                FOR PUBLICATION

  UNITED STATES COURT OF APPEALS
       FOR THE NINTH CIRCUIT

IN RE: THOMAS E. PEREZ,                   No. 13-72195

                                            D.C. No.
THOMAS E. PEREZ, Secretary, United       3:08-cv-05479-
Sates Department of Labor,                    BHS
                         Petitioner,

                 v.                         OPINION

UNITED STATES DISTRICT COURT,
TACOMA,
                      Respondent,

STATE OF WASHINGTON
DEPARTMENT OF SOCIAL AND
HEALTH SERVICES,
            Real Party in Interest.


         Petition for Writ of Mandamus to the
              United States District Court
        for the Western District of Washington
      Benjamin H. Settle, District Judge, Presiding

               Argued and Submitted
           March 4, 2014—Portland, Oregon

                  Filed April 18, 2014
2                           IN RE: PEREZ

      Before: Alfred T. Goodwin, Stephen S. Trott, and
            William A. Fletcher, Circuit Judges.

                      Opinion by Judge Trott


                           SUMMARY*


                            Mandamus

    The panel granted the Secretary of the United States
Department of Labor’s petition for a writ of mandamus, and
vacated the district court’s order compelling the Secretary’s
response to interrogatories, in the Secretary’s action against
the Washington State Department of Social and Health
Services alleging violations of the Fair Labor Standards Act.

    The Secretary of Labor’s proof of the alleged Fair Labor
Standards Act violations came from 400 employee
statements—350 of which the Secretary obtained after he had
filed suit. The district court held that the 350 employees were
not informants whose identities were protected from
discovery by the government’s informants privilege, and
ordered the Secretary to answer three interrogatories that
would disclose their identities.

    The panel granted the Secretary’s petition for a writ of
mandamus to avoid disclosing the employees’ identities
because the timing of the employees’ statements did not
affect their status as informants, and because knowledge of

  *
    This summary constitutes no part of the opinion of the court. It has
been prepared by court staff for the convenience of the reader.
                         IN RE: PEREZ                          3

the informants’ identities would not significantly aid the
Washington State Department of Social and Health Services.
The panel directed the district court to enter a protective order
consistent with its opinion.


                         COUNSEL

Rachel Goldberg (argued), Senior Attorney, M. Patricia
Smith, Solicitor of Labor, Jennifer S. Brand, Associate
Solicitor, Paul L. Frieden, Counsel for Appellate Litigation,
United States Department of Labor, Washington, D.C., for
Petitioner.

Kara A. Larsen (argued), Senior Counsel, Labor and
Personnel Division, Robert W. Ferguson, Attorney General,
Washington State Office of the Attorney General, Olympia,
Washington, for Real Party in Interest.


                          OPINION

TROTT, Circuit Judge:

    Thomas Perez, the Secretary of the United States
Department of Labor, sued the Washington State Department
of Social and Health Services (“DSHS”), alleging violations
of the Fair Labor Standards Act’s overtime and record-
keeping provisions. The Secretary’s proof of the alleged
violations comes from 400 employees’ statements – 350 of
which he obtained after he had filed suit. Over the
Secretary’s objection, the district court held that these 350
employees are not informants whose identities are protected
from discovery by the government’s informants privilege.
4                       IN RE: PEREZ

For this reason, and because it believed DSHS’s defense
depended upon knowing the identities of the informants, the
district court ordered the Secretary to answer three
interrogatories that would disclose their identities. To avoid
that result, the Secretary petitioned this court for a writ of
mandamus. Because we are convinced that the timing of the
employees’ statements does not affect their status as
informants, and because knowledge of the informants’
identities will not significantly aid DSHS, we grant the
petition.

                              I

    In 2006, the Wage and Hour Division of the Department
of Labor received a complaint from Karen Patton. Patton
claimed that, while employed as a social worker in DSHS’s
Walla Walla office, she was not paid overtime despite
working on average 45–65 hours per week. An initial
investigation followed, during which approximately 50
additional social workers made similar claims. These social
workers were told by their supervisors that it was DSHS’s
policy not to authorize overtime, except in emergencies, and
to “flex” their schedules to make up for the hours of overtime
worked. However, the demands of the social workers’
caseloads prevented them from taking “flex” time.

    This initial investigation convinced the Secretary that,
between 2006 and 2008, case-carrying, levels-II and -III
social workers regularly worked over 40 hours per week, did
not record all the hours they worked, and were not
compensated for the majority of overtime they worked. The
Secretary filed suit on behalf of these “affected employees,”
alleging that DSHS violated the Fair Labor Standards Act’s
                             IN RE: PEREZ                               5

(“FLSA” or “Act”) overtime and record-keeping provisions.
29 U.S.C. § 207 (overtime); Id. § 211(c) (record keeping).

    Early in the litigation, DSHS compiled and provided the
Secretary with a list of all affected employees, ultimately
totaling just under 2,000 social workers. The affected
employees worked (and most still do) at DSHS’s 42 offices
spread throughout seven regions of Washington. The
affected employees are all part of DSHS’s Children’s
Administration, which is divided into three primary program
areas. Social workers with Child Protective Services take and
investigate claims of child abuse and, when necessary, work
to place children in safe, alternative housing. Social workers
with Child and Family Welfare Services “provide
permanency planning and intensive treatment services for
families who need help protecting or parenting children.”
These social workers primarily work with children who are
dependents of the state and live outside of their family homes.
Social workers with Family Reconciliation Services provide
“voluntary in-home services focused on developing skills and
support within families” for at-risk youths or on resolving
family conflicts.

    With DSHS’s list in hand, the Secretary continued his
investigation into the alleged violations by mailing to 1,5001
of the affected employees a questionnaire asking the
employees about their work conditions. The Secretary told
the recipients that, if they responded, he would keep their
names and identifying information confidential, unless they



 1
  Five hundred employees were not mailed a questionnaire because their
names were added to the list of affected employees after the questionnaire
was sent.
6                        IN RE: PEREZ

authorized its release or if a court ordered its disclosure. The
Secretary received approximately 350 responses.

    During the course of discovery, DSHS served the
Secretary with the three interrogatories that prompted this
petition.

        Interrogatory No. 1: Please identify each and
        every person who has knowledge of the facts
        alleged in your Complaint or any other facts
        that support or refute the allegations in the
        Complaint and, for each such person, specify
        the precise facts of which they have [sic]
        knowledge, including but not limited to, (with
        respect to DSHS Employees) hours scheduled,
        worked, reported, or paid; days scheduled,
        worked, reported, or paid; overtime
        scheduled, worked, reported, or paid; and why
        hours, days, or overtime were or were not
        reported.

        Interrogatory No. 4: For each and every
        DSHS Employee listed in Exhibit A to the
        Complaint and for each week from February
        2006 to the present, please state the hours per
        day and per week that you allege that he or
        she worked.

        Interrogatory No. 6: For each DSHS
        employee, for whom you seek overtime
        payment, please state the weeks for which you
        seek such overtime payment, the number of
        hours worked during each of those weeks, and
        the amount allegedly due for each week.
                        IN RE: PEREZ                         7

    The Secretary objected to answering these interrogatories
on the ground that turning over the 50 statements taken
during the initial interview and the 350 returned
questionnaires “requested by [DSHS] would reveal the
identities of individuals who cooperated with [the
Secretary’s] investigation and litigation.” Acting through the
Deputy Administrator of the Wage and Hour Division, the
Secretary “invoke[d] the Government’s informant privilege
to protect from disclosure the identities, and any portions of
other documents which could reveal the identities, of persons
who have provided information to the United States
Department of Labor in the instant case.”

    However, the Secretary waived the privilege as to 150
affected employees who had authorized the disclosure of their
identities and provided DSHS with complete copies of their
statements. With respect to the 250 employees who wished
to remain anonymous, the Secretary disclosed their
statements, but he redacted any information that identified or
tended to identify the employee. This included the
employee’s name; the employee’s contact information; the
employee’s position, if it appeared to the Secretary that the
employee held a unique position; the office location where
the employee worked; and the employee’s period of
employment. These redacted statements still contained,
where available, the hours, days, and overtime worked,
scheduled, and paid.

    Unsatisfied, DSHS filed a motion to compel the Secretary
to provide the requested information, and the Secretary filed
for a protective order. The motions debated primarily (1)
whether the Secretary properly asserted the privilege and,
assuming he did, (2) whether the privilege applied in this
case. On the latter point, DSHS argued that its interrogatories
8                        IN RE: PEREZ

did not seek the identities of the informers because the
interrogatories pertained to all affected employees.
Moreover, even if the identities of informers were revealed,
DSHS argued it needed the information to show disparities
between affected employees across the state.

    In response, the Secretary explained that the information
DSHS sought only exists for those 400 employees who
provided statements during the investigation.           These
employees, continued the Secretary, are “categorically
informants because of this communication.” He had already
turned over the unredacted statements of the 150 affected
employees and the remaining redacted statements. Therefore,
the Secretary could only respond with information that would
reveal the identities of the 250 anonymous employees.

    The district court ultimately agreed with DSHS. The
court concluded that the Secretary had properly invoked the
privilege, but it held that answering the three interrogatories
would not disclose the informants’ identities. The court
reasoned that “the release of general information as to all
employees who were not paid overtime does not tend to
identify specific informants.”

     The Secretary then asked the district court to reconsider
its ruling. In support of his motion, the Secretary reiterated
that he could not provide the requested information for all
2,000 affected employees because the only information in his
possession came from the 400 employee statements. The
Secretary further explained that he intended to proceed to trial
under the burden-shifting scheme established by Anderson v.
Mt. Clemens Pottery Co., 328 U.S. 680 (1946).
                        IN RE: PEREZ                         9

    Understanding the effect of Mt. Clemens Pottery is key to
understanding the Secretary’s burden and case. In cases
where an employer has not kept accurate records of
employees’ time, Mt. Clemens Pottery allows the Secretary
to prove an FLSA violation by showing that employees
performed work for which they were improperly
compensated and producing some evidence to show the
amount and extent of that work “as a matter of just and
reasonable inference.” Id. at 687. We have held that the
Secretary’s evidence may consist of “fairly representative
testimony” from a sample of employees. McLaughlin v. Ho
Fat Seto, 850 F.2d 586, 589 (9th Cir. 1988). If the Secretary
carries his burden, “[t]he burden then shifts to the employer
to come forward with evidence of the precise amount of work
performed or with evidence to negative the reasonableness of
the inference to be drawn from the [Secretary’s] evidence.”
Mt. Clemens Pottery, 328 U.S. at 687–88. If the Secretary is
not able to carry his burden, his case may not proceed.

    The Secretary’s sample in this case would come from
only those 150 employees who had authorized the disclosure
of their identities. Through these employees’ testimony, the
Secretary would establish at trial that, “regardless of whether
[an affected employee] is in Bremerton or Bellingham or
Richland or Spokane,” his or her duties and hours worked are
a fair approximate for any other social worker employed by
DSHS.

    DSHS responded with two arguments. First, it argued
that only the 50 employees who gave their statements during
the initial investigation were protected by the informants
privilege, not those 350 employees who gave their statements
after the Secretary had filed suit. Second, assuming the
privilege attached to all 400 employees, DSHS argued that its
10                       IN RE: PEREZ

need for the information outweighed the Secretary’s interest
in keeping the information a secret. In DSHS’s opinion, a
social worker working for Child Protective Services in rural
Richland, for example, is not representative of a social
worker working for Child Protective Services in urban Seattle
because the two have clients with different needs, encounter
different obstacles associated with their disparate
geographies, and rely on different supervisors to authorize
overtime. DSHS wished to compare the complete statements
against its records to establish these differences.

    Again the district court agreed with DSHS’s arguments.
Relying on language from Does I thru XXIII v. Advanced
Textile Corp., 214 F.3d 1058, 1072 (9th Cir. 2000), the
district court held that the privilege protects only “employees
who precipitated the suit by filing complaints.” The court
also concluded that it was “essential” that DSHS receive
answers to its interrogatories so it could rebut the Secretary’s
evidence.

     This petition followed.

                               II

    Before turning to the heart of this matter, we pause to
address DSHS’s argument that the Secretary invoked the
informants privilege only in response to DSHS’s requests for
documents, not its interrogatories. Not so. The Secretary’s
assertion of the privilege made clear that he was concerned
with protecting the informants’ identities, regardless of the
form of the disclosure.
                         IN RE: PEREZ                         11

                              III

     This court has jurisdiction to issue a writ of mandamus
under the All Writs Act, 28 U.S.C. § 1651. Mandamus is a
“drastic and extraordinary remedy” reserved for “only
exceptional circumstances.” Cheney v. U.S. Dist. Court for
D.C., 542 U.S. 367, 380 (2004) (internal quotation marks and
citation omitted). Generally, this standard makes the writ
unavailable in the discovery context for two important
reasons. First, this court is particularly reluctant to interfere
with a district court’s day-to-day management of its cases.
See, e.g., In re Anonymous Online Speakers, 661 F.3d 1168,
1173 (9th Cir. 2011). Second, “the petitioner must satisfy the
burden of showing that his right to issuance of the writ is
clear and indisputable.” Cheney, 542 U.S. at 381 (internal
quotation marks, brackets, and citations omitted). Because
the district court has discretion to control discovery, it is
hardly ever the case that a petitioner’s “right to a particular
result is ‘clear and indisputable.’” See Allied Chem. Corp. v.
Daiflon, Inc., 449 U.S. 33, 36 (1980) (per curiam).
Nevertheless, we have exercised our mandamus jurisdiction
“to define the scope of an important privilege.” Perry v.
Schwarzenegger, 591 F.3d 1147, 1157 (9th Cir. 2010); see
also Mohawk Indus., Inc. v. Carpenter, 558 U.S. 100, 111
(2009) (noting that when the disclosure of privileged
information works a “manifest injustice,” mandamus may
lie). Ultimately, whether to issue the writ is within this
court’s discretion. In re Van Dusen, 654 F.3d 838, 841 (9th
Cir. 2011).

    Five factors guide our judgment:
12                      IN RE: PEREZ

       (1) whether the petitioner has other adequate
       means, such as a direct appeal, to attain the
       relief he or she desires;

       (2) whether the petitioner will be damaged or
       prejudiced in a way not correctable on appeal;

       (3) whether the district court’s order is clearly
       erroneous as a matter of law;

       (4) whether the district court’s order makes an
       “oft-repeated error,” or “manifests a persistent
       disregard of the federal rules”; and

       (5) whether the district court’s order raises
       new and important problems, or legal issues
       of first impression.

Id. (quoting Bauman v. U.S. Dist. Court, 557 F.2d 650,
654–55 (9th Cir. 1977)). “Not every factor need be present
at once; indeed, the fourth and fifth will rarely be present at
the same time.” Burlington N. & Santa Fe Ry. Co. v. U.S.
Dist. Court for the Dist. of Mont., 408 F.3d 1142, 1146 (9th
Cir. 2005). However, the third factor – clear error – is a
necessary prerequisite for the writ to issue. Id. The clear
error standard requires of us a “firm conviction” that the
district court misinterpreted the law, In re Cement Antitrust
Litig., 688 F.2d 1297, 1306–07 (9th Cir. 1982), or committed
a “clear abuse of discretion,” Cheney, 542 U.S. at 380
(internal quotation marks omitted).
                         IN RE: PEREZ                         13

                               A

    DSHS argues that the first mandamus factor is not met
because the Secretary could very well decide to violate the
district court’s order to compel. The sanction for such a
violation, DSHS continues, is normally dismissing the case,
in which event an appeal would certainly follow. Our case
law does not require a party like the Secretary to take such a
drastic step in lieu of filing a petition for mandamus. See,
e.g., Perry, 591 F.3d at 1157 (concluding that the first factor
was satisfied because “[a] discovery order . . . is interlocutory
and non-appealable under 28 U.S.C. §§ 1291, 1292(a)(1) and
1292(b)”) (internal quotation marks omitted); Hernandez v.
Tanninen, 604 F.3d 1095, 1101 (9th Cir. 2010) (same).

    The second factor is met in this case. Once the identities
of the 250 anonymous employees are disclosed, they cannot
be protected again by a successful appeal or otherwise.

    As we explain below, the limitation the district court
placed on when the informants privilege attaches is novel,
unjustified, and clearly erroneous as a matter of law.
Combined with the district court’s incorrect balancing of
interests, we conclude that the third and fifth Bauman factors
are satisfied. As is often true when the fifth factor is met, the
fourth is absent.

                               B

    Apparently to rein in what it described as a “broad
application of the privilege,” the district court held that 350
of the 400 affected employees who gave statements about
their work conditions did not qualify as informants entitled to
the protection of the privilege. The distinction the district
14                       IN RE: PEREZ

court believed justified treating the 350 employees differently
from the other 50 was the timing of their respective
disclosures. The former group of employees spoke after the
Secretary filed suit, whereas the latter group spoke before that
point. The court’s differentiation between the two groups
was clear legal error.

    In Roviaro v. United States, 353 U.S. 53 (1957), the
Supreme Court set out the modern formulation of the
informants privilege. In order to promote effective law
enforcement, the privilege protects “the identity of persons
who furnish information of violations of law to officers
charged with enforcement of that law” from “those who
would have cause to resent the communication.” Id. at
59–60. However, the privilege will give way “[w]here the
disclosure of an informer’s identity, or of the contents of his
communication, is relevant and helpful to the defense of an
accused, or is essential to a fair determination of a cause.” Id.
at 60–61. The dividing line the district court drew promotes
neither effective law enforcement nor fair trials.

    Informants are an important lot because the FLSA, and
the “great public policy which it embodies,” Mt. Clemens
Pottery, 328 U.S. at 687, relies for its enforcement “upon
‘information and complaints received from employees
seeking to vindicate rights claimed to have been denied.’”
Kasten v. Saint-Gobain Performance Plastics Corp., 131 S.
Ct. 1325, 1333 (2011) (quoting Mitchell v. Robert DeMario
Jewelry, Inc., 361 U.S. 288, 292 (1960)). The Secretary’s
dependance on these crucial employees continues even after
the complaint is filed, as this case demonstrates. The 350
affected employees that the district court held were not
covered by the privilege provided the Secretary with
information that allowed him to assess the scope of the
                         IN RE: PEREZ                        15

DSHS’s alleged violations and to identify those 150
informants who will serve as the Secretary’s representative
sample. The Secretary was able to contact these employees
only after the start of discovery when DSHS provided him
with the list that identified all of the affected employees by
name. This dynamic follows the typical progression of a civil
suit. Most often, it is after the commencement of litigation
that “parties . . . obtain the fullest possible knowledge of the
issues and facts” of their case. See Hickman v. Taylor, 329
U.S. 495, 501 (1947).

    DSHS argues that the privilege is an unnecessary
investigative tool once litigation has commenced because
employees “can be required to come forward and testify via
the subpoena process.” We reject this argument because it
would “take needed flexibility from those charged with the
Act’s enforcement.” Saint-Gobain, 131 S.Ct. at 1334. One
need not be a seasoned litigator to understand that a witness
whose assistance is compelled is going to be less helpful than
a witness whose assistance is voluntarily given. By being
able to offer an employee the protection the informants
privilege affords, the Secretary has a better chance at a candid
dialog.

     Furthermore, the timing of the employee’s disclosure is
unlikely to temper the reaction of an employer who feels he
has been betrayed by his employee. The informants privilege
is a particularly effective means of preventing retaliation. See
Does I thru XXIII, 214 F.3d at 1071 (“[C]omplaining
employees are more effectively protected from retaliation by
concealing their identities than by relying on the deterrent
effect of post hoc remedies under the FLSA’s anti-retaliation
provision . . . .”); United States v. Hemphill, 369 F.2d 539,
542 (4th Cir. 1966) (describing the FLSA’s anti-retaliation
16                       IN RE: PEREZ

provision as an insufficient sanction because “retribution can
be subtle and cunning and difficult to prove”); Wirtz v. Cont’l
Fin. & Loan Co. of W. End, 326 F.2d 561, 563–64 (5th Cir.
1964) (“[T]he most effective protection from retaliation is the
anonymity of the informer. The pressures which an employer
may bring to bear on an employee are difficult to detect and
even harder to correct.”).

    DSHS’s promise not to retaliate is similarly insufficient
to dispel such fears. A common theme in the employees’
statements is that they were told by their immediate
supervisors not to request overtime because the funding was
not available. Several employees further reported being
reprimanded or threatened with discipline when they
persisted in requesting or recording overtime. As a practical
matter, we are not convinced that DSHS can effectively
monitor all 42 supervisors’ daily conduct to enforce its
promise. Here too an ounce of prevention is worth a pound
of cure. Nor is it feasible for an employee to engage in self-
help, if the only way for an employee to enforce DSHS’s
promise would be for the employee to engage in litigation.
The privilege properly invoked relieves the employees from
the prospect of that burden.

    Denying outright the informants privilege to employees
who aid in the enforcement of the Act after commencement
of litigation summarily denies protection to a group of
informants after an arbitrary deadline and thereby dispenses
with the balancing of interests that Roviaro requires. 353
U.S. at 62. This is exactly the type of bright-line rule that the
Court has rebuffed. McCray v. Illinois, 386 U.S. 300, 311
(1967) (“What Roviaro thus makes clear is that this Court
was unwilling to impose any absolute rule requiring
disclosure of an informer’s identity . . . .”). Therefore, we
                         IN RE: PEREZ                        17

hold that the 350 affected employees who provided the
Secretary with relevant information after the complaint had
been filed in this case are informants who are eligible for the
privilege’s protection.

                              C

    The district court based its holding on this court’s opinion
in Does I thru XXIII v. Advanced Textile Corp., 214 F.3d
1058 (9th Cir. 2000). Does concerned 23 garment workers on
the island of Saipan who sued their employers for violating
the FLSA. Id. at 1063. In their complaint, the plaintiffs used
pseudonyms instead of their real names for fear that they and
their family members would suffer reprisals at the employers’
hands because of the suit. Id. The district court ordered the
disclosure of their identities, holding that the defendants’
need to investigate and defend the case plus the public’s
interest in transparent proceedings outweighed the plaintiffs’
desire for anonymity. Id. at 1064. We reversed.

    We rejected the idea that “disguising [the] plaintiffs’
identities w[ould] obstruct public scrutiny of the important
issues in th[e] case,” in part, because they simply sought the
same protection afforded “[i]n FLSA actions brought by the
Secretary of Labor, [where] the ‘informant’s privilege’ may
be used to conceal names of employees who precipitated the
suit by filing complaints with the Department of Labor.” Id.
at 1072. Read in context, we chose the words “employees
who precipitated the suit” because those informants were also
the plaintiffs before us. The passage does not suggest, much
less hold, that the informants privilege applies only to that
narrow category of employees who provide information
before litigation begins. Does does not help DSHS.
18                       IN RE: PEREZ

    The same is true of the cases DSHS cites to support the
district court’s reading of Does. While some of those cases
spoke about employees whose complaints initiated the suit,
e.g., Hemphill, 369 F.2d at 542 (accepting the risk that some
“early informants” might be identified as such when the
Secretary listed his witness); Cont’l Fin. & Loan Co. of W.
End, 326 F.2d at 562 (addressing interrogatories aimed at “all
persons who had filed complaints charging violations of the
[FLSA]”), none of them grappled with the timing issue
presented by this petition. As a result, we do not find the
support that DSHS ascribes to them.

    Roviaro already provides the limiting principle the district
court was searching for: “Where the disclosure of an
informer’s identity, or of the contents of his communication,
is relevant and helpful to the defense of an accused, or is
essential to a fair determination of a cause, the privilege must
give way.” 353 U.S. at 60–61. It is to the district court’s
balancing of interests under this standard that we now turn
our attention.

                              IV

    For the informants privilege to give way, the party
seeking disclosure has the burden of showing that its need for
the information outweighs the government’s interest in
nondisclosure. See United States v. Prueitt, 540 F.2d 995,
1003–04 (9th Cir. 1976). The proper balancing of these
competing interests lies within the discretion of the district
court, after taking into consideration “the particular
circumstances of each case.” Roviaro, 353 U.S. at 62.

    Here, DSHS argued before the district court that its
interrogatories sought information about all 2,000 affected
                        IN RE: PEREZ                        19

employees’ different positions, sub-agencies, regions, offices,
supervisors, and job duties. With this information, DSHS
argued it could then “demonstrate substantial differences
among individuals and groups [of employees] based on all of
these variables,” and the identities of the informers would
remain hidden in plain sight. The district court accepted this
contention and concluded that (1) it was “essential” for DSHS
to receive answers to its interrogatories and (2) providing
those answers would not significantly jeopardize the
Secretary’s interests. The problem is that both of these
conclusions start from a flawed perception of the universe of
responsive information in the Secretary’s possession.

    The Secretary does not have information as to all 2,000
affected employees. The only information in the Secretary’s
possession comes from the 400 statements he received during
the initial investigation and in response to the questionnaire.
This fact dramatically affects how the scales tip in this case.

    Whether the Secretary can successfully prove his
allegations at trial under Mt. Clemens Pottery will depend
almost entirely on the 150 employees who make up his
representative sample. It is with their testimony that the
Secretary will be required to show “as a matter of just and
reasonable inference” that all 2,000 affected employees’ work
conditions are substantially similar so as to merit class-wide
relief. Ho Fat Seto, 850 F.2d at 589 (quoting Mt. Clemens
Pottery, 328 U.S. at 687). DSHS knows all the details it
seeks with respect to these key employees because the
Secretary has turned over their 150 statements in total.

    Moreover, DSHS already had and has in its possession the
information it needs to compare these 150 employees against
the remaining 1,850 affected employees. How else could
20                       IN RE: PEREZ

DSHS have compiled the list of 2,000 case-carrying, levels-II
and -III social workers who worked in its 42 offices since
2006 if it did not know these employees’ dates of
employment, locations, and job duties? See Mt. Clemens
Pottery, 328 U.S. at 687 (“Due regard must be given to the
fact that it is the employer . . . who is in position to know and
to produce the most probative facts concerning the nature and
amount of work performed.”); Wirtz v. B.A.C. Steel Prods.,
Inc., 312 F.2d 14, 16 (4th Cir. 1963) (“Indeed, most of the
information needed to prosecute or defend the case was in the
defendants’ possession from the beginning; this was the
defendants’ book and records.”).

    What of the remaining 250 statements provided by
employees who have not consented to having their identities
revealed? Much of the content of these 250 employees’
statements has been turned over, including information about
the hours the employees worked, even though they will not be
called as witnesses. The information that the Secretary has
not disclosed consists of only the identifying information in
the 250 statements. While this withheld information may
meet the general standard for relevance under the Federal
Rule of Evidence 401, we are not convinced that its probative
value is so great that it is “essential” to DSHS’s defense.
DSHS cannot force the Secretary to reveal the identities of his
informants on such a weak showing. See United States v.
Valenzuela-Bernal, 458 U.S. 858, 870 (1982) (“The Roviaro
Court held that the informer’s identity had to be disclosed,
but only after it concluded that the informer’s testimony
would be highly relevant[.]”) (emphasis added); Dole v. Local
1942, Int’l Bhd. of Elec. Workers, AFL-CIO, 870 F.2d 368,
375 (7th Cir. 1989) (“The informer’s privilege will yield upon
a showing of substantial need.”); B.A.C. Steel, 312 F.2d at 16
(“Although the privilege is not absolute, the defendants have
                         IN RE: PEREZ                        21

shown no special circumstance which would justify
withdrawing the qualified privilege . . . .”); Hodgson v.
Charles Martin Inspectors of Petroleum, Inc., 459 F.2d 303,
307 (5th Cir. 1972) (“[D]efendant must . . . make a sufficient
showing to overcome the Secretary’s claim of privilege . . . .
This the defendant has not done.”).

                               V

    In sum, (1) the district court erroneously limited the scope
of the informants privilege by focusing on the timing of the
informants’ statements, and (2) DSHS does not have a
compelling need for the identities or identifying information
of the 250 employees who will not be witnesses at trial.
Accordingly, we grant the petition for a writ of mandamus.
We hereby vacate the district court’s order to compel the
Secretary’s response to DSHS’s interrogatories, and we direct
the district court to enter a protective order consistent with
this opinion.

   PETITION GRANTED.
