                 FOR PUBLICATION
 UNITED STATES COURT OF APPEALS
      FOR THE NINTH CIRCUIT

UNITED STATES OF AMERICA,                  No. 04-50161
                Plaintiff-Appellee,           D.C. No.
               v.                          CR-02-00247-
BOBBIE BEAR,                                   ABC-5
             Defendant-Appellant.
                                            OPINION

       Appeal from the United States District Court
          for the Central District of California
       Audrey B. Collins, District Judge, Presiding

                 Argued and Submitted
        September 14, 2005—Pasadena, California

                  Filed February 24, 2006

      Before: Jerome Farris, David R. Thompson, and
               Jay S. Bybee, Circuit Judges.

               Opinion by Judge Thompson




                           1995
                 UNITED STATES v. BEAR            1997


                     COUNSEL

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

Shannon P. Ryan, Assistant United States Attorney, Los
Angeles, California, for the plaintiff-appellee.
1998                 UNITED STATES v. BEAR
                             OPINION

THOMPSON, Senior Circuit Judge:

   A jury convicted Bobbie Bear of conspiracy to manufacture
and distribute methamphetamine, in violation of 21 U.S.C.
§ 846. During her trial, Bear asserted that she had been work-
ing for the government in a criminal investigation as a confi-
dential informant when she engaged in the alleged illegal drug
activities. She testified that she informed Deputy Darren
Hager about these activities. Hager was a Los Angeles County
Sheriff’s Department deputy who had been assigned to the
Drug Enforcement Administration (“DEA”).

   Bear argues that although she did not request a public
authority instruction, this was the crux of the defense reflected
in her testimony and in closing arguments of both counsel.
She argues the district court erred by not giving the jury a
public authority instruction, sua sponte. She also contends the
district court erred by permitting the government to call Dep-
uty Hager as a rebuttal witness in spite of what she argues was
a stipulation by the government not to call him as a witness
in the case.

   We have jurisdiction pursuant to 28 U.S.C. § 1291. We
conclude that the district court committed plain error by not
giving the jury, sua sponte, a public authority defense instruc-
tion, and we reverse Bear’s conviction. Because the govern-
ment may retry Bear, we also consider whether the
government properly called Hager as a rebuttal witness, and
conclude the government was not precluded from doing so.
We also conclude that the government’s stipulation pertaining
to this witness will bind it in any retrial, during which the
government may only present Hager as a witness in rebuttal,
not in its case-in-chief.

                        I.   Background

  Prior to Bear’s alleged participation in the charged conspir-
acy, she acted as a confidential source for the DEA in its
                     UNITED STATES v. BEAR                  1999
investigation of Christopher Chapman, a methamphetamine
manufacturer and distributor. She made two controlled pur-
chases of methamphetamine from Chapman in November of
2000.

   In March of 2001, the DEA intercepted phone calls indicat-
ing that Bear was engaging in additional, allegedly unautho-
rized activities with Chapman, including attempting to broker
a deal for the manufacture and distribution of twelve to fifteen
pounds of methamphetamine. On March 14, 2002, the DEA
arrested Bear in connection with these activities. During inter-
rogation, she denied that any of the DEA agents, including
Deputy Hager, had authorized these acts.

   After Bear’s arrest, the government learned that Hager was
the subject of an internal affairs investigation and disciplinary
action by the Los Angeles County Sheriff’s Department
(“LASD”) concerning allegations that he had wrongly
accused another officer of assisting drug dealers. The govern-
ment reported this to Bear by letter and informed her of a
nine-volume investigative report in the custody of the LASD
Internal Affairs Bureau. In its letter, the government summa-
rized the investigation based upon a conversation with an
internal affairs sergeant. The government also stated that “the
government does not intend on calling [Hager] as a witness at
trial.”

   A series of pretrial conferences ensued, during which coun-
sel for both sides discussed the internal affairs investigation,
as well as an agreement by the government limiting Deputy
Hager’s testimony at trial. On the third day of trial, a dispute
arose about that agreement’s scope. The government main-
tained that it had limited the agreement to its case-in-chief,
and had reserved the right to call Hager in rebuttal. Bear’s
counsel contended that the agreement barred Hager’s testi-
mony in any capacity. The district court agreed with the gov-
ernment and, after Bear testified that she believed she was
still cooperating with Hager and acting on behalf of the gov-
2000                  UNITED STATES v. BEAR
ernment when she engaged in the charged activities, the court
allowed the prosecutor to call Hager in rebuttal. Hager testi-
fied that he did not authorize the charged activities, and that
Bear never told him about them.

   When the court instructed the jury, it did not give an
instruction on public authority, governmental authorization, or
any other affirmative defense. The jury convicted Bear, who
was subsequently sentenced to 235 months imprisonment,
five years supervised release, and a $100 special assessment.
This appeal followed.

                         II.   Discussion

A.     Public Authority Instruction

   [1] Bear argues that the district court committed reversible
error by not giving the jury a sua sponte instruction on a pub-
lic authority defense. The public authority defense is properly
used when the defendant reasonably believed that a govern-
ment agent authorized her to engage in illegal acts. See Ninth
Circuit Manual of Model Criminal Jury Instructions, Instruc-
tion 6.10 (2003).

   Because defense counsel neither requested a public author-
ity instruction, nor objected to the instructions the court did
give the jury, we review for plain error. United States v.
Montgomery, 150 F.3d 983, 996 (9th Cir. 1998). To reverse
under this standard, “there must be (1) ‘error,’ (2) that is
‘plain,’ and (3) that ‘affect[s] substantial rights.’ ” Johnson v.
United States, 520 U.S. 461, 466-67 (1997) (quoting United
States v. Olano, 507 U.S. 725, 732 (1993)). If these three con-
ditions are met, we may exercise our discretion to reverse, but
“only if (4) the error seriously affect[s] the fairness, integrity,
or public reputation of judicial proceedings.” Id. at 467 (inter-
nal quotation marks removed). Bear satisfies this four-prong
test.
                     UNITED STATES v. BEAR                   2001
   [2] First, the district court erred by not instructing the jury
on a public authority defense. When a defendant actually pre-
sents and relies upon a theory of defense at trial, the judge
must instruct the jury on that theory even where such an
instruction was not requested. Cf. Montgomery, 150 F.3d at
996 (“We conclude that Montgomery did not rely on a Sears-
type defense theory at trial. Accordingly, the district court’s
failure to offer a Sears instruction sua sponte was not plain
error.”); United States v. Span, 970 F.2d 573, 578 (9th Cir.
1992) (“We conclude that the district court did not commit
plain error by failing to offer sua sponte an instruction on an
excessive force theory of defense not raised during trial.”).

  As a deputy from the Los Angeles County Sheriff’s Depart-
ment on loan to the DEA as a task force officer, Hager either
had or reasonably appeared to have the power to authorize
Bear’s illegal acts. Bear testified that she believed she was
continuing to cooperate with the government when she com-
mitted the alleged offenses, and that she kept Hager abreast
of these otherwise-illegal activities.

   In his closing argument to the jury, defense counsel stated
that Hager “lied” when he denied that Bear had told him any-
thing about the alleged offenses, and that “it’s just this credi-
bility issue that is the main important aspect of this case that
you have to make a decision on.” Defense counsel devoted
the conclusion of his closing argument entirely to this issue,
beginning as follows: “The focus of this case is whether you
believe my client, Ms. Bear, informed Deputy Hager at that
time about this transaction . . . .”

   [3] Because Bear’s testimony and closing argument clearly
presented a claim of public authority, a jury instruction on
that theory of defense was required. The district court erred
by not giving that instruction sua sponte. Bear satisfies the
first prong of the plain error test.

   [4] Bear also satisfies the second prong because the court’s
error was plain. An error is plain if it is “clear” or “obvious”
2002                 UNITED STATES v. BEAR
under current law. Johnson, 520 U.S. at 467 (citing Olano,
507 U.S. at 734). As discussed above, Bear repeatedly empha-
sized her claim of public authority throughout the trial. In
closing argument, defense counsel clearly indicated that it
was the crux of Bear’s defense. The government also devoted
a portion of its closing argument to refuting Bear’s claim of
public authority. In one representative example, after remind-
ing the jury that Bear testified to having kept Hager abreast
of her allegedly illegal activities, government counsel stated:
“That is the only little wiggle room [Bear] thought she had,
and it’s a lie. She never called Deputy Hager.”

   [5] Moreover, public authority has been a viable defense
since long before Bear’s trial in 2003. See, e.g., United States
v. Davis, 76 F.3d 311, 314 (9th Cir. 1996); United States v.
Mason, 902 F.2d 1434, 1440-41 (9th Cir. 1990). A model jury
instruction for the defense was published in this circuit in
1997 entitled “Public Authority or Government Authorization
Defense.” See Ninth Circuit Manual of Model Criminal Jury
Instructions, Instruction 6.10 (2003); Ninth Circuit Manual of
Model Criminal Jury Instructions, Instruction 6.8 (1997).
Given the public authority defense’s longstanding presence in
our circuit, and that Bear clearly presented it as the crux of
her defense, the district court’s error in omitting the instruc-
tion was plain. Cf. United States v. Burt, 143 F.3d 1215, 1218
(9th Cir. 1998) (holding that the district court’s error in giving
an inaccurate jury instruction was plain because prior case
law established the instruction’s proper parameters).

   Bear also satisfies the third prong of the plain error test
because the error affected her substantial rights. “An error
prejudices the substantial rights of a defendant when it ‘affec-
t[s] the outcome of the proceedings.’ ” United States v. Fuchs,
218 F.3d 957, 962 (9th Cir. 2000) (quoting United States v.
Baron, 94 F.3d 1312, 1318 (9th Cir. 1996)). In Fuchs, we
found that the district court’s failure to include a jury instruc-
tion affected the defendant’s substantial rights because it cre-
                     UNITED STATES v. BEAR                  2003
ated a genuine possibility that the jury convicted on a legally
inadequate ground. See id. at 963.

   [6] Despite Bear’s claim of public authority, the district
court instructed jurors that they could convict her if she know-
ingly agreed with others to manufacture or distribute metham-
phetamine. The instructions stated that “[t]he Government is
not required to prove that the defendant knew that her acts or
omissions were unlawful.” Following these instructions, the
jury could have found that Bear reasonably believed she was
acting under public authority, but still convicted her of know-
ingly committing the offense. A public authority instruction
would have precluded this possibility. The district court’s fail-
ure to give the public authority instruction, therefore, affected
Bear’s substantial rights.

   This conclusion is unaffected by counsels’ statements dur-
ing closing argument that the jury should acquit Bear if they
believed her rather than Hager. The district court instructed
the jury that “[y]our verdict must be based solely on the evi-
dence and on the law as I have given it to you in these instruc-
tions.” This clearly excludes counsels’ statements during
closing, and thus those remarks do not undermine the impact
of omitting to instruct the jury on a public authority defense.

   Regarding the fourth prong of the plain error test, we may
exercise our discretion and reverse Bear’s conviction only if
the error “seriously affects the fairness, integrity, or public
reputation of judicial proceedings.” Fuchs, 218 F.3d at 962
(citing Johnson, 520 U.S. at 467). Allowing the conviction to
stand does not have those serious effects on judicial proceed-
ings when the evidence against the defendant on the issue
erroneously explained to the jury is “overwhelming.” Id. at
963 (citing Johnson, 520 U.S. at 470). The Supreme Court
found such overwhelming evidence when the erroneous
instruction pertained to a fact that was “essentially uncontro-
verted at trial.” Johnson, 520 U.S. at 470. As we explained in
Fuchs, however, evidence is not overwhelming simply
2004                     UNITED STATES v. BEAR
because it is sufficient to support a guilty verdict. See Fuchs,
218 F.3d at 963 (stating that “[w]hile there was enough evi-
dence to support the verdict, the entire record also supports an
inference [to the contrary],” and concluding that “[a]llowing
defendants’ convictions to stand, given the likelihood that the
jury may not have convicted had they been properly
instructed, would be a ‘miscarriage of justice.’ ” (quoting
United States v. Shortman, 91 F.3d 80, 82 (9th Cir. 1996))).

   While there is strong evidence that Bear did not reasonably
believe that the government had authorized her actions, the
record would also support a contrary finding. During a post
arrest interview, Bear denied that anyone had authorized her
to commit the alleged offenses. At trial, however, she testified
that she believed she was cooperating with the government
through Deputy Hager until the moment of her arrest. She
also testified that she feared for her life at the time of her
arrest because she believed that members of the DEA task
force had been leaking her identity to people she helped
investigate. She claimed that this fear and mistrust initially
caused her to deny her cooperative status during the post
arrest interview.

   [7] Bear’s testimonial support for a finding that she acted
with a reasonable belief of public authority—especially con-
sidering that it was her sole theory of defense—is not over-
whelmed by the contrary evidence. As in Fuchs, allowing
Bear’s conviction to stand, given the likelihood that the jury
may not have convicted had they been properly instructed,
would seriously affect the fairness, integrity, or public reputa-
tion of judicial proceedings. Accordingly, we exercise our dis-
cretion to reverse.1
   1
     Federal Rule of Criminal Procedure 12.3 is inapposite to our plain error
analysis. Rule 12.3 requires defendants to provide government counsel
with pretrial notice of their intent to raise a public authority defense. Fed.
R. Crim. P. 12.3(a). A failure to comply allows the court to exclude the
testimony of any undisclosed witness except the defendant, regarding the
public authority defense. Fed. R. Crim. P. 12.3(c). The defendant Bear was
the only witness called in support of the public authority defense. There-
fore, without addressing the adequacy of Bear’s notice, we conclude that
Rule 12.3 is inapplicable to our analysis.
                     UNITED STATES v. BEAR                  2005
  B.   Pretrial Agreement

   Bear also argues that the government breached a pretrial
agreement by calling Deputy Hager as a witness in its rebuttal
case. She contends the government stipulated that it would not
call Hager at trial. The government, however, maintains that
it only agreed not to call Hager in its case-in-chief, and there-
fore acted properly by using him exclusively in rebuttal.
Because in the event of a retrial the government will be bound
by whatever agreement it made, see United States v. Shapiro,
879 F.2d 468, 472 (9th Cir. 1989) (“It is also apparent that the
government must abide by its agreement if it chooses to retry
[defendant].”), we will resolve the question of the scope of the
government’s agreement.

   [8] Interpreting the agreement is a question of law we
review de novo. See United States v. Lawton, 193 F.3d 1087,
1094 (9th Cir. 1999) (“The interpretation of stipulations is,
like the interpretation of contracts, an issue of law reviewed
de novo.” (citing Braxton v. United States, 500 U.S. 344, 350
(1991))). To effectively limit an agreement to its case-in-
chief, the government must communicate that limitation
unambiguously. See Shapiro, 879 F.2d at 472 (“If the govern-
ment intended to condition its stipulation . . . the government
was obligated to do so unambiguously.”).

   Prior to trial, government counsel sent a letter to six co-
defendants, including Bear, stating that the Los Angeles Sher-
iff’s Department had terminated Deputy Hager’s employment
as explained in a nine-volume internal affairs investigative
report. The letter also stated that “the government does not
intend on calling him as a witness at trial.” At a pretrial con-
ference one week later, Bear’s counsel requested a two-month
continuance to obtain the internal affairs files for impeach-
ment purposes. Government counsel stated that “[t]he govern-
ment does not plan on calling [Hager] as a witness in our
case, so I’m not sure what impeachment counsel is talking
about because he’s not going to be called as a witness.” Gov-
2006                  UNITED STATES v. BEAR
ernment counsel also said that the files were wholly unrelated
to Bear’s case according to internal affairs, and that they
might be difficult to obtain from the state. Nonetheless, gov-
ernment counsel offered to help Bear obtain the files, and
stated that the government had no objection to a several-
month continuance.

   The district court granted a one-week continuance, and
scheduled another pretrial conference to discuss Bear’s prog-
ress in obtaining the files and the possibility of a further con-
tinuance. At that follow-up pretrial conference, Bear’s
counsel made the following statement:

     I spoke with the U.S. Attorney Miss Wright today,
     and since we received the memo from the U.S.
     Attorney’s office that the government is not going to
     be calling Deputy Hager as a witness, and if this is
     put on the record, we would not be needing to pursue
     this avenue of investigating the reasons of taking a
     look at those nine volumes of records at the sheriff’s
     department pertaining to Deputy Hager’s termina-
     tion.

This statement refers to an off-record conversation between
counsel regarding the agreement limiting Hager’s testimony,
but does not reveal the details of that discussion or the agree-
ment’s scope. Because the agreement-defining conversation
appears to have occurred off the record, and neither party
clarified the record prior to trial, it is unclear whether, pretrial,
the government had expressly limited the agreement to its
case-in-chief.

   This ambiguity, however, evaporates upon consideration of
counsels’ discourse at trial. On the first day of trial, the prose-
cutor stated that she had “previously discussed with defense
counsel the fact that the Government does not intend to call
Deputy Hager in its case-in-chief,” and that “[p]erhaps some-
thing in Defendant’s cross-examination, as I have already dis-
                     UNITED STATES v. BEAR                   2007
cussed with defense counsel, may raise an issue in the
Government’s rebuttal case.” Defense counsel did not object
to this representation of the agreement’s limited scope,
despite its clarity and despite its reference to a prior conversa-
tion during which the government had expressly communi-
cated the limitation.
   Upon learning of Hager’s presence in court on the third day
of trial, defense counsel objected, stating that there was an
“agreement between Government counsel and Defense that
Deputy Hager is not going to testify.” The prosecutor insisted
that the government had clearly communicated the case-in-
chief limitation, and had expressly reserved the right to call
Hager in rebuttal, both prior to and during trial without objec-
tion. The district judge agreed with the prosecutor, and
allowed Hager to testify.
   [9] We affirm the district court’s determination that the
agreement not to call Hager was limited to the government’s
case-in-chief. Defense counsel failed to object on the first day
of trial to the government’s explicit description of the limited
agreement—including a right to call Hager on rebuttal—and
references to prior, consistent, scope-defining discussions.
This indicates that the government had unambiguously com-
municated the agreement’s case-in-chief limitation. Conse-
quently, in any retrial of this case against Bear, while Hager
may not testify in the government’s case-in-chief, he may tes-
tify as a rebuttal witness.
                         III. Conclusion
   The district court committed plain error by failing to give
the jury a sua sponte instruction on the public authority
defense, and that error requires reversal of Bear’s conviction.
The court did not err in interpreting the government’s agree-
ment limiting Hager’s testimony. In any retrial of this case
against Bear, the government is entitled to call Hager as a
rebuttal witness, but may not call him in its case-in-chief.
   REVERSED and REMANDED.
