                FOR PUBLICATION

  UNITED STATES COURT OF APPEALS
       FOR THE NINTH CIRCUIT

UNITED STATES OF AMERICA,                No. 12-50294
                Plaintiff-Appellee,
                                            D.C. No.
                 v.                      8:08-cr-00280-
                                             JVS-1
SALVADOR REYES VERA, AKA
Magic, AKA Albert Vera Reyes,
AKA Sas, AKA Salvador Vera,
             Defendant-Appellant.



UNITED STATES OF AMERICA,                No. 12-50366
                Plaintiff-Appellee,
                                            D.C. No.
                 v.                      8:08-cr-00280-
                                             JVS-2
ARMANDO REYES VERA, AKA
Mando, AKA Armando Vera,
            Defendant-Appellant.           OPINION


      Appeal from the United States District Court
         for the Central District of California
       James V. Selna, District Judge, Presiding

               Argued and Submitted
         May 12, 2014—Pasadena, California

                Filed October 22, 2014
2                    UNITED STATES V. VERA

    Before: John T. Noonan, Jr., Kim McLane Wardlaw
         and Raymond C. Fisher, Circuit Judges.

                     Opinion by Judge Fisher


                           SUMMARY*


                          Criminal Law

    The panel affirmed in part and vacated in part the district
court’s judgments, and remanded for further proceedings in
a case in which Salvador Reyes Vera and Armando Reyes
Vera were convicted of a drug conspiracy and use of a minor
to commit a drug trafficking offense.

    Two case agents testified at the defendants’ joint trial, one
as a gang expert and the other as an expert in drug jargon who
translated wiretapped phone calls into drug quantities and
amounts. The panel affirmed the admission of the gang
testimony. But because the testimony interpreting the
recorded calls intermingled lay and expert opinion, the panel
held that the district court’s failure to explain the distinction
to the jury constituted plain error. The panel held that this
intermingling resulted in the admission of improper expert
and lay opinions, which also constituted plain error. Because
these errors affected the drug quantities found by the jury in
a special verdict, and therefore the mandatory minimum
sentences the defendants faced, the panel held that they
affected the defendants’ substantial rights and seriously

  *
    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. VERA                       3

affected the fairness of the judicial proceedings. The panel
therefore vacated the drug quantity findings and the
defendants’ sentences. The panel affirmed the remainder of
the jury verdict.

     The panel also addressed the appropriate remedy when
trial errors affect the jury’s drug quantity findings but not the
underlying conspiracy convictions. Because drug quantity is
not an element of the conspiracy offense, the panel did not
vacate the defendants’ conspiracy convictions. The panel
further held that, under these circumstances, the Double
Jeopardy Clause does not preclude retrial of the drug quantity
issue. The panel therefore vacated the special verdict only,
and remanded for proceedings. The panel wrote that on
remand the government may elect to retry the drug quantity
issue or may seek a resentencing based solely on the
defendants’ convictions.


                         COUNSEL

Gretchen Fusilier, Carlsbad, California, for Defendant-
Appellant Salvador Reyes Vera.

Thomas Paul Sleisenger, Los Angeles, California, for
Defendant-Appellant Armando Reyes Vera.

André Birotte Jr., United States Attorney, Robert E. Dugdale,
Chief, Criminal Division, Dennise D. Willett, Chief, Santa
Ana Branch Office, Michael Anthony Brown (argued),
Assistant United States Attorney, United States Attorney’s
Office, Santa Ana, California, for Plaintiff-Appellee United
States of America.
4                    UNITED STATES V. VERA

                              OPINION

FISHER, Circuit Judge:

    This appeal requires us to revisit issues that arise when
law enforcement officers offer both expert and lay opinion
testimony interpreting the meaning of intercepted telephone
calls. We again emphasize that such expert opinions must
rest on reliable methodology; that such lay opinions may not
be supported by speculation or hearsay, or interpret
unambiguous, clear statements; and that the jury must be
instructed on how to appropriately evaluate each form of
testimony offered by the officer.

    Defendants Salvador Reyes Vera and Armando Reyes
Vera appeal their convictions and sentences for drug
conspiracy and use of a minor to commit a drug trafficking
offense.1 Two case agents testified at the defendants’ joint
trial, one as a gang expert and the other as an expert in drug
jargon who translated wiretapped phone calls into drug
quantities and amounts. We affirm the admission of the gang
testimony but reach a different conclusion regarding the
testimony interpreting the recorded calls. Because that
testimony intermingled lay and expert opinion, the district
court’s failure to explain the distinction to the jury constituted
plain error. Additionally, this intermingling resulted in the
admission of improper expert and lay opinions, which also
constituted plain error. Because these errors affected the drug
quantities found by the jury in a special verdict, and therefore
the mandatory minimum sentences the defendants faced, they
affected the defendants’ substantial rights and seriously


    1
   Following the practice adopted in the parties’ briefing, we refer to the
defendants by their first names, Salvador and Armando.
                     UNITED STATES V. VERA                            5

affected the fairness of the judicial proceedings.
Accordingly, we vacate the drug quantity findings and the
defendants’ sentences. We affirm the remainder of the jury
verdict.

    We also address the appropriate remedy when trial errors
affect the jury’s drug quantity findings but not the underlying
conspiracy convictions. Because drug quantity is not an
element of the conspiracy offense, we need not vacate the
defendants’ conspiracy convictions. We further hold that,
under these circumstances, the Double Jeopardy Clause does
not preclude retrial of the drug quantity issue. We therefore
vacate the special verdict only, and remand for proceedings
consistent with this opinion. On remand, the government
may elect to retry the drug quantity issue or may seek a
resentencing based solely on the defendants’ convictions.2

                          I. Background

    In 2007, acting on a tip from confidential informant
Gerardo Reyes, the Santa Ana Gang Task Force began
investigating drug trafficking in Bishop Manor, a high-
density apartment complex within the territory of the Minnie
Street Lopers gang. Reyes’ tip and the resulting investigation
brought the defendants to the task force’s attention. Based on
the tip, some initial surveillance and a few initial controlled
purchases, the agents believed that Salvador and Armando
were involved in the illegal distribution of several controlled
substances. To further the investigation, in May 2008, the
task force began wiretapping cell phones used by the


 2
   For the reasons given in a concurrently filed memorandum disposition,
we reject the defendants’ sufficiency of the evidence and sentencing
arguments.
6                   UNITED STATES V. VERA

defendants and their minor nephew, Ramon Vera, also known
as “Ojitos” or “Little Bear.” All told, the investigation
intercepted thousands of calls and, through contemporaneous
surveillance, corroborated certain aspects of the calls – for
example, who the speakers were and where they were
meeting. Reyes also completed a controlled purchase from
Armando of around 24 grams of heroin, the only physical
evidence of narcotics seized during the investigation.

    The Vera brothers were arrested in October 2008 and
indicted a few months later, as were several co-defendants.
In January 2012, a federal grand jury returned a three-count
superseding indictment against the defendants. Count 1
charged Salvador and Armando with conspiracy to distribute
and to possess with intent to distribute heroin, cocaine,
cocaine base and methamphetamine.3 Counts 2 and 3
charged Salvador (Count 2) and Armando (Count 3) with
using a minor to commit a drug trafficking offense. See
21 U.S.C. §§ 841(a)(2), 846, 861(a)(1).

    The wiretapped phone calls were the government’s
primary evidence during the five-day trial; over 70 recorded
calls were either played for or read to the jury. Additionally,
the two case agents primarily responsible for the investigation
were called to testify. FBI Agent Daniel Lavis, the
government’s key witness, testified about the investigation,
the surveillance that was conducted, narcotics prices, how law
enforcement agents use confidential informants, Bishop
Manor and the surrounding area, how wiretaps are obtained
and how they work, phone technology, the phones that were
wiretapped in this case, the identity of participants in the


    3
    At trial, the methamphetamine allegations were withdrawn from the
jury’s consideration.
                     UNITED STATES V. VERA                               7

wiretapped calls and their relationships, and code words used
by the participants in the wiretapped calls. Lavis also opined
about the meanings of most of the recorded calls as they were
played or read, identifying voices and nicknames, and
interpreting the conversations as referring to specific
quantities of particular controlled substances. The other case
agent, Detective John Franks, testified about gang structure
and practices generally, the Minnie Street Lopers specifically,
and the inferences he drew about Salvador’s role within the
Lopers organization. Franks also testified about the
investigation and his observations while conducting
surveillance.

    Reyes, the confidential informant, testified as well. He
gave details regarding the controlled purchase of heroin he
made from Armando and explained the structure of the
defendants’ drug dealing organization, from which he had
purchased drugs for many years and for which he had, at
times, acted as a lookout. He further explained that Salvador
was the highest ranking member of the Minnie Street Lopers
gang in the area. Reyes testified that Salvador maintained
control of narcotics trafficking in that area by giving only
certain dealers permission to sell narcotics. Anyone else
caught dealing would be “beat up.” Reyes testified that
Armando was Salvador’s “number two man” and handled
most sales, and that Salvador used his nephew and other
minors as drug runners.4



   4
      The remaining government witnesses gave very little substantive
testimony. These witnesses included three language specialists who had
translated the recorded calls from Spanish; a forensic chemist who
testified about the substance Reyes purchased from Armando; two police
officers who conducted surveillance and traffic stops; and a police officer
who cited Ramon for being out after curfew, confirming he was a minor.
8                    UNITED STATES V. VERA

    The defense did not call any witnesses or introduce any
evidence except a stipulation that a particular intercepted
phone call did not concern cocaine base, as Lavis had
testified, but actually concerned powder cocaine. The
defendants essentially conceded guilt on the conspiracy
count, focusing their closing arguments on the adequacy of
the government’s proof of drug type and quantity, and
characterizing the jury’s role as answering “an accounting
question.”

    The jury found the defendants guilty on all counts and
issued a special verdict holding both defendants responsible
for 100 grams or more of heroin, 500 grams or more of
cocaine and 280 grams or more of cocaine base. Both
defendants were sentenced to the low end of their respective
guidelines ranges: 360 months’ imprisonment for Salvador
and 210 months’ imprisonment for Armando.

                     II. Franks’ Testimony

    The defendants contend that Detective Franks’ testimony
as both a gang expert and a percipient witness to the events in
his investigation violated their Confrontation Clause rights
and Federal Rule of Evidence 403.5 We review the district

    5
      We reject the defendants’ argument that admitting this evidence
violated the Due Process Clause. The admission of evidence violates due
process only when “there are no permissible inferences the jury may draw
from the evidence” and that evidence is “of such quality as necessarily
prevents a fair trial.” Jammal v. Van de Kamp, 926 F.2d 918, 920 (9th
Cir. 1991) (quoting Kealohapauole v. Shimoda, 800 F.2d 1463, 1465 (9th
Cir. 1986)) (internal quotation marks omitted). The gang testimony was
probative of Salvador’s control over drug transactions in Bishop Manor
in which he did not directly take part. Because Armando was Salvador’s
“number two man,” establishing that Salvador controlled the drug
trafficking organization allowed the jury to infer that Armando managed
                     UNITED STATES V. VERA                              9

court’s rulings on the Confrontation Clause de novo and on
Rule 403 for abuse of discretion. See United States v. Gomez,
725 F.3d 1121, 1125 (9th Cir. 2013); United States v. Hankey,
203 F.3d 1160, 1166–67 (9th Cir. 2000). We hold that
admitting Franks’ gang testimony did not constitute
reversible error.

    A. Confrontation Clause

     The Supreme Court held in Crawford v. Washington,
541 U.S. 36 (2004), that a defendant’s Confrontation Clause
rights are violated by the admission of “testimonial
statements of a witness who did not appear at trial unless he
was unavailable to testify, and the defendant had . . . a prior
opportunity for cross-examination.”           Id. at 53–54.
Nevertheless, an expert witness may offer opinions based on
such inadmissible testimonial hearsay, as well as any other
form of inadmissible evidence, if “experts in the particular
field would reasonably rely on those kinds of facts or data in
forming an opinion on the subject.” Fed. R. Evid. 703.
Moreover, the expert may disclose to the jury the
inadmissible evidence relied on in forming his opinion “if
[its] probative value in helping the jury evaluate the opinion
substantially outweighs [its] prejudicial effect.” Id.

   Under these rules, there is generally no Crawford problem
when an expert “appli[es] his training and experience to the
sources before him and reach[es] an independent judgment.”
Gomez, 725 F.3d at 1129 (quoting United States v. Johnson,


the daily activities of a larger operation, thus widening the scope of the
conspiracy. Additionally, Franks’ testimony on this point dovetailed with
Reyes’ testimony, thereby somewhat “rehabilitat[ing] (without vouching
for)” Reyes’ credibility, which had been thoroughly impeached. United
States v. Bighead, 128 F.3d 1329, 1331 (9th Cir. 1997).
10                UNITED STATES V. VERA

587 F.3d 625, 635 (4th Cir. 2009)). But an expert exceeds the
bounds of permissible expert testimony and violates a
defendant’s Confrontation Clause rights when he “is used as
little more than a conduit or transmitter for testimonial
hearsay, rather than as a true expert whose considered opinion
sheds light on some specialized factual situation.” Id.
(quoting Johnson, 587 F.3d at 635). Accordingly, the key
question for determining whether an expert has complied with
Crawford is the same as for evaluating expert opinion
generally: whether the expert has developed his opinion by
“applying his extensive experience and a reliable
methodology.” United States v. Dukagjini, 326 F.3d 45, 54
(2d Cir. 2003).

    The Second Circuit’s opinion in United States v. Mejia,
545 F.3d 179 (2d Cir. 2008), illustrates how case agent expert
testimony can violate a defendant’s Confrontation Clause
rights. The defendants in Mejia were members of the MS-13
gang who were being tried for racketeering and related
charges. See id. at 183. An agent qualified as a gang expert,
see id. at 193–94, identified custodial interrogations of MS-13
members as at least a partial basis for his testimony “that MS-
13 taxed non-member drug dealers,” “that MS-13 treasury
funds were used to purchase narcotics and that MS-13
members used interstate telephone calls to coordinate
activities.” Id. at 199. This testimony was directly relevant
to several material issues in the case, including whether MS-
13 was an enterprise, had an effect on interstate or foreign
commerce or engaged in narcotics trafficking. See id. at 200.

    The agent’s testimony violated the Confrontation Clause,
however, because he presented testimonial hearsay “in the
guise of an expert opinion,” id. at 199 (quoting United States
v. Lombardozzi, 491 F.3d 61, 72 (2d Cir. 2007)), rather than
presenting the information to explain a bona fide expert
                  UNITED STATES V. VERA                      11

opinion. The Mejia court was “at a loss in understanding how
[the agent] might have ‘applied his expertise’ to these
statements before conveying them to the jury.” Id. Most
problematically, the agent’s drug tax testimony “was based
directly on statements made by an MS-13 member in custody
(during the course of this very investigation).” Id. (emphasis
omitted). To form his drug tax opinion, therefore, the agent
did not have to conduct a “synthesis of various source
materials” or apply any of “his extensive experience [or] a
reliable methodology.” Id. at 197 (quoting Dukagjini,
326 F.3d at 58) (internal quotation marks omitted). Instead,
the agent “communicated out-of-court testimonial statements
of cooperating witnesses and confidential informants directly
to the jury in the guise of an expert opinion.” Id. at 198
(quoting Lombardozzi, 491 F.3d at 72). The agent’s direct
repetition of testimonial hearsay about the drug tax
“impugn[ed] the legitimacy of all of his testimony,” leading
the court to suspect he had merely summarized an
investigation conducted by others, rather than applying his
expertise to draw his own conclusions. Id. at 199. The court
therefore held that the agent’s “reliance on and repetition of
out-of-court testimonial statements made by individuals
during the course of custodial interrogations violated [the
defendants’] rights under the Confrontation Clause of the
Sixth Amendment.” Id.

    Here, Detective Franks testified both as a gang expert
witness and as a percipient witness regarding his observations
during the investigation. Specifically, he testified that Bishop
Manor fell within the territory of the Minnie Street Lopers
gang and that the gang maintained control over narcotics
sales within Bishop Manor and the surrounding areas by
requiring any non-member drug dealers in the area to pay a
tax. Because he knew from reviewing intercepted telephone
calls that Salvador did not pay taxes to anyone else in the
12                UNITED STATES V. VERA

neighborhood, Franks concluded that Salvador was “one of
the leaders of the narcotics trade in Bishop Manor.” He also
testified about a recorded phone call between Salvador and a
friend that was played for the jury, opining that a rival gang
was trying to tax Salvador because they believed his friend
was selling drugs within their territory. Because the leader of
one neighborhood gang is generally the person who pays
taxes to the higher-ranking gang in another area, Franks
opined that Salvador was “[m]ore than likely the leader” of
the Minnie Street Lopers in Bishop Manor.

    The defendants contend that Franks exceeded the bounds
of permissible expert testimony by “serving as a conduit for
admission of hearsay in violation of Crawford.” They argue
that by testifying that the Minnie Street Lopers controlled
narcotics trafficking within Bishop Manor and “were able to
force non-members dealing drugs there to pay a tax,” Franks
directly “imparted important testimonial facts gleaned from
his exposure to gang members and affiliates” without
applying any independent judgment. Id. We disagree and
hold that Franks’ testimony fell within the bounds of
permissible expert opinion.

    First, Detective Franks applied his experience to his
observations to form expert opinions about the Minnie Street
Lopers and their tactics. Franks testified he had extensive
training about and experience with gangs, including some
formal classroom training, his time on the Santa Ana Gang
Task Force and his work at the Santa Ana Police Department
as a gang homicide investigator and gang suppression
detective. He was familiar with the Minnie Street Lopers
gang in particular from his contacts with members when he
worked as a deputy sheriff in the jail, when he patrolled the
area and when he transferred to the gang unit of the Santa
Ana Police Department. Unlike the gang expert in Mejia,
                  UNITED STATES V. VERA                      13

nothing in Franks’ testimony suggests that he was directly
repeating what someone else told him about the Minnie Street
Lopers during this or any other investigation. Rather, his
testimony that gangs “control the narcotics trafficking in an
area” by maintaining control “of selling drugs to buyers” and
“of the money,” and by requiring “other drug dealers in that
area that are not part of that gang” to “pay what’s called a tax
to that gang,” distilled and synthesized what he had learned
through his experience. See Mejia, 545 F.3d at 197 (implying
that the “synthesis of various source materials” constitutes
permissible expert testimony).

    More importantly, Franks did not impart this information
for its own sake, but to explain the basis for his expert
opinion that Salvador was “one of the leaders of the narcotics
trade in Bishop Manor.” He testified that he formed this
opinion by reviewing the wiretapped telephone calls, learning
that Salvador did not pay taxes to anybody in the
neighborhood and applying his knowledge and experience of
gang practices to deduce the significance of that information.
He further applied this expertise to explain the meaning of a
recorded phone call between Salvador and a friend, Walter,
that was played for the jury. According to Franks, Walter
told Salvador in the call that members of a rival gang
believed Walter was “slinging for Salvador” within their
territory and were looking for Salvador to verify that he had
paid the required tax. Based on his knowledge that the leader
of a neighborhood gang is generally responsible for paying
taxes to a higher-ranking gang, Franks testified that the phone
call further supported his opinion that Salvador was in charge
of narcotics trafficking in Bishop Manor.

    Franks’ expert opinion therefore was not merely
repackaged testimonial hearsay but was “an original product”
that could have been “tested through cross-examination,”
14                 UNITED STATES V. VERA

Gomez, 725 F.3d at 1129 (quoting Johnson, 587 F.3d at 635),
although the defendants declined to do so. Because Franks
“appl[ied] his training and experience to the sources before
him and reach[ed] an independent judgment,” his testimony
complied with Crawford and the Confrontation Clause. Id.
(quoting Johnson, 587 F.3d at 635).

     B. Rule 403

     The defendants further contend that the district court did
not balance the probative value of Franks’ testimony against
its unfair prejudice and that his testimony should have been
excluded on this basis as well. Assuming without deciding
that Franks’ testimony should have been excluded under Rule
403, we conclude that any error in admitting the testimony
was harmless. See United States v. Gonzalez-Flores,
418 F.3d 1093, 1099 (9th Cir. 2005) (holding that for
nonconstitutional errors, we will not reverse when “it is more
probable than not that the error did not materially affect the
verdict” (quoting United States v. Morales, 108 F.3d 1031,
1040 (9th Cir. 1997) (en banc)) (internal quotation marks
omitted)).

    First, because Franks’ most damning testimony was
cumulative, its impact on the jury was limited. Before Franks
testified, the jury had already heard Reyes’ testimony that
Salvador was the highest-ranking member of the Minnie
Street Lopers, that Salvador controlled all narcotics
trafficking in Bishop Manor and that anyone who dealt drugs
without his permission would be physically assaulted. This
testimony was elicited without objection from the defense,
and its admission has not been challenged on appeal.
Admittedly, corroboration from law enforcement carries
heavy weight, especially given that Reyes’ testimony had
been thoroughly impeached. Nevertheless, the jury had
                      UNITED STATES V. VERA                             15

already heard the most potentially inflammatory information
from other sources.

    Second, as to the conspiracy count, Franks’ testimony
could not have influenced the verdict because the defendants
effectively conceded guilt. Armando’s attorney stated in
closing argument that “Armando Vera is not disputing that he
distributed narcotics[.] That’s a given.” Salvador’s attorney
added that he would not “talk[] at all about guilt or innocence
as to Count 1,” but only about “quantity and types of drugs
and whether the government met their burden of proof to
prove those quantities.”

    Third, Franks’ testimony did not materially affect the
defendants’ convictions for use of a minor in Counts 2 and 3
and the special verdict on the drug quantities. The far more
specific testimony from Lavis and Reyes about the role of the
defendants’ minor nephew in the drug organization and the
extensive testimony from Lavis regarding drug type and
quantities overshadowed anything Franks may have
contributed.6

    Finally, we note that in one respect, Franks’ gang
testimony prejudiced one of the two defendants, Armando.
Because there was no evidence that Armando, as opposed to
Salvador, was a gang member, the gang testimony could have


 6
   For the same reasons, the district court did not commit reversible error
by failing to give, sua sponte, a limiting instruction regarding the purpose
of the gang testimony. See United States v. Teague, 722 F.3d 1187, 1192
(9th Cir. 2013) (noting that to satisfy plain error review, a defendant must
establish “that the error affected substantial rights,” meaning that it
“affected the outcome of the district court proceedings” (quoting United
States v. Olano, 507 U.S. 725, 734 (1993)) (internal quotation marks
omitted)).
16                UNITED STATES V. VERA

influenced the jury to view Armando in an unfairly negative
light. See Kennedy v. Lockyer, 379 F.3d 1041, 1055 (9th Cir.
2004) (noting that “evidence relating to gang involvement
will almost always be prejudicial and will constitute
reversible error”). But under the unique circumstances of this
case, this possibility is not a reason to conclude that the
admission of Franks’ testimony was prejudicial error. Reyes
also testified extensively about Salvador’s gang ties and the
activities of the Minnie Street Lopers gang, and neither
defendant has challenged the admission of that testimony.
Accordingly, Franks’ testimony was not in itself the cause of
any prejudice Armando may have suffered on that score. We
further note that Armando could have, but did not, request a
separate trial or even a limiting instruction to shield himself
from the effects of the gang-related evidence.

                            ***

    For these reasons, we hold the admission of Franks’ gang
expert testimony did not violate the defendants’
Confrontation Clause rights and did not constitute reversible
error under Rule 403.

                   III. Lavis’ Testimony

    We next consider whether admitting Lavis’ testimony
interpreting the recorded telephone calls was reversible error.
The defendants argue his testimony was improper because it
(1) impermissibly mixed lay and expert opinions; (2) served
as a conduit for testimonial hearsay in violation of Crawford,
541 U.S. 36; (3) was not the product of reliable principles and
methods; and (4) included impermissible lay opinions.

    Although some of Lavis’ opinions about the meaning of
recorded phone calls were permissible, we agree with the
                  UNITED STATES V. VERA                      17

defendants that others were erroneously admitted, and that the
district court’s failure to instruct the jury in how to evaluate
his testimony was plain error. After a careful review of the
record, we conclude these errors warrant reversal of the jury’s
drug quantity findings, but not the defendants’ convictions on
Counts 1 through 3. We consider the appropriate remedy in
Part IV, infra.

   A. Legal Background

    It is neither novel nor unusual for law enforcement
officers to interpret the meaning of phone calls recorded as
part of a narcotics investigation. Drug jargon is well
established as an appropriate subject for expert testimony and
investigating officers may testify as drug jargon experts who
interpret the meaning of code words used in recorded calls.
See, e.g., United States v. Bailey, 607 F.2d 237, 240 (9th Cir.
1979). Officers may testify about their interpretations of
“commonly used drug jargon” based solely on their training
and experience. See id.; see also United States v. Figueroa-
Lopez, 125 F.3d 1241, 1244–45 (9th Cir. 1997) (holding that
law enforcement officer testimony that certain terms
constituted code words for a drug deal was erroneously
admitted as lay opinion testimony, but the error was harmless
because the officer testified to facts supporting his
qualifications as an expert and the testimony was proper
expert opinion).

    To interpret the meaning of coded language encountered
for the first time in the specific investigation at issue,
however, an officer’s qualifications, including his experience
with narcotics investigations and intercepted
communications, are relevant but not alone sufficient to
satisfy Federal Rule of Evidence 702. See United States v.
Hermanek, 289 F.3d 1076, 1093 (9th Cir. 2002). Rather,
18                UNITED STATES V. VERA

Rule 702 requires district courts to assure that an expert’s
methods for interpreting the new terminology are both
reliable and adequately explained. See id. at 1094. “[V]ague
and generalized” explanations are not sufficient; rather, the
officer must explain how he applies his “knowledge to
interpret particular words and phrases used in particular
conversations.” Id. at 1094–95. For example, an agent may
permissibly apply his knowledge of the drug manufacturing
process to interpret words referring to that process or apply
his familiarity with a particular method for generating code
words to decode their meaning. See, e.g., United States v.
Reed, 575 F.3d 900, 923 (9th Cir. 2009) (approving expert
testimony interpreting terms the agent “knew to refer to the
reagent used in the PCP manufacturing process”); United
States v. Decoud, 456 F.3d 996, 1013–14 & n.6 (9th Cir.
2006) (approving the agent’s explanation that he interpreted
“diznerty” as slang for “dirty” based on his familiarity with
a common speaking style that creates slang versions of
specific words by adding “e” or “ez”).

     A law enforcement officer testifying as an expert in drug
jargon may also testify as a lay witness if he was involved in
the investigation. See United States v. Freeman, 498 F.3d
893, 904 (9th Cir. 2007). Such dual capacity testimony raises
additional concerns, however: an agent’s status as an expert
could lend him unmerited credibility when testifying as a
percipient witness, cross-examination might be inhibited,
jurors could be confused and the agent might be more likely
to stray from reliable methodology and rely on hearsay. See
id. at 902–03 (citing United States v. Dukagjini, 326 F.3d 45
(2d Cir. 2003)); see also United States v. York, 572 F.3d 415,
425 (7th Cir. 2009); United States v. Flores-De-Jesus,
569 F.3d 8, 21 (1st Cir. 2009); United States v. Conner,
537 F.3d 480, 488 (5th Cir. 2008).
                  UNITED STATES V. VERA                     19

    Because these risks are reduced “[i]f jurors are aware of
the witness’s dual roles,” the jury must be instructed about
“what the attendant circumstances are in allowing a
government case agent to testify as an expert.” Freeman,
498 F.3d at 904; see also United States v. Martinez, 657 F.3d
811, 817 (9th Cir. 2001) (approving admission of hybrid
testimony when “the court instructed the jury three times on
the difference between percipient and expert testimony”);
United States v. Anchrum, 590 F.3d 795, 803–04 (9th Cir.
2009) (holding that the district court “avoided blurring the
distinction between [the case agent’s] distinct role as a lay
witness and his role as an expert witness” when it “clearly
separated [the agent’s] testimony into a first ‘phase’
consisting of his percipient observations, and a second
‘phase’ consisting of his credentials in the field of drug
trafficking and expert testimony regarding the modus
operandi of drug traffickers”). Direct and cross-examination
provide additional opportunities “to clarify in the eyes of the
jury the demarcation between lay and expert testimony
offered by the same witness.” Freeman, 498 F.3d at 904; see
also Martinez, 657 F.3d at 817 (noting that “[t]he government
was nearly always exact in specifying when it was asking for
[the agent’s] testimony as an expert” in affirming admission
of the agent’s hybrid testimony).

    Finally, a law enforcement officer involved in the
investigation may offer lay opinions about the meaning of
intercepted phone calls, but those opinions are subject to the
requirements of Federal Rule of Evidence 701. See Freeman,
498 F.3d at 904–05. Rule 701 requires lay opinion testimony
to be “(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 Rule 702.” Accordingly, an officer may not
20                 UNITED STATES V. VERA

testify based on speculation, rely on hearsay or interpret
unambiguous, clear statements. See Freeman, 498 F.3d at
905. But he may interpret “ambiguous conversations based
upon his direct knowledge of the investigation,” including his
“direct perception of several hours of intercepted
conversations . . . and other facts he learned during the
investigation.” Id. at 904–05; see also United States v.
Gadson, 763 F.3d 1189 (9th Cir. 2014).

   In sum, law enforcement officers may offer lay and expert
opinions about the meaning of intercepted phone calls, but the
foundation laid for those opinions must satisfy Rules 701 and
702, respectively. Further, if a single officer offers both lay
and expert testimony, the jury must be informed of the fact
and significance of his dual roles.

     B. Analysis

    Applying these principles to this case, we hold it was
plain error not to instruct the jury on how to appropriately
evaluate Lavis’ opinions and to fail to require an adequately
specific foundation for those opinions. Together, these errors
undermine our overall confidence in the jury verdict in some
respects. If an appropriate foundation had been laid, the jury
would at least have had the information it needed to evaluate
Lavis’ opinions. If the jury had been instructed on how to
evaluate Lavis’ opinions, it would at least have known the
rules governing how much weight to give those opinions.
The absence of both an adequately laid foundation and an
appropriate instruction, however, substantially heightened the
“risk that the jury [would] defer to the officer’s superior
knowledge of the case and past experiences with similar
crimes.” United States v. Hampton, 718 F.3d 978, 981–82
(D.C. Cir. 2013).
                  UNITED STATES V. VERA                      21

    The defendants’ arguments for overturning their
convictions for these reasons are not well taken, however,
because the erroneously admitted testimony related most
fundamentally to the evidence of drug quantity. Moreover,
the defendants failed to object to Lavis’ interpretive
testimony generally and they failed to contemporaneously
object to the specific quantity opinions they belatedly
challenge on appeal. Whether the defendants’ decisions were
based on strategy or the result of oversight, they undermine
the defendants’ argument that the errors satisfy the plain error
standard, warranting reversal of their convictions, because
many of the problems could have been easily corrected had
they been timely brought to the district court’s attention.

    Nonetheless, the ultimate responsibility for assuring the
reliability of expert testimony and for instructing the jury on
how to evaluate case agent dual role testimony rests with the
district court. See Freeman, 498 F.3d at 904. Particularly
when the district court indicated it would instruct the jury on
how to evaluate Lavis’ expert opinions, its failure to do so is
not excused by the absence of a request from the defendants.
Moreover, as the proponent of Lavis’ testimony, the
government “bears the burden of laying the proper foundation
for [its] admission.” City of Long Beach v. Standard Oil Co.
of Cal., 46 F.3d 929, 937 (9th Cir. 1995). Some of the
responsibility must therefore be shouldered by the
prosecution as well.

    These general defects led to specific flaws in Lavis’
testimony, mostly relating to the reliability of his
methodology, which affected several of his opinions
regarding specific drug quantities. Aside from the 24 grams
of heroin Reyes purchased from Armando, Lavis’ opinions
interpreting the wiretapped calls were the only evidence of
specific quantities at trial. Given the vital importance of
22                UNITED STATES V. VERA

Lavis’ opinions to those drug quantity findings, and of those
findings to the defendants’ substantial sentences, the
foundational errors in Lavis’ opinions, combined with our
overall lack of confidence in the jury’s ability to
meaningfully evaluate his testimony, require us to vacate the
jury’s drug quantity findings. We affirm the remainder of the
jury verdict, however, because the defendants have not
established that their convictions were materially affected by
these or any other errors in the proceedings.

     1. Procedural History

    The history of how Lavis came to be the key government
witness on drug quantities is an important factor in our
analysis. The government proffered him as an expert witness
in its trial memorandum, filed the week before trial. The
memorandum explained Lavis would also be testifying as a
percipient witness about the investigation, specifically “the
wiretap, the recorded calls, surveillances, and interviews he
conducted,” and potentially “his familiarity with the
defendants.” This proffer adequately disclosed Lavis as a
witness who would be providing both lay and expert
testimony. Additionally, its description of his anticipated
expert testimony – that he would opine that the conspiracy
involved quantities above certain threshold amounts; that he
would interpret the meaning of certain words, code words and
phrases used in the intercepted calls; and that he would testify
as to the street values of narcotics, law enforcement
techniques, drug trafficking activities in general and at
Bishop Manor in particular – reasonably disclosed the
contours of that testimony.

    What the proffer did not reveal was that Lavis’ testimony
on drug jargon and drug quantity would include interpreting
terminology he encountered for the first time in this
                      UNITED STATES V. VERA                               23

investigation and noncoded words (such as “that” or “one”)
used in particular contexts. As a consequence, the
government did not disclose the methodology he would
employ in doing so or, more generally, the foundation on
which those opinions would rest. The proffer of his expertise
rested solely on his general qualifications, training and
experience: his employment as an agent of the FBI and his six
years as a member of the Santa Ana Gang Task Force. The
testimony elicited by the prosecutor on direct examination to
support Lavis’ expert opinions similarly focused on his
general training and experience and his familiarity with this
investigation in particular without discussing any expert
methodology he would apply.7 Up until Lavis actually began
offering his opinions about the meaning of the intercepted
calls, therefore, the defendants could have reasonably
assumed that his drug quantity testimony would be limited to
common code words for drugs that he learned through his
training and experience.

    On the first day of trial, the defendants filed written
objections to Franks’ proffered gang expert testimony and to
two recorded phone calls the government intended to offer
into evidence, which also related to the gang issues. They


  7
    This testimony included that he had developed expertise in narcotics
trafficking organizations and techniques for investigating them during his
eight years of involvement in several wiretap investigations; that, during
that time, he had listened to many telephone calls between narcotics
traffickers; that, as to this investigation, he had reviewed all the calls the
government would introduce into evidence, as well as other intercepted
calls, primarily to identify the voices in the calls, as he could not
understand Spanish beyond a few code phrases used in narcotics
trafficking, and most of the calls were in Spanish; and that he had
familiarity with code words used by traffickers “[t]o avoid detection by
law enforcement” and confirmed that the defendants used code words
throughout the intercepted calls.
24                 UNITED STATES V. VERA

explicitly disclaimed objecting “to portions of the notice
regarding . . . use of ‘code words,’ [and] the street value of
identified narcotics in the area at the time,” although they
reserved their “right to object depending upon the ultimate
foundation,” and their “right to object to any matters not
specifically identified in the notice.” They objected in a
footnote to any testimony of the form, “Defendant X is
legally responsible for participating in a conspiracy to
distribute Y amount of narcotics.” This objection was not
based on foundation under 701 or 702 but on mental state
under Federal Rule of Evidence 704(b). The defendants did
not raise any concerns about case agents testifying in both a
lay and expert capacity, nor did they request further
explanation of or the opportunity to explore Lavis’
methodology or the foundation for his opinions.

     The defendants did argue that expert reliance on “out-of-
court statements of individuals such as informants and
arrestees” constitutes “a repackaging of testimonial
statements” that is “inadmissible under the Confrontation
Clause.” When the district court heard oral argument on their
written objections before testimony began on the third day of
trial, the court acknowledged the defendants’ standing
Crawford objection, explaining their “Crawford position is
preserved,” but agreed with counsel’s suggestion that they
would contemporaneously object on all other issues.

    On the merits of the defendants’ objection, the court
stated it would “be real tight on requiring compliance with
703,” and would not “let an expert walk in hearsay.”
Significantly, the court further advised counsel that an expert
could testify “to sources that an expert in that particular field
could reasonably rely upon,” and that it would at that time
instruct the jury about “how they’re to treat the expert
testimony and distinguish between reliance on an opinion,
                       UNITED STATES V. VERA                              25

those facts not coming into evidence for the truth, as opposed
to the expert stating the bases for his opinion, consider what
he has said in terms of assessing opinion, not for the truth of
the statements.” No such instruction was ever given.

    Aside from the standing Crawford objection, the defense
affirmatively acquiesced to the admission of Lavis’ drug
quantity opinions. Defense counsel did specifically raise
Lavis’ drug quantity testimony as an issue with the court,
characterizing that testimony as “critical to the case.” The
court explained Lavis would “have to have a percipient basis
for that testimony.” The government responded with an oral
proffer regarding the type of opinions Lavis was expected to
offer.8 This proffer should have put the defendants on notice
that Lavis would testify as to the meaning of, for example, the
term “one” as opposed to common drug jargon, and that his
opinions would be based in part “on the calls he has listened
to and his knowledge of the investigation.” Nevertheless, the
defense agreed that the government could proceed to elicit
Lavis’ testimony and stated that such testimony would not be
“per se, improper.” The defense did request – and was
granted – additional time to review the summary of Lavis’
drug quantity opinions.


 8
     The government explained:

          What I expect Special Agent Lavis to testify about is,
          you know, for example, Exhibit 5. There is reference
          to get one and cook it. He is going to opine that the
          call, based on his review of all the calls, that that call is
          about one ounce of crack cocaine. And he will opine
          that there’s a series of calls on 5/13/08, all referencing
          the attempt to get one ounce of crack cocaine; and that
          is, he is going to opine based on the calls he has
          listened to and his knowledge of the investigation and
          the code words used in the calls.
26                 UNITED STATES V. VERA

    Finally, during Lavis’ testimony itself, the defense rarely
objected to his opinions, and most of those objections were
cured by rephrasing the question. This underscores that many
of the problems the defendants identify on appeal could likely
have been averted through contemporaneous objections
before the district court.

     2. Instructional Error

   On this procedural record, we review the defendants’
Crawford argument de novo, see Gomez, 725 F.3d at 1125,
and their remaining arguments for plain error, see Fed. R.
Crim. P. 52(b); United States v. Olano, 507 U.S. 725, 730–36
(1993).

    In light of our Circuit’s clearly expressed concerns about
case agents testifying in both lay and expert capacities, the
district court’s failure to give an instruction explaining Lavis’
dual roles was plain error. See Freeman, 498 F.3d at 904
(emphasizing “the necessity of making clear to the jury what
the attendant circumstances are in allowing a government
case agent to testify as an expert”). It is particularly plain
given the district court’s own statement that it would give an
instruction telling the jury how to evaluate Lavis’ expert
opinion testimony.

    The absence of such an instruction prejudiced the
defendants by materially increasing the risk that the jury gave
Lavis’ testimony undue deference, a risk that is particularly
acute with respect to the issue of drug quantity, for which –
aside from 24 grams of heroin – his opinions comprised the
sole evidence. Had the jury been instructed that the “facts”
on which Lavis based his expert opinions should not be
considered for their truth but only to assess the strength of his
opinions, the jury would have been better able to question for
                      UNITED STATES V. VERA                             27

itself the reliability of Lavis’ interpretations of wiretapped
conversations. Likewise, if the court had instructed the jury
that Lavis’ lay opinion testimony was “not based on
scientific, technical, or other specialized knowledge,” Fed. R.
Evid. 701(c), it would have deterred the jury from viewing
Lavis’ opinions as having the “imprimatur of scientific or
technical validity.” Freeman, 498 F.3d at 903. This is
especially true as to Lavis’ opinions that speakers’ vague
references such as “that, “one” or “what we talked about
earlier” were linked to narcotics transactions.

    Given the risk of undue deference from the jury, other
errors in the record that might be individually harmless
instead have a cumulative impact. For example, the
“helpfulness” requirement of Rules 701 and 702 prohibits a
witness from opining about the meaning of clear statements.
See id. at 904–05 (“Although [an expert’s] interpretation of
ambiguous statements [is] permissible under Fed. R. Evid.
701, ‘the interpretation of clear statements is not permissible,
and is barred by the helpfulness requirement of both Fed. R.
Evid. 701 and Fed. R. Evid. 702.’” (quoting United States v.
Dicker, 853 F.2d 1103, 1109 (3d Cir. 1988))).

    Nevertheless, Lavis was at times called upon to interpret
conversations that were well within the understanding of an
ordinary juror.9 Individually, such opinions did not prejudice
the defendants – after all, they were impermissible because


 9
    For example, Lavis explained that “bad” and “no good” meant that the
product was of “poor quality” or “not good.” Similarly, he interpreted the
demand that a supplier “lower the price for you, fool, because tell her that
it is a little expensive, fool,” as meaning that “whatever she is selling it
for, Mr. Vera probably feels it’s a little more expensive than what he
wants to pay for it, so he’s trying to negotiate, maybe get the price
lowered.”
28                UNITED STATES V. VERA

their meaning was already clear. Cumulatively, however,
they may have encouraged the jury to defer to Lavis’ opinions
instead of listening to the calls and reaching an independent
judgment. See id. at 903 (stating that “unnecessarily
repetitive” testimony “may come dangerously close to
usurping the jury’s function”) (quoting Dukagjini, 326 F.3d
at 54). Particularly because the jury was uninformed about
how to appropriately evaluate Lavis’ opinion testimony, these
errors further erode our confidence in the jury’s verdict.

     3. Specific Drug Quantity Problems

    Having set forth our underlying concerns with the jury
verdict generally, we next focus on drug quantity, the issue
most seriously affected by the instructional error. Given the
sentencing structure of the Controlled Substances Act, which
imposes higher statutory sentencing ranges for offenses
involving quantities above certain threshold amounts, see
21 U.S.C. § 841(b), it is not surprising that drug quantity was
the primary issue the defendants contested at trial. Drug
quantity was such a critical issue that, in closing, the defense
variously characterized the jury’s role as akin to
“accounting,” “arithmetic” or “a tax audit.” Moreover, when
multiple substances are at issue, what quantity is attributed to
a particular drug type is also material because different
threshold amounts are required for different substances; the
highest statutory sentencing range, for example, requires an
offense involving 5 kilograms of cocaine but only 280 grams
of cocaine base.          See id. § 841(b)(1)(A)(ii)–(iii).
Accordingly, unreliable opinions attributing particular
quantities of particular substances to the defendants pose a
serious risk of prejudice to their substantial rights.

    Careful review of the record shows that the general failure
to assure an adequate foundation for Lavis’ opinions resulted
                  UNITED STATES V. VERA                      29

in the admission of specific drug quantity opinions that did
not rest on reliable methods. Even though the defendants
forfeited the arguments they make on appeal by failing to
contemporaneously object to any of this specific testimony,
the district court plainly erred by allowing the admission of
such testimony in the face of its “continuing responsibility of
acting as the vigilant gatekeeper[] of expert testimony to
ensure that it is reliable.” Freeman, 498 F.3d at 904; see also
Dukagjini, 326 F.3d at 53 (requiring “vigilance by the trial
court . . . when an expert, who is also the case agent, goes
beyond interpreting code words and summarizes his beliefs
about the defendant’s conduct based upon his knowledge of
the case”).

    For example, an agent’s belief that the speaker is a
trafficker of a particular substance does not satisfy Rule 702’s
requirement that expert opinions be based on reliable
methodology. See Hermanek, 289 F.3d at 1096 (holding that
the agent’s interpretation of “cryptic language as referring to
cocaine simply because he believed appellants to be cocaine
traffickers” was “circular, subjective reasoning” that did “not
satisfy the Rule 702 reliability requirement”). Yet Lavis
relied on his belief that Manuel Duarte-Aguilera was a
cocaine base dealer who provided ounce quantities to
Salvador to interpret a reference to a “package of tortillas” as
“one ounce of cocaine base,” a substance that carries more
severe sentencing consequences than powder cocaine. The
flaw in this methodology was confirmed when the
government later admitted that Lavis’ assumption was
actually wrong. After the close of its case, the government
conceded by stipulation that this call actually “involved
powder cocaine, not cocaine base, and that Manuel Duarte-
Aguilera distributed both powder cocaine and cocaine base.”
Notwithstanding this stipulation, Lavis had relied on his
assumption that Duarte-Aguilera was an ounce distributor of
30                 UNITED STATES V. VERA

cocaine base as a partial reason to infer that several other
calls referred to ounce quantities of cocaine base. He
employed this same methodology to interpret additional calls
involving other individuals, testifying that Gloria Calderon
supplied ounce quantities of cocaine base, that Javier
Camacho supplied ounce quantities of cocaine base and that
Ruben Orejel was a heroin dealer.

    At other times, Lavis used the quoted price to deduce
whether the conversations concerned cocaine powder or
cocaine base. For example, he twice testified that the term
“work” referred to cocaine base because the supplier quoted
a price consistent with an ounce of cocaine base. There is
nothing inherently unreliable about this methodology, but he
later testified that the price range for an ounce of cocaine base
and for powder cocaine is “roughly the same.” If the price
ranges for cocaine base and cocaine powder were roughly
equivalent, Lavis’ method for distinguishing them was not
reliable.

   Finally, in one instance, Lavis’ opinion plainly rested on
nothing more than speculation. The jury heard this
conversation:

        [Phone ringing]

        ARMANDO: Hello?

        FILIPP: Hey, what’s up man? Are you uh –
        are you around right now?

        ARMANDO: Yeah.

        FILIPP: Alright, can I come – can I come by?
                     UNITED STATES V. VERA                             31

         ARMANDO: Yeah.

         FILIPP: Okay, I’ll be there in like ten
         minutes.

         ARMANDO: Alright.

         FILIPP: Alright, bye.

         [End of conversation]

As the defendants point out, “[n]either direct nor encoded
references were made that could be construed as a desire to
purchase narcotics.” Nevertheless, Lavis opined that, in this
call, Filipp “was contacting Armando to obtain two ounces of
heroin,” and that those two ounces would be “20 grams each,
so two would be 40 grams,” because that is what he “knew
[Filipp] to get in the investigation.” This opinion could not
have been “rationally based on the witness’s perception,”
Fed. R. Evid. 701(a), because Lavis’ knowledge that Filipp
had obtained 40 grams of heroin from Armando on other
occasions does not support the inference that this call – which
includes no inculpatory, ambiguous or coded statements –
was about his desire to do so again. Surveillance confirmed
that Filipp visited Bishop Manor after similar calls, but it is
pure speculation to equate a visit with the purchase of 40
grams of heroin, specifically.          Such speculation is
inadmissible testimony whether characterized as lay opinion,
expert opinion or anything else, and its admission constituted
plain error.10

 10
    There is also reason to suspect that Lavis’ lay opinion at times rested
on testimonial hearsay, violating the defendants’ Confrontation Clause
rights under Crawford, although the record does not allow a conclusive
determination. Lavis frequently opined about the meaning of ambiguous
32                    UNITED STATES V. VERA

    The government argues that this court’s recent decision in
United States v. Gadson, 763 F.3d 1189 (9th Cir. 2014),
requires a finding that Agent Lavis’ direct knowledge of the
investigation established sufficient foundation for the
admission of his testimony, including the conclusions about
drug quantity. But Gadson is distinguishable: it did not
involve a qualified expert slipping into lay opinion without a
proper jury instruction, nor did it involve such obvious flaws
in the foundation for the officer’s conclusions on specific
drug quantities.

                                  ***

    Because the jury was not instructed on how to evaluate
Lavis’ dual role in giving his drug quantity opinions and
because the general failure to establish a foundation under
Rules 701 and 702 for those opinions led to the admission of
plainly erroneous drug quantity testimony, we hold the
defendants have established that plain errors affected the
jury’s drug quantity findings. The defendants’ lengthy


statements based on what he knew “about the investigation,” or “a number
of factors in the investigation.” But his knowledge “about the
investigation” included some sources that constitute testimonial hearsay
(interviews with informants) and others that do not (intercepted
conversations). Lavis’ lay opinions based on his knowledge of the
investigation therefore might have relied on and conveyed impermissible
testimonial hearsay. For example, he testified that a “piece” of heroin is
typically 25 grams, but that he knew “based on the investigation” that
Fillip, a customer of the defendants, used the term “piece” to mean 20
grams. Given that the recorded telephone calls available for our review
were almost never so specific about quantity, this testimony at least raises
a suspicion that Lavis’ testimony relied in part on interviews or
interrogations associated with the investigation, constituting testimonial
hearsay in violation of Crawford. Because we conclude that other errors
warrant vacating the drug quantity findings, however, we need not
conclusively resolve the issue.
                  UNITED STATES V. VERA                      33

sentences depended on those drug quantity findings, so the
errors seriously affected the fairness of the proceedings and
we exercise our discretion to correct them. See Olano,
507 U.S. at 735–36.

                        IV. Remedy

    Having concluded that only the jury’s drug quantity
findings were affected by plain error, we turn to the question
of remedy. Because the special verdict included the jury’s
tainted drug quantity findings, we must vacate that portion of
the special verdict. Without those findings, the drug types
and quantities used to establish the defendants’ statutory
sentencing ranges under 21 U.S.C. § 841(b) were not proven
beyond a reasonable doubt. Sentencing the defendants using
that statutory range therefore violated the Sixth Amendment.
See Alleyne v. United States, 133 S. Ct. 2151, 2163 (2013)
(holding that “facts that increase mandatory minimum
sentences must be submitted to the jury and found beyond a
reasonable doubt”). Accordingly, we must also vacate the
defendants’ sentences.

    We next confront what appears to be a question of first
impression in this circuit: What is the appropriate remedy
when a jury finds beyond a reasonable doubt facts that
increase a defendant’s statutory sentencing range, but the
jury’s finding was affected by trial error? Specifically, we
consider whether we must (1) vacate the entire conspiracy
conviction and remand for a full retrial of Count 1; (2) vacate
only the drug quantity findings in the special verdict, deny the
government the option of retrying the drug quantity issue and
require resentencing based solely on the defendants’
convictions; or (3) vacate only the drug quantity findings in
the special verdict, but allow the government to resubmit the
34                  UNITED STATES V. VERA

drug quantity questions to a sentencing jury.11 We conclude
the last option is the appropriate procedure.

    First, vacating the jury’s drug quantity findings does not
require us to vacate the conspiracy conviction itself. The
tainted drug quantity verdict does not affect the validity of the
underlying conspiracy conviction because drug quantity was
not an element of the charged conspiracy offense; rather, it
was the “functional equivalent of an element” that had to be
submitted to a jury and proved beyond a reasonable doubt for
the purposes of sentencing alone. United States v. Toliver,
351 F.3d 423, 430 (9th Cir. 2003) (internal quotation marks
omitted), abrogated on other grounds by Blakely v.
Washington, 542 U.S. 296 (2004); cf. United States v.
Thomas, 355 F.3d 1191, 1195 (9th Cir. 2004) (explaining that
“drug type and quantity are not elements of the offense under
[21 U.S.C.] § 841”); United States v. Minore, 292 F.3d 1109,
1117 (9th Cir. 2002) (noting that “a finding of drug quantity
is not necessary to convict [the defendant] of violating
[21 U.S.C. §] 841(a)”).

    Second, the Double Jeopardy Clause does not preclude
the government from retrying the drug quantity issue in this
case. The Double Jeopardy Clause bars retrial where
insufficient evidence supported a conviction, but not where,
as here, trial error affected the jury’s determination. See
Lockhart v. Nelson, 488 U.S. 33, 38 (1988) (holding that the
government may retry a defendant who successfully
challenges his conviction based on “some error in the
proceedings leading to conviction”); Burks v. United States,
437 U.S. 1, 18 (1978) (holding that the government may not


 11
   Following oral argument, we requested supplemental briefing on this
question.
                  UNITED STATES V. VERA                      35

retry a defendant when the prosecution introduces insufficient
evidence to support his initial conviction). Here, as set forth
in the concurrently filed memorandum disposition, sufficient
evidence supports the jury’s drug quantity findings, although
some of that evidence was improperly admitted. Thus, the
Double Jeopardy Clause does not prohibit retrial.

    This conclusion is consistent with our previous case law
requiring resentencing within the lower statutory sentencing
range supported by a generic conviction. In the wake of
Apprendi v. New Jersey, 530 U.S. 466 (2000), we decided
several cases where the defendants had been convicted of
generic controlled substance offenses, were sentenced based
on judicial determinations of drug type or quantity and
challenged those sentences as violative of their Sixth
Amendment rights under Apprendi. See id. at 490 (“Other
than the fact of a prior conviction, any fact that increases the
penalty for a crime beyond the prescribed statutory maximum
must be submitted to a jury, and proved beyond a reasonable
doubt.”). In such cases, we vacated the defendants’ sentences
and remanded for resentencing within the lower statutory
ranges applicable to their generic convictions – without
giving the government the opportunity to submit the drug
type and quantity questions to a jury. See, e.g., Thomas,
355 F.3d at 1202 (remanding with instructions to resentence
the defendant based on an unspecified quantity of cocaine
base when the defendant had admitted during the plea
colloquy that he knowingly possessed cocaine base with the
intent to distribute without admitting to a specific quantity);
United States v. Banuelos, 322 F.3d 700, 706 (9th Cir. 2003)
(remanding “with instructions to the district court to
resentence Banuelos subject to the maximum sentence
supported by the facts found by the fact-finder beyond a
reasonable doubt”) (internal quotation marks omitted); United
States v. Velasco-Heredia, 319 F.3d 1080, 1086–87 (9th Cir.
36                UNITED STATES V. VERA

2003) (holding that, having established that the defendant was
guilty of a conspiracy for an unspecified amount of
marijuana, double jeopardy barred the government from
proving the quantity of marijuana beyond a reasonable
doubt).

    In those cases, however, the government did not attempt
to prove drug type or quantity beyond a reasonable doubt, but
instead relied on plea colloquys in Thomas and Banuelos, and
in Velasco-Heredia, on the facts found in a bench trial that
did not specify the quantity of drugs. Accordingly, there was
insufficient evidence – none – presented to a jury to support
a finding beyond a reasonable doubt of the facts increasing
the statutory range. The government had therefore effectively
forfeited “its opportunity to prove beyond a reasonable doubt
that [the defendant] was responsible for [a particular quantity
of drugs].” Velasco-Heredia, 319 F.3d at 1086. Here, in
contrast, the government took full advantage of its
opportunity, and the jury found that the government met its
burden of proving certain drug quantities. The defendants
have now successfully challenged those findings, but only
“because of some error in the proceedings” that rendered the
proof invalid, not necessarily lacking. Lockhart, 488 U.S. at
38. The Double Jeopardy Clause therefore poses no bar to
retrying the drug quantity issue.

    Third, vacating only the drug quantity findings in the
special verdict and affording the government an opportunity
to retry the issue accords with recent Supreme Court
authority. In Alleyne, the Supreme Court explained that
“[w]hen a finding of fact alters the legally prescribed
punishment so as to aggravate it, the fact necessarily forms a
constituent part of a new offense and must be submitted to the
jury.” 133 S. Ct. at 2162 (emphasis added); see also id.
(holding that “because the fact of brandishing aggravates the
                   UNITED STATES V. VERA                      37

legally prescribed range of allowable sentences, it constitutes
an element of a separate, aggravated offense that must be
found by the jury” (emphasis added)); id. at 2162–63 (“The
essential point is that the aggravating fact produced a higher
range, which, in turn, conclusively indicates that the fact is an
element of a distinct and aggravated crime.” (emphasis
added)).

    Alleyne suggests that facts increasing the statutory
sentencing range should be analogized to criminal statutes
increasing the punishment for individuals who commit
underlying predicate crimes in specific ways. See, e.g.,
18 U.S.C. § 924(c) (providing that if, during and in relation
to the commission of a crime of violence or drug trafficking
crime, the defendant uses, carries or possesses a firearm in
furtherance of the predicate offense, the district court must
add a consecutive sentence to the punishment for the
predicate offense); 18 U.S.C. § 1028A (providing that when
a defendant, during and in relation to certain predicate
offenses, “knowingly transfers, possesses, or uses, without
lawful authority, a means of identification of another person,”
the district court must generally impose a 2-year term of
imprisonment to run consecutive to the sentence for the
predicate offense). When a conviction for such an aggravated
offense is vacated for trial error, the government has an
opportunity to retry the defendant for the aggravating offense
alone. See, e.g., United States v. Anderson, 89 F.3d 1306,
1315 (6th Cir. 1996) (affirming conviction on predicate drug
offense but vacating conviction under 18 U.S.C. § 924(c) for
erroneous jury instructions and remanding “for a new trial or
resentencing”); United States v. Manning, 79 F.3d 212, 223
(1st Cir. 1996) (affirming conviction on predicate drug
offense, but vacating conviction of 18 U.S.C. § 924(c) and
remanding for a new trial). Our approach is consistent with
this analogy.
38                UNITED STATES V. VERA

    In concluding that only the drug quantity findings must be
vacated, we decline to follow the remedy adopted by the First
Circuit in United States v. Delgado-Marrero, 744 F.3d 167
(1st Cir. 2014), and the Fourth Circuit in United States v.
Collins, 415 F.3d 304 (4th Cir. 2005). In those cases, the
district courts gave erroneous jury instructions regarding how
to calculate the drug quantities attributable to the defendants
as part of their conspiracy convictions. See Delgado-
Marrero, 744 F.3d at 189; Collins, 415 F.3d at 314. The
errors invalidated the defendants’ sentences, but did not affect
their underlying conspiracy convictions. See Delgado-
Marrero, 744 F.3d at 190; Collins, 415 F.3d at 314. Without
the special verdicts, the defendants were subject “to the
default statutory range of penalties under § 841(b)(1)(C),
regardless of the drug quantity involved.” Delgado-Marrero,
744 F.3d at 192; accord Collins, 415 F.3d at 315. But
because the error was instructional, “the Double Jeopardy
Clause d[id] not prohibit retrial.” Delgado-Marrero,
744 F.3d at 192. We agree with the First and Fourth Circuits’
analyses up to this point.

    To remedy these errors, however, the First and Fourth
Circuits withheld judgment and gave the government a short
period to select one of two outcomes: (1) affirm the
conspiracy conviction and remand for resentencing under the
default penalty, or (2) vacate the conspiracy conviction and
remand for a new trial. See id. at 193; Collins, 415 F.3d at
315. In doing so, Delgado-Marrero and Collins imported a
remedy crafted for distinguishable cases to the circumstances
we confront here.

    The Delgado-Marrero and Collins remedy was originally,
and appropriately, adopted when (1) a defendant was
convicted of a conspiracy charge alleging multiple objects of
the conspiracy, at least one of which increased the statutory
                  UNITED STATES V. VERA                     39

sentencing range, (2) the jury did not specify which object
supported the conviction, but (3) the defendant was sentenced
using the increased statutory range determined through
judicial factfinding. See United States v. Rhynes, 196 F.3d
207, 237–40 (4th Cir. 1999), rev’d on other grounds 218 F.3d
310 (4th Cir. 2000) (en banc); United States v. Garcia,
37 F.3d 1359, 1371 (9th Cir. 1994), receded from by United
States v. Jackson, 167 F.3d 1280 (9th Cir. 1999); United
States v. Quicksey, 525 F.2d 337, 340–41 (4th Cir. 1975).
The government was allowed to choose between affirming
the convictions and resentencing the defendants based on the
conspiratorial object with the lowest statutory sentencing
range, or vacating the conspiracy convictions and remanding
for retrial with a special jury verdict. See Rhynes, 196 F.3d
at 239–40; Garcia, 37 F.3d at 1371; Quicksey, 525 F.2d at
341. Under such circumstances, retrial was possible only if
the conspiracy convictions were vacated. Because the
government must prove “the requisite intent to commit the
substantive crime,” United States v. McCaleb, 552 F.3d 1053,
1058 (9th Cir. 2009) (quoting United States v. Sullivan,
522 F.3d 967, 976 (9th Cir. 2008)), the object of a conspiracy
is an essential element of a conspiracy offense. Cf. United
States v. Arlt, 252 F.3d 1032, 1034 (9th Cir. 2001) (en banc)
(holding “that the specific offense designated as the object of
a conspiracy in a [18 U.S.C.] § 371 indictment does constitute
an element of the offense”); United States v. Alerta, 96 F.3d
1230, 1235–36 (9th Cir. 1996) (adopting a similar remedy
when the jury was not asked to decide whether the defendant
used a machine gun, as opposed to any other sort of gun,
during and in relation to his drug trafficking offense under
18 U.S.C. § 924(c) because whether the firearm was fully
automatic “is an element of the crime”), overruled on other
grounds by Arlt, 252 F.3d 1032.
40                   UNITED STATES V. VERA

    Here, in contrast, the tainted drug quantity findings were
not elements of the defendants’ conspiracy conviction, as
explained earlier. There is accordingly no reason to vacate
the entire conspiracy conviction, guilt for which the
defendants barely contested, if at all. If on remand the
government elects to retry the drug quantity issue, the district
court may empanel a sentencing jury. Sentencing juries and
other bifurcated proceedings are not unknown to the federal
criminal justice system. See, e.g., Jones v. United States,
527 U.S. 373, 376–77 (1999) (describing the “separate
sentencing hearing” required in capital cases, during which
the “sentencing jury” must determine whether the
government has established any of the statutory aggravating
factors necessary to support a death sentence); United States
v. Pena, 742 F.3d 508, 515 (1st Cir. 2014) (noting that “the
question of guilt is often bifurcated from the question of
criminal forfeiture”).

    By proceeding in this manner, we vacate only what was
affected by error: the jury’s drug quantity findings expressed
in the special verdict and the defendants’ sentences. On
remand, the government may elect to retry the drug quantity
issue before a sentencing jury, or it may request that the
district court resentence the defendants under the default
sentencing provisions in 21 U.S.C. § 841(b)(1)(C).12

     12
      In their supplemental briefing, the defendants contend that any
resentencing based on their convictions must proceed under 21 U.S.C.
§ 841(b)(3), the provision that applies to unspecified drug types, rather
than 21 U.S.C. § 841(b)(1)(C). We disagree. We required resentencing
under § 841(b)(3) in United States v. Hunt, 656 F.3d 906 (9th Cir. 2011),
because the defendant admitted during the plea colloquy that he intended
to possess and to distribute only an unspecified substance. See id. at
912–13, 916–17. Here, in contrast, the jury was instructed that it could
convict the defendants on the conspiracy count only by finding that “there
was an agreement between two or more persons to distribute heroin,
                     UNITED STATES V. VERA                            41

                           V. Conclusion

    We vacate the defendants’ sentences and the special
verdict, and remand for further proceedings consistent with
this opinion. We affirm the remainder of the defendants’
convictions.

  AFFIRMED IN PART, VACATED IN PART AND
REMANDED.




cocaine, or cocaine base.” By convicting the defendants on Count 1, the
jury found beyond a reasonable doubt that the conspiracy involved an
unspecified quantity of at least one of those three substances.
Accordingly, the defendants’ conspiracy convictions, standing alone,
warrant sentencing under 21 U.S.C. § 841(b)(1)(C), which applies to
unspecified quantities of these three substances. See also 21 U.S.C. § 812
scheds. I(b)(10), II(a)(4).
