                  FOR PUBLICATION

  UNITED STATES COURT OF APPEALS
       FOR THE NINTH CIRCUIT


UNITED STATES OF AMERICA ,               No. 12-50220
          Plaintiff-Appellee,
                                            D.C. No.
             v.                          3:11-cr-05481-
                                            MMA-1
LUIS HERNANDEZ-MEZA ,
        Defendant-Appellant.               OPINION


      Appeal from the United States District Court
         for the Southern District of California
      Michael M. Anello, District Judge, Presiding

               Argued and Submitted
         March 6, 2013—Pasadena, California

                   Filed June 21, 2013

 Before: Alex Kozinski, Chief Judge, and Kim McLane
   Wardlaw, and Ronald M. Gould, Circuit Judges.

           Opinion by Chief Judge Kozinski
2           UNITED STATES V . HERNANDEZ-MEZA

                           SUMMARY*


                           Criminal Law

     The panel vacated an illegal reentry conviction and
remanded for further proceedings in a case involving speedy-
trial and discovery issues.

    The panel held that the district court violated the Speedy
Trial Act by excluding time after the defendant notified the
court that an agreement had been reached, where nothing in
the record indicates that the defendant so notified the court.
The panel rejected the government’s contention that the two
days on which the parties appeared in court and were granted
continuances are automatically excluded as “delay resulting
from other proceedings concerning the defendant.”

     The panel held that the district court abused its discretion
in granting the government’s motion to reopen its case-in-
chief to introduce the defendant’s mother’s naturalization
certificate in order to counter the defendant’s proffered
derivative-citizenship defense. The panel observed that the
district judge’s single reason for allowing the government to
reopen – that everyone was surprised by the derivative-
citizenship defense – is not supported by the record. The
panel held that the defendant was entitled to a ruling from the
district court regarding whether the government’s failure to
produce the certificate during discovery, as an item in its
control “it intends to use . . . in its case-in-chief at trial” under
Fed. R. Crim. P. 16, precluded reopening. The panel held

  *
    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 . HERNANDEZ-MEZA                    3

that the certificate should have been disclosed in any event as
a document material to preparing the defense.

     The panel concluded that the defendant was clearly
prejudiced by the district judge’s leniency in allowing the
prosecution to fill the gaps it had left in its case. The panel
remanded for an evidentiary hearing into whether the
prosecution’s failure to disclose the certificate in discovery or
at any point before the proofs had closed was willful, and if
so, to impose appropriate sanctions. The panel instructed the
district court to dismiss the illegal reentry count on account
of the Speedy Trial Act violation, with or without prejudice,
depending on its weighing of the relevant factors.

    The panel ordered reassignment to a different district
judge, and retained jurisdiction over any other appeals in this
case.


                         COUNSEL

Harini P. Raghupathi (argued), Federal Defenders of San
Diego, Inc., San Diego, California, for Defendant-Appellant.

Mark R. Rehe (argued), Assistant United States Attorney,
Laura E. Duffy, United States Attorney, and Bruce R.
Castetter, Assistant United States Attorney, Chief, Appellate
Section Criminal Division, Office of the United States
Attorney, San Diego, California, for Plaintiff-Appellee.
4            UNITED STATES V . HERNANDEZ-MEZA

                              OPINION

KOZINSKI, Chief Judge:

   We consider a number of questions in this criminal
appeal, including the government’s discovery obligations
under Federal Rule of Criminal Procedure 16.

I. BACKGROUND

    Luis Hernandez-Meza was charged with illegal reentry.
See 8 U.S.C. § 1326. After plea negotiations with the
government broke down, he was also charged with falsely
claiming to be a United States citizen. See 18 U.S.C. § 911.
He subsequently filed a motion to dismiss the indictment,
alleging a Speedy Trial Act violation. See 18 U.S.C.
§ 3161(c). The district judge denied the motion.

     Hernandez-Meza’s strategy at trial was to cast doubt on
whether he is an alien. Under the law applicable at the time
Hernandez-Meza was a minor, he would be a derivative U.S.
citizen if both his parents were naturalized before he turned
18. See 8 U.S.C. § 1432(a) (repealed 2001); see also United
States v. Casasola, 670 F.3d 1023, 1026–28 (9th Cir. 2012).1
Hernandez-Meza argued that the government’s proof had left
open that possibility and the jury should, therefore, have
reasonable doubt as to alienage. Hernandez-Meza didn’t call
witnesses or present evidence, but he did cross-examine two
of the government’s three witnesses about facts supporting
his theory, and he discussed the issue during two sidebar
conferences. And, after both sides had rested, he proffered

 1
   The law changed in 2001 to require that only one parent be naturalized,
but the new law is not retroactive. See Casasola, 670 F.3d at 1026–28.
               UNITED STATES V . HERNANDEZ-MEZA                   5

two jury instructions supporting his derivative citizenship
defense.

    In response to these proposed instructions, the
government moved to reopen its case-in-chief to introduce
Hernandez-Meza’s mother’s naturalization certificate. The
certificate shows that she became a U.S. citizen nearly twenty
years after Hernandez-Meza turned eighteen, foreclosing his
derivative citizenship theory. Over defense counsel’s
repeated objections, the judge permitted the government to
reopen. The court observed that Hernandez-Meza’s proposed
instructions came as “a total surprise to [the government] and
everybody else,” and that “under the circumstances [the
government is] entitled, [in] fairness, to reopen [to introduce
the certificate] to make sure everybody has got the facts
straight.” The jury convicted Hernandez-Meza of illegal
reentry.2

II. DISCUSSION

    1. Speedy Trial Act. “[I]n general, time devoted to plea
negotiations is not automatically excluded . . . .” United
States v. Alvarez-Perez, 629 F.3d 1053, 1058 (9th Cir. 2010).
In denying Hernandez-Meza’s motion to dismiss, the district
court relied on a narrow exception to this general rule, which
applies when the defendant notifies the court that an
agreement has been reached. See id. (excluding such time
either under § 3161(h)(1)(G) as “delay resulting from
consideration by the court of a proposed plea agreement” or
under § 3161(h)(1)(D) as time devoted to addressing a
“pretrial motion”). But there is nothing in the record to
indicate that Hernandez-Meza so notified the district court.

 2
     It acquitted him of falsely claiming to be a U.S. citizen.
6          UNITED STATES V . HERNANDEZ-MEZA

Neither of the minute entries the government cites in support
of the district court’s ruling indicates that Hernandez-Meza
told the court a plea agreement existed. The district court
referenced the Alvarez-Perez exception but did not point to
where in the record Hernandez-Meza so indicated. The
district court may have believed that being close to an
agreement is enough but, of course, it’s not. Alvarez-Perez
is clear on this point. See id.

    The government argues that the two days on which the
parties appeared in court and were granted continuances are
automatically excluded as “delay resulting from other
proceedings concerning the defendant.” See 18 U.S.C.
§ 3161(h)(1). It’s quite a stretch to characterize as
“proceedings” brief court appearances—amounting to a page
or so of transcript—where the parties come to court just long
enough to have the case postponed to another day. Certainly,
these brief encounters look nothing like the eight proceedings
specifically listed in section 3161(h)(1). While we have
recognized that “Congress did not intend to restrict the
meaning of ‘other proceedings’ to those specifically
mentioned,” United States v. Lopez-Espindola, 632 F.2d 107,
110 (9th Cir. 1980), the Supreme Court has instructed us that,
in construing the broad language in subsection (h)(1), we
follow the specific-controls-the-general canon and avoid
interpretations that render superfluous more specific STA
provisions, see Bloate v. United States, 130 S. Ct. 1345, 1352
n.9, 1354–56 (2010). Reading subsection (h)(1) to exclude
the day on which a continuance is granted—i.e., the first day
of the continuance—would be an illegitimate end-run around
the STA subsection permitting continuances to be excluded
only when the court finds that doing so serves the ends of
justice. See 18 U.S.C. § 3161(h)(7)(A).
           UNITED STATES V . HERNANDEZ-MEZA                     7

    The government here took just two days beyond the STA
deadline to bring Hernandez-Meza to trial. The government
could have avoided this problem, had it asked the district
judge to stop the STA clock during either of the one-week
continuances granted due to the collapse of plea negotiations.
See 18 U.S.C. § 3161(h)(7)(A); Zedner v. United States,
547 U.S. 489, 507 (2006). But the government made no such
request and the STA clock ran out. Under the circumstances,
the district judge had no authority to let the case go forward.
See 18 U.S.C. § 3162(a)(2).

     2. Motion to Reopen. Hernandez-Meza repeats two of
the objections to the government’s motion to reopen that he
raised below: (a) the government was not surprised and could
have proffered the naturalization certificate before it rested its
case; and (b) the government was, in any event, not entitled
to introduce the naturalization certificate because it had failed
to produce it during discovery. Although they are closely
connected, we consider these arguments separately.

        a. Surprise. While district judges have discretion
whether to allow parties to reopen their cases, see United
States v. Ramirez, 608 F.2d 1261, 1267 (9th Cir. 1979), we
have held that “reopening a case for the purpose of
introducing overlooked evidence must be done with extreme
reluctance,” Eason v. United States, 281 F.2d 818, 822 (9th
Cir. 1960). The district judge’s reason for allowing
reopening must, in any event, be supported by the record. See
United States v. Hinkson, 585 F.3d 1247, 1261–62 (9th Cir.
2009) (en banc).
8          UNITED STATES V . HERNANDEZ-MEZA

    The record here discloses no reluctance on the part of the
district judge in allowing the prosecution to reopen, nor is his
reason supported by the record. This is the entirety of the
district court’s ruling: “I think [the AUSA is] entitled to re
open [sic]. Go back to that. This is a total surprise to him
and everybody else. So I’m going to allow him to re open
[sic] for the purpose of offering that [the mother’s
naturalization certificate] . . . .” In response to defense
counsel’s objections, the judge delivered his ruling four more
times, but gave no additional reasons.

    The district judge’s single reason for allowing the
government to reopen—that everyone was surprised by
Hernandez-Meza’s defense of derivative citizenship—is not
supported by the record. The government’s claim of surprise
rested on the AUSA’s belief that Hernandez-Meza wouldn’t
present a derivative citizenship defense because he must have
known that he wasn’t a U.S. citizen:

       Mr. Manahan: The surprise is that this would
                    be an issue because it’s the
                    United States opinion that the
                    defendant regardless of
                    discovery, is fully aware of
                    when his own mother
                    naturalized and maybe, if it
                    was like even close to his 18th
                    birthday, maybe they would
                    say, I didn’t realize but when
                    it’s almost 20 years after
                    wards [sic], defendant has to
                    know that’s not an appropriate
                    issue in this case.
           UNITED STATES V . HERNANDEZ-MEZA                 9

But a criminal defendant, unlike the government, needn’t
have a good faith belief in the factual validity of a defense.
So long as the defendant doesn’t perjure himself or present
evidence he knows to be false—and Hernandez-Meza
presented no evidence at all—he’s entitled to exploit
weaknesses in the prosecution’s case, even though he may
believe himself to be guilty.

    What matters in satisfying the government’s burden of
proof in a criminal case is not objective reality nor
defendant’s personal belief, but the evidence the government
presents in court. No competent prosecutor would be
surprised, based on what he thinks defendant should know, to
find defense counsel poking holes in the government’s case.
The argument is without merit, yet the government made it
before the district court, and again on appeal. See United
States v. Kojayan, 8 F.3d 1315, 1320, 1322 (9th Cir. 1993)
(we expect the government on appeal not to repeat specious
arguments line prosecutors make in the heat of the moment).

    There may be situations where the government can
legitimately claim surprise. For example, the Federal Rules
of Criminal Procedure require defendants to give advance
notice of an insanity defense, Fed. R. Crim. P. 12.2(a); a
public authority defense, id. 12.3(a)(1); and, if the
prosecution submits a written request, an alibi defense, id.
12.1(a). If the defendant fails to give a required notice, the
government may well be able to claim unfair surprise. But
when our rules and precedents don’t require the defendant to
give notice, he’s entitled to remain silent as to what defense
he will present, and the government must anticipate any
issues he might raise.
10         UNITED STATES V . HERNANDEZ-MEZA

    In any event, the record is clear that the government was
not surprised by Hernandez-Meza’s derivative citizenship
defense. Defense counsel clearly telegraphed her strategy in
plenty of time for the government to proffer the naturalization
certificate before it rested. During a sidebar conference
barely halfway through the government’s case-in-chief,
defense counsel clearly alluded to derivative citizenship and
the government’s lack of evidence on the point:

       Ms. Kimpel: We’d also be impeaching by
                   omission the fact that those
                   critical factors which would
                   give rise to a derivative
                   citizenship [claim] are not
                   included in the reports.

       The Court:      We’re not going to be
                       litigating a derivative
                       citizenship claim here. This is
                       not the place to do that. You
                       want the jury to speculate may
                       be [sic] he is a citizen or has
                       citizenship rights?

       Ms. Kimpel: I think what we’re saying is
                   with the evidence the
                   government presented, given
                   direct contrary evidence, he
                   hasn’t been able to prove he’s
                   not a citizen and hasn’t proved
                   he’s an alien.
           UNITED STATES V . HERNANDEZ-MEZA                11

And then again, later in the same sidebar conference:

       Ms. Kimpel: Your honor is allowing us to
                   impeach by omission if some
                   of the information is not in the
                   report.     That would be
                   important to a derivative
                   citizenship claim.

    Following this sidebar, defense counsel cross-examined
Sara Esparagoza, a customs and border protection officer who
interviewed Hernandez-Meza when he tried to enter the
country. Hernandez-Meza’s attorney questioned Esparagoza
extensively about the immigration form she filled out after
her interview with Hernandez-Meza. First, defense counsel
noted that the front page of the form listed information about
Hernandez-Meza’s parents:

       Ms. Kimpel: [T]he reason that that front
                   page has that information
                   about the parents is because
                   that can be important [to the
                   potential alien’s] immigration
                   status?

       Esparagoza:     Correct.

       Ms. Kimpel: And in fact, sometimes people
                   can be citizens, even if they
                   aren’t born in the United
                   States?
12         UNITED STATES V . HERNANDEZ-MEZA

       Esparagoza:     A person can be a citizen of
                       the United States even if they
                       are not born in the United
                       States. Yes, that’s correct.
                       That can happen.

       Ms. Kimpel: Based on the citizenship of
                   their parents?

       Esparagoza:     Correct. Sometimes.

   Defense counsel then led Esparagoza through a series of
questions, revealing that the officer had incorrectly marked
on the form that both of Hernandez-Meza’s parents were
Mexican citizens. Defense counsel showed Esparagoza a
copy of Hernandez-Meza’s mother’s U.S. passport, and
Esparagoza confirmed that the mother was a U.S. citizen.
Esparagoza also admitted that (1) she based her information
about Hernandez-Meza’s father’s immigration status on what
Hernandez-Meza told her during the interview and (2)
Hernandez-Meza told her that his father was a U.S. citizen.

    The Esparagoza cross-examination came immediately
after the first sidebar conference, where the parties discussed
the derivative citizenship defense. Defense counsel’s
questions must be read in light of the fact that, two transcript
pages earlier, she had made clear that the defense would be
challenging the government’s proof of alienage. No one
paying attention could have had any doubt as to the line of
defense that counsel was pursuing.

    Following Esparagoza’s testimony, the government
presented Jorge Rosario, the custodian of Hernandez-Meza’s
alien registration file. At defense counsel’s prompting,
           UNITED STATES V . HERNANDEZ-MEZA                13

Rosario confirmed that (1) “there are many ways people can
become United States citizens,” (2) a person can “be a United
States citizen if one of their parents was a United States
citizen” and (3) a person can “become a citizen if [he is] a
child and [his] parents naturalized” if “certain requirements”
are met. Rosario also stated that Hernandez-Meza’s father
was a naturalized U.S. citizen at the time that Hernandez-
Meza was legally admitted into the United States as a child.

    During a second sidebar, near the end of Rosario’s
testimony, defense counsel explained, in so many words, that
she would be challenging the element of alienage by
suggesting that Hernandez-Meza may be a derivative citizen:

       Ms. Kimpel: I’m challenging the element of
                   alienage. They don’t have to
                   prove it was a lawful
                   deportation. They just need to
                   prove that he’s not a citizen of
                   the United States.          And
                   whatever status that he lost
                   would not go as to whether he
                   was a citizen or not except for
                   the purposes that we’re trying
                   to raise that he had status
                   before he was 18 and that
                   could go toward derivative
                   citizenship.

(Emphasis added). It’s hard to imagine a clearer statement
than that.
14           UNITED STATES V . HERNANDEZ-MEZA

    All of this happened while the government was still
presenting its case, so it could easily have proffered the
mother’s naturalization certificate before resting.3 Nor is
there any doubt that the government understood full well that
the timing of the mother’s naturalization was crucial to
Hernandez-Meza’s defense:

         Mr. Manahan: As a matter of law, he’s not a
                      derivative citizen. His mother
                      naturalized and based on when
                      he was born for derivative
                      citizenship, it really keys in on
                      the mother, she naturalized
                      way after he turned 18. As a
                      matter of law, he’s not a
                      derivative citizen.

Defense counsel, in her turn, alerted the court and the
government to the fact that the date of the mother’s
naturalization was not reflected in any document the
government had introduced into evidence or disclosed during
discovery:




  3
    Had it done so, however, it would no doubt have been met with the
objection that the document wasn’t disclosed during discovery. See pp.
15–19 infra. The AUSA likely did not offer the naturalization certificate
before resting because he knew he was precluded from doing so by the
clear command of Federal Rule of Criminal Procedure 16(a)(1)(E)(ii),
which requires the government to disclose documents it intends to present
in its case-in-chief. The prosecutor may have hoped to introduce the
document by way of rebuttal and was surprised when defendant didn’t
present any evidence. T hat, of course, is not the type of surprise that
justifies reopening.
           UNITED STATES V . HERNANDEZ-MEZA                   15

        Ms. Kimpel: The government made a
                    representation about whether
                    Mr. Hernandez’s mother
                    became a citizen. I haven’t
                    seen any evidence in the
                    government’s case that
                    discusses that nor had I been
                    provided any in discovery.

The government did not, even then, give defense counsel a
copy of the certificate, even though the prosecutor had it with
him in court.

      Given these clear indications that Hernandez-Meza’s
derivative citizenship status would be interposed as a defense,
and that the date of his mother’s naturalization would be an
issue, it’s difficult to understand how the district judge could
have stated, only twenty-nine transcript pages later, that “this
[defense] is a total surprise to [government counsel] and
everybody else.” Indeed, the government lawyer conceded
that he “became first aware this would be a possible defense
. . . moments before we rested.” If the AUSA knew before he
rested that derivative citizenship would be a “possible
defense,” he couldn’t very well have been surprised when
defense counsel proceeded to argue just that after he rested.
Because the district court’s ruling—allowing the government
to introduce evidence after the proofs had closed—failed to
show the proper degree of reluctance and misstated the
record, it was an abuse of discretion. See Hinkson, 585 F.3d
at 1261–62.

         b. Discovery. Upon a proper request by the
defendant, the government must produce items in its control
that it “intends to use . . . in its case-in-chief at trial.” See
16         UNITED STATES V . HERNANDEZ-MEZA

Fed. R. Crim. P. 16(a)(1)(E)(ii). The government doesn’t
contest that the mother’s naturalization certificate was in the
government’s control or that Hernandez-Meza made a timely
Rule 16 request.

    In defense counsel’s view, there was no point in allowing
the government to reopen because it had failed to disclose the
certificate during discovery and so was precluded from
introducing it as part of its case-in-chief. Despite defense
counsel’s attempts to engage the district court on this issue,
the court never addressed it. When defense counsel reiterated
the argument, the judge brushed her off: “We’re beyond
that,” he said, and moved on.

     But defense counsel had raised a legitimate issue and was
entitled to a ruling from the district court. Giving an
explanation for significant rulings is an important component
of due process. It lets the adversely affected party know that
the judge has heard and understood its argument, and that the
judge’s ruling is based on the facts and the law. An
explanation also allows the judge to confirm that his ruling is
correct. If he is unable to articulate a plausible rationale for
his ruling, he may think better of it. Finally, and not least, by
failing to give any indication that he applied the correct legal
standard, the district judge made appellate review difficult.
See Hinkson, 585 F.3d at 1261–62; cf. United States v.
Taylor, 487 U.S. 326, 336–37 (1988) (“[A] district court must
. . . clearly articulate [its reasoning] in order to permit
meaningful appellate review.”).

   Had the district judge paused to consider defense
counsel’s argument, he may well have realized that the
government was seeking to reopen in order to present a
document during its case-in-chief that it had failed to disclose
           UNITED STATES V . HERNANDEZ-MEZA                17

during discovery. But, by failing to disclose, the government
undertook the clear risk that it would be precluded from
presenting the document as part of its principal case. See
Fed. R. Crim. P. 16(a)(1)(E)(ii); id. 16(d)(2). Allowing the
government to reopen in order to introduce the document
circumvented the government’s self-imposed limitation. This
was unfair to Hernandez-Meza, who was entitled to build his
defense strategy on the assumption that he had seen all the
items the government would present as part of its case.

    The naturalization certificate should have been disclosed
in any event under the separate prong of Rule 16 that applies
to documents “material to preparing the defense.” See Fed.
R. Crim. P. 16(a)(1)(E)(i). Materiality is a low threshold; it
is satisfied so long as “the information [in the certificate]
would have helped” Hernandez-Meza prepare a defense.
United States v. Doe, 705 F.3d 1134, 1151 (9th Cir. 2013).
Information is material even if it simply causes a defendant
to “completely abandon” a planned defense and “take an
entirely different path.” Id. Had Hernandez-Meza known
that the government had the certificate, he may not have
staked his case on his derivative citizenship theory. The
certificate is unquestionably material and should have been
disclosed by the government.

    The government argues that it couldn’t have known the
certificate was material to the defense. But one of the
elements of illegal reentry is alienage. See United States v.
Sandoval-Gonzalez, 642 F.3d 717, 721–22 (9th Cir. 2011).
And Hernandez-Meza was also charged with falsely claiming
to be a U.S. citizen. His U.S. citizenship or lack thereof was
thus central to the case. The AUSA didn’t need much
imagination to realize that Hernandez-Meza might try to cast
doubt on the government’s proof of his alienage. The AUSA
18         UNITED STATES V . HERNANDEZ-MEZA

must have understood that derivative citizenship was a
possible line of defense—why else would he have had the
mother’s naturalization certificate with him in court?

    A defendant needn’t spell out his theory of the case in
order to obtain discovery. Nor is the government entitled to
know in advance specifically what the defense is going to be.
The relevant subsection of Rule 16 is written in categorical
terms: Upon defendant’s request, the government must
disclose any documents or other objects within its possession,
custody or control that are “material to preparing the
defense.” Fed. R. Crim. P. 16(a)(1)(E)(i). Unlike the
preceding and subsequent subsections, which both require
that “the government knows—or through due diligence could
know—that the” item exists, see Fed. R. Crim. P.
16(a)(1)(D), (F), subsection (E) is unconditional. Lack of
knowledge or even a showing of due diligence won’t excuse
non-compliance.

    It thus behooves the government to interpret the
disclosure requirement broadly and turn over whatever
evidence it has pertaining to the case. See United States v.
Leal-Del Carmen, 697 F.3d 964, 969 n.4 (9th Cir. 2012); see
also Editorial, Beyond the Brady Rule, N.Y. Times, May 19,
2013, at SR10. When there has been a proper Rule
16(a)(1)(E)(i) request, and the prosecution finds itself holding
a document during the trial that it should have turned over, as
happened here, it must promptly advise opposing counsel and
the court that it hasn’t complied with its Rule 16 obligations.
See Fed. R. Crim. P. 16(c). The district court can then take
such remedial measures as it deems appropriate, including
continuing the trial or declaring a mistrial. See Fed. R. Crim.
P. 16(d)(2).
           UNITED STATES V . HERNANDEZ-MEZA                  19

    The record suggests that the government may have
deliberately withheld the naturalization certificate from
Hernandez-Meza, perhaps hoping to lock him into a defense
he couldn’t win. It may have hoped to present the certificate
by way of rebuttal—under the mistaken impression that it did
not need to disclose the document if it didn’t intend to present
it in its case-in-chief—and was then outflanked when
defendant did not put on any evidence. We infer this from
the record as a whole and particularly from the fact that the
prosecution knew the date of Hernandez-Meza’s mother’s
naturalization and its relevance to the case, yet didn’t produce
the certificate even after defense counsel pointed out the
lacuna. See pp. 14–15 supra. However, this is a factual
finding that must be made by a district court in the first
instance. If the government willfully withheld the certificate,
then it should be precluded from introducing the document at
any retrial of Hernandez-Meza, or perhaps even suffer a
dismissal of the indictment with prejudice. See Kojayan,
8 F.3d at 1325 (remanding for a decision as to whether
indictment should be dismissed with or without prejudice).

        c. Prejudice. The government rattles off a long list
of reasons Hernandez-Meza wasn’t prejudiced, but none of
these changes the fact that, had the court denied the motion to
reopen, Hernandez-Meza would have been left with a viable
derivative citizenship defense. Without the certificate, the
government hadn’t conclusively foreclosed that defense
during its case-in-chief, which is doubtless why it moved to
reopen its case after Hernandez-Meza asked for jury
instructions on that very point. Hernandez-Meza was clearly
prejudiced by the district judge’s leniency in allowing the
prosecution to fill the gaps it had left in its case.

                       *       *       *
20         UNITED STATES V . HERNANDEZ-MEZA

    We vacate the conviction and remand for an evidentiary
hearing into whether the prosecution’s failure to disclose the
certificate in discovery or at any point before the proofs had
closed was willful. If it was willful, the district court shall
impose appropriate sanctions. The district court shall, in any
event, dismiss the illegal reentry count of the indictment on
account of the STA violation, with or without prejudice,
depending on its weighing of the relevant factors. See
18 U.S.C. § 3162(a)(2); United States v. Lewis, 349 F.3d
1116, 1121–22 (9th Cir. 2003).

    We are perturbed by the district court’s handling of the
reopening issue. The court persisted in giving a reason for
allowing the government to reopen that was contradicted by
the record, despite defense counsel’s repeated attempts to
point out the error. The court also ignored defendant’s twice-
raised Rule 16 objection and made a questionable ruling
regarding defendant’s Speedy Trial Act claim.

    “Whether or not [the district judge] would reasonably be
expected to put out of his mind” his previous rulings, and
“without ourselves reaching any determination as to his
ability to proceed impartially, to preserve the appearance of
justice, . . . we conclude reassignment is appropriate,” and we
so order. See Ellis v. U.S. Dist. Court (In re Ellis), 356 F.3d
1198, 1211 (9th Cir. 2004) (en banc).

    VACATED and REMANDED. This panel retains
jurisdiction over any further appeals in this case.
