                FOR PUBLICATION

  UNITED STATES COURT OF APPEALS
       FOR THE NINTH CIRCUIT


UNITED STATES OF AMERICA,                 No. 12-50477
                Plaintiff-Appellee,
                                            D.C. No.
                 v.                      3:11-cr-03876-
                                             AJB-1
MARTIN ALCANTARA-CASTILLO,
            Defendant-Appellant.            OPINION


     Appeal from the United States District Court
        for the Southern District of California
     Anthony J. Battaglia, District Judge, Presiding

              Argued and Submitted
       December 4, 2013—Pasadena, California

                  Filed June 11, 2015

  Before: Dorothy W. Nelson, Kim McLane Wardlaw,
      and Johnnie B. Rawlinson, Circuit Judges.

              Opinion by Judge Wardlaw;
              Dissent by Judge Rawlinson
2         UNITED STATES V. ALCANTARA-CASTILLO

                           SUMMARY*


                          Criminal Law

    Reversing a conviction for illegal reentry, the panel held
that the government’s improper cross-examination and
argument deprived the defendant of the fair trial guaranteed
by the Due Process Clause.

    The panel held that error occurred when the prosecutor
implicitly and then explicitly asked the defendant to comment
on a Border Patrol agent’s veracity during cross-examination.
The panel also held that, as the government conceded, the
government improperly vouched for the Border Patrol agent’s
credibility by referring during its rebuttal argument to facts
not before the jury – that Border Patrol agents are “sworn to
uphold the law” – in a credibility showdown between the
Border Patrol agent and the defendant.

    The panel did not need to decide whether to apply
harmless error analysis because even under the more
restrictive plain error standard the combined misconduct
requires reversal.

    Dissenting, Judge Rawlinson wrote that the prosecutor’s
isolated question in response to the defendant’s spontaneous
challenge to the Border Patrol agent’s veracity during cross-
examination does not rise to the level of plain error; that the
district court did not abuse its discretion in denying a curative
instruction during the prosecutor’s rebuttal argument, where

  *
    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. ALCANTARA-CASTILLO                3

it granted the defendant’s motion to strike and instructed the
jury to disregard the prosecutor’s comment that the Border
Patrol agents were “sworn to uphold the law”; and that it is
highly unlikely that the prosecutor’s comment materially
affected the verdict.


                        COUNSEL

Paul A. Barr (argued), Federal Defenders of San Diego, Inc.,
San Diego, California, for Defendant-Appellant.

Laura E. Duffy, United States Attorney, Bruce R. Castetter,
Assistant United States Attorney, Chief, Appellate Section,
Criminal Division, and Kyle W. Hoffman (argued), Assistant
United States Attorney, San Diego, California, for Plaintiff-
Appellee.


                         OPINION

WARDLAW, Circuit Judge:

     Martin Alcantara-Castillo (Alcantara) appeals his jury
trial conviction for illegal reentry in violation of 8 U.S.C.
§ 1326. Because the government’s improper cross-
examination and argument deprived Alcantara of the fair trial
guaranteed by the Due Process Clause, we reverse.

                              I.

    On June 26, 2011, Border Patrol Agent Aaron Hunter
responded to a report that a motion sensor had been activated
approximately seven miles east of the Tecate port of entry.
4        UNITED STATES V. ALCANTARA-CASTILLO

Searching the area, he found Alcantara lying next to an
abandoned cargo container approximately one mile north of
the Mexican border. Alcantara was carrying a backpack and
was very dirty. Agent Hunter approached Alcantara,
questioning him in Spanish. Alcantara admitted that he was
a “citizen of Mexico and that he did not have any documents
allowing him to be in the United States.”

    Agent Hunter testified that as he escorted Alcantara
toward the highway where he had parked his patrol car,
Alcantara spontaneously began talking. According to Agent
Hunter, Alcantara volunteered that he had crossed the border
on foot the previous night with a group that had been chased
by border patrol agents on all-terrain vehicles. Alcantara said
he had become separated from the group and had decided to
turn around and return to Mexico. As Agent Hunter and
Alcantara returned to the highway, two other Border Patrol
agents joined them. They searched Alcantara, finding empty
bottles and food containers in his backpack.

    On cross-examination, Agent Hunter acknowledged that
he did not personally search Alcantara’s backpack, that he did
not take an inventory of its contents, and that he could not
specifically identify what was inside. Agent Hunter also
testified that on the day of Alcantara’s arrest he provided
information about the arrest to another agent who prepared an
official report, after which Agent Hunter wrote a detailed
addendum to the report. Neither of those documents contain
any mention of Alcantara’s spontaneous admissions about
crossing the border with a group, being chased by border
patrol agents on all-terrain vehicles, and attempting to return
to Mexico. Nor could Agent Hunter recall that he told
anyone at all about these spontaneous statements until he met
         UNITED STATES V. ALCANTARA-CASTILLO                 5

with prosecutors in preparation for Alcantara’s trial seven
months after Alcantara’s arrest.

    Border Patrol Agent Joseph Moore testified that the night
before Alcantara’s arrest, he was notified that a group of nine
aliens had been observed near the border. Four of the group
had been apprehended immediately, but five had fled. Agent
Moore searched the area and was able to apprehend four more
aliens, but he could not locate the ninth member of the group,
whose sex and identity were unknown.

    Taking the witness stand, Alcantara testified that he had
unknowingly entered the United States during a period of
methamphetamine-induced psychosis. Border Patrol Agent
Luis Martinez, who interviewed Alcantara shortly after his
arrest, testified that pursuant to Border Patrol policy, he
immediately terminated that interview when Alcantara stated
that he was under the influence of methamphetamine.
However, Agent Martinez did not observe anything in
Alcantara’s demeanor that led him to believe Alcantara was
under the influence of methamphetamine, although Alcantara
was hunched over during the interview.

    Alcantara admitted that he had been addicted to
methamphetamine since 1995 and used the drug daily,
stopping only when he was incarcerated. On June 24, 2011,
while high on methamphetamine, he impulsively decided to
enter a rehabilitation program after talking with another
methamphetamine user about a friend who had died three
months earlier due to drug abuse. Alcantara went to a bus
depot in Tijuana, where he lived, early in the morning on
June 25, for the purpose of traveling to a drug rehabilitation
facility located in El Hongo, east of Tecate. Before boarding,
6        UNITED STATES V. ALCANTARA-CASTILLO

however, he purchased some more methamphetamine near
the bus depot in Tijuana.

     Upon his arrival in Tecate, Alcantara decided to visit a
friend who lived on the outskirts of the city to tell him that he
was going to check into a rehabilitation clinic, but he never
reached his friend’s home. While walking there along some
railroad tracks, he encountered two men in a railroad tunnel
with whom he began a conversation. Alcantara ended up
smoking methamphetamine with these men—a larger
quantity of methamphetamine than he had ever used before.
Alcantara testified that he began to hallucinate, and that the
next thing he remembered was walking down a road, seeing
a small farm with some palm trees, picking up a bottle of
water, and lying down next to a container of some sort.
Without objection, the defense introduced a photograph of the
railroad tunnel, and Alcantara showed the jury where he had
been walking, where the train tracks were, and where he
stumbled upon the two men.

    Alcantara thought he was on the road that goes from
Tecate to Mexicali in Mexico. It was not until Agent Hunter
approached and he saw Agent Hunter’s uniform that he
realized he was in the United States.             Alcantara
acknowledged that he told Agent Hunter he was from
Mexico, but did not remember saying anything else to him
except to ask for water.

    Two additional witnesses testified for the defense. A
medical expert in addiction psychiatry who had interviewed
Alcantara opined that Alcantara was severely
methamphetamine dependent, based upon Alcantara’s
description of his methamphetamine use. He further testified
that people who use methamphetamine daily may suffer
           UNITED STATES V. ALCANTARA-CASTILLO                              7

hallucinations, paranoia, and disorientation as to time and
place, especially if they are also suffering from sleep
deprivation, dehydration, or extreme heat. A defense
investigator also testified that she had visited a drug
rehabilitation facility in El Hongo, along the highway from
Tecate to Mexicali, and had located a railroad tunnel near the
border in the eastern outskirts of Tecate. The defense also
introduced a photograph of a gap in the border fence near the
site of Alcantara’s arrest.

    The jury found Alcantara guilty, and the district court
sentenced him to a forty-month term of imprisonment.
Alcantara timely appealed.

                                     II.

    We have jurisdiction pursuant to 28 U.S.C. § 1291.
Where the defendant has objected to alleged prosecutorial
misconduct at trial, we review for harmless error.1 We view
the challenged conduct “in the entire context of the trial,” and
reverse “only if it appears more probable than not that
prosecutorial misconduct materially affected the fairness of
the trial.” Ruiz, 710 F.3d at 1082 (quoting Younger, 398 F.3d
at 1190). Where the defendant has not objected to the alleged
misconduct at trial, we review for plain error. We may


   1
     “Misconduct” is the term of art that we regularly use to describe
improper behavior by prosecutors that is inconsistent with the due process
requirements of a fair trial. See, e.g., United States v. Ruiz, 710 F.3d 1077,
1082 (9th Cir.), cert. denied, 134 S. Ct. 488 (2013); United States v.
Wright, 625 F.3d 583, 609–10, 613 (9th Cir. 2010); United States v.
Younger, 398 F.3d 1179, 1190 (9th Cir. 2005); United States v. Kerr,
981 F.2d 1050, 1051–52 (9th Cir. 1992). The use of this generic term
does not necessarily imply that the prosecutor intentionally broke the rules
or acted in bad faith.
8        UNITED STATES V. ALCANTARA-CASTILLO

reverse if: (1) there was error; (2) it was plain; (3) it affected
the defendant’s substantial rights; and (4) “viewed in the
context of the entire trial, the impropriety seriously affected
the fairness, integrity, or public reputation of judicial
proceedings.” United States v. Combs, 379 F.3d 564, 568
(9th Cir. 2004) (quoting United States v. Geston, 299 F.3d
1130, 1135 (9th Cir. 2002)). When assessing the combined
prejudicial effect of multiple errors, only as to some of which
the defense registered a timely objection, we apply the plain
error standard. See United States v. Weatherspoon, 410 F.3d
1142, 1150–51 (9th Cir. 2005).

                               III.

    A prosecutor “is the representative not of an ordinary
party to a controversy, but of a sovereignty whose obligation
to govern impartially is as compelling as its obligation to
govern at all; and whose interest, therefore, in a criminal
prosecution is not that it shall win a case, but that justice shall
be done.” Berger v. United States, 295 U.S. 78, 88 (1935).
A “prosecutor’s job isn’t just to win, but to win fairly, staying
well within the rules.” United States v. Maloney, 755 F.3d
1044, 1046 (9th Cir. 2014) (en banc) (quoting United States
v. Kojayan, 8 F.3d 1315, 1323 (9th Cir. 1993)).

    A prosecutor must not ask defendants during cross-
examination to comment on the truthfulness of other
witnesses. See, e.g., United States v. Harrison, 585 F.3d
1155, 1158 (9th Cir. 2009); Combs, 379 F.3d at 572; United
States v. Sanchez 176 F.3d 1214, 1219–20 (9th Cir. 1999).
This rule is “black letter law,” Harrison, 585 F.3d at 1158,
and it ensures that determinations of credibility remain within
the sole province of the jury. See Sanchez, 176 F.3d at
1219–20. Nor may prosecutors “vouch” for a witness by
        UNITED STATES V. ALCANTARA-CASTILLO                9

offering their personal opinion of a witness’s testimony, or
suggesting that information exists outside the record that
verifies the witness’s truthfulness. See, e.g., Weatherspoon,
410 F.3d at 1146–48; Combs, 379 F.3d at 574–75; Sanchez,
176 F.3d at 1224. Vouching compromises the integrity of the
trial and denies the defendant due process because the
“prosecutor’s opinion carries with it the imprimatur of the
Government and may induce the jury to trust the
Government’s judgment rather than its own view of the
evidence.” United States v. Reyes, 577 F.3d 1069, 1077 (9th
Cir. 2009) (internal quotation marks omitted).

    Alcantara argues that the government engaged in
improper questioning or vouching on four occasions during
his trial. We conclude that there were two instances of
improper conduct.

                             A.

    Error occurred when the prosecutor implicitly and then
explicitly asked Alcantara to comment on Agent Hunter’s
veracity during cross-examination. Agent Hunter had
testified to certain “spontaneous” admissions made by
Alcantara, but Alcantara testified that he only asked Agent
Hunter for water and acknowledged his Mexican citizenship.
Toward the end of the government’s cross-examination of
Alcantara, the prosecutor initiated the following exchange:

       Q: Now, it’s your testimony you didn’t recall
          any additional statements you made to the
          Border Patrol Agent on the day of your
          arrest for this case, correct?
10    UNITED STATES V. ALCANTARA-CASTILLO

     A: I don’t remember having told him
        anything.

     Q: You sat here throughout this trial, correct?

     A: Yes.

     Q: And you heard Border Patrol Agent
        Hunter testify that you had told him about
        coming in the day before with a group?
        You’ve heard that, correct?

     A: I don’t remember. I don’t remember.

     Q: You were sitting right here yesterday.

     A: Yes, but I don’t remember if he said that.

     Q: You don’t remember him saying, and your
        attorney repeatedly asking him, about
        your statements: that you had crossed over
        the day before and gone further north with
        a group? You don’t remember that?

     A: I don’t think so. I don’t think I crossed
        with people. I wasn’t with people.

     Q: That is not what I’m asking you. I’m
        asking you if you remember Agent
        Hunter, yesterday, telling the jury that you
        had made the statement that you had told
        him that you had crossed and gone further
        north?
        UNITED STATES V. ALCANTARA-CASTILLO               11

       A: Agent Hunter, he can say whatever he
          wants. He is saying I had a black sweater
          the day of my arrest, that I had food in my
          backpack, and there is nothing of that.
          That was all invented. All these things
          were invented.

       Q: Your testimony is that Agent Hunter is
          inventing stories about you; is that
          correct?

       A: Where are my things?

    Defense counsel objected to “this line of questioning as
vouching for Agent Hunter’s testimony.” The district court
erred by overruling this objection. But even if we view
counsel’s objection as untimely, it was plain error to permit
the prosecutor to ask, “Your testimony is that Agent Hunter
is inventing stories about you; is that correct?” We found
analogous questioning improper in Combs, 379 F.3d at 567,
572. There, a DEA agent testified that the defendant admitted
to manufacturing methamphetamine. Id. at 567. The
defendant testified that he never made such an admission, and
on cross-examination, the prosecutor questioned the
defendant as follows:

       Q: You told Special Agents Bailey and
          Cory that you last manufactured
          methamphetamine on or about August 5,
          isn’t that correct?

       A: I did not.
12       UNITED STATES V. ALCANTARA-CASTILLO

       Q: So Special Agent Bailey is making that
          up?

       A: I told you what happened. He said. I
          didn’t say. He answered. I ended the
          interview.

       Q: So you are saying that Special Agent
          Bailey is lying in his testimony?

Id. Just as the prosecutor asked the defendant in Combs if
Special Agent Bailey was “making that up” or “lying in his
testimony,” the prosecutor here asked Alcantara if Agent
Hunter was “inventing stories about you.” In Combs, we
concluded that the prosecutor’s questioning constituted plain
error. Id. at 572. See also Harrison, 585 F.3d at 1158
(finding error where the prosecutor asked the defendant if two
testifying police officers were lying); Sanchez, 176 F.3d at
1219–20 (finding error where the prosecutor forced the
defendant to call a U.S. marshal who testified a liar).

    The dissent, assuming that plain error is the correct legal
standard, finds a “crucial distinction” between this case and
others because the prosecutor used the word “invent” instead
of the word “lie.” Dissent at 32–33. This distinction is not
meaningful, much less “crucial.” In the context we address,
to “lie” and to “invent” have identical meanings: to fabricate
information. See Black’s Law Dictionary 1062 (10th ed.
2014) (defining “lie” as “[a] false statement or other
indication that is made with knowledge of its falsity; an
untruthful communication intended to deceive”); Webster’s
Third New International Dictionary 1188 (2002) (defining the
secondary meaning of the verb “invent” as “to think up or
imagine: concoct mentally: fabricate”); id. at 1305 (defining
         UNITED STATES V. ALCANTARA-CASTILLO                 13

the verb “lie” as “to make an untrue statement with intent to
deceive: tell a lie”); see also 8 Oxford English Dictionary 39
(2d ed. 1989) (defining the secondary meaning of the verb
“invent” as “[t]o devise something false or fictitious: to
fabricate, feign, ‘make up’”); id. at 905 (defining the verb
“lie” as “[t]o tell a lie or lies, to utter falsehood; to speak
falsely”). No matter which words are used to mean
“intentional deception,” the concept remains the same: it is
improper to compel the defendant “to comment on the
truthfulness of another witness.” Harrison, 585 F.3d at 1158.

    The dissent’s reliance on United States v. Greer, 640 F.3d
1011 (9th Cir. 2011), is misplaced. We noted in Greer that
we had “not yet addressed whether it is improper for the
prosecutor to ask the defendant, as the prosecutor did in [that]
case, if a witness testified ‘inaccurately.’” Id. at 1023. We
distinguished that question from asking “whether a
government witness had been ‘less than candid’ during his
testimony.” Id., n.8. Reasoning that “[b]ecause we see no
difference between asking whether a witness was ‘lying’ or
being ‘less than candid,’” we held that the “less than candid”
question “was improper.” Id.

    Here, the prosecutor did not ask whether the agent’s
testimony was inaccurate; he asked whether the agent was
“inventing stories” about Alcantara. Inaccuracy or mistake
can be achieved through inadvertence or other unintentional
error. Lying, making up, or inventing are all deliberate and
intentional falsehoods, like “being less than candid.” Do we
really want to narrow the prohibition against asking the
defendant to comment on the veracity of another agent to the
use of the word “lie?” Prosecutors could simply evade the
rule by asking whether another witness was “not telling the
truth,” fibbing, fabricating, making the story up, falsifying,
14        UNITED STATES V. ALCANTARA-CASTILLO

committing perjury, being “less than candid,” or whether his
story was “cock and bull.”2 Surely the admonition against
asking a defendant to comment on a government witness’s
veracity is violated equally when any of these formulations is
used. The remaining questions to be asked on plain error
review should be answered by addressing the circumstances
of each case.

    We also reject the government’s assertion that the
prosecutor was merely following up appropriately after
Alcantara “spontaneously attacked” Agent Hunter’s
credibility. In United States v. Moreland, 622 F.3d 1147 (9th
Cir. 2010), the government summarized the relevant
testimony of one of its witnesses and asked the defendant
whether he remembered the testimony. Id. at 1159. The
defendant responded, “That’s what her testimony was. That
is not true.” Id. We held that this response did not justify
further questioning of the defendant about the witness’s
credibility. Id. at 1160. Indeed, we found the government’s
argument that “the prosecution had no choice but to follow up
Moreland’s statement by asking whether [the witness] was
lying” to “make[] little sense.” Id. While the follow-up
questions about the witness’s credibility in Moreland were
more extensive than the single follow-up question here, the
principle nonetheless applies.

    Moreover, Alcantara’s comments about Agent Hunter’s
testimony were not spontaneous, but were in fact induced by
the line of the prosecutor’s questioning, in which he pressed
Alcantara five times about Agent Hunter’s testimony before


     2
    “Tell a tale of cock and bull, / Of convincing detail full; / Tale
tremendous, / Heaven defend us! / What a tale of cock and bull!” W.S.
Gilbert, The Yeomen of the Guard, Act II (1888).
         UNITED STATES V. ALCANTARA-CASTILLO                 15

Alcantara responded that the Agent’s testimony as to the
black sweater, food in the backpack, and “[a]ll these things
were invented.” There is only one plausible explanation for
the prosecutor’s persistent effort to confirm that Alcantara
had heard Agent Hunter’s previous testimony: to induce
Alcantara to comment on whether that testimony was true.
And the prosecutor ultimately achieved the desired result:
Following Alcantara’s “[a]ll these things were invented”
testimony, the prosecutor immediately pounced with, “Your
testimony is that Agent Hunter is inventing stories about you;
is that correct?” Alcantara was once again forced to comment
on Agent Hunter’s veracity, and he did by asking the
prosecutor “Where are my things?,” as if to prove Agent
Hunter was lying when he testified as to the contents of
Alcantara’s backpack.

     The government argues that the prosecutor might have
asked these questions to determine whether Agent Hunter’s
testimony had refreshed Alcantara’s recollection of his
statements on the day of his arrest. This explanation makes
little sense, however, as Alcantara had just testified on direct
that he did not recall making those statements, so it was
already evident that his memory had not been refreshed by
Agent Hunter’s testimony the day before. The natural and
sole purpose of asking Alcantara about Agent Hunter’s
testimony recounting Alcantara’s alleged statements—rather
than simply asking about the statements themselves—was to
induce Alcantara to comment on Agent Hunter’s veracity.
Whether Alcantara “remembered” Agent Hunter’s testimony
was of no import to the case; the prosecutor achieved what he
wanted when his questioning resulted in Alcantara’s
testimony that Agent Hunter had invented his story. Thus,
the prosecutor improperly created a scenario that forced
Alcantara to comment on Agent Hunter’s veracity.
16       UNITED STATES V. ALCANTARA-CASTILLO

                              B.

    The prosecutor’s initial closing argument was not plainly
improper. The central theme of the government’s argument
was to compare Agent Hunter’s credibility with Alcantara’s
credibility. The prosecutor began his argument by stating:
“Credibility. This case is largely going to come down to the
issue of credibility.” He then compared the two key
witnesses’ competing narratives of events. “[I]f you believe
Border Patrol Agent Aaron Hunter,” the prosecutor argued,
then Alcantara confessed to having knowingly entered the
United States with a group. “If you believe the defendant’s
story,” by contrast, “then it would have been impossible” for
Alcantara to have confessed because he did not know he had
entered the United States. The prosecutor then argued that
“one of those two witnesses is not telling the truth.”
Alcantara contends that this last statement amounted to
misconduct.

    Because it was reasonable to infer from the evidence that
either Agent Hunter or Alcantara was lying, the challenged
statement was not plainly improper. Prosecutors must
generally avoid statements “to the effect that, if the defendant
is innocent, government agents must be lying.” Sanchez,
176 F.3d at 1224 (internal quotation marks omitted).
However, the government must be given reasonable latitude
in closing argument, and in “a case that essentially reduces to
which of two conflicting stories is true, it may be reasonable
to infer, and hence to argue, that one of [the] two sides is
lying.” United States v. Wilkes, 662 F.3d 524, 541 (9th Cir.
2011) (quoting United States v. Molina, 934 F.2d 1440, 1445
(9th Cir. 1991)). For example, the government is allowed to
argue that “somebody is lying” when the government and
defense witnesses present wholly incompatible testimony
         UNITED STATES V. ALCANTARA-CASTILLO                  17

regarding who initiated a drug transaction. Molina, 934 F.2d
at 1445; see also Wilkes, 662 F.3d at 541 (finding no
impropriety in the government’s argument that “[y]ou can’t
believe both” the defendant and prosecution witnesses). This
case similarly reduces to which of two conflicting accounts
is true. Agent Hunter’s narrative and Alcantara’s narrative
cannot be reconciled, and “the inference is unavoidable” that
one of them was lying. Molina, 934 F.2d at 1445.

    Nor did the prosecutor’s vouching for Agent Hunter’s
credibility rise to the level of plain error when he later
argued: “Agent Hunter’s testimony remained consistent. It
remained believable, and it remained logical.” This
ambiguous statement is reasonably understood in either of
two ways: as an impermissible assertion of the prosecutor’s
personal opinion that Agent Hunter’s testimony was
consistent, believable, and logical; or as a permissible
argument that the jury should find Agent Hunter’s testimony
consistent, believable, and logical. We have held that a
prosecutor’s summary of what “we know” about the evidence
does not constitute improper vouching when the surrounding
context suggests that, despite the personal language, the
prosecutor is drawing inferences from evidence in the record
rather than offering an opinion. Younger, 398 F.3d at
1190–91. Here, when the statement is viewed in context, the
prosecutor appears to be employing the language of the
district court’s jury instruction as to credibility to argue that
the jury should believe Agent Hunter based upon inferences
it could draw from the evidence. The challenged statement
was ambiguous, and it did not clearly “place[] the prestige of
the government behind a witness through personal assurances
of the witness’s veracity.” Id. at 1190 (quoting United States
v. Leon-Reyes, 177 F.3d 816, 822 (9th Cir. 1999)). It
therefore did not amount to plain error.
18       UNITED STATES V. ALCANTARA-CASTILLO

                              C.

    The government concedes that it improperly vouched for
Agent Hunter’s credibility when it began its rebuttal
argument by stating: “Ladies and gentlemen, this case boils
down to the credibility of a 15-year methamphetamine addict,
a man who has every incentive to lie, versus the testimony
and the evidence of Border Patrol agents who are sworn to
uphold the law.” There was no evidence in the record that
Border Patrol agents are “sworn to uphold the law.” As the
government appropriately concedes, the prosecutor vouched
for Agent Hunter’s credibility by referring to facts not before
the jury to convince it in this credibility showdown that Agent
Hunter was telling the truth, as he was sworn to do. See, e.g.,
Combs, 379 F.3d at 574; Sanchez, 176 F.3d at 1224–25. We
have previously made clear that a prosecutor may not argue
that “the existence of legal and professional repercussions”
for law enforcement officers serves to “ensure the credibility
of the officers’ testimony.” Weatherspoon, 410 F.3d at 1146.
That is precisely what the prosecutor did here.

                             IV.

    While Alcantara timely objected to the prosecutor’s
improper rebuttal argument, and arguably timely objected to
the prosecutor’s improper cross-examination, we need not
decide whether to apply harmless error analysis here. Even
under the more restrictive plain error standard the combined
misconduct requires reversal. Id. at 1151.

    Under the plain error standard, where prosecutorial
misconduct affects the defendant’s substantial rights and
seriously affects the fairness, integrity, or reputation of
judicial proceedings, the misconduct is reversible error. See
         UNITED STATES V. ALCANTARA-CASTILLO               19

Combs, 379 F.3d at 568. To determine whether the
misconduct affected the defendant’s substantial rights, we
“look to the substance of any curative instructions, and the
strength of the case against the defendant absent the
misconduct.” United States v. Sanchez, 659 F.3d 1252, 1257
(9th Cir. 2011). There is no bright-line rule for determining
whether reversal is appropriate. Rather, we may consider
various relevant factors, including the form and timing of the
misconduct, the extent to which the prosecutor asserted a
personal opinion or implied extra-record knowledge, the
importance of the testimony to which the improper conduct
related, and the specificity and timing of any curative
instruction. See Ruiz, 710 F.3d at 1085.

    We have repeatedly reversed convictions for plain error
in cases in which “witness credibility was paramount” and the
prosecutor sought to bolster critical testimony through
improper conduct. Combs, 379 F.3d at 573 (quoting Geston,
299 F.3d at 1137); see also Weatherspoon, 410 F.3d at 1151;
Kerr, 981 F.2d at 1054. There is no question that witness
credibility was paramount in this case. As the prosecutor
himself stated: “Credibility. This case is largely going to
come down to the issue of credibility.”

    This particular credibility contest was made even closer
by the significant credibility problems of each of the
contestants. Alcantara’s drugged memory was spotty and
selective at best. He remembered some highly specific
details of his journey, such as the quantities of
methamphetamine he purchased en route, and filling up a
water bottle with dirty water near palm trees, while providing
inconsistent testimony about his prior use of
methamphetamine, among other subjects. And Alcantara’s
four prior convictions for illegal reentry, which he
20        UNITED STATES V. ALCANTARA-CASTILLO

acknowledged during cross-examination, surely impaired his
credibility.

    On the other hand, Agent Hunter’s testimony that
Alcantara spontaneously confessed to having knowingly
entered the United States was not particularly believable.
Agent Hunter failed to make any contemporaneous record of
Alcantara’s alleged confession. The statements do not appear
in either the Border Patrol’s report or Agent Hunter’s own
“detailed” addendum. Nor did he tell anyone else about
Alcantara’s alleged statements for at least seven months
thereafter. It was not until Agent Hunter met with the
prosecutors in this case that he somehow managed to recall
and report Alcantara’s alleged spontaneous confession to the
elements of a § 1326 violation. Moreover, Agent Hunter’s
testimony that Alcantara had water bottles and empty food
containers in his backpack was vague, unconvincing, and
substantially undermined on cross-examination. On cross,
Agent Hunter admitted that he had not personally searched
Alcantara’s bag and was unable to recall the specific items it
may have contained, contrary to his direct testimony. There
was also no contemporaneous record or physical evidence of
the bag’s alleged contents.3

    Although Alcantara was a poor witness, the defense at
least provided some corroboration of the essential details of
his exculpatory narrative. The El Hongo rehabilitation center


  3
    During cross-examination of the defense’s psychiatric expert, some
mention was made of a hospital record that indicated Alcantara had food
and water at some point. It was unclear who had provided this
information or when Alcantara had either possessed or been given the
food and water, and no mention was made of Alcantara’s backpack. The
record itself was not introduced into evidence.
        UNITED STATES V. ALCANTARA-CASTILLO               21

and the abandoned railroad tunnel where Alcantara testified
he used methamphetamine actually existed. Evidence
showed a gap in the border fence near the location of
Alcantara’s arrest, which, Alcantara argued, allowed him to
enter the United States easily. And a psychiatric expert
provided unrebutted testimony that a habitual
methamphetamine user could suffer hallucinations and
disorientation as to time and place, especially if dehydrated
and exposed to extreme heat. While this jury did not believe
Alcantara, a jury in a trial unaffected by improper
prosecutorial conduct reasonably could have believed him
and concluded that he did not knowingly enter the United
States—or at least that the government failed to prove beyond
a reasonable doubt that he did so.

    The government’s conduct of the trial illuminates the
closeness of the case and demonstrates that a conviction was
far from assured. The more junior of the two U.S. attorneys
handling the case, who was actually trying his first case,
handled almost the entire trial. He gave the opening
statement, examined Agent Hunter, cross-examined
Alcantara, and offered the government’s initial closing
argument. Then the more senior prosecutor stood up to argue
the government’s rebuttal. After reintroducing himself to the
jury, the senior prosecutor opened the rebuttal with the
improper statement comparing “the credibility of a 15-year
methamphetamine addict” to “the evidence of Border Patrol
agents who are sworn to uphold the law.”

   The senior prosecutor had ample opportunity to consider
how to proceed in rebuttal. He chose to begin his remarks
with a comment that an experienced Assistant United States
Attorney would surely know approached, if not exceeded, the
bounds of propriety. That the supervising prosecutor at
22       UNITED STATES V. ALCANTARA-CASTILLO

trial—who, unlike us, actually observed the critical testimony
and the jury’s response to the key witnesses—felt motivated
to take this risk suggests he may have had doubts about the
outcome. Indeed, this improper comment was not the only
way in which the senior prosecutor aggressively pushed the
limits of propriety in his rebuttal argument. The district court
sustained an objection to the prosecutor’s misstatement of the
evidence, and then spontaneously chided him for “trying to
get around” the objection when he attempted to restate the
point obliquely. The district court also admonished the
prosecutor twice during his remarks for going beyond the
proper scope of rebuttal, and then again after the jury had
retired for “overd[oing] the true meaning of close by having
a second bite of the apple.” That the government felt the
need to engage in these improper tactics only enforces just
how close the credibility contest was, further demonstrating
that the combined misconduct, the questioning about Agent
Hunter’s veracity and the improper rebuttal, was highly
prejudicial.

    Defense counsel did timely object to the senior
prosecutor’s improper rebuttal argument, and the district
court sustained the objection and instructed the jury to
disregard the comment. We are not convinced, however, that
the trial court’s instruction sufficiently cured the error. Our
cases concerning prosecutorial vouching often require more
than a quick statement that “the jury will disregard” the
vouching to neutralize any prejudice. United States v.
Simtob, 901 F.2d 799, 806 (9th Cir. 1990). In Simtob, for
instance, we found that the effect of vouching was not cured
even though the district court had instructed the jury to
disregard the comment and had provided relevant general jury
instructions on credibility. Id. In other cases, we have found
that “the manner in which [defense] objections were sustained
         UNITED STATES V. ALCANTARA-CASTILLO                  23

unfortunately did not deliver the required strong cautionary
message,” Weatherspoon, 410 F.3d at 1151, and we have
suggested that a “strongly worded curative instruction” may
be necessary to cure vouching, Sanchez, 659 F.3d at 1258.
See also Kerr, 981 F.2d at 1053 (examining the substance of
a curative instruction to determine whether vouching was
prejudicial). Here, a firmer and more specific curative
instruction would have been particularly appropriate.
Because the government’s rebuttal was the last thing the jury
heard before beginning its deliberations, “the impact” of the
misconduct was “likely to be significant.” Sanchez, 659 F.3d
at 1259.

     For these reasons, we conclude that the errors at trial
affected Alcantara’s substantial rights. It was fundamentally
unfair and prejudicial to Alcantara to compel him to impugn
the veracity of Agent Hunter’s critical, and possibly
determinative, testimony. Combs, 379 F.3d at 573. This
error was “compounded” by improper vouching that was not
fully remedied by the district court’s minimal curative
instruction. Id. at 574. As the government itself argued, the
jury was faced with a choice between believing Agent Hunter
or believing Alcantara. Both witnesses’ accounts of the
events in question were profoundly flawed, and given the
government’s burden of proving guilt beyond a reasonable
doubt, the jury plausibly could have acquitted Alcantara if the
trial had been untainted by prosecutorial misconduct. In light
of the senior prosecutor’s conduct in rebuttal argument, we
also conclude that the errors “seriously affect[ed] the fairness,
24        UNITED STATES V. ALCANTARA-CASTILLO

integrity, or public reputation of judicial proceedings.” Ruiz,
710 F.3d at 1085 (quoting Sanchez, 659 F.3d at 1256).4

                                  V.

   By asking Alcantara to comment on the credibility of the
key witness against him, and then referring to evidence not
before the jury to bolster that witness’s testimony, the
government crossed the fine line separating the vigorous
pursuit of justice from the overzealous pursuit of victory.
These improper tactics compromised the fairness of the trial.
We reverse Alcantara’s conviction and remand for further
proceedings consistent with the demands of due process.

     REVERSED AND REMANDED.




 4
   Because we reverse on the basis of prosecutorial misconduct, we need
not reach Alcantara’s argument that the jury instructions misstated the
law. We have, however, repeatedly upheld the use of the Ninth Circuit
model jury instruction on reasonable doubt. See, e.g., United States v.
Ruiz, 462 F.3d 1082, 1087 (9th Cir. 2006); United States v. Clayton,
108 F.3d 1114, 1118 (9th Cir. 1997); see also United States v. Meraz-
Olivera, 472 F. App’x 610, 612 (9th Cir. 2012) (rejecting the same
arguments Alcantara makes here).
        UNITED STATES V. ALCANTARA-CASTILLO               25

RAWLINSON, Circuit Judge, dissenting:

    I respectfully dissent.    Martin Alcantara-Castillo
(Alcantara) challenges his conviction for being a deported
alien found in the United States in violation of 8 U.S.C.
§ 1326. Alcantara contends that a new trial is warranted
because the government improperly compelled Alcantara to
challenge the veracity of a government witness during the
government’s cross-examination and impermissibly vouched
for government witnesses during closing arguments. The
majority agrees with Alcantara. I agree with the district
court.

I. BACKGROUND

    Alcantara was charged with one count of being a deported
alien found in the United States in violation of 8 U.S.C.
§ 1326.

   A. Trial Testimony

    Border Patrol Agent Aaron Hunter testified that, on June
26, 2011, he was informed that a motion sensor had been
triggered approximately seven miles east of the Tecate port
of entry. Agent Hunter described the area as “very
mountainous, rugged terrain” one mile north of the border.

    According to Agent Hunter, he discovered Alcantara
lying on the ground in the area, alongside a cargo container.
When questioned in Spanish, Alcantara responded that he
was a Mexican citizen and lacked any documents permitting
him to be in the United States. Agent Hunter arrested
Alcantara, who remained calm and submissive. Agent Hunter
opined that, if Alcantara had been under the influence of
26       UNITED STATES V. ALCANTARA-CASTILLO

narcotics, Agent Hunter would have contacted the local
police for safety reasons. Based on his training, Agent
Hunter did not believe that Alcantara was under the influence
of narcotics because Alcantara “seemed fully aware of the
situation” and answered Agent Hunter’s questions
appropriately.

    According to Agent Hunter, Alcantara spontaneously
informed Agent Hunter that he was part of a group of aliens
who had been chased by border patrol agents during the
previous night and that he was attempting to return to
Mexico.

    During a subsequent search, border patrol agents other
than Agent Hunter found a backpack with empty bottles and
food containers, but no illegal narcotics or drug
paraphernalia. Agent Hunter related that Alcantara also
provided a false name to the agents.

    On cross-examination, Agent Hunter acknowledged that
the arrest report did not include Alcantara’s statement that he
had been separated from a group of aliens entering the United
States. Agent Hunter also did not mention the statement to
his fellow agent, or when he drafted an addendum to the
report.     Agent Hunter informed the government of
Alcantara’s statement when preparing for trial. Agent Hunter
explained that the statement was not in the report or
addendum because it was “not relevant to the arrest.” Rather,
the facts relevant to Alcantara’s arrest were Alcantara’s
presence in the United States; his statement that he was a
Mexican citizen; and the lack of documents permitting
Alcantara to enter or remain in the United States.
         UNITED STATES V. ALCANTARA-CASTILLO                27

    Border Patrol Agent Luis Martinez testified that, on June
26, 2011, he interviewed Alcantara. Agent Martinez
terminated the interview within one minute pursuant to
Border Patrol policies because Alcantara stated that he was
under the influence of methamphetamine. However, Agent
Martinez related that, based on his training, there were no
objective indications that Alcantara was under the influence
of “any mind-altering substance.”

    According to Alcantara, he had been using
methamphetamine almost daily since 1995. He decided to
enter a rehabilitation clinic on June 24, 2011, the day before
his arrest in the United States, because one of his friends had
died of an overdose. Intending to enter a clinic near El
Hongo, Mexico, he left on a bus to Tecate on June 25, but
purchased methamphetamine prior to leaving. After arriving
in Tecate, Alcantara intended to go to the home of a friend.
However, Alcantara met two men along the way in a tunnel
near a bridge and smoked methamphetamine with them, more
methamphetamine than he had ever smoked before.

    Alcantara did not remember leaving the tunnel, and
awakened the next day on the side of the road, thinking he
was on the road between Tecate and Mexicali. According to
Alcantara, he was resting on a board next to a container when
he was approached by an individual in a uniform. Alcantara
informed the man in uniform that he was Mexican. Alcantara
did not remember saying anything more to the man.

    Alcantara acknowledged that he had been convicted of
illegal reentry in 1995, 1997, 2002, and 2009. Alcantara also
conceded that he had lied during a prior arrest when he stated
that he had never used methamphetamine.
28       UNITED STATES V. ALCANTARA-CASTILLO

    The prosecutor asked Alcantara if he remembered Agent
Hunter’s testimony from the previous day concerning
statements made by Alcantara. Alcantara stated that he did
not remember Agent Hunter’s testimony. Alcantara also
responded:

       Agent Hunter, he can say whatever he wants.
       He is saying I had a black sweater the day of
       my arrest, that I had food in my backpack, and
       there is nothing of that. That was all invented.
       All these things were invented.

The prosecutor subsequently inquired, “Your testimony is
that Agent Hunter is inventing stories about you; is that
correct?” When Alcantara responded, “[w]here are my
things,” the prosecutor asked, “do you remember him telling
that story?” After overruling the defense’s objection that the
government was vouching for Agent Hunter, the district court
stated there was “a confusion as to time. Did you hear the
story the agent told yesterday?” Alcantara finally responded,
“Yes, I did.”

   Dr. Clark Smith, a specialist in psychiatry and addiction
psychiatry, testified that he interviewed Alcantara for three
hours and determined that Alcantara was methamphetamine-
dependent.

    Lorena Garcia (Garcia), an investigator for the Federal
Defenders of San Diego, traveled to Mexico and visited the
rehabilitation clinic in El Hongo. Garcia related that the
clinic went by the acronym “CRREAD” and that it was
located to the east of Tecate. Garcia also located a tunnel “on
the outskirts of Tecate . . .”
            UNITED STATES V. ALCANTARA-CASTILLO                        29

      B. Closing Arguments

      During closing arguments, the prosecutor stated:

           Credibility. This case is largely going to
           come down to the issue of credibility. You
           have heard two versions of the facts in this
           case. Two witnesses: the defendant testifying
           that he didn’t know what happened, that he
           was blacked out; and the prosecution’s
           witness, Border Patrol Agent Aaron Hunter,
           who testified that the defendant calmly and
           coherently told him how he had knowingly
           entered the United States the day before, and
           proceeded north with a group that had been
           scouted by . . . border patrol agents on ATVs.

The prosecutor argued that the jury could not believe both
Agent Hunter’s testimony and Alcantara’s testimony and
“one of those two witnesses is not telling the truth.” Relying
on the credibility instruction provided by the district court,1

 1
     The district court instructed the jury:

           In deciding the facts in this case, you may have to
           decide which testimony to believe and which testimony
           not to believe. You may believe everything a witness
           says, or part of it, or none of it. In considering the
           testimony of any witness, you may take into account:
           (1) the witness’s opportunity and ability to see or hear
           or know the things testified to; (2) the witness’s
           memory; (3) the witness’s manner while testifying;
           (4) the witness’s interest in the outcome of the case, if
           any; (5) the witness’s bias or prejudice, if any;
           (6) whether other evidence contradicted the witness’s
           testimony; (7) the reasonableness of the witness’s
30       UNITED STATES V. ALCANTARA-CASTILLO

the prosecutor asserted that “Agent Hunter’s testimony
remained consistent. It remained believable, and it remained
logical.”

    The prosecutor emphasized that Alcantara remembered
numerous events, such as smoking methamphetamine, resting
at the container, and picking up a water bottle on the
roadside, but was unable to remember key facts concerning
his entry into the United States. The prosecutor argued that
Alcantara was not credible and had “every motive to lie . . .”

    In rebuttal, the prosecutor reiterated that “this case boils
down to the credibility of a 15-year methamphetamine addict,
a man who has every incentive to lie, versus the testimony
and the evidence of border patrol agents who are sworn to
uphold the law.” The district court sustained the defense’s
objection and instructed the jury to disregard the
government’s comment. However, the district court denied
the defense’s request for a curative instruction that “law
enforcement officers are not entitled to any greater credibility
as compared to any other witness. . . .” The district court held
that the jury had been thoroughly instructed on the credibility
of witnesses and that a curative instruction was unwarranted
in light of the district court’s instruction for the jury to
disregard the comment.




       testimony in light of all the evidence; and (8) any other
       factors that bear on believability. The weight of the
       evidence as to a fact does not necessarily depend on the
       number of witnesses who testify. What is important is
       how believable the witnesses were, and how much
       weight you think their testimony deserves.
           UNITED STATES V. ALCANTARA-CASTILLO             31

       C. Conviction and Sentence

    The jury found Alcantara guilty and the district court
sentenced Alcantara to forty months’ imprisonment.
Alcantara filed a timely notice of appeal.

II. STANDARDS OF REVIEW

    “We review alleged vouching for harmless error when . . .
the defendant objected at trial.” United States v. Stinson,
647 F.3d 1196, 1211 (9th Cir. 2011), as amended (citation
omitted). “We review for abuse of discretion a district
court’s rulings on alleged prosecutorial misconduct, including
vouching.” Id. (citation omitted). We review claims of
misconduct for plain error when the defendant failed to
object. See United States v. Doss, 630 F.3d 1181, 1193 (9th
Cir. 2011), as amended. Denial of a requested curative
instruction is reviewed for abuse of discretion. See United
States v. Skinner, 667 F.2d 1306, 1310 (9th Cir. 1982).

III.      DISCUSSION

       A. The Prosecutor’s Cross-Examination

    Because Alcantara did not object to the cross-examination
during trial, we review for plain error. See Doss, 630 F.3d at
1193. To be plain, an error must be so obvious that the judge
should be able to detect the error even in the absence of an
objection. See United States v. Matus-Zayas, 655 F.3d 1092,
1098 (9th Cir. 2011). “Improper questioning was [not] an
organizational theme for the prosecutor’s entire cross-
examination.” United States v. Harrison, 585 F.3d 1155,
1159 (9th Cir. 2009), as amended. Rather, Alcantara
spontaneously challenged Agent Hunter’s testimony when the
32       UNITED STATES V. ALCANTARA-CASTILLO

prosecutor merely inquired whether Alcantara remembered
that testimony. The prosecutor followed up by inquiring if it
was Alcantara’s “testimony . . . that Agent Hunter [was]
inventing stories about [him].” The prosecutor did not
otherwise compel Alcantara to comment on Agent Hunter’s
veracity. Cf. United States v. Geston, 299 F.3d 1130, 1135
(9th Cir. 2002) (asking five times whether the government
witness “would be lying” if his testimony contradicted that of
the witness).

    The crucial distinction between this case and the cases
cited in the majority opinion is the absence of the word
“lying” in the questions posed by the prosecutor in this case.
Use of that word appears to be the common denominator in
those cases holding that plain error occurred. See, e.g.,
Geston, 299 F.3d at 1134 (asking if the government witness
“would be lying”); United States v. Combs, 379 F.3d 564, 572
(9th Cir. 2004) (questioning whether agent “was lying” in his
earlier testimony); Harrison, 585 F.3d at 1158 (inquiring if
witnesses were “swearing on oath to testify to the truth and
then lying”); United States v. Sanchez, 176 F.3d 1214, 1220
(9th Cir. 1999) (asking if the witness “would say [another
witness] was lying” when he testified); United States v.
Moreland, 622 F.3d 1147, 1159 (9th Cir. 2010) (“You heard
his testimony. . . . He’s lying?”) (emphases added).

    The majority seeks to lessen the precedential effect of
these cases by resorting to dictionary definitions. See
Majority Opinion, p. 12–13. Yet, we resort to dictionary
definitions only when the meaning of language in a statute is
unclear, not to reword our precedent. See, e.g., San Jose
Christian College v. City of Morgan Hill, 360 F.3d 1024,
1035 (9th Cir. 2004) (“To determine the plain meaning of a
term undefined by a statute, resort to a dictionary is
         UNITED STATES V. ALCANTARA-CASTILLO                     33

permissible . . .”) (citation omitted). The fact remains that the
majority has cited no case where prosecutorial misconduct
was found based on an inquiry regarding “invention” of
testimony, particularly when that characterization was first
used by the testifying defendant. Without clear precedent on
this issue, it cannot be fairly said that the district court plainly
erred.

    Indeed, the majority has not cited one case where there
was a determination of plain error in the absence of use of
the word “lying” or some variant of “lie.” Yet, there are
cases in our precedent concluding that there was no plain
error when the prosecutor was accused of forcing the witness
to comment on veracity, but stopped short of using the L-
word. See, e.g., United States v. Greer, 640 F.3d 1011, 1023
(9th Cir. 2011) (observing that “[a]lthough we have
repeatedly stated that a prosecutor may not ask the defendant
to comment on the veracity of another witness, we have
found improper prosecutorial questioning in only one
particular context: when the prosecutor specifically asked the
defendant whether another witness was lying”) (citing
Harrison, Combs, Geston and Sanchez).

    The majority argues that my reliance on Greer is
misplaced. See Majority Opinion, p. 13. I beg to differ.
Greer states definitively the point that makes plain error
inapplicable to this case—“we have found improper
prosecutorial questioning in only one particular context:
when the prosecutor specifically asked the defendant whether
another witness was lying.” 640 F.3d at 1023 (citations
omitted) (emphasis in the original). We declined to conclude
that there was plain error when the prosecutor asked whether
another witness testified “inaccurately” because neither the
Supreme Court nor our court had yet ruled on whether asking
34       UNITED STATES V. ALCANTARA-CASTILLO

about “inaccurate” testimony was improper. Id. Similarly,
neither the Supreme Court nor this court has ruled that asking
about “invented” testimony is improper, particularly when the
term is first used by the testifying defendant. Notably, this
case cites the exact cases cited by the majority, but
acknowledges that these cases concluding that questioning
was improper are limited to “one particular context: when the
prosecutor specifically asked the defendant whether another
witness was lying. . . .” Id. (emphasis in the original); see
also United States v. Wright, 625 F.3d 583, 612 (9th Cir.
2010) (holding that there was no plain error when the
prosecutor asked the defendant questions concerning a “rogue
agent” during “a fairly argumentative cross-examination in
order to poke holes in [the defendant’s] version of the facts”).

     The facts of this case diverge substantially from those
relied upon by the majority. An initial and important
difference is that the first comment on the veracity of Agent
Hunter’s testimony came unprompted from Alcantara when
he stated that Agent Hunter had “invented things” about
Alcantara. Unlike in the cases where plain error occurred, the
prosecutor did not follow up by asking Alcantara if Agent
Hunter was lying when he testified. Rather, he used the same
word utilized by Alcantara to ask Alcantara: “Your
testimony is that Agent Hunter is inventing stories about you;
is that correct?”

    There was nothing inappropriate about the prosecutor
asking Alcantara if he heard Agent Hunter’s testimony, and
the majority has cited no authority otherwise. Cf. Hoxsie v.
Kerby, 108 F.3d 1239, 1244 (10th Cir. 1997) (rejecting a
claim of prosecutor misconduct where the attorney asked the
defendant if he had heard the testimony); see also Wright,
625 F.3d at 612 (“There was nothing improper about the
         UNITED STATES V. ALCANTARA-CASTILLO                  35

prosecutor’s” questions forcing the defendant to call the
investigating agent a “rogue agent”).

    The majority intimates that its holding of plain error is
valid because the prosecutor “forced” Alcantara to comment
on Agent Hunter’s truthfulness. Majority Opinion, pp.
14–15. However, this contention lacks persuasive force
because we have expressly held that no plain error occurred
during a “fairly argumentative cross-examination” that forced
a defendant to call an agent a “rogue agent.” See Wright,
625 F.3d at 612.

    Finally, even if it was error for the district court to allow
the prosecutor to follow-up on Alcantara’s comment that
Agent Hunter “made up things,” “the error was not so clear-
cut, so obvious, a competent district judge should have been
able to avoid it without benefit of objection. . . .” Greer,
640 F.3d at 1023 (citation, alterations and internal quotation
marks omitted). In Greer, we concluded that “[b]ecause
neither the Supreme Court nor this court has yet ruled on the
propriety of the prosecutor’s questions in this case [whether
witnesses testified inaccurately], the district court did not
err.” Id. The same is true in this case. As mentioned, we
have limited our cases involving plain error to those where a
witness is asked if another witness is lying. See id. Neither
the United States Supreme Court nor this court has gone
further to impute plain error when the prosecutor asks if
another witness “made up things,” especially when the
defendant used the phrase first and the prosecutor merely
repeated the phrase in the form of a question. Because the
facts in this case differ so dramatically from those where
plain error occurred, I would hold that the trial judge was not
obligated to sua sponte object to the prosecutor’s questions to
Alcantara. See Matus-Zayas, 655 F.3d at 1098.
36       UNITED STATES V. ALCANTARA-CASTILLO

     B. The Prosecutor’s Closing Arguments

    “Improper vouching consists of placing the prestige of the
government behind a witness through personal assurances of
the witness’s veracity, or suggesting that information not
presented to the jury supports the witness’s testimony. . . .”
United States v. Ruiz, 710 F.3d 1077, 1085 (9th Cir. 2013)
(citation and internal quotation marks omitted).
“[C]redibility is a matter to be decided by the jury.” Id. at
1082 (citation omitted). “To that end, prosecutors have been
admonished time and again to avoid statements to the effect
that, if the defendant is innocent, government agents must be
lying.” Id. at 1082–83 (citation and internal quotation marks
omitted). “It is also true, however, that the prosecution must
have reasonable latitude to fashion closing arguments.
Inherent in this latitude is the freedom to argue reasonable
inferences based on the evidence. In a case that essentially
reduces to which of two conflicting stories is true, it may be
reasonable to infer, and hence to argue, that one of the two
sides is lying.” Id. (citations omitted).

     Reversal of Alcantara’s conviction based on the
prosecutor’s closing arguments is not warranted given
Alcantara’s credibility problems and the evidence presented
at trial. Alcantara was found in the United States in an area
described as “very mountainous, rugged terrain” north of the
United States-Mexico border. The government presented
photographs to the jury evincing the rugged and mountainous
terrain through which Alcantara maintained that he blindly
and unconsciously wandered as he was under the influence of
methamphetamine. Despite Alcantara’s contention that he
was engaged in methamphetamine-induced wandering, Agent
Hunter testified that border patrol agents found empty food
containers and bottles in Alcantara’s backpack and that
         UNITED STATES V. ALCANTARA-CASTILLO                  37

Alcantara did not appear to be under the influence of
narcotics. Alcantara’s alleged statement to Agent Hunter that
Alcantara was separated from a group of aliens traveling to
the United States after being dispersed by border patrol
agents was consistent with Agent Joseph Moore’s testimony
concerning similar events that occurred that evening.

     Alcantara also suffered from an extensively selective
memory. He testified in great detail about his decision to
enter a rehabilitation clinic on the day before his arrest; the
one thousand pesos he won at a casino “on Revolucion and
Third Street” after purchasing a fifty-peso ticket he used to
buy six balloons of methamphetamine on the night before
making his decision to seek rehabilitation; his purchase of
five bags of methamphetamine at the Hotel Nizan on the
same evening; his bus trip at five o’clock in the morning on
June 25th to Tecate; his purchase of two bags of
methamphetamine immediately before his bus trip; his arrival
in Tecate at eight o’clock in the morning; his cab ride to “the
Andalucia neighborhood” to meet a friend, Juan, who had a
small home near Tecate with sheep; his consumption of two
balloons of methamphetamine with two men in a tunnel near
a bridge and railroad tracks; and his subsequent
methamphetamine purchase for seven hundred pesos. After
waking up the next day in the United States, Alcantara
remembered seeing “a small little farm that had some palm
trees”; picking up a water bottle from the side of the road;
cleaning a board on the ground next to a container so that he
could rest; being approached by an individual “dressed in
green”; asking Agent Hunter for water because Alcantara had
filled his water bottle “over . . . where the palm trees were at,
and the water was dirty”; and picking up a water bottle as he
was walking with Agent Hunter.
38       UNITED STATES V. ALCANTARA-CASTILLO

    Despite Alcantara’s detailed recollection of the former
events, Alcantara did not remember traveling through a
rugged and mountainous area into the United States, any
statement to Agent Hunter about his entry into the United
States, or even Agent Hunter’s trial testimony from the day
before until finally answering the district court’s question.

    Moreover, Alcantara’s credibility was severely
undermined by his admissions that he had been convicted of
illegal reentry in 1995, 1997, 2002, and 2009. Notably,
Alcantara was arrested for illegal reentry on two occasions
after traveling into the United States from Tecate. Alcantara
also conceded that he lied during a prior arrest when he
falsely stated that he had never used methamphetamine.

    Although the prosecutor did improperly vouch for
government witnesses by mentioning during rebuttal
argument that the border patrol agents were “sworn to uphold
the law,” the district court immediately sustained the defense
attorney’s objection, and instructed the jury to disregard the
comment, rendering any error harmless. See United States v.
Parks, 285 F.3d 1133, 1141 (9th Cir. 2002) (holding that
improper statement was rendered harmless because the
district court “sustained [the defendant’s] objection . . . and
admonished the jury to disregard the statement”). The district
court did not abuse its discretion in denying Alcantara’s
request for a curative instruction, as the district court properly
held that the jury had been fully instructed concerning the
credibility of government witnesses, and its prompt
instruction to disregard the isolated comment sufficiently
remedied any error. See United States v. Dorsey, 677 F.3d
944, 955 (9th Cir. 2012) (holding that the district court’s swift
response instructing the jury to disregard the improper
comment “prevented . . . [the] improper comment from
         UNITED STATES V. ALCANTARA-CASTILLO                39

materially affecting the verdict”) (citation omitted); see also
United States v. Washington, 462 F.3d 1124, 1136 (9th Cir.
2006) (“A judge’s prompt corrective action in response to
improper comments usually is sufficient to cure any problems
arising from such improper comments. . . .”) (citations
omitted).

    Considering Alcantara’s significant credibility problems,
the evidence presented at trial of his illegal presences in the
United States, and the curative instruction given by the trial
judge, Alcantara failed to demonstrate that “in the context of
the entire trial, it is more probable than not that [the
prosecutor’s comment] materially affected the verdict. . . .”
Dorsey, 677 F.3d at 954 (citation and internal quotation
marks omitted). Stated another way, any error in vouching
for the witnesses was harmless. See id. at 955. Finally, there
was no abuse of discretion in denying the requested curative
instruction. See Skinner, 667 F.2d at 1310 (recognizing that
use of curative or limiting instructions is within the district
court’s discretion).

    Our decision in United States v. Weatherspoon, 410 F.3d
1142 (9th Cir. 2005), does not compel a contrary result. In
that case, the prosecutor extensively vouched for government
witnesses. The prosecutor started out by describing a police
witness as “a credible officer.” Id. at 1146. Despite being
instructed not to vouch, the prosecutor went on to argue that
the police officers

       had no reason to come in here and not tell you
       the truth. I guess, if you believe . . . defense
       counsel, they must have lied at the scene
       there; they came into this court and they lied
       to you; they lied to this judge; they lied to me;
40       UNITED STATES V. ALCANTARA-CASTILLO

        they lied to my agent . . . I guess they lied to
        the dispatcher when they called it in. These
        are officers that risk losin’ [sic] their jobs, risk
        losin’ [sic] their pension, risk losin’ [sic] their
        livelihood. And, on top of that if they come in
        here and lie, I guess they’re riskin’ bein’ [sic]
        prosecuted for perjury. . . .

Id.

    The prosecutor used the “they lied” refrain six
consecutive times, and told the jury that the officers risked
losing their jobs, losing their pensions, losing their livelihood,
and being prosecuted for perjury. Id. In contrast, the
prosecutor in this case simply stated once that the agent was
sworn to uphold the law. Unlike in Weatherspoon, see id.,
the prosecutor in this case did not continue to vouch for the
agent after the court sustained the defense objection.
Moreover, unlike in Weatherspoon, see id., the court in this
case gave a curative instruction. The two cases are so
different that Weatherspoon does not dictate the result in this
case. In Weatherspoon, we held that reversal of the
defendant’s conviction was warranted because the district
court’s approach

        did not produce any meaningful alteration of
        the prosecutor’s arguments, and the manner in
        which such objections were sustained
        unfortunately did not deliver the required
        strong cautionary message . . .

Id. at 1151. We opined that
         UNITED STATES V. ALCANTARA-CASTILLO               41

       [s]uch failures to correct the improper
       statements at the time they were made cannot
       be salvaged by the later generalized jury
       instruction reminding jurors that a lawyer’s
       statements during closing argument do not
       constitute evidence. In short, the curative
       instructions offered . . . did not neutralize the
       harm of the improper statements because they
       did not mention the specific statements of the
       prosecutor and were not given immediately
       after the damage was done.

Id. (citations, alteration, and internal quotation marks
omitted). The district court in this case immediately
sustained the defense’s objection and instructed the jury to
disregard the isolated comment. Unlike in Weatherspoon,
Alcantara does not contend that the government continued to
improperly vouch for government witnesses after the district
court’s ruling. See Dorsey, 677 F.3d at 955 (noting that the
judge’s curative action prevented any improper comment
from “materially affecting the verdict”); see also Parks,
258 F.3d at 1141 (same).

IV.    CONCLUSION

    The prosecutor’s isolated question in response to
Alcantara’s spontaneous challenge to Agent Hunter’s veracity
during extensive cross-examination does not rise to the level
of plain error as reflected in our precedent.

    The district court did not abuse its discretion in denying
a curative instruction during the prosecutor’s rebuttal
argument, as it granted Alcantara’s motion to strike and
instructed the jury to disregard the prosecutor’s comment that
42       UNITED STATES V. ALCANTARA-CASTILLO

the border patrol agents were “sworn to uphold the law.”
Any prejudice stemming from the government’s comment
was cured by the district court’s instruction and no additional
curative instruction was required. In any event, in the context
of the entire trial, it is highly unlikely that the prosecutor’s
comment materially affected the verdict.

     There is no such thing as a perfect trial, and district court
judges are not held to that standard. See Brown v. United
States, 411 U.S. 223, 231–32 (1973). Considering the trial in
its entirety, the proceedings were fundamentally fair, and on
that basis we should affirm this conviction. See id.; see also
United States v. Del Toro-Barboza, 673 F.3d 1136, 1150 (9th
Cir. 2012).
