FOR PUBLICATION
  UNITED STATES COURT OF APPEALS
       FOR THE NINTH CIRCUIT

UNITED STATES OF AMERICA,                    No. 05-30261
                Plaintiff-Appellee,
               v.                              D.C. No.
                                            CR-03-00311-MJP
ALFONSO ALLAN BROOKS,
                                               OPINION
             Defendant-Appellant.
                                       
        Appeal from the United States District Court
          for the Western District of Washington
        Marsha J. Pechman, District Judge, Presiding

                   Argued and Submitted
            April 13, 2007—Seattle, Washington

                   Filed November 29, 2007

      Before: Alex Kozinski and Raymond C. Fisher,
  Circuit Judges, and Andrew J. Guilford,* District Judge.

                  Opinion by Judge Guilford




   *The Honorable Andrew J. Guilford, United States District Judge
for the Central District of California, sitting by designation.

                             15379
15382              UNITED STATES v. BROOKS


                         COUNSEL

Lenell Nussbaum, Seattle, Washington, for the defendant-
appellant.

Todd L. Greenberg (argued) and Sarah Y. Vogel, Assistant
United States Attorneys, Seattle, Washington, for the
plaintiff-appellee.


                         OPINION

GUILFORD, District Judge:

   Appellant Alfonso Allan Brooks (“Brooks”) appeals his
drug-related convictions, challenging aspects of the jury
instructions, the indictment, the sentencing, and testimony he
                   UNITED STATES v. BROOKS               15383
claims was reversible vouching. We affirm, although we do
not condone the vouching.

                      BACKGROUND

   The drug investigation in this case began in New York and
moved to Seattle, where the Drug Enforcement Administra-
tion (“DEA”) obtained a wiretap and intercepted Brooks’s
calls from April 4, 2003 through August 1, 2003. Two teams
of agents in Seattle also conducted full-time surveillance of
Brooks and his associates. The coordinated efforts revealed
that Brooks and others were obtaining, distributing, and
exchanging illegal drugs.

   Brooks was arrested on August 4, 2003. The final indict-
ment charged him with multiple counts of possessing drugs
and firearms. During a long trial lasting most of June 2004,
the government presented extensive testimony, wiretap evi-
dence, and seized items, including drugs and a TEC DC9 9
millimeter handgun. During closing argument, defense coun-
sel conceded “that the proper verdicts in this case on behalf
of Mr. Brooks would be to find him guilty of [Counts] 15, 17,
and 18.” The jury found Brooks guilty of all counts.

   Brooks was sentenced to imprisonment of 20 years on the
drug counts—the mandatory minimum—and five years on the
firearm count, with 10 years of supervised release.

  We review in turn the four areas of concern raised on
appeal.

                         ANALYSIS

1.   JURY INSTRUCTION FOR COUNT 18

   Brooks challenges a jury instruction for Count 18, posses-
sion of a firearm in furtherance of a drug trafficking crime in
violation of 18 U.S.C. § 924(c). First, Brooks argues the
15384              UNITED STATES v. BROOKS
instruction improperly failed to define the crucial phrase “in
furtherance of.” Second, Brooks claims that the instruction
improperly included “aiding and abetting” language. Third,
Brooks asserts that the instruction permitted the jury to find
that he possessed the gun in furtherance of crimes he commit-
ted far from where he kept the gun.

  The instruction stated:

      Defendant Brooks is charged in Count 18 of the
    Indictment with Possession of a Firearm in Further-
    ance of a Drug Trafficking Crime on or about
    August 4, 2003, at 

Street, Coving-
    ton, Washington, in violation of Section 924(c) of
    Title 18 of the United States Code. In order for the
    defendant to be found guilty of that charge, the gov-
    ernment must prove each of the following elements
    beyond a reasonable doubt:

       First, the defendant committed a drug trafficking
    crime, specifically one of the following, as alleged in
    the Indictment: Count 1 — Conspiracy to Distribute
    Controlled Substances; Count 15 — Possession with
    Intent to Distribute Cocaine on or about August 4,
    2003; Count 16 — Possession with Intent to Distrib-
    ute Methamphetamine on or about August 4, 2003;
    or Count 17 — Possession with Intent to Distribute
    MDMA (ecstacy) on or about August 4, 2003, with
    all of you agreeing as to the particular crime; and

      Second, on or about August 4, 2003, the defendant
    knowingly possessed a TEC DC9 9 mm caliber
    semi-automatic pistol, or aided and abetted the pos-
    session of the pistol; and

     Third, the defendant possessed the TEC DC9 9
    mm caliber semi-automatic pistol, or aided and abet-
                    UNITED STATES v. BROOKS                15385
     ted its possession, in furtherance of the drug traffick-
     ing crime.

(Emphasis added)

   Brooks did not object to the instruction at trial, so we
review for plain error. United States v. Steward, 

,
320 (9th Cir. 1994). In a plain error case involving a jury
instruction, “we correct an error . . . only where the error (1)
is plain, (2) affects substantial rights, and (3) ‘seriously
affects the fairness, integrity or public reputation of judicial
proceedings.’ ” United States v. Tirouda, 

, 688
(9th Cir. 2005) (quoting United States v. Jordan, 

, 926 (9th Cir. 2001)). Here, the instruction is plainly erro-
neous if “there is a significant possibility the jury might have
acquitted if it had considered the matter.” 

. This instruction was not plain error.

   [1] All of Brooks’s arguments on the Count 18 instruction
are foreclosed because his counsel twice conceded during
closing argument that Brooks should be found guilty of Count
18. Specifically, defense counsel said that “the proper verdicts
in this case on behalf of Mr. Brooks would be to find him
guilty of [Counts] 15, 17, and 18. . . . [T]hese are the counts
that I believe the government has proven, and those are the
counts I believe you should find him guilty of.” Defense
counsel also said, “the only weapon [count] that you should
find him guilty of is count 18.” With these concessions, there
is no “significant possibility the jury might have acquitted” on
Count 18, and attacks concerning Count 18 cannot succeed.

.

2.   INDICTMENT

   For the first time on appeal, Brooks argues that several
counts of the indictment were multiplicitous. Because Brooks
did not raise this indictment issue before trial, he has waived
his right to appeal it.
15386               UNITED STATES v. BROOKS
   Under Rule 12(b)(3) and 12(e) of the Federal Rules of
Criminal Procedure a defendant waives any “defect in the
indictment” not raised “before trial.” We have recognized that
claims of multiplicity are subject to Rule 12(b)(3). United
States v. Klinger, 

, 708 (9th Cir. 1997) (concern-
ing an earlier version of Rule 12(b)). Brooks has waived any
claim that the indictment is multiplicitous.

3.   SENTENCE ENHANCEMENT

   Brooks challenges his sentence enhancement, arguing that
his prior conviction was not a felony drug offense, which is
necessary for the enhancement under 21 U.S.C. § 841(b).
Brooks also argues that the Sixth Amendment required the
government to prove his prior conviction to a jury. Both argu-
ments fail.

   [2] The statutory procedure for imposing the enhancement
in this case provides that “[i]f the person denies any allegation
of the information of prior conviction, or claims that any con-
viction alleged is invalid, he shall file a written response to
the information.” 21 U.S.C. § 851(c)(1). Absent good cause,
any challenge not raised by response to the information is
waived. 

   Here, the government filed an Enhanced Penalty Informa-
tion under 21 U.S.C. § 851 and sought a mandatory minimum
of 20 years imprisonment under 21 U.S.C. § 841(b) because
of Brooks’s prior Arizona felony drug offense. Brooks filed
a response denying every allegation of this information, but
not specifically challenging the validity or nature of his con-
viction.

   [3] Elsewhere, however, Brooks conceded the fact of his
prior conviction. In his Motion to Dismiss the Enhanced Pen-
alty Information, Brooks’s counsel stated that Brooks had
pleaded guilty on drug importation charges. He further stated
that “[t]he court sentenced him to 3.5 years . . . . The offense
                    UNITED STATES v. BROOKS                15387
is a class 3 felony under Arizona law.” Brooks’s counsel con-
firmed this at the sentencing hearing, where he admitted that
the prior drug conviction had a term of imprisonment of three
and one half years, and where the district court immediately
concluded that “[i]t was treated as a felony by the state of Ari-
zona.” It was not error for the court to apply the sentence
enhancement because Brooks failed to fully object, and
because Brooks’s counsel stated more than once that Brooks
had been convicted on a drug count with a sentence of over
one year. See 21 U.S.C. § 802(44) (definition of “felony drug
offense”).

  [4] Brooks cannot successfully challenge the sentence
enhancement.

4.   VOUCHING

   Brooks’s final argument is that there was improper vouch-
ing requiring reversal. First, Brooks argues there was vouch-
ing in the direct examination of three witnesses. Second,
Brooks argues that the redirect examination of one of these
witnesses implied that the court and others had made conclu-
sions about the witness’s veracity. Third, Brooks argues there
was vouching in the government’s evidence about the wiretap
authorization process. We agree with Brooks that the govern-
ment engaged in improper vouching. Nevertheless, we affirm
because the error did not affect Brooks’s substantial rights.
Fed. R. Crim. P. 52(b).

   [5] “Improper vouching typically occurs in two situations:
(1) the prosecutor places the prestige of the government
behind a witness by expressing his or her personal belief in
the veracity of the witness, or (2) the prosecutor indicates that
information not presented to the jury supports the witness’s
testimony.” United States v. Hermanek, 

, 1098
(9th Cir. 2002). Because Brooks failed to object to the vouch-
ing, we review for plain error. Fed. R. Crim. P. 52(b); United
States v. Molina, 

, 1444 (9th Cir. 1991). In
15388               UNITED STATES v. BROOKS
vouching cases under the plain error standard, “[w]e reverse
only if, viewing the error in the context of the entire record,
the impropriety ‘seriously affects the fairness, integrity or
public reputation of judicial proceedings, or where failing to
reverse a conviction would amount to a miscarriage of jus-
tice.’ ” United States v. Necoechea, 

, 1276 (9th
Cir. 1993) (quoting 

). After first
examining the claims of vouching, we then determine if there
is plain error requiring reversal.

   First, Brooks claims there was vouching in the direct exam-
ination of cooperating witnesses. One witness testified that his
plea agreement required him “to say the truth about every-
thing I know and make sure everything is the truth because if
they find out I’m lying, they will rip up the agreement and I’ll
end up with 25 to life.” Another witness testified that under
his plea agreement, any false testimony by him would greatly
increase his sentence. A third witness testified that if he “gave
truthful testimony against Alfonso Brooks in this case,” then
he “may receive a downward departure for time off.” Wit-
nesses testified that they were speaking the truth before the
jury and were living up to the terms of their plea agreements.

   These statements are mild forms of vouching because they
suggest that the witness, “who might otherwise seem unreli-
able, has been compelled by the prosecutor’s threats and the
government’s promises to reveal the bare truth.” United States
v. Wallace, 

, 1474 (9th Cir. 1988). Such refer-
ences imply that “the prosecutor can verify the witness’s testi-
mony and thereby enforce the truthfulness condition of its
plea agreement.” 

Brooks claims there was vouching in the redi-
rect examination of the cooperating witness Juan Soriano
(“Soriano”) concerning Soriano’s earlier plea agreement that
greatly reduced his sentence. Soriano agreed with the prose-
cutor’s statement that under his plea agreement he had to
“give truthful testimony and that [he] could not lie in [his] tes-
                    UNITED STATES v. BROOKS                15389
timony.” Soriano also agreed with the prosecutor’s suggestion
that the prosecutors and the judge in other trials believed he
testified truthfully, and that if he had “lied, given false testi-
mony at those trials,” he would not have been given a reduc-
tion in his sentence. When Soriano was asked about the
Brooks trial, he testified that if he gave false testimony, the
government “[would] break up my agreement and they
[would] end up giving me 25 to life.”

   [7] It is generally permissible to address an issue on redi-
rect examination that has been raised in cross-examination,
United States. v. Sarkisian, 

, 989 (9th Cir. 1999),
and here, Soriano’s credibility had been attacked on cross.
Still, this questioning was improper vouching. The testimony
left “the implication that the court, as well as law enforce-
ment, can, has, and will monitor the [witness’s] truthfulness.”
United States v. Ortiz, 

, 1279 (9th Cir. 2004).
The testimony about previous courts monitoring Soriano’s
statements and making positive assessments improperly bol-
stered Soriano’s credibility. “Whether the witnesses have tes-
tified truthfully, of course, is entirely for the jury to
determine; it is improper to communicate that a credibility
determination has been made by the AUSA, law enforcement
agents, or the court, or that the government knows whether
the witness is being truthful and stands behind the veracity of
the witness’s testimony.” 

candidly con-
cedes that its questioning “may constitute error.” It is vouch-
ing.

   [8] Third, Brooks claims there was vouching in the exten-
sive testimony about the process of obtaining wiretap authori-
zation. This wiretap testimony referenced approval by DEA
authorities, the United States Attorney’s Office, and state and
federal judges. It implied that the government and courts were
monitoring Brooks’s conduct and had determined he was
guilty.
15390              UNITED STATES v. BROOKS
   In United States v. Cunningham, 

(7th Cir.
2006), the Seventh Circuit examined the propriety of exten-
sive testimony on the wiretap authorization process.

       The obvious purpose of the evidence was to show
    the jury there were several senior government attor-
    neys and agents who all believed there was probable
    cause that the defendants were involved in a drug
    conspiracy, and, indirectly, that they all believed, in
    their professional judgment, the defendants were in
    fact committing drug-related crimes.

The court held that “[t]he government witness was
improperly vouching for how good the evidence was,” and
that the procedures detailed extensively by the witness,
“served only to bolster the credibility of the unnamed attor-
neys’ and agents’ respective determinations.” 

testimony here encouraged the jury to draw infer-
ences against Brooks. By discussing at length the process
involved in obtaining a wiretap authorization, the government
improperly bolstered its case. As in Cunningham, such testi-
mony indicated that many government attorneys and a federal
judge had decided that Brooks was guilty. This is vouching.

   The government’s argument that such testimony was per-
missible to lay a foundation for the wiretap evidence fails.
Although the parties did not stipulate to the admissibility of
the wiretap evidence, the authenticity of the recordings could
have been adequately established without such extensive
detail. As in Cunningham, the “government does not have to
prove that the electronic recording of the conversation was
properly authorized by a judge to establish the recording was
‘true, accurate and authentic.’ ” 

.

   [10] Having found different forms of vouching ranging
from mild to more serious, we now determine whether the
                    UNITED STATES v. BROOKS                15391
vouching requires reversal. We have not adopted a bright-line
rule about when vouching requires reversal. Instead, “[t]o
ascertain whether the . . . vouching amounts to plain error, the
court balances the seriousness of the vouching against the
effectiveness of any curative instruction and the closeness of
the case.” United States v. Daas, 

, 1178 (9th
Cir. 1999).

   [11] Here, the prejudice from vouching was reduced by
curative instructions wisely given twice by the district court.
At the trial’s beginning, the district court instructed the jury
to make careful credibility assessments of witnesses who had
“pleaded guilty to crimes arising out of the same events for
which the defendants are on trial,” and to “consider those wit-
nesses’ testimony with great caution, giving it the weight that
you feel it deserves.” A similar instruction was given at the
end of trial.

   [12] The strongest factor in concluding there is no plain
error here is that this was not a close case. The strength of the
government’s case is reflected in the fact that the defense con-
ceded liability on numerous counts. We have upheld convic-
tions in vouching cases where there is substantial independent
evidence of guilt. See 

(no plain error
where there was “other ‘non-vouched’ evidence” of criminal
intent); United States v. Lew, 

, 223-24 (9th Cir.
1989) (no plain error where there was substantial independent
evidence against the defendant). In a case involving wiretaps,
we found vouching errors were harmless, noting “[t]he tapes
themselves, as well as the physical evidence, created a strong
case that the wiretap evidence referred to cocaine transac-
tions.” 

.

   Reviewing specifically the vouching that occurred in direct
examination, we conclude there was no plain error. The plea
agreement references are only mild forms of vouching. And
because the credibility of these witnesses would almost cer-
tainly have been challenged during cross-examination, there
15392               UNITED STATES v. BROOKS
was justification to bolster credibility. In fact, defense counsel
did cross-examine these witnesses about the terms of their
plea agreements and their motivation for cooperating with the
government. On cross-examination, Soriano agreed with
defense counsel’s statement that, depending on his coopera-
tion, he could receive a sentence allowing him “to walk out
the jailhouse door.” With this interrogation, defense counsel
attacked Soriano’s credibility by suggesting his testimony had
been bought with sentencing concessions. Other cooperating
witnesses had similar cross-examinations.

  [13] With the curative instructions and the strength of the
government’s case, there is no plain error in the direct exami-
nations.

   [14] Soriano’s redirect examination and the improper
examination on the wiretap authorization process present
more serious issues. Although the curative instructions
reduced the overall impact of the vouching that occurred, they
were specifically directed to testimony from witnesses who
had pleaded guilty. They did not address the implication,
made by some of the vouching, that the government and
courts were monitoring Brooks’s conduct and had determined
he was guilty. Still, the government’s case was so strong that
the improper redirect and wiretap examinations do not require
reversal, even without perfectly worded curative instructions
applicable to all the vouching. At trial, defense conceded lia-
bility on numerous counts. In the context of the entire record
we have reviewed, the redirect and wiretap examinations did
not seriously affect the fairness, integrity, or public reputation
of judicial proceedings, and a miscarriage of justice does not
result from failing to reverse. 

.

   [15] Finally, we must consider “whether the . . . instances
of vouching cumulatively require reversal.” 

Our
conclusion does not change. Ultimately, the vouching did not
undermine the strong evidence presented against Brooks in a
lengthy trial, which began and ended with curative instruc-
                    UNITED STATES v. BROOKS                 15393
tions. Viewing the vouching cumulatively in the context of
the entire trial, the fairness, integrity, and public reputation of
judicial proceedings were not seriously affected, and failing to
reverse would not amount to a miscarriage of justice. Necoe-

. Thus, the seriousness of the vouching
did not outweigh all other considerations supporting the ver-
dict.

   The vouching here was within the broad bounds of the
plain error standard, but pushed hard against those bounds and
threatened the integrity of the verdict. It is not a model for
future trials.

                        CONCLUSION

  The judgment is AFFIRMED.