 United States Court of Appeals
         FOR THE DISTRICT OF COLUMBIA CIRCUIT



Argued February 10, 2016             Decided August 5, 2016

                       No. 14-5220

                     JEFFREY LABOW,
                       APPELLANT

                             v.

         UNITED STATES DEPARTMENT OF JUSTICE,
                      APPELLEE


        Appeal from the United States District Court
                for the District of Columbia
                    (No. 1:11-cv-01256)


    Jeffrey Light argued the cause and filed the briefs for
appellant.

    John G. Interrante, Assistant U.S. Attorney, argued the
cause for appellee. With him on the brief was R. Craig
Lawrence, Assistant U.S. Attorney.

    Before: HENDERSON, ROGERS and SRINIVASAN, Circuit
Judges.

    Opinion for the Court filed by Circuit Judge SRINIVASAN.
                              2
     SRINIVASAN, Circuit Judge: In 2011, appellant Jeffrey
Labow came to learn that he had been identified as an
anarchist extremist by an FBI agent. Labow then submitted a
request to the FBI under the Freedom of Information Act for
any records about himself. Although the FBI released some
responsive records to Labow, it withheld disclosure of, or
redacted information from, other responsive documents, citing
various grounds.      The district court upheld the FBI’s
withholdings and redactions in full, and granted summary
judgment in favor of the agency. We agree in some respects
and disagree in others. We therefore affirm in part, reverse in
part, and remand the case for further proceedings.

                              I.

     Because we are reviewing a grant of summary judgment,
“we view the facts in the light most favorable to” Labow.
Chambers v. U.S. Dep’t of Interior, 568 F.3d 998, 1000 (D.C.
Cir. 2009). In 2008, anarchists protesting against the World
Bank and International Monetary Fund vandalized the Four
Seasons hotel in Washington, D.C. The FBI’s Joint Terrorism
Task Force investigated the incident. One of the targets of the
investigation sued the government. In the course of a
deposition in connection with that lawsuit, an FBI agent
mentioned Jeffrey Labow as another known extremist. The
agent refused to answer a question about whether the FBI
maintained a file about Labow because answering might
reveal information about ongoing law enforcement activities.
Based on the agent’s answers in the deposition, Labow
suspected that the FBI maintained records about him.

    Labow then filed a request under the Freedom of
Information Act (FOIA) with the FBI, seeking “files,
correspondence, or other records concerning [him]self.” J.A.
26. The FBI initially claimed that it had no responsive
                              3
records. Labow, after exhausting the administrative appeals
process, then brought this action in district court. He later
amended his complaint to add a request for records about a
person named Lawrence Kuhn, another target of the FBI’s
investigation into the Four Seasons incident.

      As Labow’s lawsuit progressed, the FBI found several
hundred pages of records concerning Labow and more than a
thousand pages about Kuhn. The FBI released some of these
records to Labow. With regard to other documents, the FBI
redacted information from them or refused to release them at
all, invoking various statutory exemptions.

     The government moved for summary judgment against
Labow on his claims seeking disclosure of the withheld
documents and redacted information. In his opposition,
Labow challenged the government’s reliance on FOIA’s
exemptions, and he also contended that the government had
improperly relied on a statutory exclusion from FOIA’s
coverage. After in camera review of documents submitted ex
parte by the government, the district court rejected Labow’s
arguments and granted the government’s summary judgment
motion in full. Labow now appeals.

                             II.

     We review the district court’s grant of summary
judgment de novo. Pub. Inv’rs Arbitration Bar Ass’n v. SEC,
771 F.3d 1, 3 (D.C. Cir. 2014). We first consider the FBI’s
reliance on various statutory exemptions as the basis for
redacting information from responsive documents or
withholding their release altogether. Our review calls for
“ascertain[ing] whether the agency has sustained its burden of
demonstrating that the documents requested are . . . exempt
from disclosure.” Id. (quoting ACLU v. Dep’t of Justice, 655
                                4
F.3d 1, 5 (D.C. Cir. 2011)). We take up, in turn, each FOIA
exemption as to which Labow raises a challenge.

                               A.

     We first consider the FBI’s reliance on FOIA Exemption
3 to withhold information associated with a pen register order.
A pen register is a device installed on a phone line to enable
recording the phone numbers dialed on that line.

     Exemption 3, in relevant part, provides that FOIA’s
disclosure obligation “does not apply to matters that are . . .
specifically exempted from disclosure by [another] statute,” if
the statute “(i) requires that the matters be withheld from the
public in such a manner as to leave no discretion on the
issue,” or “(ii) establishes particular criteria for withholding
or refers to particular types of matters to be withheld.” 5
U.S.C. § 552(b)(3)(A). In this case, the FBI withheld certain
responsive documents and information about Labow on the
rationale that they were “specifically exempted from
disclosure by statute,” id., i.e., the Pen Register Act, 18
U.S.C. § 3123(d). The district court upheld the FBI’s reliance
on the Pen Register Act under Exemption 3.

     When assessing whether a statute “specifically
exempt[s]” matters “from disclosure” for purposes of
Exemption 3, 5 U.S.C. § 552(b)(3), we ask two questions:
“Does the statute meet Exemption 3’s requirements? And
does the information that was withheld fall within that
statute’s coverage?” Newport Aeronautical Sales v. Dep’t of
the Air Force, 684 F.3d 160, 165 (D.C. Cir. 2012). Here, we
affirm the district court as to the first question but reverse and
remand as to the second.
                               5
     To address the first question, we look to the terms of the
statute invoked by the government—the Pen Register Act.
That statute provides:

    An order authorizing or approving the installation
    and use of a pen register or a trap and trace device
    shall direct that—

       (1) the order be sealed until otherwise ordered by
           the court; and

       (2) the person owning or leasing the line or other
           facility to which the pen register or a trap and
           trace device is attached, or applied, or who is
           obligated by the order to provide assistance to
           the applicant, not disclose the existence of the
           pen register or trap and trace device or the
           existence of the investigation to the listed
           subscriber, or to any other person, unless or
           until otherwise ordered by the court.

18 U.S.C. § 3123(d).

     That statute fits within Exemption 3 if, as noted, it either
“(i) requires that . . . matters be withheld from the public in
such a manner as to leave no discretion on the issue” or “(ii)
establishes particular criteria for withholding or refers to
particular types of matters to be withheld.” 5 U.S.C.
§ 552(b)(3)(A)(i)-(ii). Because the Pen Register Act satisfies
the latter test, we need not consider the former. The statute
identifies “particular types of matters to be withheld,” 5
U.S.C. § 552(b)(3)(A)(ii), in that it requires the sealing of
“[a]n order authorizing or approving the installation and use
of a pen register or a trap and trace device,” 18 U.S.C.
§ 3123(d). That description is at least as specific as other
                               6
statutes which we have held adequately specify “matters to be
withheld” for purposes of Exemption 3.

     For instance, we have held that Title III, another
electronic surveillance statute, is a qualifying statute under
Exemption 3 because it applies to “intercepted
communications,” a category sufficiently “narrow and well-
defined” to implicate the exemption. Lam Lek Chong v. U.S.
Drug Enf’t Admin., 929 F.2d 729, 733 (D.C. Cir. 1991). We
have similarly determined that “proprietary information”
under the Tariff Act is a particular matter for purposes of
Exemption 3. Mudge Rose Guthrie Alexander & Ferdon v.
ITC, 846 F.2d 1527, 1529-31 (D.C. Cir. 1988). We reached
the same conclusion with regard to information “pertaining to
the issuance or refusal of visas” under the Immigration and
Nationality Act. Medina-Hincapie v. Dep’t of State, 700 F.2d
737, 742 (D.C. Cir. 1983). Orders authorizing the installation
or use of a pen register likewise “refer[] to particular types of
matters to be withheld” within the meaning of Exemption 3.
5 U.S.C. § 552(b)(3)(A)(ii).

     Because the Pen Register Act is a qualifying statute under
Exemption 3, we next ask whether that statute authorized
withholding the particular information at issue in this case.
See Newport Aeronautical Sales, 684 F.3d at 165. Labow
argues that the Pen Register Act permits the government to
withhold only a sealed pen register order itself. As a result,
he contends, the statute does not justify withholding all
information appearing in (or associated with) a sealed pen
register order, even if the same information is contained in
other responsive records beyond the order. In that event,
Labow submits, because the Pen Register Act would not call
for sealing the other records, Exemption 3 should not shield
those other records from FOIA’s disclosure mandate.
                                7
     As a general matter, we agree with Labow’s reading of
the Pen Register Act. By its terms, the statute provides for
sealing of a pen register order itself, not sealing of any and all
information the order may contain even if appearing in other
documents. See 18 U.S.C. § 3132(d)(1). Although the statute
additionally bars disclosures by certain private parties about
the existence of a pen register order in the absence of a court
order allowing disclosure, id. § 3123(d)(2), that limitation
does not apply to the government. As a result, Exemption 3
of FOIA, as regards the Pen Register Act, primarily
authorizes the government to withhold a responsive pen
register order itself, not all information that may be contained
in or associated with a pen register order.

     To the extent the statute arguably authorizes withholding
documents other than a pen register order, we have no
occasion to address the issue because we do not know
whether this case involves withholding of any records beyond
a pen register order. The FBI’s chief of records management,
David M. Hardy, describes the withheld material as
information “surrounding FBI [agents] making arrangements
to set up and install a pen register and trap and trace device
during a criminal investigation,” including the “identities and
phone numbers of the individuals subject to pen registers in
this case.” Hardy Decl. ¶ 73 (J.A. 93). Hardy, however, does
not specifically say whether that information was contained in
a pen register order itself, and whether, if so, it also appeared
in other responsive records.

     In these circumstances, we conclude that the district court
erred in sustaining the government’s reliance on the Pen
Register Act based solely on Hardy’s declaration. See Labow
v. U.S. Dep’t of Justice, 66 F. Supp. 3d 104, 120 (D.D.C.
2014). We remand for the district court to assess whether the
specific information withheld in this case is protected by the
                              8
Pen Register Act. If the government withheld information
contained exclusively in a pen register order, the information
would necessarily fall under the Pen Register Act’s
nondisclosure requirements and thus would be shielded under
Exemption 3 (assuming the pen register order remains
sealed). But if the government withheld information found in
other responsive documents on the ground that a pen register
order also contained the same information, the potential
applicability of the Pen Register Statute (and hence of
Exemption 3) would be far less clear. As it currently stands,
we do not know whether this case involves the latter situation,
or, if so, whether there may be some justification for
withholding the information beyond the mere fact that it also
appears in a pen register order.

                              B.

    Labow next challenges the government’s withholding of
records subpoenaed by a grand jury, also under Exemption 3.
This court has already held that Federal Rule of Criminal
Procedure 6(e) is a qualifying statute under Exemption 3.
Fund for Constitutional Gov’t v. Nat’l Archives & Records
Serv., 656 F.2d 856, 868 (D.C. Cir. 1981). Consequently, the
sole question before us is whether the documents withheld
from disclosure fall within Rule 6(e).

     Rule 6(e) bars disclosure of “matter[s] occurring before a
grand jury.” Fed. R. Crim. P. 6(e). In this case, the
government withheld “copies of specific records provided to a
federal grand jury in response to federal grand jury
subpoenas” because they “could reveal the inner workings of
a federal grand jury.” Hardy Decl. ¶ 74 (J.A. 94). The district
court found the withholding permissible because releasing the
documents would “reveal the strategy or direction of the
investigation.” Labow, 66 F. Supp. 3d at 121 (alterations
                              9
omitted) (quoting Senate of P.R. v. U.S. Dep’t of Justice, 823
F.2d 574, 582 (D.C. Cir. 1987)). But the court provided no
explanation of why the records would reveal anything about
the investigation, and without knowing more, we do not think
they necessarily would.

     Rule 6(e) does not “draw ‘a veil of secrecy . . . over all
matters occurring in the world that happen to be investigated
by a grand jury.’” Senate of P.R., 823 F.2d at 582 (quoting
SEC v. Dresser Indus. Inc., 628 F.2d 1368, 1382 (D.C. Cir.
1980) (en banc)). Instead, the “touchstone” is whether the
information sought would reveal something about the grand
jury’s identity, investigation, or deliberation. Id. The mere
fact that information has been presented to the grand jury does
not itself permit withholding. Id. at 584.

     The government argues that documents subpoenaed by a
grand jury are more revealing than documents merely
presented to a grand jury, because they reveal the direction of
the grand jury’s investigation. If the documents would reveal
to the requester that they had been subpoenaed, we would
agree. See Lopez v. Dep’t of Justice, 393 F.3d 1345, 1349-50
(D.C. Cir. 2005) (allowing withholding of grand jury
subpoenas).      But subpoenaed documents would not
necessarily reveal a connection to a grand jury. After all,
Labow did not request documents related to a grand jury; he
sought documents about particular people. The government
revealed the existence of a grand jury by withholding
documents under Rule 6(e).

     It is possible that, had the government released the
documents without invoking Exemption 3, Labow would
never have known that any of the documents had been
subpoenaed by a grand jury. Of course, it is also possible that
the documents do somehow reveal that they were subpoenaed
                               10
by a grand jury. That might be the case, for instance, if the
government’s sole copies of the documents were marked as
grand jury exhibits, or if documents referenced the grand jury
subpoena. On the current record, however, we do not know
whether the documents at issue somehow necessarily evince
their connection to a grand jury, much less do so in a manner
that could not be dealt with through redactions.

     The government’s declaration only offers the conclusory
statement that “[a]ny disclosure of this information would
clearly violate the secrecy of the grand jury proceedings and
could reveal the inner workings of a federal grand jury.”
Hardy Decl. ¶ 74 (J.A. 94). The government later clarified
that “documents obtained by the FBI independently of a grand
jury were not withheld pursuant to Exemption 3,” Second
Hardy Decl. ¶ 11 (J.A. 132), but we do not know why
documents obtained through the grand jury’s subpoenas
would necessarily reveal that connection. As in Senate of
Puerto Rico, “[i]t may turn out, in this case, that most, or even
all, of the material withheld pursuant to exemption (b)(3)
cannot be disclosed without compromising the secrecy of a
grand jury’s deliberations. We hold only that the defendants
have not yet supplied the information a court must have in
order to intelligently make that judgment.” 823 F.2d at 584.
The mere fact the documents were subpoenaed fails to justify
withholding under Rule 6(e).

     We therefore remand for the district court to consider
whether the release of the documents subpoenaed by the
grand jury would reveal something about the grand jury’s
investigation. Of course, if the documents are now belatedly
released, it might be apparent that they had been subpoenaed
by a grand jury given that the potential connection with a
grand jury is now known. That fact, however, should not bar
disclosure. As we have previously held, the relevant question
                               11
is whether the documents would have revealed the inner
workings of the grand jury had they been released in response
to the initial FOIA request. See Wash. Post Co. v. U.S. Dep’t
of Justice, 863 F.2d 96, 100 (D.C. Cir. 1988). The district
court therefore should consider whether the documents would
have revealed something about the workings of the grand jury
had they been released with other requested documents.

                               C.

     Labow also contests the FBI’s withholding of
information provided by confidential informants under
Exemption 7(D). That exemption protects “records or
information compiled for law enforcement purposes, but only
to the extent that the production of such law enforcement
records or information . . . could reasonably be expected to
disclose the identity of a confidential source.” 5 U.S.C.
§ 552(b)(7). A source counts as confidential “if the source
provided information under an express assurance of
confidentiality or in circumstances from which such an
assurance could reasonably be inferred.” Williams v. FBI, 69
F.3d 1155, 1159 (D.C. Cir. 1995) (quoting U.S. Dep’t of
Justice v. Landano, 508 U.S. 165, 172 (1993)) (internal
quotation marks omitted). The district court permitted
withholdings based on both express and implied assurances of
confidentiality, Labow, 66 F. Supp. 3d at 124-25, but Labow
appeals only the withholdings based on implied assurances.
At this point, the government has withheld only one page of
one document based solely on implied assurances of
confidentiality.

     “The agency invoking Exception 7(D) bears the burden
of proving that it applies, and with respect to the FBI, it is not
enough for the agency to claim that all sources providing
information in the course of a criminal investigation do so on
                              12
a confidential basis.” Roth v. U.S. Dep’t of Justice, 642 F.3d
1161, 1184 (D.C. Cir. 2011). We consider four factors when
assessing an implied assurance of confidentiality: “the
character of the crime at issue, the source’s relation to the
crime, whether the source received payment, and whether the
source has an ongoing relationship with the law enforcement
agency and typically communicates with the agency only at
locations and under conditions which assure the contact will
not be noticed.” Id. (quoting Landano, 508 U.S. at 179)
(internal quotation marks omitted).

    In this case, David M. Hardy, who as noted is the FBI’s
chief of records management, has submitted several
declarations describing informants who provided information
withheld from Labow. Based on those declarations, we
conclude that the four Roth factors favor a finding of implied
confidentiality for purposes of Exemption 7(D).

     The first factor, the character of the crime, contemplates
that sources likely expect confidentiality when they report on
serious or violent crimes, risking retaliation. See Landano,
508 U.S. at 179; Mays v. Drug Enf’t Admin., 234 F.3d 1324,
1330 (D.C. Cir. 2000). Hardy’s declaration states that “[t]he
disclosure of the identities of these sources and the
information they provided could have disastrous
consequences because disclosure could subject these third
parties, as well as their families, to embarrassment,
humiliation, and/or physical or mental harm.” Hardy Decl.
¶ 96(a) (J.A. 109).       He further explains that “sources
providing information to the FBI about extremist activities do
so at great peril to themselves and have faced retaliation and
threats (including death threats) when their assistance to the
FBI has been publicly disclosed.” Id.
                             13
     Although Labow correctly observes that the withholdings
at issue are contained in a document predating the incident at
the Four Seasons, Hardy’s explanation of the risks of
informing on anarchist groups spoke to the potential dangers
posed by anarchist extremists in general, not solely by the
particular individuals who planned the Four Seasons attack.
And while Labow argues that Hardy’s explanations are too
general and conclusory, we have credited the FBI’s
assessment of risks faced by informants even if described in
relatively broad strokes. In Hodge v. FBI, 703 F.3d 575, 581
(D.C. Cir. 2013), for example, an FBI declaration stated that
disclosure “could have disastrous consequences” and “subject
[informants] to violent reprisals.” We found that explanation
sufficient, and we do the same here. The government need
not provide justifications specific to a particular group of
offenders when inferences can reasonably be drawn from the
type of crime committed.

     The second Roth factor calls for considering the source’s
relationship to the crime, because sources divulging non-
public, identifying information are more “vulnerable to
retaliation.” Mays, 234 F.3d at 1330. Here, Hardy’s
declarations do not claim that the informants directly
participated in the crime about which they provided
information. But a source of course need not have personally
participated in a crime in order to know information about it
that could reveal her identity were the information to be
released. In this case, Hardy explains, the informants were
“in a position to have ready access to and/or knowledge about
targets and others involved in extremist activities.” Hardy
Decl. ¶ 96(a) (J.A 108). And those sources “provided specific
detailed information that is singular in nature.” Id. That
describes the kind of information that, if it were revealed to
the public, could be traced to a particular source.
                               14
     With regard to the third Roth factor, all parties agree that
the sources did not receive payment. That fact weighs against
a finding of confidentiality, but it is not itself dispositive.

     Finally, the fourth Roth factor concerns the duration of
the source’s relationship with law enforcement and the
manner of communication.           Consistent and secretive
communications indicate a source’s expectation of
confidentiality. Here, we have no information about the
sources’ manner of communication. But Hardy’s declaration
does indicate that the sources provided information “over a
period of time that had proven to be reliable.” Id. That factor
thus weighs at least modestly in favor of a finding of
confidentiality.

     Considering the four factors together, we agree with the
district court that they suggest the sources expected
confidentiality. Although the sources were not paid, they
provided ongoing, singular information about serious crimes.
In those circumstances, the district court correctly sustained
the FBI’s reliance on Exemption 7(D).

                               D.

     Earlier in this appeal, Labow had also challenged a
withholding under Exemption 7(A), which exempts “records
or information compiled for law enforcement purposes” if
disclosure “could reasonably be expected to interfere with
enforcement proceedings.” 5 U.S.C. § 552(b)(7)(A). The
government has now released the documents it initially
withheld under Exemption 7(A), Appellee’s Br. 17, so that
issue is no longer a live one. We will grant Labow’s request
to vacate the district court’s grant of summary judgment to the
government with regard to its use of Exemption 7(A). See
Carlisle Tire & Rubber Co. v. U.S. Customs Serv., 663 F.2d
                             15
210, 213 (D.C. Cir. 1980). Vacatur is appropriate when a
party moots an issue it won in a lower court, precluding
review on appeal and preserving the lower-court opinion as
precedent. See 13C Charles Alan Wright et al., Federal
Practice and Procedure § 3533.10.1 (3d ed. 2008). Although
district court opinions do not establish binding precedent on
other courts, the government has not objected to vacatur here.
We thus grant Labow’s request.

                             III.

     Labow’s final challenge concerns the government’s
possible reliance on a FOIA exclusion. See 5 U.S.C. § 552(c).
Exclusions differ from exemptions in that the government
need not affirmatively claim the former. Rather, when an
exclusion applies, the government may “treat the records as
not subject to the requirements” of FOIA at all, id., and can
thus withhold the documents without comment.

    Although the government has not publicly invoked an
exclusion in this case, Labow suspects that the government
withheld records based on the exclusion set forth in 5 U.S.C.
§ 552(c)(1). That exclusion applies if:

       a request is made which involves access to
       records described in [Exemption 7(A)] and—

       (A) the investigation or proceeding involves a
           possible violation of criminal law; and

       (B) there is reason to believe that (i) the
           subject of the investigation or proceeding
           is not aware of its pendency, and (ii)
           disclosure of the existence of the records
                              16
            could reasonably be expected to interfere
            with enforcement proceedings

5 U.S.C. § 552(c)(1). Exemption 7(A) in turn, as noted,
encompasses records whose production “could reasonably be
expected to interfere with enforcement proceedings.” Id.
§ 552(b)(7)(A). The two provisions together thus exclude
records from FOIA’s disclosure mandate if production would
interfere with enforcement proceedings and the documents
relate to a criminal investigation about which the target is
unaware.

     In this case, the district court, adhering to standard FBI
practice when confronting a challenge to the suspected use of
the exclusion at issue here, reviewed an ex parte FBI affidavit
in camera to determine whether the exclusion had in fact been
applied, and, if so, whether its application was appropriate.
Labow, 66 F. Supp. 3d at 128; see ACLU of Mich. v. FBI, 734
F.3d 460, 470-71 (6th Cir. 2013). In rejecting Labow’s
challenge to the suspected use of the exclusion, the district
court said only that, “if an exclusion was in fact employed, it
was, and continues to remain, amply justified.” Labow, 66 F.
Supp. 3d at 128. Labow thus remains unsure of whether the
government actually made use of the exclusion to withhold
records.

     We review the district court’s decision to review
evidence ex parte for abuse of discretion. See Lykins v. U.S.
Dep’t of Justice, 725 F.2d 1455, 1465 (D.C. Cir. 1984). The
specific question is whether the court abused its discretion by
relying on in camera review of the ex parte affidavit rather
than following an alternative method presented by Labow for
addressing a challenge to the government’s possible use of a
FOIA exclusion. While we have explained that a court should
resort to in camera review only in limited circumstances, see
                              17
Yeager v. Drug Enf’t Admin., 678 F.2d 315, 324 (D.C. Cir.
1982), we find no abuse of discretion here.

     Under Labow’s alternative proposal, the parties would
first assume that an exclusion had been applied and would
submit public briefs on whether the hypothetical reliance on
the exclusion would be appropriate. The district court would
then issue a public opinion addressing whether the exclusion,
in theory, would be applicable in the circumstances. If the
theoretical use of the exclusion were invalid, the court would
then review ex parte submissions to determine whether the
government in fact made use of the exclusion. In essence,
Labow’s proposal inverts the approach followed by the
district court: instead of initially assessing whether an
exclusion in fact was used and then, if so, assessing the
permissibility of its use, Labow would first ask whether
reliance on the exclusion would be permissible and then, if so,
assess whether it in fact was used.

     Labow’s suggested approach would generally enable a
FOIA requester to learn whether the government’s use of an
exclusion would (at least in theory) be justified in the
circumstances. But district courts would be in the business of
considering and deciding abstract questions about the
theoretical applicability of a FOIA exclusion in circumstances
in which the government might have never relied on the
exclusion in the first place.

     Two courts of appeals have rejected proposals paralleling
Labow’s. The Sixth Circuit refused to require the same
procedure, for reasons including the risks of revealing
information during the briefing process. ACLU of Mich., 734
F.3d at 470-72.       The more the government turns to
hypothetical arguments to avoid revealing any information,
the court reasoned, the less productive the adversarial briefing
                               18
would be: “Open-ended hypothetical questions are not well
suited to the litigation process.” Id. at 472. And the
government would be “tasked with responding to [abstract]
shots in the dark” in circumstances in which “fashioning a
response is fraught with concerns of accidentally disclosing
the existence or nonexistence of secret information.” Id. The
Third Circuit later came to the same conclusion. ACLU of
N.J. v. FBI, 733 F.3d 526, 533-35 (3d Cir. 2013). Here, the
district court did not abuse its discretion in declining to follow
a process rejected by those decisions and instead adhering to a
practice endorsed by them.

     We must finally review de novo whether the district court
was wrong in finding no error in the FBI’s reliance, if any, on
an exclusion in this case. We, like the district court, have
reviewed the government’s submissions about the exclusion
in camera. And we, like the district court, will not comment
on whether the FBI in fact relied on an exclusion. Instead, we
hold only that no documents have been withheld pursuant to
any impermissible use of an exclusion.

                       *   *    *   *    *

     For the foregoing reasons, we affirm the district court’s
grant of summary judgment in favor of the government on the
claims under Exemption 7(D) and under the exclusion set
forth in 5 U.S.C. § 552(c)(1). We reverse the grant of
summary judgment on both challenges to withholdings under
Exemption 3 and remand for further proceedings consistent
with this opinion. Finally, we vacate the district court’s
opinion with regard to Exemption 7(A).

                                                     So ordered.
