                    FOR PUBLICATION
  UNITED STATES COURT OF APPEALS
       FOR THE NINTH CIRCUIT

UNITED STATES OF AMERICA,                       No. 03-50608
               Plaintiff-Appellant,
               v.                                 D.C. No.
                                                CR-02-00419-ER
CHING TANG LO, aka Jeff Lo,
              Defendant-Appellee.
                                          

UNITED STATES OF AMERICA,                       No. 04-50223
                Plaintiff-Appellee,
               v.                                 D.C. No.
                                                CR-00419-ER-1
CHING TANG LO, aka Jeff Lo,
                                                  OPINION
             Defendant-Appellant.
                                          
         Appeal from the United States District Court
            for the Central District of California
          Edward Rafeedie, District Judge, Presiding

                  Argued and Submitted
          November 16, 2005—Pasadena, California

                       Filed May 19, 2006

   Before: Procter Hug, Jr. and Kim McLane Wardlaw,
  Circuit Judges, and James K. Singleton,* District Judge.

                     Opinion by Judge Hug

   *The Honorable James K. Singleton, United States District Judge for
the District of Alaska, sitting by designation.

                                5447
5452                  UNITED STATES v. LO


                          COUNSEL

Michael J. Raphael, Assistant United States Attorney, Los
Angeles, California, for the plaintiff-appellant/cross-appellee.

Benjamin L. Coleman, San Diego, California, for the
defendant-appellee/cross-appellant.


                          OPINION

Hug, Circuit Judge:

   The Government appeals the district court’s order granting
defendant Ching Tang Lo’s motion for acquittals on a charge
of possessing ephedrine, a listed chemical used to manufac-
ture methamphetamine, and a related money laundering
charge. Lo contends that this court does not have jurisdiction
to consider this appeal and that there was insufficient evi-
dence to support the verdicts. We hold that we do have juris-
diction to consider the Government’s appeal and that there
was sufficient evidence to support the jury’s verdicts. We
therefore reverse the district court’s order granting the acquit-
tals.

   Lo cross-appeals the district court’s denial of his motion for
a judgment of acquittal on the charge of conspiracy. He con-
tends that the district court erred by denying the motion
because the jury acquitted Leslie Kuan, the only other charged
co-conspirator, and because there was no evidence that he
conspired with anyone besides government agents. We hold
                     UNITED STATES v. LO                   5453
that there was sufficient evidence that Lo conspired with
Kuan to achieve all four of the charged objects of the conspir-
acy and that Lo’s conviction may be based on this evidence
even though the jury acquitted Kuan of conspiracy.

   We also reject Lo’s claim that the district court committed
plain error by giving incorrect jury instructions regarding the
mens rea required for violation of 21 U.S.C. § 841(c)(2) and
by failing to provide complete jury instructions for the aiding
and abetting objects of the conspiracy charge.

   Finally, Lo appeals his sentence. He argues that United
States v. Booker, 543 U.S. 220, 125 S. Ct. 738 (2005) over-
ruled United States v. Buckland, 289 F.3d 558 (9th Cir. 2002)
(en banc), and that it was therefore error for him to be subject
to the mandatory minimum sentences contained in 21 U.S.C.
§ 841(b). We reject this argument and hold that Lo is subject
to those mandatory minimum sentences. We conclude, how-
ever, that Lo is entitled to a limited remand for sentencing
purposes pursuant to United States v. Ameline, 409 F.3d 1073
(9th Cir. 2005) (en banc).

                               I.

           Factual and Procedural Background

A.   The Offense

  This case concerns two listed chemicals. One listed chemi-
cal, 3,4-methylenedioxyphenyl-2-propanone (“MDP-2-P”) is
used to manufacture the controlled substance 3,4-
methylenedioxymethamphetamine (“MDMA” or “Ecstacy”).
Ma huang is a plant that is also known as ephedra. Ma huang
contains ephedrine, a listed chemical used in the manufacture
of methamphetamine, a controlled substance.

   In December 2001, an informant told a government agent
that Lo previously had sold him precursor chemicals used to
5454                  UNITED STATES v. LO
manufacture a variety of controlled substances. Lo had sold
the informant very large quantities of ephedrine pills, iodine
products, and an oil base for Ecstasy. The informant pur-
chased these chemicals and resold them for the purpose of
manufacturing illegal drugs such as Ecstasy, speed, and “ice.”

   This information prompted government agents to initiate a
series of meetings with Lo, which the agents monitored. On
January 7, 2002, Lo gave price quotes to the informant for
bags of iodine and ephedrine barrels or bags. Lo said that he
was having trouble bringing the ephedrine into the United
States from Mexico. On January 15, 2002, Lo provided the
informant with a sample containing MDP-2-P, which the
informant then gave to government agents.

   On February 16, 2002, the informant introduced Lo to an
undercover officer who was posing as a methamphetamine
manufacturer. At that meeting, Lo asked the officer to manu-
facture one million tabs of Ecstasy for him. In addition, at that
meeting, and again at a later meeting, Lo agreed to provide
the chemicals for the manufacture of Ecstasy as well as
ephedrine for the manufacture of methamphetamine. On
March 13, 2002, Lo provided the informant with a box con-
taining MDP-2-P. On April 4, 2002, Lo, with his ex-wife Les-
lie Kuan, met with a government agent to discuss the status
of the manufacturing process for the Ecstasy and to discuss
the estimated delivery date for the Ecstacy.

  Lo obtained barrels of ma huang extract from a company
called Essential Pharmaceuticals. The ma huang extract was
obtained from the ma huang plant and contained approxi-
mately eight percent ephedrine, a higher concentration of
ephedrine than the unprocessed ma huang plant contains. A
company employee testified that he delivered barrels of ma
huang extract to both Lo and Kuan. He also testified that he
saw Kuan and Lo remove labels from the barrels of ma huang
extract with a knife or blade. On April 11, 2002, officers
observed Lo and Kuan unloading barrels and large trash bags
                         UNITED STATES v. LO                       5455
of ma huang extract into a storage locker. The following day,
officers observed Lo and Kuan loading barrels of ma huang
extract into a van outside of the Essential Pharmaceuticals
company. On that same day, officers executed a search war-
rant on Lo’s storage locker and found 230 barrels of ma
huang extract, which a field test showed tested positive for
ephedrine. Officers found an additional 40 barrels of the ma
huang extract at the defendant’s home. Agents later found 297
more barrels of ma huang extract at another storage locker
registered to Kuan and Lo. Invoices showed that a pharma-
ceutical company delivered 32,675 kilograms (1,307 barrels)
of ma huang extract to Lo and Kuan at a total supplier’s cost
of $272,367.50.

B.    The Indictment

   In the first amended superseding indictment, Count One
charged Lo and Kuan and others known and unknown with
conspiring to commit the following offenses: 1) To distribute
ephedrine, a listed chemical, knowing and1 having reasonable
cause to believe that the ephedrine would be used to manufac-
ture a controlled substance, methamphetamine, in violation of
21 U.S.C. § 841(c)(2); 2) To aid and abet the manufacture of
more than 500 grams of a mixture or substance containing a
detectable amount of methamphetamine, a controlled sub-
stance, in violation of 21 U.S.C. § 841(a)(1) and 18 U.S.C.
§ 2; 3) To distribute MDP-2-P, a listed chemical, knowing
and having reasonable cause to believe that the MDP-2-P
would be used to manufacture Ecstacy, a controlled sub-
stance, in violation of 21 U.S.C. § 841(c)(2); and 4) To aid
and abet the manufacture of Ecstasy, a controlled substance,
in violation of 21 U.S.C. § 841(a)(1) and 18 U.S.C. § 2.

     Count Two charged Lo with violating 21 U.S.C.
  1
   Although the statute itself requires knowledge “or reasonable cause to
believe,” see 21 U.S.C. § 841(c)(2) (emphasis added), the indictment
repeatedly used the word “and,” not “or.”
5456                  UNITED STATES v. LO
§ 841(c)(2) by knowingly and intentionally distributing MDP-
2-P, a listed chemical, knowing and having reasonable cause
to believe that the MDP-2-P would be used to manufacture
MDMA, a controlled substance.

   Count Three charged Lo and Kuan with violating 21 U.S.C.
§ 841(c)(2) by knowingly and intentionally possessing MDP-
2-P, a listed chemical, knowing and having reasonable cause
to believe that the MDP-2-P would be used to manufacture
Ecstasy, a controlled substance.

   Count Four charged Lo and Kuan with violating 21 U.S.C.
§ 841(c)(2) by knowingly and intentionally possessing ephed-
rine, a listed chemical, knowing and having reasonable cause
to believe that the ephedrine would be used to manufacture
methamphetamine, a controlled substance.

  Count Five charged Lo with violating 18 U.S.C. § 1957 by
using money obtained from the unlawful distribution of
ephedrine to buy a Lexus coupe.

  Lo also was charged and acquitted of other counts not rele-
vant to this appeal.

C.     District Court Proceedings

   Lo and Kuan were tried beginning on July 15, 2003. At
trial, the defendants and the Government both presented
expert testimony regarding the contents of the ma huang
extract, the extraction of ephedrine from ma huang, and the
use of ephedrine in the manufacture of methamphetamine.

   Lo testified at trial. He admitted that he provided the infor-
mant with 5 gallons of “oil” (MDP-2-P) on March 13, 2002,
and that he told the informant that the oil was worth
$200,000. He also admitted that he had called the informant
to ask when the Ecstasy pills were going to be ready because
he was under a lot of pressure. In addition, he admitted that
                     UNITED STATES v. LO                  5457
he agreed to provide the agents with ephedrine as part of his
payment for the Ecstasy.

   Lo claimed that he never intended to get involved in mak-
ing Ecstasy and that he was only trying to swindle buyers
rather than enabling them to make drugs. He testified that he
never intended for the ephedrine to be extracted from the ma
huang extract and made into methamphetamine. Instead, he
claimed, he wanted to cheat people by selling them ma huang
instead of ephedrine.

   On July 25, 2003, the jury returned its verdicts, convicting
Lo on counts One through Five of the indictment and acquit-
ting Kuan on all counts. Pursuant to Rule 29 (c) of the Federal
Rules of Criminal Procedure, Lo then moved for a judgment
of acquittal notwithstanding the verdict on Count One, which
charged him with conspiracy, and Counts Four and Five,
which charged him with possession of ephedrine and related
money laundering. The court denied the motion for Count
One, but granted the motion for Counts Four and Five. Both
parties moved for reconsideration. The judge denied both
motions.

   On April 20, 2004, the district court sentenced Lo to 235
months imprisonment. He also sentenced Lo to five years of
supervised release on Count One and three years of super-
vised release on Counts Two and Three, to be served concur-
rently.

                              II.

A.   Appellate Jurisdiction to Review the Acquittals

  Lo contends that we do not have jurisdiction to consider the
Government’s appeal of the district court’s order granting the
motion for acquittals on Counts Four and Five. Section 3731
of the Criminal Code provides:
5458                  UNITED STATES v. LO
    In a criminal case an appeal by the United States
    shall lie to a court of appeals from a decision, judg-
    ment, or order of a district court dismissing an
    indictment or information or granting a new trial
    after verdict or judgment, as to any one or more
    counts, or any part thereof, except that no appeal
    shall lie where the double jeopardy clause of the
    United States Constitution prohibits further prosecu-
    tion.

18 U.S.C. § 3731.

   [1] Lo claims that section 3731 does not authorize the Gov-
ernment to appeal a district court order granting a judgment
of acquittal. He acknowledges that we ruled in United States
v. Sharif, 817 F.2d 1375, 1376 (9th Cir. 1987), that we do
have jurisdiction to consider a government appeal of a district
court’s order granting a judgment of acquittal after a jury has
returned a guilty verdict. Nevertheless, Lo argues that the
plain language of section 3731 does not mention acquittals
and that, as a result, section 3731 does not provide jurisdiction
for appeals from acquittals. He therefore requests that this
panel call for en banc review and overturn cases such as Sha-
rif.

   [2] It is true that the language of section 3731 does not
mention acquittals and that Sharif did not discuss the plain
language of the statute, addressing only a Double Jeopardy
argument. However, the Sharif court relied in part upon the
Supreme Court’s decision in United States v. Wilson, 420
U.S. 332 (1975). See Sharif, 817 F.2d at 1376. Lo attempts to
distinguish Wilson on the ground that Wilson involved the dis-
missal of an indictment rather than an acquittal, and the lan-
guage of section 3731 does include dismissing indictments. In
fact, though, the Supreme Court did not rest its decision in
Wilson on a conclusion that the district court had dismissed
the indictment.
                      UNITED STATES v. LO                   5459
   In Wilson, the defendant was found guilty by a jury. 420
U.S. at 334. Following the verdict, the district court dismissed
the indictment on the ground that preindictment delay was
unreasonable and had substantially prejudiced the defendant’s
right to a fair trial. Id. The government sought to appeal the
dismissal pursuant to section 3731. Id. at 335. The Court of
Appeals found that the district court’s ruling was in effect an
acquittal, but concluded that the government could not appeal
the acquittal because of the Double Jeopardy Clause. Id.

   [3] Significantly, the Supreme Court found it unnecessary
to determine whether the district court actually had granted an
acquittal or had dismissed an indictment. See id. at 336-39.
Examining the legislative history of section 3731, the Court
concluded that the Senate Report “indicated that the Judiciary
Committee intended to extend the Government’s appeal rights
to the constitutional limits.” Id. at 339. After examining the
legislative history, the Court concluded that “it seems ines-
capable that Congress was determined to avoid creating non-
constitutional bars to the Government’s right to appeal.” Id.
at 340. The Court therefore held that the district court’s order
was appealable unless there was a constitutional bar to the
appeal, implicitly ruling that section 3731 authorizes appeals
from a court’s grant of acquittal unless the appeal is barred by
the Constitution. Id. The Court then went on to hold that
“when a judge rules in favor of the defendant after a verdict
of guilty has been entered by the trier of fact, the Government
may appeal from that ruling without running afoul of the Dou-
ble Jeopardy Clause.” Id. at 353-54.

   [4] Thus, Supreme Court precedent establishes that we do
have jurisdiction when a district court grants an acquittal after
a jury reaches a guilty verdict. We are bound by this prece-
dent, and we therefore have jurisdiction to consider the Gov-
ernment’s appeal of the district court’s order granting Lo’s
motion for acquittals following the jury verdicts.
5460                      UNITED STATES v. LO
B.     Possession of Ephedrine

  The jury found Lo guilty of violating section 841(c)(2)2 by
possessing ephedrine knowing, or having reasonable cause to
believe, that the ephedrine would be used to manufacture a
controlled substance. Following the verdict, however, the
judge granted acquittals on this count and the related Count
Five. The judge reasoned that Lo possessed ma huang, not
ephedrine, and that the defendant’s expert showed that
extracting ephedrine from ma huang extract required a labori-
ous process. The Government argues that there was sufficient
evidence for the jury to find that Lo possessed ephedrine
because the ma huang extract seized from Lo contained
ephedrine.

   We review de novo the district court’s grant of a Fed. R.
Crim. P. 29(c) acquittal motion. United States v. Martinez,
122 F.3d 1161, 1163 (9th Cir. 1997). “A judgment of acquittal
is improper if, viewing the evidence in the light most favor-
able to the government, a rational trier of fact could have
found the defendant guilty beyond a reasonable doubt.”
United States v. Alston, 974 F.2d 1206, 1210 (9th Cir. 1992).

   [5] Both parties primarily rely upon our decision in United
States v. Daas, 198 F.3d 1167 (9th Cir. 1999), to support their
arguments. The parties differ, however, in their interpretations
of that case, and they present different tests for determining
when a chemical that is combined with other substances is
considered a “listed chemical.” We hold that, in order for a
chemical that is commingled with other substances to be con-
sidered a listed chemical for purposes of section 841(c), the
  2
    Section 841(c)(2) penalizes “[a]ny person who knowingly or intention-
ally — possesses or distributes a listed chemical knowing, or having rea-
sonable cause to believe, that the listed chemical will be used to
manufacture a controlled substance except as authorized by this subchap-
ter.” 21 U.S.C. § 841(c)(2). “Ephedrine, its salts, optical isomers, and salts
of optical isomers” are listed chemicals. 21 U.S.C. § 802(34)(C).
                         UNITED STATES v. LO                      5461
chemical must: 1) maintain its distinct chemical identity
within the combination rather than changing into a different
chemical; and 2) must maintain its utility in the manufacture
of a controlled substance.

1.       Maintaining a Distinct Chemical Identity

   In Daas, we considered whether products that include
ephedrine may be considered “list I chemicals” for purposes
of 21 U.S.C. § 802 (34). Daas, 198 F.3d at 1173-79. Daas was
convicted of distributing listed chemicals with reasonable
cause to believe they would be used to manufacture metham-
phetamine. Id. at 1171. Daas sold large quantities of two
brands of over-the-counter decongestants to convenience
stores. Id. These products contained ephedrine and
pseudoephedrine, but also contained other ingredients such as
binders and an expectorant. Id. Daas argued that section
841(d)(2) criminalized only the distribution of pure ephedrine
and pseudoephedrine. Id. We disagreed and held that the plain
meaning of “listed chemical” included the ephedrine found in
the over-the-counter products Daas sold. Id. at 1175.

   In holding that the ephedrine and pseudoephedrine con-
tained in the over-the-counter products were listed chemicals,
we noted that the ephedrine and pseudoephedrine in the prod-
ucts retained a separate existence. Id. As part of our analysis,
we determined that the over-the-counter products were “mix-
tures” containing extractable ephedrine and pseudoephedrine.
Id. The fact that the products were mixtures was significant
because, by definition, a mixture’s components retain a sepa-
rate existence; we defined a “mixture” as “ ‘a portion of mat-
ter consisting of two or more components3 that do not bear a
     3
   Lo contends that the Government was required to prove that all the ma
huang extract components other than the ephedrine functioned solely as a
carrier medium or packaging material. Daas provides no support for such
a contention. Nowhere in Daas did we suggest that the other components
combined with the ephedrine must function as a carrier medium or pack-
5462                     UNITED STATES v. LO
fixed proportion4 to one another and that however thoroughly
commingled are regarded as retaining a separate existence.”
Id. at 1174-75 (quoting Chapman v. United States, 500 U.S.
453, 461 (1991)).

   [6] In contrast, we explained that a “chemical compound”
is something that “necessarily implies not a mere mingling of
components but a chemical combination of them, resulting in
their destruction as distinct entities and in the development of
a new substance possessing properties radically different from
those of its constituent elements.” Id. at 1175 (internal quota-
tion omitted). It makes sense that a substance may not be con-
sidered a listed chemical merely because it is capable of
reacting with other substances to produce a listed chemical.
Just as possession of a listed chemical that can be used to
manufacture a controlled substance is not sufficient to prove
possession of a controlled substance, possession of a precur-
sor to a listed chemical is not sufficient to prove possession
of the listed chemical. Congress did not criminalize the pos-
session of all materials that are important to the manufacture
of a controlled substance; the material must be one of the
identified listed chemicals. See 21 U.S.C. § 841(c). Thus, the
Government was required to prove that the ephedrine main-
tained a separate existence within the ma huang extract seized

aging material. In fact, we concluded in Daas that the substances other
than the ephedrine and pseudoephedrine that were contained in the over-
the-counter products were “irrelevant.” Daas, 198 F.3d at 1175. We
reached this conclusion partly because the ephedrine and pseudoephedrine
did not disappear or become different chemicals when added to the other
substances. Id.
   4
     Relying on Daas, Lo argues that the prosecution was required to prove
that the ephedrine did not bear a fixed proportion to the other components
in the ma huang extract. However, the Daas court did not even discuss
whether there was a fixed proportion when it reached the conclusion that
the ephedrine contained in the pills was a listed chemical. Although evi-
dence regarding a lack of fixed proportions might be useful in proving that
a chemical maintained its separate identity within a combination of sub-
stances, such evidence regarding proportions is not required.
                     UNITED STATES v. LO                  5463
from Lo. It would not have been sufficient if the ma huang
extract was a precursor material that could be used to create
ephedrine.

   During the trial and other proceedings before the district
court, Lo never argued that the ephedrine did not maintain a
separate identity within the ma huang extract and he did not
introduce any evidence that would support a finding that the
ephedrine did not maintain a separate existence within the ma
huang extract. Although Lo’s expert questioned exactly how
much ephedrine could be extracted from the ma huang
extract, he never contested the fact that the ma huang extract
seized from Lo contained ephedrine. Nevertheless, on appeal,
Lo argues that there was insufficient evidence that the ephed-
rine retained a separate existence within the ma huang extract.

   [7] Examining the evidence in the light most favorable to
the Government, we hold that there was sufficient evidence
that the ephedrine maintained a separate existence within the
ma huang extract. The Government expert, a chemist, testified
that the ma huang extract contained approximately 8% ephed-
rine. When asked how she reached this conclusion, she testi-
fied that she performed high performance liquid chromatogra-
phy (“HPLC”). She explained that HPLC “basically
quantitates how much sample is present in your second sam-
ple, how much pure sample is in there,” and she further
explained that, by “pure sample,” she was referring to ephed-
rine.

   The district court concluded that the Government had
merely proved that the ma huang could be changed into
ephedrine through a chemical process. The judge apparently
was basing this conclusion on the HPLC testing process. In
order to conduct the HPLC analysis, the Government expert
dissolved the ma huang extract in alcohol. There was no evi-
dence at all, however, that there was a chemical reaction that
resulted in the production of ephedrine. The Government
expert testified that she was merely diluting the ma huang
5464                  UNITED STATES v. LO
extract in the alcohol and that she also could have performed
this procedure using water instead of alcohol. She repeatedly
testified that the ma huang extract contained ephedrine, not
that the ma huang extract could be used as an ingredient to
make ephedrine. Not surprisingly, in a field test, the ma huang
extract seized from Lo tested positive for ephedrine.

   [8] Testimony by other experts also supports the jury’s ver-
dict. A DEA agent with specialized training in clandestine
drug laboratories testified that ma huang contains ephedrine.
Lo’s own expert testified that the ma huang extract he tested
was like other ma huang extract that contained 8% ephedrine.
He also testified that the assay showing the ephedrine content
in the ma huang extract “is a determination of how much
some material of interest is contained in some sample, like sil-
ver in a silver dollar.” In addition, he testified that ephedrine
had been extracted from ma huang and that an “extraction
process is a removal of something from something else; a
pulling out.” All of this testimony provides sufficient evi-
dence that the ephedrine maintained its existence within the
ma huang extract and was not merely subsequently derived
from a chemical reaction with the ma huang extract.

2. Utility of the Ephedrine in the Production of
Methamphetamine

   Lo contends that the Government was required to prove
that ephedrine easily could be extracted from the ma huang
extract and used to manufacture methamphetamine, and he
further contends that the Government failed to provide suffi-
cient evidence of these facts. Although the Daas court did
conclude that the ephedrine in that case was “easily extract-
able” from the cold tablets, the court did not rule that easy
extraction was required. Daas, 198 F.3d at 1175. The Daas
court directed its analysis toward determining whether com-
bining the ephedrine with other substances affected the utility
of the ephedrine. See id. Given the legislative scheme at issue,
such an analysis makes sense. If the chemical that is mingled
                           UNITED STATES v. LO                           5465
with other substances cannot ever be used to manufacture a
controlled substance, there cannot be a violation of the statute;
the reason for statutorily identifying chemicals as listed chem-
icals is to prevent their use in the manufacture of controlled
substances. Section 802(34) defines a list I chemical as a
“chemical that is used in manufacturing a controlled sub-
stance.” 21 U.S.C. § 802(34). Thus, if the ephedrine in the ma
huang extract cannot be used to manufacture a controlled sub-
stance, then it cannot be considered a listed chemical.

   [9] The fact that it is difficult to use a particular chemical
to manufacture a controlled substance, however, does not
mean that the chemical cannot or will not be used in the man-
ufacture of controlled substances. Drug sales can be
extremely lucrative and the selling price of a controlled sub-
stance may make it worth the effort and cost to engage in a
difficult process to be able to manufacture the drug. Thus, a
person is not exempt from prosecution for possession of a
listed chemical simply because combining the chemical with
other substances makes it difficult to use the chemical to man-
ufacture a controlled substance.

   [10] For example, DEA regulations exempt unaltered5 ma
huang plant material and other ma huang products with rela-
tively low concentrations of ephedrine from certain registra-
tion and record-keeping requirements concerning the sale and
importation of listed chemicals. See 21 C.F.R. § 1310.12(c),
(d)(1). Nevertheless, the regulations explicitly state that an
exemption from the record keeping and reporting regulations
  5
    The ma huang extract at issue in this case would not qualify for such
an exemption. The exemption for plant material is limited to plant material
that preserves the natural constituents in ratios that are found in the plant’s
natural state. 21 C.F.R. § 1310.12(d)(1). The regulation explicitly states
that “[p]lant material subjected to chemical or physical extraction, concen-
tration, chemical reaction, or other treatment that alters the plant’s natural
constituents or the ratios of the plant constituents are not exempt.” Id. This
kind of extracted and concentrated material is precisely the kind of mate-
rial at issue in the instant case.
5466                     UNITED STATES v. LO
does not affect “the criminal liability for illegal possession,
distribution, exportation, or importation of listed chemicals
contained in the exempt chemical mixture.” 21 C.F.R.
§ 1310.12(b). Therefore, in a case such as the instant one,
where the ephedrine concentration in the ma huang extract is
too high for the extract even to qualify for an exemption from
the registration and record keeping requirements,6 criminal
  6
    The DEA established the concentration limit based on its concern that
exempted chemical mixtures, including ma huang, were providing drug
traffickers with an unregulated source for obtaining listed chemicals. See
68 Fed. Reg. 23195, 23196 (May 1, 2003). The DEA was aware that ma
huang and ma huang extracts containing ephedrine had been seized from
clandestine methamphetamine laboratories. See id. at 23198. The DEA
explicitly noted: “DEA studies confirm that the ephedrine contained in
such extracts and some dietary supplement products can be readily recov-
ered and can be easily used in the production of methamphetamine.” Id.
Thus, the DEA concluded that “Ephedra (in the form of dietary supple-
ments or bulk ephedra extract), therefore, can and is being used as the
source of precursor material for the illicit production of methamphet-
amine.” Id.
   At first, the DEA responded to these concerns by proposing regulating
ma huang products, including ma huang extracts, whenever the percentage
of ephedrine exceeded 2%. Id. at 23199. However, members of the dietary
supplement industry protested that the regulations would be too burden-
some and that their products were not likely to be used to manufacture
methamphetamine; therefore, they suggested limiting the regulation of ma
huang products to products containing more than 6% ephedrine. Id. at
23199-200. Recognizing that a 2% limit would create a significant regula-
tory burden, the DEA agreed to raise the concentration limit above 2%. Id.
at 23195.
   However, the DEA agreed to raise the concentration limit only to 5%
because it believed that higher concentrations of bulk ephedra extracts are
practical sources for a methamphetamine precursor. Id. at 23200. Thus, the
DEA concluded that the 5% concentration limit was “expected to exempt
the vast majority of dietary supplements containing ephedrine/
pseudoephedrine while allowing bulk ephedra extract to be treated as a
regulated chemical.” Id. (emphasis added). This 5% limit is now con-
tained in 21 C.F.R. § 1310.12(c). The uncontradicted testimony in Lo’s
case was that the ma huang extract seized from him was an extract that
contained 8% ephedrine. Therefore, the ma huang extract seized from Lo
would not qualify for the regulatory exemption.
                     UNITED STATES v. LO                   5467
liability certainly should be possible even if it is not easy to
extract the ephedrine and use it to manufacture methamphet-
amine.

   There was sufficient evidence in the record from which a
reasonable juror could find that the ephedrine in the ma huang
extract seized from Lo could be used to manufacture metham-
phetamine. The Government’s expert witness, a chemist, testi-
fied that she extracted ephedrine from the ma huang extract
seized from Lo and that one could use the ephedrine in the ma
huang extract to manufacture methamphetamine. She also tes-
tified about an alternate method that could be used to extract
the ephedrine from the ma huang extract and that this ephed-
rine could be used to make methamphetamine. In addition, the
DEA special agent, who had specialized training in clandes-
tine drug laboratories, testified that ephedrine is used to man-
ufacture methamphetamine.

   [11] Even Lo’s own expert testified about articles he had
read in which people had extracted ephedrine from ma huang.
He also testified that he found a method where he could suc-
cessfully extract ephedrine from ma huang extract and he did,
in fact, extract ephedrine oxylate, an ephedrine salt that is a
listed chemical. Thus, although Lo’s expert testified that it
would be difficult to extract the ephedrine and manufacture
methamphetamine, there was sufficient evidence for a jury to
find that the ephedrine in the ma huang extract could be used
to manufacture methamphetamine.

   [12] Because we hold that there was sufficient evidence
that the ephedrine maintained its separate identity within the
ma huang extract and that it could be used to manufacture
methamphetamine, we reverse the district court’s grant of
acquittals on Counts Four and Five.

C.   Conspiracy

  Lo was tried for conspiring to achieve four objects of the
conspiracy: 1) to distribute ephedrine, knowing or having rea-
5468                    UNITED STATES v. LO
sonable cause to believe the ephedrine would be used to man-
ufacture a controlled substance; 2) to aid and abet the
manufacture of methamphetamine; 3) to distribute MDP-2-P,
knowing or having reasonable cause to believe the MDP-2-P
would be used to manufacture a controlled substance; and 4)
to aid and abet the manufacture of Ecstacy. In a special ver-
dict, the jury convicted Lo of conspiring to achieve all four
objects of the conspiracy. The jury acquitted Kuan of conspir-
acy. Following the verdict, the district court denied Lo’s
motion for an acquittal on the conspiracy conviction and then
denied Lo’s motion for reconsideration. Lo appeals, claiming
that there was insufficient evidence to support a conviction
for conspiracy.

   We review de novo the denial of a motion for a Fed. R.
Crim. P. 29(c) acquittal, examining the evidence in the light
most favorable to the Government to determine whether any
rational trier of fact could have found the essential elements
of the crime beyond a reasonable doubt. United States v.
Pacheco-Medina, 212 F.3d 1162, 1163 (9th Cir. 2000).

1.       Lo’s Co-Conspirator

   Lo contends that there was insufficient evidence to support
the conspiracy conviction because most of his interactions
were with undercover operatives. It is true that the agreement
in a conspiracy cannot be established with evidence that the
defendant had an agreement with a government informer.7 See
United States v. Escobar de Bright, 742 F.2d 1196, 1198-
2000 (9th Cir. 1984). The question, therefore, is whether there
was sufficient evidence to find a conspiracy with someone
other than government agents and informants.
     7
   In fact, the judge instructed the jury as follows: “Before being con-
victed of a conspiracy, an individual must conspire with at least one
coconspirator. There can be no conspiracy when the only person with
whom the defendant allegedly conspired was a government informer who
secretly intended to frustrate the conspiracy.”
                           UNITED STATES v. LO                           5469
   Lo also argues that any conviction for conspiracy cannot be
based on a theory that the convicted person conspired with
someone whom the jury acquitted of conspiracy. Therefore,
because the jury acquitted Kuan of conspiracy, Lo claims that
we may not rely on evidence of an agreement with Kuan to
find sufficient evidence that he committed conspiracy.

   [13] Lo’s argument has no merit. It is well established that
a person may be convicted of conspiring with a co-defendant
even when the jury acquits that co-defendant of conspiracy.
United States v. Valles-Valencia, 823 F.2d 381, 382 (9th Cir.
1987), modifying 811 F.2d 1232 (9th Cir. 1987). Indeed, in
Valles-Valencia, we affirmed8 a conspiracy conviction even
though there was insufficient evidence that the convicted con-
spirator conspired with anyone other than people whom the
jury acquitted of conspiracy. Id. at 382, modifying 811 F.2d
at 1239; see also United States v. Hughes Aircraft Co., 20
F.3d 974, 977-78 (9th Cir. 1994) (affirming conspiracy con-
viction where “indispensable co-conspirator” was acquitted of
conspiracy on identical evidence); United States v. Ayers, 924
F.2d 1468, 1483 (9th Cir. 1991) (affirming conspiracy convic-
tion and concluding that “the acquittal of all conspirators but
one does not necessarily indicate that the jury found no agree-
ment” with the acquitted co-conspirators). As a result of this
  8
    In Valles-Valencia, we originally concluded that the appellant’s con-
spiracy conviction had to be reversed because his co-conspirators had been
acquitted of conspiracy. 811 F.2d at 1239. However, we then reconsidered
our opinion in light of United States v. Powell, 469 U.S. 57 (1984). In
Powell, the Supreme Court rejected a rule that had allowed defendants to
challenge a conviction based on the fact that the conviction was inconsis-
tent with the jury’s other verdicts. Powell, 469 U.S. at 66. The Supreme
Court reasoned that inconsistent verdicts do not necessarily lead to the
conclusion that the guilty verdict was the incorrect verdict. Id. at 65. In
Valles-Valencia, we relied upon Powell to conclude that “inconsistent ver-
dicts can just as easily be the result of jury lenity as a determination of the
facts. Thus, the acquittal of all conspirators but one does not necessarily
indicate that the jury found no agreement to act.” Valles-Valencia, 823
F.2d at 381-82. We therefore affirmed the conspiracy conviction based on
an agreement with acquitted co-defendants. Id.
5470                   UNITED STATES v. LO
legal precedent, we must affirm Lo’s conviction for conspir-
acy if there is sufficient evidence that he conspired with
Kuan, even though the jury acquitted Kuan of conspiracy.

2.    The Sufficiency of the Evidence

   To establish a drug conspiracy, the Government must
prove: 1) an agreement to accomplish an illegal objective; and
2) the intent to commit the underlying crime. United States v.
Iriarte-Ortega, 113 F.3d 1022, 1024 (9th Cir. 1997), amended
on denial of reh’g, 127 F.3d 1200 (9th Cir. 1997). Proof of the
agreement may be based on circumstantial evidence from
which the jury may draw an inference of an agreement. Id. at
1024. Thus, a conspiracy may be proven by circumstantial
evidence that the defendants acted together towards a com-
mon goal. Id.

   Here, the crimes that were the alleged objects of the con-
spiracy were illegal distribution of listed chemicals and aiding
and abetting the manufacture of controlled substances. Illegal
distribution of a listed chemical in violation of section 841(c)
requires knowingly distributing a substance that is a listed
chemical knowing or having reasonable cause to believe that
the listed chemical will be used to manufacture a controlled
substance. 21 U.S.C. § 841(c)(2).

     Aiding and abetting contains four elements:

      (1) that the accused had the specific intent to facili-
      tate the commission of a crime by another, (2) that
      the accused had the requisite intent of the underlying
      substantive offense, (3) that the accused assisted or
      participated in the commission of the underlying
      substantive offense, and (4) that someone committed
      the underlying substantive offense.

United States v. Garcia, 400 F.3d 816, 818 n.2 (9th Cir. 2005)
(citations and emphasis omitted).
                         UNITED STATES v. LO                       5471
   [14] Section 841(a) prohibits “knowingly or intentionally”
manufacturing a controlled substance. 21 U.S.C. § 841(a). As
with unlawful possession under section 841(a), there is a
criminal intent requirement for unlawfully manufacturing a
controlled substance in violation of section 841(a), so knowl-
edge that one is manufacturing an unlawful substance is a
required element. Cf. United States v. Lopez-Martinez, 725
F.2d 471, 474 (9th Cir. 1984) (holding that to prove unlawful
possession under section 841, the defendant must have knowl-
edge that he possessed a controlled substance). Therefore, the
charge of conspiracy to aid and abet the manufacture of a con-
trolled substance requires a belief that the chemicals will be
used to manufacture a controlled substance, not just reason-
able cause to believe that the chemical will be used to manu-
facture controlled substances.

   Examining the evidence in the light most favorable to the
Government, we hold that there was sufficient evidence to
support a verdict that Lo conspired with Kuan9 to achieve the
methamphetamine-related objects of the conspiracy. On Janu-
ary 15, 2002, surveillance agents saw Kuan loading barrels
into vans and then unloading the barrels at a trash dump. The
agent also testified that the barrels he observed looked like the
seized barrels that contained ma huang extract. On April 11,
2002, Kuan helped Lo load approximately 18 heavy and large
trash bags from a storage locker into a van. Kuan and Lo then
took the van to their apartment and backed the van into the
garage. On April 12, 2002, a special agent observed Kuan
closing the door to her van with barrels inside of it. Kuan and
Lo then took the barrels to the apartment and into the parking
garage, where they then unloaded the barrels. Later that day,
agents seized 40 barrels of ma huang extract from that loca-
tion. The agents subsequently found 297 more barrels at
another storage locker to which Kuan and Lo had joint access.
  9
   The Government also claims that there is sufficient evidence to prove
that Lo conspired with persons whose names are unknown, as charged in
the indictment. Since we hold that there is sufficient evidence to find a
conspiracy between Lo and Kuan, we need not reach this issue.
5472                     UNITED STATES v. LO
   A witness from the pharmaceutical company testified that
he delivered the barrels of ma huang extract to both Lo and
Kuan. Even more significantly, that witness also testified that
he saw both Kuan and Lo remove the identifying labels from
the barrels of ma huang extract. Since possession of ma huang
extract was not in and of itself illegal, this is compelling evi-
dence that Kuan and Lo actually believed that the huge vol-
ume of ma huang extract they were hiding in storage units
was going to be used to manufacture methamphetamine and
that they were trying to hide their unlawful conduct. Thus, we
hold that, viewing the evidence in the light most favorable to
the Government, there was sufficient evidence that Lo and
Kuan conspired to distribute ephedrine,10 knowing or having
reasonable cause to believe the ephedrine would be used to
manufacture a controlled substance and that they conspired to
aid and abet the manufacture of methamphetamine.

   There also was sufficient evidence to support the jury ver-
dicts relating to the Ecstasy related objects of the conspiracy.
On April 11, 2002, agents saw Kuan come out of the apart-
ment garage and give Lo a plastic bottle containing brown liq-
uid. On April 12, 2002, agents seized from that same location
a five-gallon box containing the brown liquid, which was
MDP-2-P.

   [15] Kuan also was present at a meeting in which Lo and
others discussed the progress of the Ecstasy manufacturing,
including the estimated date that the Ecstacy would be deliv-
  10
     Lo argues that, at the very least, there was insufficient evidence
regarding the object of distributing ephedrine because he agreed only to
distribute ma huang, not ephedrine. There are two problems with this
argument. First, as discussed above, there was sufficient evidence to find
that the ma huang extract contained ephedrine. Second, Lo did not have
to possess ephedrine to conspire to distribute ephedrine. Even if Lo pos-
sessed only ma huang extract and not ephedrine, there is sufficient evi-
dence that he was part of a conspiracy where there was an agreement to
ensure that ephedrine was obtained from the ma huang extract and distrib-
uted for purposes of manufacturing methamphetamine.
                      UNITED STATES v. LO                   5473
ered to Lo. Her presence was not mere happenstance; the
agents had been informed ahead of time that she was going
to attend the meeting. Examining the evidence in the light
most favorable to the Government, there is sufficient evidence
to support a verdict that Kuan and Lo conspired to distribute
MDP-2-P, knowing or having reasonable cause to believe the
MDP-2-P would be used to manufacture a controlled sub-
stance and that they conspired to aid and abet the manufacture
of Ecstasy. Therefore, we affirm the district court’s denial of
Lo’s motion for an acquittal on the conspiracy count.

D.   Jury Instructions

   On appeal, Lo contends that a number of jury instructions
were erroneous. At trial, Lo did not object to any of the jury
instructions he now challenges. Therefore, we review the jury
instructions for plain error. See Jones v. United States, 527
U.S. 373, 388 (1999). Under the plain error standard, the
defendant must prove that: 1) there was error; 2) the error was
plain; and 3) the error affected substantial rights. United
States v. Olano, 507 U.S. 725, 732 (1993). Even if a defen-
dant makes all three of these showings, a court should exer-
cise its discretion to reverse a conviction only if the error
seriously affects the fairness, integrity or public reputation of
judicial proceedings. Id. An error is not plain unless it “is so
clear-cut, so obvious, a competent district judge should be
able to avoid it without benefit of objection.” United States v.
Turman, 122 F.3d 1167, 1170 (9th Cir. 1997). Reversal on the
basis of plain error is an exceptional remedy and an improper
jury instruction rarely justifies reversal of a conviction for
plain error. United States v. Still, 857 F.2d 671, 671-72 (9th
Cir. 1988).

1. The Mens Rea Jury Instructions for Possession of a
Listed Chemical

   On the section 841(c)(2) count for possession of MDP-2-P,
the district court instructed the jury as follows:
5474                 UNITED STATES v. LO
       The defendants are charged in Count Three of the
    first amended superseding indictment with the pos-
    session of MDP-2-P.

       In order for the defendant to be found guilty of
    that charge, the government must prove beyond a
    reasonable doubt : First, that the defendants know-
    ingly possessed MDP-2-P; second, the defendants
    knowingly possessed it, knowing or having reason-
    able cause to believe that it would be used to manu-
    facture a controlled substance.

       It does not matter whether the defendants knew
    that MDP-2-P was a list chemical. It is sufficient that
    the defendants knew or had reasonable cause to
    believe that it would be used to manufacture a con-
    trolled substance or some other prohibited drug.

The jury instructions for Counts Two and Four were the same
for all relevant purposes. Lo contends that it was plain error
to give these jury instructions regarding mens rea because the
instructions did not require the Government to prove that Lo
knew that the substances were listed chemicals.

   To determine what mental state is required to prove a viola-
tion of a statute, the court must look to the language of the
statute and the intent of Congress. United States v. Johal, 428
F.3d 823, 826 (9th Cir. 2005). Where the language of the stat-
ute is not dispositive, the court looks to the congressional
intent revealed in the history and purposes of the statutory
scheme. Adams Fruit Co. v. Barrett, 494 U.S. 638, 642
(1990).

   [16] Section 841(c)(2) mandates punishment for “[a]ny per-
son who knowingly or intentionally — possesses or distrib-
utes a listed chemical knowing, or having reasonable cause to
believe, that the listed chemical will be used to manufacture
                     UNITED STATES v. LO                   5475
a controlled substance except as authorized by this chapter.”
21 U.S.C. § 841(c)(2).

   Lo argues that the jury instructions eliminate the first mens
rea requirement, “knowingly,” and therefore conflict with the
plain language of section 841(c)(2). He apparently believes
that the word “knowingly” plainly modifies the term “listed
chemical” rather than modifying the term “possesses or dis-
tributes.” It is not at all obvious from the statute’s phrasing
that knowingly applies to “listed chemical.”

   However, it also is not entirely clear from the grammar
alone that “knowingly” does not modify both the phrase “pos-
sesses or distributes” and “listed chemical.” In Liparota v.
United States, 471 U.S. 419, 421 n.1 (1985), the Supreme
Court considered a statute11 that provided that “whoever
knowingly uses, transfers, acquires, alters, or possesses cou-
pons or authorization cards in any manner not authorized by
this chapter or the regulations issued pursuant to this chapter
shall, if such coupons or authorization cards are of a value of
$100 or more, be guilty of a felony.” The Government argued
that the term “knowingly” applied only to the use, acquisition,
transfer, alteration and possession part of the statute. Id. at
424. The defendant argued that “knowingly” required that the
defendant know that the acquisition, use, transfer, or posses-
sion was in a manner not authorized by statute or regulation.
Id. The Court concluded that either interpretation would
accord with ordinary usage and noted that such ambiguity fre-
quently exists in other contexts where, as a matter of gram-
mar, the word “knowingly” could be interpreted in a variety
of ways to modify several words or terms. Id. at 425 and 425
n.7.

  Although the legislative history contained nothing that
would clarify the congressional purpose, the Liparota Court
  11
   The statute was the former 78 Stat. 708, as amended, 7 U.S.C.
2024(b)(1).
5476                      UNITED STATES v. LO
determined that the appropriate interpretation of the statute
was to require proof that the defendant knew that his conduct
was unauthorized by statute or regulation. Id. at 425-26. The
Court reasoned that criminal offenses requiring no mens rea
are generally disfavored and that “to interpret the statute oth-
erwise would be to criminalize a broad range of apparently
innocent conduct.”12 Id. at 427.

   As in Liparota, at first blush, the grammar used in section
841(c)(2) may create some ambiguity here regarding which
terms the word “knowingly” modifies. Nevertheless, Lo’s
case clearly is distinguishable from Liparota. First, unlike in
Liparota, where the statute contained no mens rea require-
ment, there is a mens rea requirement in section 841(c)(2).13
  12
      Similarly, the other cases on which Lo relies also created or extended
statutory mens rea requirements based on the principles that criminal stat-
utes usually should require criminal intent and statutes should be con-
strued so that they do not lead to the absurd result of criminalizing
seemingly innocent conduct. See Arthur Andersen LLP v. United States,
125 S. Ct. 2129, 2134-36 (2005) (holding that statutory term “knowingly”
modified “corruptly persuades” because alternative interpretation would
criminalize “innocent conduct”); United States v. X-Citement Video, Inc.,
513 U.S. 64, 68-69 (1994) (holding that the use of “knowingly” in a child
pornography distribution statute modified “the use of a minor” because
some form of scienter was required for the criminal statute and the alterna-
tive interpretation would lead to the absurd result of punishing people who
had no idea they even were dealing with sexually explicit material); Sta-
ples v. United States, 511 U.S. 600, 606, 608-14 (1994) (reading into stat-
ute that criminalized possession of a machine gun the requirement that the
defendant know that the firearm is a machine gun because offenses that
require no mens rea are disfavored and firearm owners otherwise might
be subject to criminal penalties without even knowing their firearms had
the illegal features).
   13
      Lo essentially is asking this Court to read into the statute a provision
that would exonerate a defendant who was ignorant about which sub-
stances were deemed listed chemicals under the law. However, even in
cases where courts must read into a statute a mens rea requirement, that
“mens rea presumption requires knowledge only of the facts that make the
defendant’s conduct illegal, lest it conflict with the related presumption,
‘deeply rooted in the American legal system,’ that, ordinarily, ‘ignorance
of the law or a mistake of law is no defense to criminal prosecution.’ ”
Staples v. United States, 511 U.S. 600, 622 n.3 (1994) (Ginsburg, J. con-
curring) (quoting Cheek v. United States, 498 U.S. 192, 199 (1991)).
                         UNITED STATES v. LO                        5477
See Johal, 428 F.3d at 827 (holding that section 841(c)(2)
requirement of knowledge or “reasonable cause to believe”
imposes a mens rea requirement). This mens rea requirement
ensures that apparently innocent conduct is not criminalized.
Id. (rejecting argument that section 841(c)(2) puts unwitting
store clerk at risk of going to prison simply for selling
decongestants containing pseudoephedrine).

   Second, unlike in Liparota, where the legislative history
was unilluminating, the legislative history available for sec-
tion 841(c)(2) indicates that Congress did not intend for the
word “knowingly” to mean that the Government was required
to prove that the defendant knew that the substance was a
listed chemical. The current version of section 841(c)14
resulted from an amendment of earlier statutory language.
Congress substituted “possesses or distributes a listed chemi-
cal knowing, or having reasonable cause to believe, that the
listed chemical will be used to manufacture a controlled sub-
stance except as authorized by this subchapter” for “possesses
any piperidine knowing, or having reasonable cause to
believe, that the piperidine will be used to manufacture phen-
cyclidine except as authorized by this subchapter.” Anti-Drug
Abuse Act of 1988, Pub. L. No. 100-690 § 6055(a)(1988).
Thus, the word “knowingly” was in the earlier version of the
statute that did not even mention listed chemicals. Therefore,
it is unreasonable to conclude that, when Congress made the
decision to include the word “knowingly” in the statute, it
included that word in order to insert an additional requirement
that people convicted under the statute know that the sub-
stance was a listed chemical.

  [17] Moreover, it seems very unlikely that Congress would
  14
    The current version of section 841(c) was denoted section 841(d) until
the original section 841(c) was repealed. The original version of section
841(d), however, differed from what is now section 841(c). The amend-
ment at issue here took place when the statutory provision still was
denominated section 841(d)(2).
5478                 UNITED STATES v. LO
have chosen to make prosecution more difficult by requiring
proof that the defendant knew that the chemical was a listed
chemical, while at the same time seeking to expand the scope
of prosecution for the possession and distribution of precursor
chemicals by increasing the number of chemicals that could
provide the basis for prosecution. Thus, the legislative history
reveals that Congress did not intend to require that the Gov-
ernment prove that defendants knew that the chemicals they
possessed were listed chemicals.

   Lo argues that, to the extent the meaning of “knowingly”
is unclear, the panel should apply the rule of lenity and adopt
Lo’s interpretation of the statute. However, “the rule of lenity
is not to be applied where to do so would conflict with the
implied or expressed intent of Congress.” Liparota, 471 U.S.
at 427. Here, the implied intent of Congress was that the word
“knowingly” would not modify the term “listed chemical.”
Therefore, the rule of lenity does not apply.

   [18] Because section 841(c)(2) does not require that defen-
dants know that the substances they possess or distribute are
listed chemicals, we hold that the district court did not err by
providing the disputed mens rea instructions for the section
841(c)(2) counts.

2.   The Aiding and Abetting Jury Instructions

   Two of the alleged objects of the conspiracy were aiding
and abetting the manufacture of controlled substances. Lo
contends that the district court committed plain error when it
failed to instruct the jury on the elements of aiding and abet-
ting the manufacture of a controlled substance.

   The judge’s conspiracy instructions included the following
instructions:

     The defendants are charged in Count One of the first
     amended superseding indictment with the crime of
                     UNITED STATES v. LO                    5479
    conspiracy, conspiring to do one of four things — to
    violate the law in one of four ways: The first is to
    distribute ephedrine, a List I chemical, knowing and
    having reasonable cause to believe that the ephedrine
    would be used to manufacture a controlled sub-
    stance, namely, methamphetamine, a Schedule II
    controlled substance. That’s one of the alleged pur-
    poses of the conspiracy.

       Number 2, it is alleged they conspired to aid and
    abet the manufacture of more than 500 grams of a
    mixture of a substance containing a detectable
    amount of methamphetamine, a Schedule II con-
    trolled substance.

      The third law that they are alleged to have con-
    spired to violate is to distribute MDP-2-P, which is
    a List I chemical, knowing and having reasonable
    cause to believe that the MDP-2-P would be used to
    manufacture a controlled substance, namely — the
    big long name here. But basically, it would be used
    to manufacture what is abbreviated as MDMA, a
    Schedule I controlled substance.

       The fourth is the unlawful object of a conspiracy
    to aid and abet the manufacture of a controlled sub-
    stance, namely, MDMA, a Schedule I controlled
    substance, in violation of Title 21, United States
    Code, Sections 846 and 841(a)(1).

   The judge did not further explain the meaning of aiding and
abetting while giving the conspiracy instructions. However,
after providing instructions specifically relating to Counts
Two, Three, and Four, the judge provided the jury with aiding
and abetting instructions regarding the distribution and pos-
session of listed chemicals.

  Lo argues that the jury instructions constituted plain error
because the jurors could not properly determine whether he
5480                 UNITED STATES v. LO
had the requisite intent to commit the crime unless they knew
the mens rea elements of the underlying crime. The intent
necessary to commit the underlying substantive offense is an
essential element of a conspiracy, so jury instructions that
erroneously construe the requisite intent for underlying
offenses can cause the jury to misunderstand the intent
required for the conspiracy count. United States v. Kim, 65
F.3d 123, 126 (9th Cir. 1995).

   [19] The jurors in Lo’s case could have extracted general
aiding and abetting elements from the jury instructions on aid-
ing and abetting the possession or distribution of listed chemi-
cals and then applied those elements to the allegations of
conspiracies to aid and abet the manufacture of controlled
substances. The problem, however, was that the jury did not
receive any instructions regarding the mens rea requirements
for manufacturing a controlled substance in violation of sec-
tion 841(a). This was an obvious error. Lo contends that the
erroneous jury instructions regarding the conspiracy to aid
and abet the manufacture of controlled substances affected the
verdict. He argues that the only substantive offense instruc-
tion that the jury received in the conspiracy instructions was
for the section 841(c)(2) distribution offense, which statu-
torily requires a mens rea requirement of “knowing, or having
reasonable cause to believe.” Therefore, Lo contends, the jury
could have mistakenly relied upon the “reasonable cause to
believe” standard and erroneously believed that Lo could be
convicted of conspiring to aid and abet the manufacture of
controlled substances even if he met only this lower mens rea
standard.

  The mens rea requirement of “reasonable cause to believe”
presents an evidentiary burden very similar to actual knowl-
edge. As we recently observed in Johal:

    [R]easonable cause to believe is not purely objective,
    but turns on the facts actually known by the defen-
    dant in a particular case — facts from which the jury
                     UNITED STATES v. LO                    5481
     can infer that any reasonable person in the defen-
     dant’s position would have had to know that the
     ingredients were being bought to make illegal drugs.
     As a practical matter, therefore, the differences
     between actual and constructive “knowledge” under
     the statute are not substantial.

United States v. Johal, 428 F.3d 823, 828 (2005) (emphasis
omitted).

   [20] In some cases, however, the slight difference in these
standards might make a difference in the verdict. There is a
complicating factor here, though, that makes the distinction
between the standards irrelevant. When the judge instructed
the jurors on the conspiracy charges and explained the distri-
bution objects of the conspiracy, the judge actually used the
phrase “knowing and having reasonable cause to believe”
rather than “knowing or having reasonable cause to believe.”
Thus, when the jurors were considering the aiding and abet-
ting objects of the conspiracy, if they mistakenly relied on the
mens rea requirements from the distribution objects of the
conspiracy, “knowledge” would have been the mens rea stan-
dard they applied. If anything, the burden arguably was higher
in the instant case because the jurors may have concluded that
the belief also had to be a reasonable one. Since the erroneous
jury instructions did not lower the mens rea standard for con-
spiring to aid and abet the manufacture of controlled sub-
stances, the error did not affect Lo’s substantial rights.

E.   Sentencing

   The district court sentenced Lo based on an offense level
of 38, with no departures or adjustments to the base offense
level. The base offense level was a result of the quantity of
ephedrine. The court concluded that, even using the more
conservative drug quantity figures calculated by the defen-
dant’s expert, there would be 170 kilograms of ephedrine,
which is far more than the three kilograms that results in the
5482                  UNITED STATES v. LO
base offense level of 38 pursuant to U.S.S.G. § 2D1.11(d)(1).
The court sentenced Lo to 235 months, the very bottom of the
235-293 month range that applied to the total offense level of
38 and criminal history category I.

   The court also sentenced Lo to five years of supervised
release on Count One and three years of supervised release on
Counts Two and Three, to be served concurrently. The five-
year term of supervised release was a mandatory minimum
term imposed pursuant to 21 U.S.C. § 841(b)(1)(A)(viii)
because of the special verdict finding that Lo had conspired
to aid and abet the manufacture of at least 500 grams of a
mixture or substance containing a detectable amount of
methamphetamine. Based on that special verdict finding on
the aiding and abetting object of the conspiracy, pursuant to
21 U.S.C. § 841(b), Lo also was subject to a mandatory mini-
mum prison sentence of ten years, although the actual sen-
tence far exceeded ten years. Lo makes multiple arguments
regarding his sentencing.

1.   The Applicability of Section 841(b)

   First, Lo contends that it was error for the district court to
ask the jury to determine the amount of methamphetamine
involved and that he therefore should not be subject to the
mandatory minimum penalties contained in 21 U.S.C.
§ 841(b). He bases these arguments on his contention that the
Supreme Court’s decision in United States v. Booker, 543
U.S. 220 (2005), effectively overruled the Ninth Circuit’s
holding in United States v. Buckland, 289 F.3d 558 (9th Cir.
2002) (en banc), and that the penalty provisions contained in
section 841(b) are unconstitutional and must be severed from
the “unlawful acts” provisions contained in section 841(a).

   In Buckland, the defendant challenged the constitutionality
of 21 U.S.C. § 841(b)(1)(A). The jury convicted the defendant
of possession of methamphetamine, but it was the judge who,
applying a preponderance of the evidence standard, deter-
                      UNITED STATES v. LO                    5483
mined the amount of methamphetamine involved. Id. at 562-
63. The judge sentenced him based on that quantity. Id. Buck-
land argued that section 841 was facially unconstitutional
because it required a judge to determine the drug quantity and
to apply a preponderance of the evidence standard. Id. at 563-
64. The Government acknowledged that the judge should
have submitted the question of drug quantity to the jury for
a finding beyond a reasonable doubt, id. at 563, but urged us
to resolve the problem through severance, id. at 564.

   We determined that severance was unnecessary. Id. at 567.
Relying on basic rules of statutory construction, we recog-
nized that “if an otherwise acceptable construction of a statute
would raise serious constitutional problems, and where an
alternative interpretation of the statute is ‘fairly possible,’ we
are obligated to construe the statute to avoid such problems.”
Id. at 564 (internal quotation marks and citations omitted).
Examining the language of section 841, the court noted that
the statute neither specified who would determine the drug
quantity nor identified the appropriate burden of proof. Id. at
565. We therefore construed the language of section 841 as
requiring that the drug quantity and type be charged in the
indictment, submitted to the jury, subjected to the rules of evi-
dence, and proved beyond a reasonable doubt. Id. at 568. As
a result, we concluded that the statute was constitutional and
there was no need to sever anything from the statute. Id. at
567.

   Lo argues, however, that Booker essentially stands for the
proposition that, whenever a sentencing provision can be
interpreted to violate the Sixth Amendment, the appropriate
judicial response is severance. Therefore, he claims, Booker
requires severance of the enhanced penalty provisions con-
tained in section 841(b).

  Booker does not support this proposition. In Booker, the
Supreme Court explained that “[i]f the Guidelines as currently
written could be read as merely advisory provisions that rec-
5484                     UNITED STATES v. LO
ommended, rather than required, the selection of particular
sentences in response to differing sets of facts, their use
would not implicate the Sixth Amendment.” Booker, 543 U.S.
at 233. However, the Court concluded that the language of the
statute clearly made the Guidelines mandatory and binding on
all judges. Id. The Court therefore concluded that the manda-
tory Guidelines violated the Sixth Amendment and then sev-
ered certain statutory provisions as a remedy. Id. at 244-68.

  [21] Thus, in Booker, the Supreme Court resorted to sever-
ing some statutory provisions only because the statute could
not be construed in a constitutional manner. As we found in
Buckland, however, the penalty provisions in section 841(b)
can reasonably be construed in a constitutional manner.
Booker does nothing to change this. Therefore, we hold that
Lo is subject to the mandatory minimums15 for terms of
imprisonment and supervised release contained in section
841(b).

2.   Ameline Remand

   [22] Lo contends that he is entitled to a limited remand pur-
suant to United States v. Ameline, 409 F.3d 1073 (9th Cir.
2005) (en banc). Because Lo was sentenced under the then-
mandatory Sentencing Guidelines and it is not clear from the
record whether the court would have imposed a materially
different sentence had it known that the Guidelines were only
advisory, it is appropriate to remand to the sentencing court
for a determination of whether that court would have imposed
a different sentence. See id.; see also United States v.
Moreno-Hernandez, 419 F.3d 906, 916 (9th Cir. 2005)
(extending Ameline’s limited remand procedure to cases
involving non-constitutional Booker errors).
  15
     Lo contends that, if he is subject to the minimum sentence, in accor-
dance with Booker, the minimum should be an advisory minimum, not a
mandatory minimum. There is nothing in Booker to suggest that statutorily
mandated minimum sentences are merely advisory if the sentence is based
on facts found by a jury by a preponderance of the evidence.
                    UNITED STATES v. LO                5485
                        Conclusion

   We REVERSE the district court’s grant of acquittals on
Counts Four and Five and AFFIRM the district court’s denial
of Lo’s motion for acquittal on Count One. We REMAND for
reconsideration of Lo’s sentence in accordance with Ameline.
