                FOR PUBLICATION

  UNITED STATES COURT OF APPEALS
       FOR THE NINTH CIRCUIT


UNITED STATES OF AMERICA,             No. 12-10171
                Plaintiff-Appellee,
                                         D.C. No.
                v.                    2:08-cr-00064-
                                       RLH-GWF-2
EVE MAZZARELLA,
            Defendant-Appellant.



UNITED STATES OF AMERICA,             No. 13-10401
                Plaintiff-Appellee,
                                         D.C. No.
                v.                    2:08-cr-00064-
                                       RLH-GWF-2
EVE MAZZARELLA,
            Defendant-Appellant.



UNITED STATES OF AMERICA,             No. 13-10658
                Plaintiff-Appellee,
                                         D.C. No.
                v.                    2:08-cr-00064-
                                       RLH-GWF-2
EVE MAZZARELLA,
            Defendant-Appellant.        OPINION
2               UNITED STATES V. MAZZARELLA

        Appeal from the United States District Court
                 for the District of Nevada
       Roger L. Hunt, Senior District Judge, Presiding

                 Argued and Submitted
       November 17, 2014—San Francisco, California

                       Filed April 20, 2015

          Before: Ronald M. Gould, Paul J. Watford,
          and Michelle T. Friedland, Circuit Judges.

                     Opinion by Judge Gould


                           SUMMARY*


                          Criminal Law

    The panel vacated the district court’s orders denying the
defendant’s motions for a new trial, and remanded for further
proceedings, in a case in which the defendant was convicted
of twelve felony counts related to a complex mortgage fraud
scheme.

    After her conviction, the defendant filed two motions for
a new trial, contending that the government withheld material
exculpatory evidence in violation of Brady v. Maryland and
violated her right to be free from unreasonable searches under


  *
    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. MAZZARELLA                     3

the Fourth Amendment. The defendant requested discovery
and an evidentiary hearing on these issues.

    The panel held that based on the record before the district
court, the court erred in concluding that the defendant’s rights
under Brady and the Fourth Amendment had not been
violated.

     The panel held that the defendant has not shown prejudice
based solely on the Brady disclosures, first revealed after her
trial and sentencing. But the panel remanded the Brady
issues for the district court to reconsider them on an open
record, in conjunction with the additional disclosure with
which the defendant sought to augment the record on appeal,
the Fourth Amendment issue, and any further impeachment
or exculpatory evidence that comes to light from discovery.

    The panel held that the district court erred in concluding
on the record before it that an employee’s copying of
documents from the defendant’s real estate and investment
offices was not a search implicating the Fourth Amendment.
The panel wrote that more discovery is required to determine
whether an unlawful search occurred and whether there were
evidentiary fruits of an unlawful search. The panel wrote that
after making these determinations on remand, the district
court should consider again the cumulative effect of the
impeachment evidence it considered before, and the
additional impeachment evidence that the defendant sought
to place before this court. The panel wrote that this material
must be considered together with any evidence that should
have been excluded from trial under the Fourth Amendment
to determine whether any of the defendant’s convictions must
be vacated and a new trial granted.
4             UNITED STATES V. MAZZARELLA

    The panel also held that the district court abused its
discretion in denying the defendant’s requests for an
evidentiary hearing and for discovery. The panel wrote that
more findings, which will require reasonable discovery and
an evidentiary hearing, are needed to resolve whether there
was an immunity agreement in place for a prosecution
witness, and whether there was an unlawful search that
resulted in tainted evidence being used at trial. The panel
wrote that the district court should also consider an additional
disclosure with which the defendant sought to supplement the
record before this court. The panel rejected the defendant’s
argument that the district court should have imposed the very
detailed discovery guidelines from a 2010 Department of
Justice memorandum to federal prosecutors.

  The panel addressed other issues in a concurrently filed
memorandum disposition.


                         COUNSEL

John D. Cline (argued), Law Office of John D. Cline, San
Francisco, California; Mark H. Allenbaugh, Law Offices of
Mark H. Allenbaugh, Cleveland, Ohio, for Defendant-
Appellant.

Daniel G. Bogden, United States Attorney, Elizabeth O.
White, Appellate Chief, Peter S. Levitt (argued), Assistant
United States Attorney, Las Vegas, Nevada, for Plaintiff-
Appellee.
                 UNITED STATES V. MAZZARELLA                               5

                               OPINION

GOULD, Circuit Judge:

    Eve Mazzarella was convicted of twelve felony counts
related to a complex mortgage fraud scheme. After her
conviction, Mazzarella filed two motions for a new trial,
contending that the government had withheld material
exculpatory evidence in violation of Brady v. Maryland,
373 U.S. 83 (1963), and had violated her right to be free from
unreasonable searches under the Fourth Amendment.
Mazzarella requested discovery and an evidentiary hearing on
these issues. The district court denied both motions, and
Mazzarella’s appeal from those orders is before us.1 We have
jurisdiction under 28 U.S.C. § 1291. We hold that based on
the record before the district court, the court erred in
concluding that Mazzarella’s rights under Brady and the
Fourth Amendment had not been violated. We also hold that
the district court abused its discretion in denying
Mazzarella’s request for an evidentiary hearing and for
discovery. We vacate the district court’s orders and remand.




  1
    Mazzarella also challenges her underlying convictions and sentence
directly, raising an ineffective assistance of counsel challenge, a
sufficiency of the evidence challenge, and challenges to the district court’s
evidentiary rulings, jury instructions, and sentencing decisions. We
dismiss the ineffective assistance claim and affirm the district court on all
the other issues except the sentencing challenge in a concurrently filed
memorandum disposition. We do not reach Mazzarella’s contentions
related to sentencing error, which she may raise again if on remand the
district court does not vacate any of her convictions and re-sentence her.
6             UNITED STATES V. MAZZARELLA

                               I

    Mazzarella, a real estate agent and principal of Distinctive
Real Estate & Investments (“DREI”), was accused of
conspiring with Steven Grimm, Melissa Beecroft, and others
to defraud federally insured banks and private citizens. The
scheme involved recruiting straw buyers with excellent credit
histories to acquire full or nearly full financing to purchase
homes. The straw buyers’ loan applications contained
materially false statements related to their income, assets,
employment, and intent to use the home as a primary
residence.

    The homes to be purchased by the straw buyers were
offered for sale at distressed prices below fair market value,
but the mortgages and the purchase offers were for fair
market value. The difference between the two figures was
paid at closing to business entities controlled by Mazzarella
and her co-defendants. The government calls these payments
“third party disbursements.” The government charged that
defendants created numerous limited liability companies
(“LLCs”) and caused straw buyers to transfer their interest in
the purchased properties to the LLCs in exchange for a fee.
Defendants controlled the bank accounts for those entities and
eventually defaulted on mortgage payments on the properties,
resulting in significant losses to the lender, while the
defendants retained much of the money from the third party
disbursements.

    The key unlawful component of the scheme was the false
information in the loan applications. Testimony at trial, much
of which came from cooperating witnesses, showed that
Mazzarella knew that the straw buyers were submitting false
information. One such witness, Skip Young, testified: (1)
             UNITED STATES V. MAZZARELLA                    7

that he had engaged in “fraudulent transactions for Eve
Mazzarella”; (2) that Mazzarella personally gave
misinformation to lenders by suggesting a fake job title at
DREI and inflated income for one of her employees who was
recruited as a straw buyer; and (3) that Mazzarella developed
a plan to create spreadsheets to track which straw buyers
applied to which banks after problems arose with buyers
seeking loans from the same bank on multiple homes and
indicating an intent to reside in each as a primary residence.
Another cooperating witness, Shauna Labee, testified that
Mazzarella had personally induced her to agree to be a straw
buyer and that Mazzarella observed Labee signing blank loan
application forms in Mazzarella’s office. There was also
testimony about Mazzarella’s knowing involvement in other
aspects of the plan that would have been lawful absent the
fraudulent applications.

    The jury found Mazzarella guilty of the conspiracy, bank
fraud, mail fraud, and wire fraud counts, and Mazzarella
appealed.

     While the appeal from her convictions and sentence was
pending, the district court twice denied motions for a new
trial for which Mazzarella moved on the basis of post-trial
government disclosures under Brady v. Maryland. The
government disclosures involved information potentially
helpful to Mazzarella about Kim Brown, Alicia Hanna, and
Jennifer Wolff, who had all testified as prosecution witnesses
in Mazzarella’s trial.

    After the Mazzarella trial, Brown, one of Mazzarella’s
employees at DREI who had testified regarding the
conspiracy charge and one of the mail fraud charges, testified
during the trial of another person connected to the mortgage
8             UNITED STATES V. MAZZARELLA

fraud scheme. In her testimony at that later trial, she said that
while the federal investigation of Mazzarella was pending,
she had, at the request of either the FBI or the IRS, copied
thousands of pages of documents from the DREI offices and
given them to the government. During that related trial, the
government’s statements and Brown’s own testimony
indicated that Brown had received an informal promise from
the government that she would not be prosecuted if she
cooperated. The information about the copied documents and
the informal immunity promise had not been disclosed to
Mazzarella before or at her trial.

     The government also disclosed to Mazzarella information
concerning Alicia Hanna, who had testified at Mazzarella’s
trial about the materiality of the false statements to the
lending banks and that one of the defrauded banks was
federally insured at the time of the transactions. At the time
of trial, Hanna was a former employee of a defrauded lender
bank. After trial, the government gave Mazzarella a copy of
an email exchange between Hanna and an FBI agent from
before Mazzarella’s trial. Hanna’s email contained a
statement indicating that she might wish to work for the FBI
one day, and asking the agent to keep an eye out for job
openings in the Charlotte field office. That statement may
have been a literal hope or a casual joke, but in either event
it might have been urged by Mazzarella as a basis to cross-
examine Hanna and undercut her credibility.

    The district court denied Mazzarella’s first motion for a
new trial, which was based on the disclosures related to
Brown and Hanna. The district court determined that the
evidence was not necessarily impeaching, because the
government’s alleged promise to Brown that she had nothing
to worry about if she cooperated was in response to a
              UNITED STATES V. MAZZARELLA                      9

question asked by another witness cooperating in the
investigation against Mazzarella, and could not reasonably be
construed as a promise to Brown specifically. Also, any
agreement would not impeach her because Brown had
testified that she initially contacted the FBI out of a desire to
do the right thing, belying the notion that her cooperation was
motivated by a desire to avoid prosecution. The district court
deemed the email from Hanna innocuous and unlikely to
serve as impeachment evidence. The district court further
ruled that even if the evidence was impeaching, there was no
prejudice because the jury would likely have found Brown
and Hanna credible despite any impeachment evidence. Also
there was substantial other evidence of Mazzarella’s guilt,
and Hanna’s testimony had been verified by independent
documentation and the testimony of several other witnesses.
The district court additionally ruled that Brown was not a
government actor and that her copying of documents did not
implicate the Fourth Amendment, and further that there was
no evidence that any copied documents were given to the
government, or that any were used by the government at trial.
Mazzarella timely appealed the district court’s order denying
her motion.

   Later, the government made yet another disclosure to
Mazzarella. Jennifer Wolff, who had testified against
Mazzarella, testified on cross-examination during the trial of
another person in the scheme that she understood that she
would not be prosecuted in return for testifying. The
government told Mazzarella that it was aware of no such
promise.

    Mazzarella moved a second time for a new trial based on
the Brady disclosures. The district court concluded that the
notion that Wolff was promised immunity in exchange for
10              UNITED STATES V. MAZZARELLA

testimony against Mazzarella was “tenuous at best,” because
it was unclear even from Wolff’s testimony whether she was
referring to an agreement that was for her testimony in
Mazzarella’s trial, or only in the later trial of Mazzarella’s co-
schemer. Moreover, the government had filed an affidavit
explaining that Wolff’s belief arose from a misunderstanding
and that she was never actually promised immunity. Once
again, the district court concluded that even if there had been
an immunity agreement and even alongside the earlier
disclosures, the additional evidence against Mazzarella was
so substantial that there was no prejudice that would
undermine confidence in the verdict.2

                                   II

   We review de novo a district court’s denial of a new trial
motion based on a Brady claim, as well as the issue of
materiality under Brady. United States v. Sedaghaty,
728 F.3d 885, 899–900 (9th Cir. 2013).

    We review de novo a district court’s legal conclusion that
a search did not violate the Fourth Amendment because it was
private. United States v. Reed, 15 F.3d 928, 930 (9th Cir.
1994).



    2
      Before oral argument in this case, Mazzarella filed a motion to
supplement the record with the details of another Brady disclosure. We
deny that motion in an order filed simultaneously with this opinion. Even
in combination with the other disclosures on the existing record, we would
not reverse the district court. Rather, as we explain below, we vacate the
district court’s orders denying Mazzarella’s new trial motions, and remand
for further proceedings. The district court should consider the additional
disclosure in the first instance on remand, and assess any cumulative
effect of the combined Brady disclosures and Fourth Amendment issues.
              UNITED STATES V. MAZZARELLA                   11

    We review discovery rulings for an abuse of discretion.
United States v. Muniz-Jaquez, 718 F.3d 1180, 1183 (9th Cir.
2013). A denial of an evidentiary hearing is also reviewed for
an abuse of discretion. United States v. Olsen, 704 F.3d
1172, 1178 (9th Cir.), reh’g en banc denied, 737 F.3d 625
(9th Cir. 2013), cert. denied, 134 S. Ct. 2711 (2014).

                             III

    Mazzarella argues that the government’s failure to
disclose the Brown immunity agreement and document
copying, the Hanna email about job openings at the FBI, and
the possible immunity agreement for Wolff violated Brady.
Mazzarella also argues that Brown’s copying documents from
the DREI offices and turning them over to the government
violated her rights under the Fourth Amendment. Finally,
Mazzarella contends that the district court abused its
discretion by not granting discovery or holding an evidentiary
hearing on those issues. We agree with the last contention.
We conclude that we cannot vacate any of Mazzarella’s
convictions on the present record. But the district court erred
in denying her motions for a new trial without correctly
analyzing the Fourth Amendment issue and then deciding
whether any evidence submitted was the fruit of an illegal
search, and then considering in light of those decisions,
whether there was prejudice from the challenged failures to
disclose. We vacate the challenged orders and remand so that
the district court, after allowing reasonable discovery and
conducting an evidentiary hearing, may decide on an open
record whether to grant Mazzarella’s request for a new trial.
12            UNITED STATES V. MAZZARELLA

     A. Mazzarella has not shown prejudice based on the
        Brady disclosures alone

    The Fifth Amendment’s Due Process Clause requires the
government to produce exculpatory information to the
defense. Brady, 373 U.S. at 86–87. This includes
information that may be used to impeach prosecution
witnesses. Giglio v. United States, 405 U.S. 150, 152–54
(1972). A prosecutor has a duty under Brady to learn of and
disclose evidence known to others acting on the government’s
behalf, including the police. See Kyles v. Whitley, 514 U.S.
419, 432, 437 (1995).

     In the post-trial context, a Brady violation has three
components: (1) the information must be favorable to the
defense; (2) it must not have been disclosed by the
government before or at trial; and (3) there must have been
resulting prejudice. See United States v. Wilkes, 662 F.3d
524, 535 (9th Cir. 2011). Prejudice ensues “if there is a
reasonable probability that, had the evidence been disclosed
to the defense, the result of the proceeding would have been
different.” United States v. Kohring, 637 F.3d 895, 902 (9th
Cir. 2011) (internal quotation mark omitted). “A reasonable
probability is one that is sufficient to undermine confidence
in the outcome of the trial.” Olsen, 704 F.3d at 1183 (internal
quotation marks omitted). “The need for disclosure is
particularly acute where the government presents witnesses
who have been granted immunity from prosecution in
exchange for their testimony. We have previously recognized
that criminals who are rewarded by the government for their
testimony are inherently untrustworthy, and their use triggers
an obligation to disclose material information to protect the
defendant from being the victim of a perfidious bargain
             UNITED STATES V. MAZZARELLA                   13

between the state and its witness.” Carriger v. Stewart,
132 F.3d 463, 479 (9th Cir. 1997) (en banc).

    We conclude that the Brown and Hanna disclosures, first
revealed after Mazzarella’s trial and sentencing, were
favorable to Mazzarella and that to the extent the district
court ruled otherwise, that conclusion was error. As to
Brown, the district court reasoned that a prosecutor’s
statement to two people, one of whom was Brown, that there
was “nothing to worry about” if the truth were told could not
reasonably be construed as a promise of immunity to Brown
specifically.    But that conclusion is belied by the
government’s own statements: in the later trial at which
Brown testified, the same prosecutor who prosecuted
Mazzarella told the court that he had promised Brown that
she would not be prosecuted. The district court’s analysis of
the Brown disclosure collapsed the distinction between the
favorable prong and the issue of prejudice by concluding that
Brown’s testimony that she had approached the FBI out of a
desire to do the right thing meant the immunity agreement
was not favorable. The same is true of the district court’s
characterization of Hanna’s statements about jobs at the FBI
as innocuous. It is potential impeachment evidence to
suggest that a government witness has a bias—here, seeking
government employment—that might color the witness’s
testimony.

    The district court determined that the notion that Wolff
had an immunity agreement in place was “tenuous at best,”
but did not hold an evidentiary hearing to settle the matter,
nor permit discovery on the issue. In light of our conclusions
on the Fourth Amendment issue, which we discuss below,
this was an abuse of discretion.
14              UNITED STATES V. MAZZARELLA

    On the record as it now stands, we agree with the district
court’s conclusion that even assuming all of the disclosed
evidence was favorable impeachment evidence, no prejudice
resulted from the government’s not disclosing the
impeachment evidence. More than 50 witnesses testified, and
there were more than 1300 exhibits introduced at trial. Skip
Young testified extensively about Mazzarella’s knowledge of,
and involvement in, the use of false information in the loan
applications. Shauna Labee offered testimony that she had
signed blank loan applications in Mazzarella’s presence and
at Mazzarella’s urging. While both Young and Labee were
co-schemers testifying in exchange for deals, their detailed
testimony, coupled with the ample evidence of Mazzarella’s
involvement in all the other aspects of the business plan,
suggests that even after accounting for the disclosures, on the
record before us, there is not a fair probability that a jury
would have reached a contrary result. The strength of the
prosecution’s case, coupled with the relative weakness of the
proffered impeachment evidence, leads us to conclude that
there was no prejudice.3

    But we must remand the Brady issues for the district court
to reconsider them on an open record, in conjunction with the
additional disclosure with which Mazzarella sought to
augment the record on appeal, the Fourth Amendment issue
discussed below, and any further impeachment or exculpatory
evidence that comes to light from discovery. If the district
court again denies the new trial motion, it should provide a


  3
     There is some uncertainty, on the record before us, about whether
Mazzarella’s conviction for mail fraud under Count 11 could stand if, in
light of the immunity agreement, the jury had wholly discounted Brown’s
testimony, and also about how Wolff’s testimony merely duplicated or
corroborated other evidence at trial.
             UNITED STATES V. MAZZARELLA                   15

specific explanation for its conclusion that confidence in the
verdict is not undermined.

   B. The district court erred in concluding on the record
      before it that there was no search implicating the
      Fourth Amendment

    One or more of Mazzarella’s convictions may need to be
vacated if there was evidence admitted at trial that should
have been suppressed as the fruit of an unlawful search. But
more discovery is required to determine whether an unlawful
search occurred and whether there were evidentiary fruits of
an unlawful search. The district court should make those
determinations in the first instance on remand.

    We have held that whether a private individual acts as a
government agent for Fourth Amendment purposes requires
an inquiry into whether the government knew of or
acquiesced in the intrusive conduct, and whether the party
performing the search intended to assist law enforcement
efforts or further his or her own ends. United States v. Reed,
15 F.3d 928, 931 (9th Cir. 1994). In Reed, a hotel manager
called the police to report suspected drug activity by one of
the hotel’s guests and asked for police protection as he
searched the guest’s room, which the police provided. Id.
We held that the search fell within the Fourth Amendment’s
ambit. Id. at 932. We also rejected crime prevention as an
independent private motive, reasoning that if crime
prevention were deemed a private motive, searches by private
parties would never implicate the Fourth Amendment. Id.

    If an unwarranted search did occur—and there is no
dispute that Brown’s copying was not pursuant to a
warrant—our precedents establish that such a search would
16           UNITED STATES V. MAZZARELLA

generally be unreasonable, absent an exception such as valid
consent. See United States v. Ziegler, 474 F.3d 1184, 1191
(9th Cir. 2007) (upholding search of employee’s workplace
computer where employer gave consent). A third party with
“common authority over or other sufficient relationship to the
premises or effects sought to be inspected” may consent to a
government search without the search violating the Fourth
Amendment. Id.; see also United States v. Kim, 105 F.3d
1579, 1582 (9th Cir. 1997) (holding that consent may be
given by person with actual or apparent authority to do so,
and that defendant, by authorizing associate to rent storage
unit for defendant in associate’s name, assumed the risk that
associate would consent to a search of the unit).

    Here, Brown testified at another trial that after she
approached the authorities during the Mazzarella
investigation, either the FBI or the IRS told her to get as
much documentation from DREI as she could, and that she
did so. She testified that she agreed she would gather
documents, and made “a very huge stack” of copies of
documents without Mazzarella’s knowledge, and gave it to
“the proper people to give it to.” There was also testimony
from that same trial that the investigating FBI agent who
investigated Mazzarella testified that he did not recall
receiving any documents taken from DREI.

    The district court concluded that: (1) the Fourth
Amendment was not implicated because Brown testified that
she was motivated by a desire to do the right thing; (2) there
was no evidence that any documents were given to the
government; and (3) there was no evidence that any
documents that were turned over were used by the
government at trial. But we cannot affirm any of the district
court’s conclusions on this issue on the present record.
              UNITED STATES V. MAZZARELLA                    17

     First, the desire to “do the right thing” that the district
court identified here is indistinguishable from the crime
prevention motive that we rejected in Reed. Also, per
Brown’s testimony, the government did not merely acquiesce
but asked Brown to gather evidence. If Brown’s testimony is
accurate, her copying may have implicated the Fourth
Amendment. We cannot say on the present record whether
Brown had actual or apparent authority to turn over the
documents to the government. Testimony from the related
trial from a DREI employee who apparently assisted Brown
with the copying that “Eve [Mazzarella] would have gone
insane if she knew that we were . . . copying old investor
files,” at least suggests that Brown lacked actual authority to
copy and disclose the documents. But there is no further
evidence on this issue in the record, no evidence at all related
to Brown’s apparent authority or the other DREI employee’s
apparent authority, and the district court made no findings on
the issue.

    Second, the district court’s conclusion that there is no
evidence that documents were actually disclosed to the
government is not supported by the record. That finding is
contradicted by Brown’s sworn testimony that she turned
over her copies to the appropriate people. While one FBI
agent testified that he did not recall receiving any copied
documents from Brown, further discovery is necessary to
resolve the issue, and the district court should make findings
of fact on this issue.

    Third, the government’s declaration that none of the
exhibits introduced at trial were from documents obtained by
Brown, even if true, does not resolve the potential Fourth
Amendment problem. The exclusionary rule bars the
introduction of “derivative evidence, both tangible and
18            UNITED STATES V. MAZZARELLA

testimonial, that is the product of the primary evidence, or
that is otherwise acquired as an indirect result of the unlawful
search, up to the point at which the connection with the
unlawful search becomes so attenuated as to dissipate the
taint.” Murray v. United States, 487 U.S. 533, 536–37 (1988)
(internal quotation marks omitted). After determining
whether a search within the meaning of the Fourth
Amendment occurred and whether any documents from that
search were given to the government, the district court must
also determine what trial evidence, if any, was the fruit of an
unlawful search such that it should have been suppressed.

     After making these determinations, the district court
should consider again the cumulative effect of the
impeachment evidence it considered before, and the
additional impeachment evidence that Mazzarella sought to
place before this court. This material must be considered
together with any evidence that should have been excluded
from trial under the Fourth Amendment to determine whether
any of Mazzarella’s convictions must be vacated and a new
trial granted.

     C. The district court abused its discretion in denying
        Mazzarella’s requests for discovery and an
        evidentiary hearing

    Mazzarella contends that the district court abused its
discretion by not permitting discovery or holding an
evidentiary hearing on the Brady and Fourth Amendment
issues. We agree to an extent. More findings, which will
require reasonable discovery and an evidentiary hearing, are
needed to resolve whether there was an immunity agreement
in place for Wolff, and whether there was an unlawful search
of the DREI offices that resulted in tainted evidence being
              UNITED STATES V. MAZZARELLA                   19

used at trial. Finally, the district court should also consider
the additional disclosure with which Mazzarella sought to
supplement the record before us.

    Having concluded that the district court abused its
discretion in denying an evidentiary hearing and not
permitting any discovery on these issues, we will not as an
appellate panel impose unduly onerous specifications related
to the scope of discovery. We reject Mazzarella’s argument
that the district court should have imposed the very detailed
discovery guidelines from a 2010 Department of Justice
memorandum to federal prosecutors. See David W. Ogden,
Dep. Att’y General, Memorandum for Department
Prosecutors: Guidance for Prosecutors Regarding Criminal
Discovery (Jan. 4, 2010). The Ogden Memorandum says that
it “is not intended to have the force of law or to create or
confer any rights, privileges, or benefits.” Id. at 1.
Mazzarella has pointed to no authority suggesting that an
appellate court can or should impose such specific
requirements on a question governed by the district court’s
discretion, especially based on a document only meant to
provide policy guidance. Cf. United States v. Canori,
737 F.3d 181, 183–85 (2d Cir. 2013) (rejecting an argument
that another Justice Department memorandum, which gave
guidance for federal prosecutors in states that have
decriminalized marijuana, in any way prevented those
prosecutors from enforcing federal drug laws); In re Grand
Jury Subpoena, Judith Miller, 438 F.3d 1141, 1152 (D.C. Cir.
2006) (as amended) (rejecting argument that a contempt
finding against a journalist for not disclosing a source had to
be reversed because the government did not comply with the
procedures set out in 28 C.F.R. § 50.10, governing subpoenas
for reporters, in part because the government guidelines state
that they do not create an enforceable right for any person).
20            UNITED STATES V. MAZZARELLA

                           * * *

    We vacate the orders denying Mazzarella’s motions for a
new trial. On remand, the district court should authorize
appropriate discovery and hold an evidentiary hearing to
determine whether an unlawful search occurred and, if so,
what evidence was obtained by the government or derived
from the unlawful search. In addition, the district court
should determine whether Wolff was promised immunity in
exchange for testimony against Mazzarella. Finally, based on
the result of these determinations, the district court should
consider anew whether the cumulative effect of the Brady
disclosures and the suppression of unlawfully obtained
evidence requires vacating Mazzarella’s convictions and
ordering a new trial.

    There is a serious need for constant vigilance in both
prosecutors’ offices and federal courtrooms to safeguard
individuals’ Fifth Amendment rights as explained in Brady
and Giglio. This is no less true of the Fourth Amendment,
and the important individual interests in privacy and personal
security that it protects.

    Those charged with crime deserve a fair shake from
government prosecutors. The prosecutors’ duty is not to gain
conviction at any cost but rather to help ensure that justice is
done. Prosecutors have a critical role in the criminal justice
system. Of course, we expect prosecutors to be able and
aggressive advocates, in the best traditions of the American
bar, and they may enlist many of the tools used by private
advocates as they put the government’s case in its most
appealing form. But our system maintains important
safeguards of individual rights and this constrains the actions
of the government. Prosecutors cannot withhold from
             UNITED STATES V. MAZZARELLA                   21

disclosure information that it has that is favorable to the
accused, nor knowingly present false testimony.

    Similar principles constrain law enforcement. Although
we want vigorous enforcement of the law, we insist that law
enforcement honor the constitutional rights of those suspected
of crime. We place limits on searches for evidence to
preserve individual privacy, with the Constitution generally
requiring probable cause for searches of a private business
and a warrant preceding the search except in defined
circumstances. We impose a broad mandate for fair
procedure implemented through many particular
requirements.

    On remand, the district court should permit discovery
suitable to ensure that the prosecutors in this case have
respected Mazzarella’s constitutional rights. If it is shown
that they have not, and that those failures were neither
harmless nor immaterial under our court’s precedents,
Mazzarella is entitled to a new trial on one or more of the
charges against her.

                             IV

    For the foregoing reasons, we vacate the district court’s
orders denying Mazzarella’s motions for a new trial. This
case is remanded for further proceedings consistent with this
opinion.

   VACATED and REMANDED.
