jury that “the originals were not submitted into
evidence, can’t be provided at this time.”

     Although I agree with defendants’ appellate argument that it would
have been prudent for the district court to require the government to
isolate the portions of the telephone calls played at trial and admit them
into evidence, defendants forfeited any argument in this regard by
consenting to the district court’s chosen solution.
76                  UNITED STATES V. GADSON

    Kevin Freeman allows the jury’s critical factfinding role
to be usurped by law enforcement testimony based on
evidence not presented at trial. As other circuits have held,
this procedure has no basis in the Federal Rules of Evidence,
undermines trial by jury, and cannot be allowed.4

                                    II.

   Even under Kevin Freeman, the admission of some of
Officer Thompson’s testimony was in error.

    The bulk of Officer Thompson’s testimony appears to
have involved interpretation of “not only code words but also
common words used in common ways.” Marcus Freeman,
730 F.3d at 598. Kevin Freeman held that an officer’s
interpretation of statements “that were not encoded drug
jargon, but instead were phrases that were more likely to be
understood by the jurors without assistance” violates Rule
701. 498 F.3d at 900.

    For example, Kevin Freeman held “not helpful to the
jury,” id. at 905, the officer’s interpretation of one


 4
   The majority opinion references six other circuits, which it says “allow
officers to provide interpretations of recorded conversations based on their
knowledge of the investigation, subject to various safeguards.” See Maj.
Op. at 27 n.5. A careful review of the cases cited makes clear that they do
not condone what happened here. See, e.g., United States v. Albertelli,
687 F.3d 439, 444–48 (1st Cir.2012) (approving officer’s testimony where
it did not “rely on broad appeals to ‘the totality of the investigation’ but
instead usually pointed to sources of information”); United States v.
Jayyousi, 657 F.3d 1085, 1102–03 (11th Cir. 2011) (approving police
officer’s testimony regarding the meaning of code words used in recorded
telephone calls); United States v. Rollins, 544 F.3d 820, 830–33 (7th Cir.
2008) (same).
                UNITED STATES V. GADSON                     77

defendant’s “instruct[ion] [to another] to speak with him later
so that they ‘can get all the particulars,’” as being “a
reference to the ‘details,’” id. at 900. Similarly, when one
defendant asked another “how everything had turned out,” we
held unhelpful the officer’s testimony that the defendant “was
asking . . . how did the ‘drug deal turn out, how did
everything go?’” Id. This testimony was particularly
troubling because it involved the case agent’s speculation as
to whether the defendant was involved in a drug conspiracy,
the precise issue the jury was required to decide. We noted
in Kevin Freeman that the case agent’s “specialized
knowledge of the particular language of drug traffickers did
not give him carte blanche to testify as to the meaning of
other words in recorded telephone calls without regard to
reliability or relevance.” Id. at 904.

    In this case, Officer Thompson translated phrases that
were similarly “likely to be understood by the jurors without
assistance.” Id. at 900. For example, much of Officer
Thompson’s testimony appears to have involved simply
repeating the words said on the recorded telephone calls, in
case the jury “couldn’t hear it.” Other testimony consisted of
Officer Thompson’s speculation as to the meaning of
statements made up of clear terms. For example, during one
of the calls, Wilson said something to the effect of “whoever,
the CI [(confidential informant)] is, it’s close.” When asked
what Wilson meant by that, Officer Thompson stated he
meant “close to them” physically, as opposed to “close to
reality or close to actuality.” This testimony amounts to pure
speculation on the part of Officer Thompson as to what
Wilson meant when he said the CI was “close.” Although
Officer Thompson’s interpretation was a reasonable one, it
was unhelpful to the jury, which had the same ability — and
the responsibility — to interpret such ordinary language.
78               UNITED STATES V. GADSON

    Similarly, in a recorded call the day after the altercation
with Donny Pitka, Wilson is described as having said, “‘You
know, he’s the one that started this shit.’ . . . ‘That time with
Batman, that was him.’” Officer Thompson then explained
to the jury that “Batman” is a nickname for alleged co-
conspirator, Brandon Haynes. This testimony, which was
derived directly from his knowledge of the investigation and
was not within the jury’s own powers of reason, would be
permissible under Kevin Freeman. 498 F.3d at 901–02
(approving testimony regarding coded drug jargon). Officer
Thompson went on, however, to explain, “[i]t appears that
[Wilson]’s referring back to the November incident, where
Mr. Pitka was in fact . . . the one who was setting up the
purchase from Mr. Brandon Haynes.” This statement usurped
the jury’s function, even under Kevin Freeman’s limited
acknowledgment of that function. Once informed that
Batman was, in fact, Brandon Haynes, the jury was more than
capable of interpreting Wilson’s statement without the
assistance of Officer Thompson.

     As Officer Thompson’s testimony consisted largely of
“either speculation or repetition of already clear statements,”
its admission violated Rule 701 as interpreted by this court.
Kevin Freeman, 498 F.3d at 905.

                               III.

    Although the district court’s error was plain, relief is not
warranted unless the error “affected substantial rights” and
“seriously affected the fairness, integrity, or public reputation
of the judicial proceedings.” United States v. Vences,
169 F.3d 611, 613 (9th Cir. 1999) (internal quotation marks
and citation omitted). The requirement that an error “‘affect[]
substantial rights’ . . . in most cases . . . means that the error
                 UNITED STATES V. GADSON                     79

must have been prejudicial: It must have affected the outcome
of the district court proceedings.” United States v. Olano,
507 U.S. 725, 734 (1993). On plain error review, the
defendant “bears the burden of persuasion with respect to
prejudice.” Id.

    Wilson has met that burden only with respect to his
conviction on Count 7 for retaliation against a witness in
violation of 18 U.S.C. § 1513(b)(2). I therefore dissent only
with respect to Count 7.

    Section 1513(b)(2) punishes “[w]hoever knowingly
engages in any conduct and thereby causes bodily injury to
another person . . . with intent to retaliate against any person
for . . . information relating to the commission . . . of a
Federal offense . . . given by a person to a law enforcement
officer. . . .” To convert a simple assault into a § 1513(b)(2)
violation, therefore, the offense must have been committed
with the specific intent to retaliate against a witness for
providing information to law enforcement. See United States
v. Maggitt, 784 F.2d 590, 593–94 (5th Cir. 1986).

    Officer Thompson’s “translat[ion]” of and testimony
regarding the recorded phone calls contained the only direct
evidence of Wilson’s intent to retaliate against Pitka for
providing information to law enforcement.              Officer
Thompson testified regarding a call between Wilson and his
cousin, Gabriella Haynes, the day after the incident with
Pitka. Officer Thompson testified that Wilson admitted to
having hit “‘Donny’” because “‘he’s the one that started this
shit.’” Officer Thompson testified about another call in
which “Wilson [is] talking about how they put Mr. Pitka’s
name . . . in the paper[,]” meaning “the documents that went
to the jail.” Officer Thompson also told the jury that Wilson
80               UNITED STATES V. GADSON

stated in a call the morning of the assault that “[s]nitches
can’t go into the hallways.” Added to Officer’s Thompson’s
testimony about the informant being “close” and the reference
to the “November incident,” his speculation and professed
“translat[ion]” of these “already clear statements[,]” Kevin
Freeman, 498 F.3d at 905, provided a direct link between the
assault and Wilson’s intent to retaliate against Pitka for being
a “[s]nitch[.]”

    Aside from Officer Thompson’s testimony, the evidence
of Wilson’s intent was minimal. Wilson was not present in
the gym when Defendant Anthony Gadson and alleged co-
conspirator Donte Edwards confronted Pitka about being a
“snitch.” Edwards, who testified for the prosecution, never
said that he shared with Wilson his suspicions that Pitka had
been a confidential informant. Pitka himself testified that
Wilson said nothing to him before, during, or after the alleged
assault, and that Pitka did not know why he was attacked.
Although Pitka testified that he later believed it was because
the government “sen[t] paperwork in on me,” he provided no
basis for his speculative conclusion. Without Officer
Thompson’s prejudicial testimony, there is a “reasonable
probability that the jury would not have convicted” Wilson on
Count 7. United States v. Teague, 722 F.3d 1187, 1192–93
(9th Cir. 2013).

    Finally, there is no question that Officer Thompson’s
testimony “seriously affected the fairness, integrity, or public
reputation of the judicial proceedings.” Vences, 169 F.3d at
613 (internal quotation marks omitted). In “offer[ing] a
narrative gloss . . . consist[ing] almost entirely of [his]
personal opinions of what the conversations meant[,]”
Peoples, 250 F.3d at 640, Officer Thompson’s unhelpful
testimony “usurped the function of the jury to decide what to
                UNITED STATES V. GADSON                     81

infer from the content of the calls,” Grinage, 390 F.3d at 750.
Nothing could be more central to the integrity of judicial
proceedings than the right to have the jury — not the police
or the prosecution — decide a defendant’s guilt or innocence.
For these reasons, I dissent from Part III (B) of the majority
opinion.
