 United States Court of Appeals
         FOR THE DISTRICT OF COLUMBIA CIRCUIT



Argued March 24, 2016              Decided January 24, 2017

                        No. 12-7139

 ACT NOW TO STOP WAR AND END RACISM COALITION AND
   MUSLIM AMERICAN SOCIETY FREEDOM FOUNDATION,
                    APPELLEES

                             v.

                  DISTRICT OF COLUMBIA,
                       APPELLANT


                 Consolidated with 12-7140


        Appeals from the United States District Court
                for the District of Columbia
                    (No. 1:07-cv-01495)


    Carl J. Schifferle, Assistant Attorney General, Office of
the Attorney General for the District of Columbia, argued the
cause for appellant/cross-appellee. With him on the briefs
were Karl A. Racine, Attorney General, Todd S. Kim,
Solicitor General, and Loren L. AliKhan, Deputy Solicitor
General.

    Mara E. Verheyden-Hilliard argued the cause for
appellees/cross-appellants. With her on the briefs were Carl
L. Messineo and Andrea Costello.
                               2

   Before: ROGERS and PILLARD, Circuit Judges, and
SENTELLE, Senior Circuit Judge.

    PILLARD, Circuit Judge: Like many municipalities
around the country, the District of Columbia regulates the
manner in which members of the public may post signs on the
District’s lampposts. District of Columbia law allows a
posted sign to remain on a public lamppost for up to 180 days.
But a sign relating to an event must be removed within 30
days after the event, whether the 180-day period has expired
or not. Thus, the District’s rule may in some cases give less
favorable treatment to signs that relate to an event than to
signs that do not.

     Two nonprofit organizations, the Act Now to Stop War
and End Racism Coalition (ANSWER) and the Muslim
American Society Freedom Foundation (MASF) (together,
the organizations), challenge the District’s sign-posting rule.
MASF brings a pre-enforcement challenge to the rule as
unconstitutional on its face in violation of the First
Amendment and due process. MASF first argues that the
distinction between event-related and other signs is content
based yet cannot meet strict First Amendment scrutiny and
that, even if the rule is not content based, it fails the
intermediate scrutiny applicable to content-neutral time,
place, and manner restrictions. Second, MASF contends that
the regulation delegates an impermissible degree of
enforcement discretion to the District’s inspectors in violation
of due process. It further challenges what it contends is strict
liability on the originators of posters for any violation of the
sign-posting rule, which MASF argues also contravenes its
speech and due process rights. ANSWER, unlike MASF, was
cited by the District for violations of the regulation.
ANSWER seeks damages under section 1983, contending that
                               3
it did not in fact violate the regulation and that citations were
unconstitutional retaliation against it for its postering.

     The district court granted summary judgment to MASF,
invalidating the regulation’s treatment of event-related posters
on both First Amendment and due process grounds, but
rejecting MASF’s strict-liability objection. The court also
sanctioned the District for seeking discovery in the face of an
order granting limited discovery to plaintiffs. The district
court granted summary judgment to the District on
ANSWER’s section 1983 damages claim for lack of a
showing of a policy, custom, or practice of retaliatory
enforcement, as required by Monell v. Dep’t of Soc. Servs. of
City of New York, 436 U.S. 658 (1978). The District and the
organizations cross-appealed.

     We conclude that the regulation does not impose a
content-based distinction because it regulates how long
people may maintain event-related signs on public lampposts,
not the content of the signs’ messages. The “event-related”
category is not itself content based. Under the intermediate
First Amendment scrutiny that is therefore applicable, the rule
is a reasonable time, place, and manner restriction. It is
narrowly tailored to further a well-established, admittedly
significant governmental interest in avoiding visual clutter.
The regulation’s definition of event-based signs also guides
officials’ enforcement discretion sufficiently to avoid facial
invalidation on due process grounds. Accordingly, we reverse
the grant of summary judgment in MASF’s favor and remand
for the district court to enter summary judgment for the
District.

     On the organizations’ cross-appeal, we affirm the district
court’s dismissal of ANSWER’s section 1983 damages claim
that the District retaliated against it in violation of the First
                               4
Amendment, and MASF’s claim that the District’s regulation
imposes a system of strict liability the First Amendment does
not allow. Finally, because discovery is presumptively
available to all parties pursuant to the Federal Rules of Civil
Procedure in the absence of a court order to the contrary, we
vacate the district court’s imposition of discovery sanctions
against the District for seeking discovery without leave of
court.

                       I.   Background

     The District of Columbia began its regulation of signs on
public lampposts with an outright prohibition in 1902. D.C.
Police Regulations, Art. XII, § 2 (1902). The District
partially relaxed that ban in 1958 to allow for the posting of
signs on lampposts only with the permission of the District’s
Commissioners. D.C. Police Regulations, Art. 20 § 2 (1958).
After the District’s Corporation Counsel advised that the
regulation might be constitutionally infirm for lack of clearly
articulated standards, see Letter from Louis P. Robbins,
Acting Corporation Counsel, to James W. Hill, Director,
Dep’t of Licenses, Investigations, and Inspections (October
12, 1978) (Gov’t Add. 13) [hereinafter Robbins Letter], the
District revised the regulation to add specific criteria to limit
enforcing officers’ discretion, see Street Sign Regulation
Amendment Act of 1979, D.C. Law 3-50, 26 D.C. Reg. 2733
(1979); see also Crime Prevention Sign Posting Act of 1980,
D.C. Law 3-148, 27 D.C. Reg. 4884. Following the revisions,
signs “not relate[d] to the sale of goods” could be affixed to
lampposts for up to 60 days; election signs for District of
Columbia candidates for public office were exempt from that
overall limit but had to be taken down within 30 days after the
election; and signs intended to aid neighborhood crime
prevention were exempted from the time limits. See D.C.
MUN. REGS. tit. 24 § 108.4-108.6 (1980). Commercial signs
                              5
could not be affixed to public lampposts at all. See id.
§ 108.4.     The revised rule also articulated specific
requirements for the manner in which signs could be posted
on a lamppost “or appurtenances of a lamppost” to
“minimiz[e] the need to repair lamp posts defaced by signs
attached by adhesives or other permanent methods and the
need to remove abandoned or improperly secured signs from
lamp posts, the sidewalks and the streets.” Robbins Letter at
2; see D.C. MUN. REGS. tit. 24, § 108.8-108.9 (1980). During
the pendency of this case, the District twice further amended
its lamppost rules, as described below.

     In the meantime, ANSWER, a “grassroots civil rights
organization” that works to end war and oppose racism,
Affidavit of Brian Becker ¶ 2 (Mar. 14, 2008), J.A. at 32, had
posted signs advertising rallies in the District, including
events in September 2007 and March 2010. MASF, an
unincorporated nonprofit association that conducts “civil and
human rights advocacy with a focus on empowering the
Muslim American community,” Affidavit of Imam Mahdi
Bray (Oct. 26, 2013) ¶ 6, Organizations’ Add. 2, has in the
past and intends in the future to post signs that combine
general messages of advocacy and references to specific
events, see id. at 6-8. MASF “has sought to engage in
postering to the same extent as is afforded others, including
those favored within the District of Columbia municipal
regulation system.” Id. at 9. The District of Columbia has
not cited MASF, but in 2007 the District issued multiple
citations against ANSWER under the then-current lamppost
rule.

     ANSWER and MASF sued the District, seeking a
declaratory judgment that the District of Columbia’s lamppost
rule violates their First Amendment and due process rights,
and an injunction barring its enforcement. First Amended
                              6
Complaint, Act Now To Stop War & End Racism Coal. v.
District of Columbia (ANSWER I), 570 F. Supp. 2d 72
(D.D.C. 2008) (No. 07-1495). The district court dismissed
both ANSWER’s and MASF’s claims for lack of standing,
and in abstention from pending local administrative
enforcement proceedings. ANSWER I, 570 F. Supp. 2d at 75-
78. The organizations appealed.

     This court reversed in part and remanded. Act Now to
Stop War & End Racism Coal. v. District of Columbia
(ANSWER II), 589 F.3d 433, 434 (D.C. Cir. 2009). The court
held that MASF had standing based on “a credible statement
of intent to engage in violative conduct,” and had shown
sufficient likelihood of enforcement against it because its
allegations raised “somewhat more than the ‘conventional
background expectation that the government will enforce the
law.’” Id. at 435 (quoting Seegars v. Gonzales, 396 F.3d
1248, 1253 (D.C. Cir. 2005)). At the motion to dismiss stage,
the court reasoned, an affidavit from MASF’s director stating
an intention to violate the regulation sufficed to establish
standing. Id. at 436. As to ANSWER, the court found that
the district court had correctly abstained under Younger v.
Harris, 401 U.S. 37 (1971), to the extent that charges against
ANSWER for violations of the challenged regulation
remained pending in the District of Columbia’s administrative
process. ANSWER II, 589 F.3d at 436.

     While MASF and ANSWER’s appeal was pending
before this court, the District of Columbia Department of
Transportation amended the lamppost regulation. The 2010
final rule made one distinction relevant to the plaintiffs’
claims: Signs “not related to a specific event” could be
posted for up to 60 days while signs “related to a specific
event” could be posted at any time beforehand, but had to be
removed within 30 days after the event. 57 D.C. Reg. 528
                               7
(January 8, 2010) (amending D.C. MUN. REGS. tit. 24,
§§ 108.5 & 108.6). Thus, in theory, event-related signs could
be posted for months or years before the event they
announced and for an additional 30 days thereafter, while
signs that were not event related could be posted for a
maximum of 60 days.

     On remand, ANSWER voluntarily dismissed its claims
for prospective relief. See Stipulation of Dismissal, Act Now
To Stop War & End Racism Coal. v. District of Columbia
(ANSWER III), 798 F. Supp. 2d 134 (D.D.C. 2011) (No. 07-
1495).     MASF, the only party still challenging the
constitutionality of the District’s regulation going forward,
amended its complaint in light of the revised rule, adding an
as-applied challenge to the “event-related” distinction as
content based.      See Supplemental Pleading ¶¶ 16-17,
ANSWER III, 798 F. Supp. 2d 134 (No. 07-1495). Because
neither the earlier nor the revised regulation had been
enforced against MASF, the district court dismissed MASF’s
as-applied challenge, leaving only its facial challenges under
the First Amendment and the Due Process Clause. ANSWER
III, 798 F. Supp. 2d at 143. Those claims, the court held,
could proceed to discovery. Id. at 150-51.

     Meanwhile, in its supplemental pleading after remand,
ANSWER alleged that the District had “attacked” it with
ninety-nine enforcement actions in March and April 2010 in
retaliation for the content of its postering activity. The court
dismissed that claim, holding that ANSWER had failed
adequately to allege that the claimed retaliation resulted from
a municipal custom or practice. ANSWER III, 798 F. Supp.
2d at 154-55. The court also dismissed MASF’s claim that
the regulation imposes a system of “strict liability” in
violation of the First Amendment. Id. at 153.
                              8
     In 2012, the District revised the regulation once more,
yielding the version now before us. See 59 D.C. Reg. 273
(Jan. 20, 2012). Section 108 currently provides that any
sign—including those announcing events—may be affixed to
a publicly owned lamppost for a maximum of 180 days, but
that signs relating to specific events must be removed within
30 days after the event. D.C. MUN. REGS. tit. 24, §§ 108.5,
108.6. The regulation also continues to restrict the method of
affixing signs on public lampposts: All signs must be
“affixed securely to avoid being torn or disengaged by normal
weather conditions,” id. § 108.8, but cannot “be affixed by
adhesives that prevent their complete removal from the
fixture, or that do damage to the fixture,” id. § 108.9. Signs
may not be posted on “any tree in public space,” id. § 108.2,
and no more than three copies of any sign may be posted on
either side of the street on a given block, id. § 108.10. The
2012 revision also added subsection 108.13, which defines an
“event” as “an occurrence, happening, activity or series of
activities, specific to an identifiable time and place, if
referenced on the poster itself or reasonably determined from
all circumstances by the inspector.” See 59 D.C. Reg. 273
(codified at D.C. MUN. REGS. tit. 24, § 108.13).

    After discovery—which we discuss in Part II.E., infra, in
connection with the sanctions order—the District and MASF
cross-moved for summary judgment. The court granted
summary judgment to MASF, reasoning that even if the
regulation does not distinguish on the basis of content,
subsections 108.5 and 108.6 nevertheless fail intermediate
scrutiny under the First Amendment for want of admissible
evidence showing how the regulation advances the city’s
content-neutral purposes. Act Now to Stop War & End
Racism Coal. v. District of Columbia (ANSWER IV), 905 F.
Supp. 2d 317, 340-41 (D.D.C. 2012). It also held that
subsection 108.13 was an impermissible delegation of
                                9
enforcement discretion in violation of the Due Process
Clause. Id. at 332. The court sanctioned the District for
seeking discovery in violation of the court’s scheduling order.
Act Now to Stop War & End Racism Coal. v. District of
Columbia, 286 F.R.D. 117 (D.D.C. 2012). The District and
the organizations cross-appealed.

     We held these appeals in abeyance pending the Supreme
Court’s resolution of Reed v. Town of Gilbert, 135 S. Ct. 2218
(2015), see Order, Act Now to Stop War & End Racism Coal.
v. District of Columbia, No. 12-7139 (D.C. Cir. August 20,
2014), and, once Reed was decided, requested supplemental
briefing addressing its applicability here.

                         II. Analysis

     We begin by addressing the District’s contention that
MASF lacks standing to sue. Finding standing, we proceed to
MASF’s First Amendment and due process facial challenges.
As to both, we find MASF’s challenges fall short, and
accordingly reverse the district court’s grant of summary
judgment in its favor. We affirm the court’s dismissal of
ANSWER’s section 1983 claim for damages and MASF’s
claim that the District’s rule imposes strict liability in
violation of the First Amendment. Finally, we vacate the
discovery sanctions again the District.

    A. MASF Has Standing to Challenge the District’s
       Lamppost Regulation

     The District argues that MASF ceased operating in 2011,
so has “lost standing” during the pendency of its suit. Gov’t
Br. at 19. Even if MASF exists, the District asserts, it has
failed to establish that the regulation causes it to suffer injury
in fact. We disagree: An affidavit from MASF’s Imam Bray
attests that MASF continues to exist as an unincorporated
                              10
nonprofit association, and the District’s submissions raise no
real question on that point.

     1. Evidence Shows MASF Exists. For a federal court
to exercise jurisdiction, “an actual controversy must be extant
at all stages of review, not merely at the time the complaint is
filed.” Davis v. Fed. Election Comm’n, 554 U.S. 724, 733
(2008); see also Lujan v. Defs. of Wildlife, 504 U.S. 555, 561
(1992) (plaintiff must support standing “with the manner and
degree of evidence required at the successive stages of the
litigation”). Thus, “[e]ven where litigation poses a live
controversy when filed, we must dismiss a case as moot if
events have so transpired that the decision will neither
presently affect the parties’ rights nor have a more-than-
speculative chance of affecting them in the future.” Chamber
of Commerce of U.S. v. E.P.A., 642 F.3d 192, 199 (D.C. Cir.
2011) (alteration in original) (internal quotation marks
omitted). The District contends that this case has become
moot because MASF no longer exists, thus eliminating it as a
party whose rights could be affected.

     MASF, as the party invoking our jurisdiction, “bears the
burden of establishing” its standing, Lujan, 504 U.S. at 561, a
burden that is “correlative to the burden” to establish the
substantive elements of its claims, Sierra Club v. E.P.A., 292
F.3d 895, 900 (D.C. Cir. 2002). Even though the District did
not challenge MASF’s existence when it moved for summary
judgment because it learned of the evidence that it believes
calls MASF’s existence into question only after noticing its
appeal, we consider MASF’s standing de novo, as we would
had it been challenged at the procedural stage to which the
case had progressed in the district court. Scenic America, Inc.
v. Anthony Foxx, 836 F.3d 42, 49-50 (D.C. Cir. 2016).
Accordingly, on appeal from denial of summary judgment in
MASF’s favor, there must be no material dispute about the
                              11
facts that support its standing. We view the evidence and
inferences therefrom in the light most favorable to the District
as the nonmoving party on MASF’s cross-motion for
summary judgment. See Dunaway v. Int’l Bhd. of Teamsters,
310 F.3d 758, 761 (D.C. Cir. 2002).

     Imam Bray’s affidavit suffices as an authoritative
statement of MASF’s continued existence as an
unincorporated nonprofit association under District of
Columbia law. An “unincorporated nonprofit association” is
“an unincorporated organization, consisting of 2 or more
members joined under an agreement that is oral, in a record,
or implied from conduct, for one or more common, nonprofit
purposes.” D.C. Code § 29-1102(5) (2016). Such a nonprofit
is “a legal entity distinct from its members and managers” and
has “perpetual duration” unless otherwise provided. Id. § 29-
1105(a), (b). To operate as an unincorporated nonprofit
association an organization need not be registered with the
District, see id. § 29-1102(5), and it has the capacity on a
member or manager’s initiative to sue in its own name, id. §
29-1109.

     In his affidavit, Imam Bray attested that, “[t]hroughout
the period of litigation, there have always been two or more
persons (i.e. ‘members’ as that term is used in the District’s
Uniform Unincorporated Nonprofit Association Act) who
have participated in the management of the affairs of MASF
or in the development of the policies and activities of MASF.”
Bray Affidavit ¶ 4, Organizations’ Add. 2. The District has
no evidence that the organization in fact lacks “2 or more
members,” D.C. Code § 29-1102(5), who have joined together
for a “common, nonprofit purpose,” id., namely “to engage in
civil and human rights advocacy with a focus on empowering
the Muslim American community,” Bray Affidavit ¶ 6,
Organizations’ Add. 2.
                             12
     The District challenges MASF’s existence based on an
online newspaper report and a record from the District of
Columbia Department of Consumer and Regulatory Affairs.
While this appeal was pending, the District learned of an
online Muslim Link article reporting that MASF “announced
its closure on June 17, 2011.” Gov’t Add. 40. The Link cited
a statement from someone identifying himself as a MASF
member that the organization did not have “the resources that
would allow [continuing] advocacy and organizing work.” Id.
(alterations in original). In the online “comments” section of
the document as printed and filed by the District, however, a
member of the Muslim American Society’s Board of
Trustees, Mazan Mokhtar, explained that the “reports of MAS
Freedom’s closing are greatly exaggerated.” Gov’t Add. 42.
Imam Bray’s declarations attest to MASF’s continued
existence. Bray Affidavit ¶¶ 10-29, Organizations’ Add. 3-9.
The conclusory and ambiguous Link document,
unaccompanied by a declaration of the quoted individual or
anyone else attesting to personal knowledge of the putative
closing, fails to call into question MASF’s continued
existence.

     The District also points to a record from the District of
Columbia Department of Consumer and Regulatory Affairs
(DCRA) stating that an entity referred to as “MASF, Inc.,”
had its incorporation status “revoked.” See Gov’t Br. Add.
44. MASF, however, avers that it is not the organization
described in that DCRA record. MASF’s complaint does not
refer to the organization as “MASF, Inc.,” see First Amended
Complaint at 5, ANSWER I, 570 F. Supp. 2d 72 (No. 07-
1495), nor is it so described in the corporate disclosure
statement to this court, see Corporate Disclosure Statement,
Docketed February 28, 2013. For further confirmation,
MASF points to Imam Bray’s sworn affidavit attesting that
MASF has never been incorporated. See Bray Affidavit,
                              13
Organizations’ Add. 2-3. Imam Bray explains that he “was
involved with the formation and abandonment of that short-
lived separate corporation. Those papers were filed with the
intent to create a 501(c)(4) corporation that would engage in
activities coinciding with the 2008 Presidential election.
However, the project was abandoned. The incorporation
papers were, essentially, a false start.” Id. at 3. Thus, the
District has not raised a material factual dispute as to whether
the organization whose incorporation is listed as “revoked” is
the party before us.

    Neither of the District’s submissions suffices to call into
question MASF’s continued existence.

    2. MASF Has Established its Injury. The District also
contends that, even if MASF exists, the lamppost regulation
causes it no injury.

     MASF brings a pre-enforcement challenge to the
regulation before it has faced any punishment. As we
explained when this case was previously before us, “standing
to challenge laws burdening expressive rights” may require
“only ‘a credible statement by the plaintiff of intent to commit
violative acts and a conventional background expectation that
the government will enforce the law.’” ANSWER II, 589 F.3d
at 435 (quoting Seegars v. Gonzales, 396 F.3d 1248, 1253
(D.C. Cir. 2005)). Here, MASF encounters “somewhat more
than the ‘conventional background expectation that the
government will enforce the law.’” Id. (quoting Seegars, 396
F.3d at 1253). Given the District’s energetic issuance of
multiple citations against ANSWER, the threat of
enforcement against MASF is not “imagined or wholly
speculative,” Seegars, 396 F.3d at 1252, nor is there reason to
think “the challenged law is rarely if ever enforced,” id.
                               14
    The District now argues that the 2012 amendment of the
lamppost regulation during the pendency of this case has
eliminated the risk of harm that MASF identified. The
District says that MASF has “never asserted an intent to
poster in violation of the regulations invalidated on summary
judgment”—i.e., the current rule, as promulgated in 2012.
Gov’t Br. at 27. MASF’s only claimed injury, the District
contends, stems from the disfavored status afforded to signs
not related to an event under the superseded 2010
Regulation—a disadvantage the current regulation eliminates.

    The 2010 rule favored signs related to an event but, in
eliminating that leeway, the 2012 version could be viewed to
have swung too far in the other direction so as to disfavor
event-related signs. See 59 D.C. Reg. 273 (2012). Under the
2010 rule, signs “not related to a specific event” could be
posted for up to 60 days; the rule did not specify how far in
advance signs “related to a specific event” might be posted, so
long as they were removed within 30 days of the event. 57
D.C. Reg. 528 (Jan. 8, 2010). Thus, the 2010 rule on its face
allowed event-related signs to remain on lampposts for
months or years leading up to an event, while it restricted total
posting time for signs not related to an event. Under the
current rule as amended in 2012, however, no sign—whether
or not related to an event—may remain affixed to a public
lamppost for more than 180 days. D.C. MUN. REGS. tit. 24,
§ 108.5 (2012). Signs relating to a specific event must, as
before, be removed within 30 days after the event. Id.
§ 108.6. The current rule thus treats event-related signs, in
some circumstances, less favorably than signs unrelated to
any event: Assuming an event-related sign is posted fewer
than 150 days before the event, the requirement that it be
removed within 30 days after the event means it may not be
displayed for the full 180-day period it would otherwise enjoy
under the regulation if it were unrelated to an event.
                               15
     The District notes that MASF filed its amended
complaint on the heels of the 2010 rule, and contends that the
Complaint expressed only MASF’s intent to violate the then-
comparatively-restrictive 60-day limit that the 2010 rule
imposed on signs not related to an event. But MASF’s intent
is not so narrowly circumscribed: It intends to “engage in
postering to the same extent as is afforded others.” Bray
Affidavit ¶ 32, Organizations’ Add. 9. The organization has
reasserted, since the rule revision in 2012, that it plans to post
signs that would “violate the challenged regulations,
specifically keeping them affixed for 180 days despite the
regulations requiring any poster that is ‘related to a specific
event’ to be removed 30 days post-event.” Id. ¶ 35. MASF
also intends to post signs that contain both information related
to events and information of continuing relevance and
expresses uncertainty as to whether such signs are subject to
the 30-day post-event limitation. See id. ¶ 37. The District’s
arguments that MASF lacks standing therefore fail.

   B.    The District’s Rule Does Not Violate the First
         Amendment

      The District’s regulation of the public’s use of city
lampposts as convenient places to post signs is a content-
neutral time, place, and manner restriction that is sufficiently
tailored to a significant governmental interest in avoiding
clutter to comport with the First Amendment. As the district
court held, “the District’s lampposts are a textbook example
of a limited or designated public forum.” ANSWER III, 798 F.
Supp. 2d at 145. The District might have chosen not to make
its lampposts available as a place for the people to put up their
signs. Members of the City Council v. Taxpayers for Vincent,
466 U.S. 789, 814-15 (1984). But once it allows members of
the public to post signs on its lampposts, the government
lacks the “power to restrict expression because of its message,
                              16
its ideas, its subject matter, or its content.” Police Dep’t of
City of Chicago v. Mosley, 408 U.S. 92, 95 (1972).

     The level of constitutional scrutiny is determinative here.
MASF contends that the lamppost rule is content-based so
subject to strict scrutiny under Reed v. Town of Gilbert,
whereas the District of Columbia says the rule is a content-
neutral time, place, and manner restriction quite different
from the content-based sign-posting regulations struck down
in Reed. “Content-based laws—those that target speech based
on its communicative content—are presumptively
unconstitutional and may be justified only if the government
proves that they are narrowly tailored to serve compelling
state interests.” Reed, 135 S. Ct. at 2226. Government may,
however, impose content-neutral limitations on the duration
and manner in which the public uses government property for
expressive conduct like sign-posting. “‘[C]ontent-neutral’
time, place, and manner regulations are acceptable so long as
they are designed to serve a substantial governmental interest
and do not unreasonably limit alternative avenues of
communication.” City of Renton v. Playtime Theatres, Inc.,
475 U.S. 41, 47 (1986).

    We review de novo the district court’s grant of summary
judgment to the organizations on their First Amendment
claim. Hodge v. Talkin, 799 F.3d 1145, 1155 (D.C. Cir.
2015).

     1. The Rule Is Content Neutral. The District of
Columbia’s lamppost rule makes a content-neutral distinction
between event-related signs and those not related to an event.
The District requires that, whatever their content or
viewpoint, event-related signs be removed within thirty days
after the event to prevent them from accumulating as visual
clutter. That rule is not a “regulation of speech,” but “a
                              17
regulation of the places where some speech may occur.” Hill
v. Colorado, 530 U.S. 703, 719 (2000). It does not target the
“communicative content” of those signs, such as by
distinguishing among various events by topic, see Reed, 135
S. Ct. at 2226-27, but uniformly restricts the duration that
event notices may remain physically affixed to public
lampposts. The rule’s clutter-minimizing rationale does not
depend on the content of a sign’s message. See Hill, 530 U.S.
at 723; United States v. O’Brien, 391 U.S. 367, 376 (1968).

     Content distinctions are of special concern under the First
Amendment because they pose the risk that government is
favoring particular viewpoints or subjects. But a broad-based,
general distinction between event-based signs and other signs
poses no such risk. It instead simply reflects the common-
sense understanding that, once an event has passed, signs
advertising it serve little purpose and contribute to visual
clutter. The promulgation and function of the District of
Columbia’s wholly viewpoint neutral lamppost rule reveals
“not even a hint of bias or censorship.” Taxpayers for Vincent,
466 U.S. at 804.

     The fact that District officials may look at what a poster
says to determine whether it is “event-related” does not render
the District’s lamppost rule content-based. The “event-
related” definition is just as content neutral as was Colorado’s
“free zone” sustained in Hill, which prevented persons
approaching patients on the sidewalk outside abortion clinics
to come closer than eight feet to engage “in ‘oral protest,
education, or counseling’ rather than pure social or random
conversation.” 530 U.S. at 721. The Court in Hill
acknowledged that “the content of the oral statements made
by an approaching speaker must sometimes be examined to
determine whether the knowing approach is covered by the
statute,” but noted that such “cursory examination” did not
                              18
render the statute facially content based. Id. at 720, 722. So,
too, laws banning “picketing,” and injunctions aimed at
“demonstrating” that do not bar other types of expressive
conduct are not rendered content based merely because, at a
general level, the character of the expressive activity must be
taken into account to discern whether the law applies. See id.
at 722-23 & n.30 (citing Schenck v. Pro-Choice Network of
Western New York, 519 U.S. 357, 366-67 n.3 (1997); Madsen
v. Women’s Health Ctr., Inc., 512 U.S. 753, 759 (1994);
Frisby v. Schultz, 487 U.S. 474 (1988); United States v.
Grace, 461 U.S. 171 181 n.10 (1983); Police Dept. of
Chicago v. Mosley, 408 U.S. at 98). So, too, the fact that a
District of Columbia official might read a date and place on a
sign to determine that it relates to a bygone demonstration,
school auction, or church fundraiser does not make the
District’s lamppost regulation content based.

     MASF contends that Reed requires us to apply strict
scrutiny because “[t]he regulation singles out specific subject
matter—that deemed ‘related to a specific event’—for
differential treatment,” and that, per Reed, there is no
“exception from the content-neutrality requirement for event-
based laws.” Cross-Appellants’ Supp. Br. at 6 (quoting Reed,
135 S. Ct. at 2231). But Reed does not view a bare distinction
between event-related and other signs as itself content-based.
The aspect of the Sign Code invalidated in Reed that the
Court held to be content-based was its further distinctions
among signs—including among event-related signs—based
on their subject matter.

    The Town of Gilbert’s complex Sign Code exempted
twenty-three categories of signs—based on their content—
from the town’s general ban on posting outdoor signs, and
made additional content distinctions among the categories of
exempted signs, including several content distinctions among
                              19
event-related signs. 135 S. Ct. at 2224-25. In particular, the
Sign Code gave different amounts of leeway to event-related
signs depending on whether the event was, for example,
political, commercial, construction-related, “special-event,” or
religious or charitable.      Political signs, including any
“temporary sign designed to influence the outcome of an
election called by a public body,” id. (quoting Gilbert, Ariz.,
Land Development Code (Sign Code or Code), Glossary of
General Terms, at 23 (2005)), enjoyed relatively generous
time limits; they could be posted for up to sixty days before a
primary election, and, if the candidate to which they referred
advanced to the general election, they could remain posted
until fifteen days following the general election, id. at 2225.
Signs relating to Temporary Uses and Special Events could be
posted up to 24 hours in advance and remain posted through
the day of the event, whereas Garage Sale signs and Bazaar
signs could remain posted only until the “end of the sale.”
Gilbert, Ariz., Land Development Code, Art. 4.402(K), (O),
(Y). The Gilbert Sign Code permitted builders to post
weekend directional signs “no earlier than 4:00 p.m. on
Friday of each week” and had to remove them “no later than
8:00 a.m. on the following Monday.” Id. Art. 4.405(B)(2)(f).

     The Town of Gilbert’s Sign Code gave least favorable
treatment to the kind of sign that the petitioner church in Reed
sought to use: “Temporary Directional Signs Relating to a
Qualifying Event.” 135 S.Ct. at 2225. Such a sign, defined
as one that directed people to any “assembly, gathering,
activity, or meeting sponsored, arranged, or promoted by a
religious, charitable, community service, educational, or other
similar non-profit organization,” could only be displayed for
twelve hours before the event, and had to be removed within
an hour after the event. Id. The Sign Code thus afforded
more leeway to electioneering signs and even signs relating to
specified Temporary Uses such as farmers’ markets or
                              20
fireworks displays than to signs for morning church services,
which for the most part could not go up until after dark in
winter, and had to be removed the next morning before coffee
and doughnuts were fully digested.

     The rule the organizations here challenge, in contrast,
distinguishes only between signs that are event-related and
signs that are not. That distinction is not itself content-based
under Reed. The organizations assert that Reed held that the
“event-based” category is necessarily content-based because it
“singles out specific subject matter—that deemed ‘related to a
specific event’—for differential treatment.” Appellee Supp.
Br. at 6. But Reed did not so hold. The passage the
organizations invoke was directed at the notion the court of
appeals had advanced that an otherwise “obvious content-
based inquiry,” such as the distinction between “political” and
“ideological” signs relating to an upcoming election, would
be somehow rendered content-neutral and thereby “evade
strict scrutiny review simply because an event (i.e. an
election) is involved.” Reed, 135 S. Ct. at 2231.

     Indeed, Reed makes clear that a municipality may
continue to treat event-related signs differently from non-
event-related signs by means of time, place, and manner
restrictions, as long as it does not distinguish among types of
event based on content. What Reed held constitutionally
suspect was the way in which the Town of Gilbert’s Sign
Code made content-based distinctions among different types
of issues and events, and even different types of signs relating
to the same event. See Reed, 135 S Ct. at 2227. Unlike the
content-based treatment of event-related signs invalidated in
Reed, District of Columbia law treats all event-related signs
alike and is thus content neutral.
                              21
     The Court in Reed emphasized that differences in time
limits depending on the “communicative content” of the signs
was what subjected the Town of Gilbert Sign Code to strict
scrutiny. See id. at 2227. Because Gilbert’s Sign Code
treated “the Church’s signs inviting people to attend its
worship services . . . differently from signs conveying other
types of ideas,” it was content-based regulation. Id. The
Court emphasized that the Sign Code’s distinctions did not
merely “hinge on ‘whether and when an event is occurring,’”
and did not just “permit citizens to post signs on any topic
whatsoever within a set period leading up to an election.” Id.
at 2231. Rather, the Code impermissibly required town
officials to examine each sign to determine whether, for
example, it was “designed to influence the outcome of the
election” and so must come down within fifteen days
thereafter, or more generally “ideological,” in which case no
time limit applied. Id. at 2231.

     Justice Alito’s concurring opinion in Reed even more
squarely rejects the position the organizations advance here
that the distinction between event-related and other signs is
itself content-based. Writing for three of the six justices in
the majority, Justice Alito specifies that a regulation
“imposing time restrictions on signs advertising a one-time
event” does not by token of the “event-related” category as
such amount to a content-based distinction. Id. at 2233
(Alito, J., concurring). Rules treating event-related signs as a
group differently based on their time-limited nature “do not
discriminate based on topic or subject and are akin to rules
restricting the times within which oral speech or music is
allowed.” Id. That is, such rules are time, place, or manner
restrictions, constitutionally permissible if they are narrowly
tailored to serve a significant governmental interest. The
three justices who concurred in Reed also clearly would not
strictly scrutinize the rule we face here. See id. at 2236
                              22
(Breyer, J., concurring in the judgment) (concluding that even
the regulation at issue there “does not warrant ‘strict
scrutiny’”); id. at 2236-38 (Kagan, J., joined by Ginsburg and
Breyer, JJ., concurring in the judgment) (“The absence of any
sensible basis for these and other distinctions dooms the
Town’s ordinance under even the intermediate scrutiny that
the Court typically applies to ‘time, place, or manner’ speech
regulations. Accordingly, there is no need to decide in this
case whether strict scrutiny applies to every sign ordinance in
every town across this country containing a subject-matter
exemption.”).

     All four of the opinions in Reed confirm that the District
of Columbia’s lamppost rule is not a content-based regulation
of speech. The District’s rule governs the time event-related
signs may remain on public lampposts after the event has
passed because obsolete signs cause a particular aesthetic
harm; the rule makes no distinctions among event-related
signs based on their particular communicative content.
Reed’s definition of content-based regulation does not sweep
in rules like the District’s that merely distinguish between all
signs related to events and all non-event-related signs. It is
therefore not subject to the strict scrutiny applicable to
content-based regulation of speech, but must only meet the
lesser constitutional scrutiny applicable to content-neutral
rules affecting speech.

    Accordingly, we proceed to consider the validity of the
regulation under the standard applicable to content-neutral
regulation of speech.

    2. The Regulation Withstands Intermediate Scrutiny.
Even if the regulation is content neutral, MASF argues, it
nevertheless violates the First Amendment. The district court
granted partial summary judgment to MASF on the ground
                              23
that the regulation could not pass muster under the
intermediate scrutiny applicable to content-neutral regulation
of speech.

     A basic principle of the First Amendment—that “[e]ven
protected speech is not equally permissible in all places and at
all times,” Cornelius v. NAACP Legal Def. & Educ. Fund,
Inc., 473 U.S. 788, 799 (1985)—permits the government to
impose “reasonable time, place, and manner regulations as
long as the restrictions ‘are content-neutral, are narrowly
tailored to serve a significant government interest, and leave
open ample alternative channels of communication.’” United
States v. Grace, 461 U.S. 171, 177 (1983) (quoting Perry
Educ. Ass’n v. Perry Local Educators’ Ass’n, 460 U.S. 37, 45
(1983)); see Clark v. Cmty. for Creative Non-Violence, 468
U.S. 288, 298 n.8 (1984). Those same standards apply
whether the regulated speech occurs in a traditional public
forum—i.e. streets and parks—or on public property that the
government has designated for the public’s use as a forum for
speech and other expressive conduct, such as the lampposts in
this case. Perry Educ. Ass’n, 460 U.S. at 45-46. It is the
District of Columbia’s burden to show that its regulation
serves a substantial governmental purpose and is tailored to
that purpose. See McCullen v. Coakley, 134 S. Ct. 2518, 2540
(2014); Edwards v. District of Columbia, 755 F.3d 996, 1002-
03 (D.C. Cir. 2014). We conclude that it meets that burden
here.

    The District’s interest is plainly significant.
“[M]unicipalities have a weighty, essentially esthetic interest
in proscribing intrusive and unpleasant formats for
expression.” Taxpayers for Vincent, 466 U.S. at 806; see also
Metromedia, Inc. v. City of San Diego, 453 U.S. 490, 507-08
(1981) (finding no “substantial doubt” that the governmental
objective of furthering “the appearance of the city” is a
                                24
“substantial governmental goal[]”); Mahoney v. Doe, 642
F.3d 1112, 1118 (D.C. Cir. 2011). The district court accepted
that the prevention of clutter and litter is a substantial interest,
see ANSWER IV, 905 F. Supp. 2d at 334 n.4, and MASF does
not challenge that conclusion here, see Organizations’ Br. 44.

     Instead, MASF argues that the District of Columbia has
failed to show that its regulation actually serves that interest.
But the event-related distinction in the District’s regulation
turns on the very non-speech feature of that activity that
makes it proscribable in the first place—that is, the visual
blight of superannuated event signs.               The District
distinguishes event-related from non-event-related signs
based on its “weighty, essentially esthetic interest in
proscribing intrusive and unpleasant formats for expression.”
Taxpayers for Vincent, 466 U.S. at 806. The District’s
reasoning is straightforward:           All signs have both
communicative value and aesthetic costs. Leading up to an
event, the communicative value of a sign related to that event
outweighs the aesthetic harm that sign causes. But after the
event, the communicative value of the sign is greatly
diminished. The sign then becomes, from the District’s
perspective, little more than visual clutter. See Robbins Letter
at 2. There is also greater risk that an event-related sign will
be abandoned after the event it announces, and not maintained
like a sign with continuing relevance. Failure to remove such
a sign is itself a manifestation of neglect.

     As the Supreme Court has explained, where the basis for
distinguishing between types of communicative conduct
“consists entirely of the very reason the entire class of speech
at issue is proscribable, no significant danger of idea or
viewpoint discrimination exists.” R.A.V. v. City of St. Paul,
505 U.S. 377, 388 (1992). Such is the case here. That is not
to say that an event-related sign loses all communicative
                               25
value after the event has occurred. A viewer might have some
interest, for example, in knowing what kinds of events had
taken place (or been advertised) in the neighborhood in the
past, even though she had missed the event itself. That an
event-related sign might have some residual continuing
relevance, however, does not bar the District from
determining, in a content-neutral, across-the-board manner,
that the visual clutter outweighs any such interest.

     The district court held that the District, “by submitting no
evidence whatsoever” of the relationship between its
admittedly substantial interest and the challenged regulation,
had failed to meet its burden on summary judgment.
ANSWER IV, 905 F. Supp. 2d at 344. The District responds
that it has sought, since it first established criteria for
permitting the public to post signs on District lampposts, to
protect “legitimate governmental interests in caring for city
lampposts       and      neighborhood        aesthetics     while
contemporaneously affording citizens ample opportunity to
exercise their First Amendment rights.” D.C. Council, Report
on Bill 3-179, at 3 (Sept. 26, 1979). The District was not
required in these circumstances to submit studies, statistics or
other empirical evidence in order to defend the event-related
distinction as a narrowly tailored means to serve its
substantial aesthetic interest. That relationship is less a matter
to be established by empirical evidence than it is the result of
a straightforward line of reasoning: “A poster for an event
that has already occurred is more likely to constitute litter and
blight than a poster for a future event” or a non-event-related
sign. ANSWER III, 798 F. Supp. 2d at 148. As the Supreme
Court has observed, “[t]he quantum of empirical evidence
needed to satisfy heightened judicial scrutiny of legislative
judgments will vary up or down with the novelty and
plausibility of the justification raised.” Nixon v. Shrink
Missouri Gov’t PAC, 528 U.S. 377, 391 (2000).
                              26
     The District’s aesthetic judgment that an event-related
sign for an event that has passed contributes to visual clutter
is utterly plausible and not novel. See Nat’l Ass’n of Mfrs. v.
Taylor, 582 F.3d 1, 16 (D.C. Cir. 2009) (explaining that
because “a value judgment based on the common sense of the
people’s representatives” is not like a justification based on
“economic analysis that [is] susceptible to empirical
evidence,” such a common-sense judgment need not be
supported by an evidentiary showing); see also Blount v.
S.E.C., 61 F.3d 938, 944-45 (D.C. Cir. 1995) (holding that
there is no need to show evidence of any specific quid pro quo
to support the regulation against First Amendment challenge
because the dynamic to which regulation responded was “self-
evident[]”). The justification for the rule’s requirement that
event-related signs be removed within thirty days of the event
is just the sort of common-sense judgment for which
empirical data is likely to be both unavailable and
unnecessary.

     The District has also shown that its lamppost rule leaves
open ample alternative channels of communication. The rule
does not limit anyone’s ability to say in multiple ways and for
unlimited duration the very same thing she or he seeks to
announce on lamppost posters. People may hand out leaflets
or speak to passers-by with the same message, or put that
message on bumper stickers. They may circulate or march
wearing or holding the very same signs, post or erect the same
signs on private property with the owners’ permission, and
post messages on various electronic and physical billboards,
publications, or pages to communicate about their events.
Nothing in the challenged rule prevents anyone from using
such channels for as long as they like, even after their event
has taken place. The challenged rule merely limits event-
related posters from continuing to occupy the limited space on
                               27
publicly owned lampposts more than thirty days after the
relevant event has passed.

     There are admitted advantages to postering: It is a
relatively inexpensive method for an organization to
broadcast its message; it can be targeted to a particular
neighborhood; and it requires less time commitment than
leafletting or a direct-advocacy campaign.         See, e.g.,
Taxpayers for Vincent, 466 U.S. at 812. But the District’s
regulation does not foreclose affixing posters to public
lampposts as a channel of communication; it merely imposes
reasonable limits on the duration that a poster may be left up
after the event has passed. Moreover, as the Supreme Court
explained in upholding a complete ban on the posting of signs
on publicly owned lampposts, even a full ban does

   not affect any individual’s freedom to exercise the
   right to speak and to distribute literature in the same
   place where the posting of signs on public property is
   prohibited. To the extent that the posting of signs on
   public property has advantages over these forms of
   expression, there is no reason to believe that these
   same advantages cannot be obtained through other
   means.

Id. at 812 (citation and footnote omitted); see also id. n.30.

     The District’s regulation amounts to a reasonable time,
place, and manner restriction.          Given the nature and
plausibility of the District’s justification for requiring event-
related signs to be removed within thirty days of the event,
there was no need for the District to introduce evidence
demonstrating the relationship between that justification and
the regulation.
                               28
   C.    MASF’s Vagueness Challenge Fails

     MASF presents a further facial challenge to the lamppost
regulation on the ground that it is unconstitutionally vague. A
law may be vague in violation of the Due Process Clause for
either of two reasons: “First, it may fail to provide the kind of
notice that will enable ordinary people to understand what
conduct it prohibits; second, it may authorize and even
encourage arbitrary and discriminatory enforcement.” City of
Chicago v. Morales, 527 U.S. 41, 56 (1999); see F.C.C. v.
Fox Television Stations, Inc., 132 S. Ct. 2307, 2317 (2012).
MASF made both types of arguments to support its vagueness
claim, but in granting summary judgment to MASF the
district court addressed only the discriminatory-enforcement
theory, holding that the definition of “event” in section 108.13
of the regulation delegates impermissible enforcement
discretion to the District’s inspectors. ANSWER IV, 905 F.
Supp. 2d at 348. The court found it unnecessary to decide
whether section 108.13 also fails to give constitutionally
adequate notice of what amounts to an event-related sign, see
id., and on appeal MASF does not press a notice theory of
vagueness. We therefore consider only whether section
108.13 delegates impermissibly unbridled enforcement
discretion.

     First, we address a potential threshold obstacle. The
District contends that a facial vagueness challenge is
foreclosed by the Supreme Court’s decision in Holder v.
Humanitarian Law Project, 561 U.S. 1 (2010). Under
Humanitarian Law Project, a party whose own expressive
activity is clearly proscribed cannot challenge a law’s
vagueness as it might apply to facts not before the court. Id.
at 20. Humanitarian Law Project addressed “only whether
the statute ‘provide[s] a person of ordinary intelligence fair
notice of what is prohibited,’” 561 U.S. at 20 (quoting United
                               29
States v. Williams, 553 U.S. 285, 304 (2008)), observing that
“Plaintiffs do not argue that the material-support statute grants
too much enforcement discretion to the Government.” Id.
We are aware of no decision that has applied Humanitarian
Law Project to bar a facial challenge like MASF’s that a law
is so vague as to subject the challenger itself to standardless
enforcement discretion. See Fox, 132 S. Ct. at 2317-18
(assuming facial vagueness challenges remain available when
based on an enforcement-discretion theory).

     Indeed, it is not apparent how the Humanitarian Law
Project rule—barring a person to whom a legal provision
clearly applies from challenging its facial failure to give
sufficient notice to others, see 561 U.S. at 20—could apply to
a claim that a law is so vague as to fail to guide the
government’s enforcement discretion. At least in a pre-
enforcement posture, such a claim is by its nature facial.
“Self-censorship is immune to an ‘as applied’ challenge, for it
derives from the individual’s own actions, not an abuse of
government power.” City of Lakewood v. Plain Dealer
Publ’g Co., 486 U.S. 750, 757 (1988). “It is not merely the
sporadic abuse of power by the censor but the pervasive threat
inherent in its very existence that constitutes the danger to
freedom of discussion.” Thornhill v. Alabama, 310 U.S. 88,
97 (1940). Therefore, “only a facial challenge can effectively
test the statute.” City of Lakewood, 486 U.S. at 758; see also
Morales, 527 U.S. at 52 (holding that vagueness that “fails to
establish standards for the police and public that are sufficient
to guard against the arbitrary deprivation of liberty interests”
is subject to facial challenge).

    Whereas Humanitarian Law Project determined that the
law’s applicability to the particular plaintiff was clear, a court
faced with an arbitrary-enforcement theory has no way to
discern in advance whether the exercise of unbridled
                              30
enforcement discretion will spare the plaintiff’s
constitutionally protected expression from prosecution. Cf.,
e.g., Forsyth Cty. v. Nationalist Movement, 505 U.S. 123, 133
n.10 (1992) (describing as “irrelevant” the uncodified criteria
actually applied to the challenger’s case by officials allegedly
imbued with undue enforcement discretion). And once
enforcement discretion has been exercised to punish
constitutionally protected expression and the speaker defends
on that ground, the vagueness defect escapes review. We thus
proceed on the assumption that a facial, pre-enforcement
vagueness challenge of the kind MASF presents here is
consistent with Humanitarian Law Project. Cf. Agostini v.
Felton, 521 U.S. 203, 237 (1997) (noting that lower courts
should not conclude that cases overrule precedent by
implication).

     On the merits of MASF’s claim that section 108.13 is
void for vagueness, we begin with the “basic principle of due
process that an enactment is void for vagueness if its
prohibitions are not clearly defined.” Grayned v. City of
Rockford, 408 U.S. 104, 108 (1972). A statute authorizes an
impermissible degree of enforcement discretion—and is
therefore void for vagueness—where it fails to “set
reasonably clear guidelines for law enforcement officials and
triers of fact in order to prevent ‘arbitrary and discriminatory
enforcement.’” Smith v. Goguen, 415 U.S. 566, 573 (1974)
(quoting Grayned, 408 U.S. at 108). “When speech is
involved,” the Supreme Court has cautioned, “rigorous
adherence” to the requirement of a reasonable degree of
clarity “is necessary to ensure that ambiguity does not chill
protected speech.” Fox, 132 S. Ct. at 2317.

     Section 108.13 sets reasonably clear guidelines for law
enforcement officers to determine whether a sign is event
related, and therefore is not unconstitutionally vague. The
                               31
regulation defines an “event” as “an occurrence, happening,
activity or series of activities, specific to an identifiable time
and place, if referenced on the poster itself or reasonably
determined from all circumstances by the inspector.” D.C.
MUN. REGS. tit. 24, § 108.13. Section 108.13 does not give
enforcement officials so little guidance as to permit them to
“act in an arbitrary or discriminatory way.” Fox, 132 S. Ct. at
2317. In any system that relies on the administration of laws
of general applicability in many different circumstances, some
degree of ambiguity is all but inevitable. And, indeed, there is
some evidence in this record that section 108.13 is susceptible
of inconsistent application. “What renders a statute vague,”
however, “is not the possibility that it will sometimes be
difficult to determine whether the incriminating fact it
establishes has been proved; but rather the indeterminacy of
precisely what that fact is.” Williams, 553 U.S. at 306. Here,
the fact targeted by the “event-related” limitation is clear: To
relate to an “event,” a sign must relate to “an occurrence,
happening, activity or series of activities, specific to an
identifiable time and place.” That is not a vague standard.

     Those laws that courts have held to be constitutionally
infirm for vagueness gave significantly less guidance to
enforcement agents than does 108.13’s definition of an event-
related sign. In Kolender, for example, a statute requiring a
suspect to present “credible and reliable” identification gave
police impermissibly open-ended enforcement discretion.
Kolender v. Lawson, 461 U.S. 352, 358-60 (1983). That
statute “contain[ed] no standard for determining” how to meet
the highly subjective “credible and reliable” requirement. Id.
at 358. In Niemotko v. Maryland, too, no standard or
guideline whatsoever cabined the Park Commissioner’s and
the City Council’s discretion whether to grant a permit to hold
a demonstration in the city park; officers were empowered to
rely on nothing more than their own inclinations regarding
                               32
each permit request. 340 U.S. 268, 271-72 (1951); see also,
e.g., Armstrong v. D.C. Pub. Library, 154 F. Supp. 2d 67, 81-
82 (D.D.C. 2001) (striking for vagueness a regulation
prohibiting “objectionable” appearance in a library). The
District of Columbia’s criteria for defining an “event-related”
lamppost sign, in contrast, adequately specify that the post-
event time limitation applies to signs announcing an event or
series of events of the type that occur at a specified time and
place.

      MASF sees impermissible leeway in section 108.13’s
explicit recognition of the enforcement officer’s authority to
refer to “all circumstances” to determine whether a poster is
event related. See D.C. MUN. REGS. tit. 24, § 108.13. In
particular, section 108.13 directs enforcement officers to
consider not only the poster itself, but to use their common
sense and background knowledge to determine whether, in
context, a poster in fact relates to “an occurrence, happening,
activity or series of activities, specific to an identifiable time
and place.” Thus, the event-relatedness of even a terse sign
announcing a renowned local athletic event, a seasonal charity
event, or a candidate for election could be determined to be
event related in part based on circumstances apart from the
poster itself. Nothing about such an inquiry renders the law
vague.      To the extent enforcement agents draw on
surrounding circumstances to unreasonably infer that a sign is
event related in accordance with the District’s rule, the event-
relatedness restriction would not apply. See D.C. MUN. REGS.
tit. 24, § 108.13. So long as their inferences are reasonable,
however, the rule’s open-endedness about the evidence that
may be used to meet that standard does not convert its
otherwise clear limitation into an impermissibly vague one.

    MASF highlights deposition testimony from the
District’s inspectors that, it argues, shows the unconstrained
                             33
discretion section 108.13 affords the police inspectors.
Inspectors confirmed that they had some leeway to assess
event-relatedness, see ANSWER IV, 905 F. Supp. 2d at 347 &
n.10, and were not unanimous as to whether a 2012 poster
stating simply “GRAHAM!” pertained to the reelection
campaign of City Council member Jim Graham and so was
event-related. MASF also highlights testimony of Inspectors
who had difficulty deciding the time limitation applicable to
posters listing multiple events with different dates. But the
most that evidence shows is that section 108.13 might be
misapplied in certain cases. It does not show that section
108.13 lacks criteria to cabin enforcement discretion.

     As the Supreme Court explained in the analogous context
of a facial First Amendment challenge to a licensing scheme,
“the success of a facial challenge on the grounds that an
ordinance delegates overly broad discretion to the
decisionmaker rests not on whether the administrator has
exercised his discretion [unlawfully], but whether there is
anything in the ordinance preventing him from doing so.”
Forsyth Cty, 505 U.S. at 133 n.10. The District’s regulation
guards against the unlawful exercise of discretion by
delimiting what qualifies as an event: “an occurrence,
happening, activity or series of activities, specific to an
identifiable time and place.” D.C. MUN. REGS. tit. 24,
§ 108.13.      Ostensible vagueness about “whether the
incriminating fact . . . has been proved” is not vagueness at
all. Williams, 553 U.S. at 306. We accordingly hold that
section 108.13 is not void for vagueness.

    D. The District Court Correctly Dismissed the
       Organizations’ Other Claims

    We next consider the organizations’ cross-appeal. They
appeal from the district court’s 2011 dismissal of ANSWER’s
                               34
claim that the District retaliated against it in violation of the
First Amendment by citing as violations posters that were
lawful under the regulation. ANSWER III, 798 F. Supp. 2d at
153-55. They also appeal the court’s dismissal of MASF’s
claim that the District’s regulation imposes a system of “strict
liability” in violation of the First Amendment. Id. at 152-53.
We review de novo the district court’s decision under Rule
12(b)(6) to dismiss those claims, see English v. District of
Columbia, 717 F.3d 968, 971 (D.C. Cir. 2013), and we affirm.

     1. ANSWER Fails to State a § 1983 Claim. In its
complaint, ANSWER alleged that the District’s issuance of
ninety-nine notices of violation against it had been “in bad
faith and for the purpose of harassment.” Supplemental
Complaint ¶¶ 42-43, ANSWER III, 798 F. Supp. 2d 134 (No.
07-1495). The district court found that ANSWER had
plausibly pled a constitutional violation, but dismissed the
complaint for failure to allege that a custom or policy of the
District had caused that violation. ANSWER III, 798 F. Supp.
2d at 154-55.

      Section 1983 “give[s] a remedy to parties deprived of
constitutional rights, privileges and immunities by an
official’s abuse of his position.” Monroe v. Pape, 365 U.S.
167, 172 (1961) overruled on other grounds by Monell v.
Dep’t of Soc. Servs. of City of New York, 436 U.S. 658 (1978).
Both states and cities can be sued under section 1983, Monell,
436 U.S. at 663, 690, and for that purpose the District of
Columbia is treated as a city, Jones v. Horne, 634 F.3d 588,
600 (D.C. Cir. 2011). The District may be liable under
section 1983, but only to the extent permitted under Monell—
i.e., only based on action that “implements or executes a
policy statement, ordinance, regulation, or decision officially
adopted and promulgated by that body’s officers” or for harm
“visited pursuant to governmental ‘custom’ even though such
                              35
custom has not received formal approval.” Monell, 436 U.S.
at 690-91. Under Monell, “a municipality cannot be held
liable solely because it employs a tortfeasor—or, in other
words, a municipality cannot be held liable under § 1983 on a
respondeat superior theory.” Id. at 691. The “touchstone of”
a section 1983 claim against a municipality is that “official
policy is responsible for a deprivation of rights protected by
the Constitution.” Id. at 690. That is, the alleged policy or
custom must have “caused the violation.” Warren v. District
of Columbia, 353 F.3d 36, 38 (D.C. Cir. 2004).

      ANSWER has not alleged that a custom or policy lay
behind the notices of violation the District issued to it. On
appeal, ANSWER argues that “the 99 enforcement actions
were sufficiently pervasive and numerous to constitute a
custom.” Organizations’ Br. 67. A section 1983 plaintiff
may establish causation in several ways, but ANSWER has
not contended that any District custom or policy was “the
moving force of the constitutional violation.” Jones, 634 F.3d
at 601. Nor has ANSWER sought to show causation based on
a failure to train or “deliberate indifference.” See Baker v.
District of Columbia, 326 F.3d 1302, 1306 (D.C. Cir. 2003).
It makes no case that a policymaker knowingly ignored the
alleged pattern of retaliatory enforcement. See Jones, 634
F.3d at 601. ANSWER does not even identify by name or
title any policy maker who knew of the enforcement actions
the District took against it. The closest ANSWER comes to
claiming a role for a policymaking official is its discussion of
the District’s Department of Public Works’ General Counsel’s
voluntary dismissal of the enforcement actions against
ANSWER.         But at most that shows a policymaker’s
involvement      in    curbing    allegedly    unconstitutional
enforcement.
                               36
      The district court was correct, then, to dismiss
ANSWER’s claims because the organization “never
coherently allege[d] the existence of a broader municipal
custom or practice that explains the issuance of those tickets”
citing ANSWER for violating the sign posting rule. ANSWER
III, 798 F. Supp. 2d at 154.

     2. The Regulation Does Not Impose “Strict Liability.”
MASF contends that the District’s regulation imposes a “strict
liability” regime in violation of the First Amendment. Strict
liability in criminal statutes burdening speech is “generally
disfavored.” United States v. Sheehan, 512 F.3d 621, 629
(D.C. Cir. 2008). But we need not decide whether the
imposition of civil fines on a strict-liability basis would be
constitutional here because, as we construe the regulation, it
does not impose strict liability.

     Section 108.1 says, “No person shall affix a sign,
advertisement, or poster to any public lamppost or
appurtenances of a lamppost, except as provided in
accordance with this section.” D.C. MUN. REGS. tit. 24,
§ 108.1. MASF asserts in its complaint that the District
“imposes strict liability for violation of these regulations upon
persons or groups whose name or address is identified in a
poster even if the person/group did not produce the poster.”
First Am. Compl. ¶ 25, ANSWER I, 570 F. Supp. 2d 72
(No. 07-1495); see id. ¶¶ 25-32. By “strict liability,” MASF
seems to mean something closer to “vicarious liability”—that
is, holding one party liable for the actions of another. See
generally Liability, Black’s Law Dictionary (10th ed. 2014).

     Section 108.1 by its terms provides that no person may
“affix” an offending sign to a lamppost. On its face,
therefore, section 108.1 does not impose liability on anyone
other than the person who “affixes” the sign to the lamppost.
                              37
The District in defending the rule assures us that it makes “a
person liable only if that person is responsible for the
unlawfully posted sign because, for example, he or she
directed or encouraged the posting or his or her employee or
agent posted it.” Gov’t Reply Br. at 39.

    MASF invokes Schneider v. New Jersey, 308 U.S. 147
(1939), in which the Supreme Court held that a municipal
ordinance imposing liability on the distributors of pamphlets
for the litter left by the recipients of the pamphlets was
unnecessarily burdensome on the speech rights of the
pamphleteers. Id. at 162. The Schneider Court held that
imposing liability on the distributor of the pamphlets could
not be justified by the cities’ interest in preventing litter
because the cities had an obvious alternative method to
prevent litter: They could impose liability on “those who
actually throw papers on the streets.” Id.

     But MASF gives us no reason to think that an
organization would be held liable under section 108.1 if it did
not “affix” a sign, but rather had its sign affixed by someone
else acting without its authority who then failed timely to
remove it. Nor has MASF raised a material question of fact
as to whether the District has enforced the regulation to
impose the type of strict or vicarious liability of which the
Schneider Court disapproved. In light of the District of
Columbia’s binding assurances and the lack of record
evidence to the contrary, we do not read section 108.1 to
impose strict or vicarious liability, and so affirm the district
court’s decision to dismiss MASF’s strict-liability claim.

    E. Discovery Sanctions are Vacated

    Finally, we address the discovery sanctions the district
court imposed against the District of Columbia under Federal
Rule of Civil Procedure 16(f). We review the district court’s
                              38
award of sanctions for an abuse of discretion, see Perkinson v.
Gilbert/Robinson, Inc., 821 F.2d 686, 689 (D.C. Cir. 1987),
and vacate it.

     Rule 16(f)(2) gives courts a tool to enforce compliance
with its scheduling orders. That rule directs that a court,
“[i]nstead of or in addition to any other sanction, . . . must
order the party, its attorney, or both to pay the reasonable
expenses—including attorney’s fees—incurred because of
any noncompliance with this rule, unless the noncompliance
was substantially justified or other circumstances make an
award of expenses unjust.” Fed. R. Civ. P. 16(f)(2). But a
court may award sanctions under Rule 16(f) only where a
party violates an unambiguous order. See Ashlodge, Ltd. v.
Hauser, 163 F.3d 681, 684 (2d Cir. 1998), overruled on other
grounds, as stated in New Pac. Overseas Grp. (U.S.A.) Inc. v.
Excal Int’l Dev. Corp., 272 F.3d 667, 669 (2d Cir. 2001) (“To
sustain sanctions under Rule 16(f), an order must be
unambiguous . . . .”); cf. United States v. Day, 524 F.3d 1361,
1372 (D.C. Cir. 2008). The order that the District allegedly
violated here was ambiguous.

     The court’s scheduling order authorized MASF to take
discovery but was silent as to the District. Before the court
issued the order, the District and MASF had submitted a joint
status report. The joint report explained that the District
believed discovery was “unnecessary here, as the remaining
facial vagueness challenge presents a purely legal question.”
J.A. at 97. MASF, however, proposed that the court allow it
to propound ten interrogatories, ten requests for production,
fifteen requests for admission, and allow it to take six
depositions. In response to MASF’s suggestion, the District
suggested the court allow MASF ten interrogatories, five
requests for production, and one deposition. Neither party
                               39
addressed the scope of District’s anticipated discovery in the
event that the court imposed discovery constraints on MASF.

     MASF and the District each submitted a proposed
scheduling order: The District’s order contemplated that
“each party may not propound more than ten (10)
interrogatories (including sub-parts) and five (5) requests for
production of documents, and may not take more than one (1)
deposition.” J.A. at 103. That is, the District’s proposed
order tracked the limited discovery it had suggested in the
Joint Status Report, contemplating that the limits would apply
equally to both parties. MASF’s proposed order suggested
less restrictive limits on its own discovery, and did not specify
whether or to what extent the District’s discovery would be
restricted. With some stylistic modifications, the court
adopted MASF’s proposed order, stating that “plaintiff is
authorized to propound not more than” the specified numbers
of interrogatories, requests for production, requests for
admission, and deposition notices; the order made no mention
of any discovery restriction on the District of Columbia.

     The District sent eleven interrogatories and three requests
for production to MASF and ANSWER. After plaintiffs’
counsel objected, the District withdrew six of its
interrogatories but insisted on its right to conduct discovery.
MASF then moved for a protective order and sanctions. The
court granted the motion.

    We acknowledge the district courts’ prerogative to
sanction parties for noncompliance with their orders, but we
must vacate the sanctions here because the underlying order
was ambiguous as to whether it limited the District’s
discovery rights. It expressly lowered the default caps in the
Federal Rules of Civil Procedure only as to the plaintiffs. The
order referred more generally to the earliest date on which
                                40
“discovery requests may be served” and when “the parties”
should file their dispositive motions. J.A. at 105. In context,
the order could reasonably be read (a) to leave the District’s
discovery rights as specified in the Federal Rules, (b) to
implicitly subject it to the same lower caps the court applied
to plaintiffs, or (c) to permit limited discovery to the plaintiffs
while by negative implication barring any discovery
whatsoever by the District.

     In the context of the dueling proposed orders—one
equally limiting both parties and the other, which the court
accepted, speaking only to plaintiffs—the court’s order could
reasonably be read to constrain only the plaintiffs. Such one-
sided treatment seems sensible enough given that the District,
which as defendant did not bear the burden of proof, was
unlikely to need extensive discovery in any event. That same
reasoning might, alternatively, support reading the order as
setting limits equally applicable to both parties, given that the
District had urged the court to proceed without any discovery
and presumably was willing to work within any constraints it
could persuade the court to impose. Alternatively, framed as
it was affirmatively to “authorize” the plaintiffs, and only
plaintiffs, to take the specified discovery, and issuing against
the backdrop of the District’s initial argument against any
discovery for either party, the order might be read—as the
court evidently intended—to preclude the District from taking
any discovery.

    There are, however, strong background principles that cut
against the district court’s intended reading. Under Rule 26, a
party may take discovery “regarding any nonprivileged matter
that is relevant to any party’s claim or defense and
proportional to the needs of the case.” Fed. R. Civ. P.
26(b)(1). Critically, a party has that prerogative without the
order of a court. A court order may “otherwise limit[]” a
                              41
party’s discovery right, but a court’s affirmative permission is
not a prerequisite to the taking of discovery. Id. Given the
general discovery authorizations in the Federal Rules of Civil
Procedure, which are not contingent on court orders granting
permission, the district court’s scheduling order was
ambiguous. Sanctions for the District’s service of discovery
requests were therefore unwarranted, and are vacated.

                             ***

    For the foregoing reasons, we reverse the district court’s
grant of summary judgment to MASF on its facial First
Amendment and due process challenges to the District of
Columbia’s regulation and remand for the district court to
enter summary judgment for the District. We affirm the
court’s decision to dismiss ANSWER’s claim for damages
and MASF’s claim alleging an impermissible strict liability
regime. Finally, we vacate the court’s award of sanctions.

                                                    So ordered.
