                   FOR PUBLICATION
  UNITED STATES COURT OF APPEALS
       FOR THE NINTH CIRCUIT

LAWRENCE ROSENBAUM; ERIC                 
LIVINGSTON,
                Plaintiffs-Appellants,
                  v.
CITY AND COUNTY OF SAN
FRANCISCO; FRED LAU, in his
official capacity as Chief of the              No. 05-15266
San Francisco Police Dept.; JOEL
ROBINSON, in his official capacity              D.C. No.
                                             CV-96-03409-MMC
as Superintendent of the
                                                 OPINION
Recreation and Parks Dept., City
and County of San Francisco;
ANTHONY DELUCCHI, in his official
capacity as Director of Property,
Real Estate Dept., City and
County of San Francisco,
              Defendants-Appellees.
                                         
       Appeal from the United States District Court
          for the Northern District of California
       Maxine M. Chesney, District Judge, Presiding

                 Argued and Submitted
       December 7, 2006—San Francisco, California

                     Filed April 30, 2007

     Before: Thomas G. Nelson, Ronald M. Gould, and
          Consuelo M. Callahan, Circuit Judges.

                   Opinion by Judge Gould


                              4687
4692   ROSENBAUM v. CITY AND COUNTY OF SAN FRANCISCO


                         COUNSEL

Russell Davis, San Francisco, California; and Frederick H.
Nelson, American Liberties Institute, Orlando, Florida, for the
plaintiffs-appellants.

Dennis J. Herrera, City Attorney; Molly Stump, Chief Attor-
ney, Public Protection Unit; and Margaret W. Baumgartner,
Deputy City Attorney, for defendant-appellee City of San
Francisco.


                         OPINION

GOULD, Circuit Judge:

  We here consider the free speech rights of Christian evan-
gelists who operate religious outreach with the use of ampli-
       ROSENBAUM v. CITY AND COUNTY OF SAN FRANCISCO        4693
fied sound in the streets of San Francisco, and whose efforts
have collided with the City of San Francisco’s prerogative
under its noise ordinance and permitting scheme to ensure
that its citizens are not subject to unreasonably loud speech
and music. Plaintiffs-Appellants Lawrence Rosenbaum and
Eric Livingston filed suit in the Northern District of Califor-
nia alleging constitutional claims under the First and Four-
teenth Amendments that arose out of appellee City of San
Francisco’s permitting process and noise ordinance enforce-
ment, which the district court denied after a bench trial. We
have jurisdiction under 28 U.S.C. § 1291.

   On appeal, appellants claim that San Francisco police offi-
cers unevenly enforced the municipal noise ordinance, in vio-
lation of equal protection, by frequently stopping or
conditioning appellants’ use of amplified sound while leaving
other groups’ and individuals’ loudspeaker use unmolested.
Appellants also contend that city officials engaged in view-
point discrimination. In particular, appellants claim that city
officials implemented a “heckler’s veto” by responding to
complaints by citizens who were hostile to appellants’ Chris-
tian message. Appellants lodge a second viewpoint discrimi-
nation claim that issuance of permits and enforcement were
marred by unbridled discretion, and that city police stopped
giving permits to appellants for amplified sound activities
relying on noise abatement as a pretext to mask viewpoint dis-
crimination. As a third viewpoint discrimination claim, appel-
lants assert that city police cited appellants for disturbing the
peace without probable cause because of disagreement with
the subject-matter of appellants’ speech. Appellants also
claim that city officials improperly denied sound permits due
to prior restraint where applications were rejected based on
appellants’ past non-compliance with permit conditions and
past violations of the noise ordinance. Finally, appellants
argue that the district court erred in not granting relief under
the California Constitution’s broader protections of free
speech. We affirm the district court.
4694     ROSENBAUM v. CITY AND COUNTY OF SAN FRANCISCO
                                     I

   Appellants are Christian evangelists who are staff members
of American Christian Enterprises, a non-profit charity orga-
nization. Appellant Rosenbaum operates a ministry affiliated
with the “SOS Ministries” in San Francisco, which conducts
religious outreach. Since 1978, appellants have preached a
Christian evangelical message in the streets and parks of San
Francisco with amplified sound.

   Appellee City of San Francisco (“the City”) has adopted
under section 47.2 of the San Francisco Police Code (“Police
Code”) a time, place, and manner restriction that provides,
inter alia, that “[a]mplified speech and music shall not be
unreasonably loud, raucous, jarring or disturbing to persons of
normal sensitiveness.” See S.F.P.C. § 47.2(5). However, indi-
viduals or groups seeking to use amplified sound that might
exceed volume levels prohibited under § 47.2 may apply for
permits under § 43 of the Police Code. Under § 43, the police
commissioner1 has discretion to issue permits for amplified
sound for a variety of purposes including public affairs inter-
ests. Applicants must designate the time, location and purpose
of the permit, see § 43(c), and are subject to conditions under
S.F.P.C. §§ 47.2 and 49.2 Denied permits may be contested
before the head of the Permit Section where public comment
can be considered, or in an administrative proceeding. Police
investigations of excessive noise, due to unpermitted amplifi-
cation, amplification contrary to permit restrictions or volume
  1
    After the time of the relevant conduct in this appeal, the official body
within the City that adjudicates challenges to denied permits has been re-
designated as the “Entertainment Commission.” See S.F.P.C. § 43.
  2
    Of concern here is subsection 47.2(7), which provides that amplified
sound may be halted if it is audible beyond 250 feet of the attendant audi-
ence. See S.F.P.C. § 47.2(7). Also, section 49 generally prohibits “amplifi-
cation of sound or human voice in such a manner as to produce raucous
noises or . . . disturb the peace, quiet and comfort of persons in the neigh-
borhood or with volume louder than . . . necessary for convenient hear-
ing.” S.F.P.C. § 49.
       ROSENBAUM v. CITY AND COUNTY OF SAN FRANCISCO        4695
of amplification, are typically initiated after a citizen com-
plaint. San Francisco police officers may inquire about unac-
ceptably loud noise, issue citations and/or arrest the speaker/
performer if they have probable cause under section 415 of
the California Penal Code that a user of sound amplification
intends to “maliciously and willfully” create “loud and unrea-
sonable noise.” See Cal. Pen. Code § 415.

   For almost three decades, Rosenbaum and Livingston have
requested and from time to time received numerous permits
from the City for sound amplification to conduct their out-
reach. Beginning in late 1995, however, many of appellants’
permit applications were denied or issued with significant
restrictions for specific events. In addition, appellants began
to encounter increasing attention from the San Francisco
police who, in response to citizen complaints on specified
occasions, admonished, cited or arrested appellants, or threat-
ened such sanctions, for not having a necessary permit for
their amplified sound, for not complying with the limitations
on their permit, or for using excessively loud amplification.

   On September 19, 1996, appellants filed suit in the United
States District Court for the Northern District of California
against the City and County of San Francisco and three city
officials in their official capacity (collectively “the City”),
seeking injunctive and declaratory relief. Appellants asserted
eight claims based on events alleged to have occurred
between May 28, 1990 and August 9, 1996: (1) “Enjoinment
of San Francisco Police Code § 47.2 on grounds of vagueness
and overbreadth”; (2) “Enjoinment of Police Code § 47.2 and
Penal Code § 415 and unlawful permitting procedures on
equal protection grounds”; (3) “Enjoinment of enforcement of
the ‘heckler’s veto’ against plaintiffs”; (4) “Enjoinment of the
denial of government permits because said denial is a prior
restraint on the free speech rights of the plaintiffs”; (5) “For
violation of Title 42 U.S.C. Section 1983”; (6) “For civil con-
spiracy and for conspiracy to interfere with civil rights in vio-
lation of 42 U.S.C. section 1985”; (7) “Violation of the
4696   ROSENBAUM v. CITY AND COUNTY OF SAN FRANCISCO
Religious Freedom Restoration Act”; and (8) “Pendent State
Claim for violation of California Constitution Article I, sec-
tions 1, 2 and 4.” Thereafter, appellants moved for a prelimi-
nary injunction to prohibit the City from enforcing § 47.2 of
the Police Code and § 415 of the California Penal Code. On
November 8, 1996, the district court denied the preliminary
injunction, which we upheld on March 26, 1997. See Rosen-
baum v. City & County of San Francisco, 110 F.3d 69 (9th
Cir. 1997) (“Rosenbaum I”) (unpublished opinion).

   In January 1998, the City filed the first of two summary
judgment motions. On June 15, 1998, the district court
granted partial summary judgment in favor of the City on
appellants’ First, Sixth and Seventh claims, concluding that
the amplification restrictions under § 47.2 were facially con-
stitutional. Appellants did not appeal these rulings. On August
30, 1999, the district court granted the City’s motion for sum-
mary judgment on the balance of appellants’ claims. On April
19, 2001, we reversed, holding that genuine issues of material
fact remained regarding appellants’ equal protection and First
Amendment claims. See Rosenbaum v. City & County of San
Francisco, 8 Fed. Appx. 687 (9th Cir. 2001) (“Rosenbaum
II”) (unpublished opinion). In reaching this decision with
respect to the equal protection claims, we relied on facts not
alleged in the complaint, namely allegations that “small
groups were allowed to engage in amplified speech activities
in the same locations for which plaintiffs were denied permits,
and that other small groups were violating the noise ordi-
nances in the same manner as plaintiffs but were not cited or
arrested.” Id. at 691. As examples of this alleged conduct, we
referred to incidents that post-dated the filing of the complaint
to support our conclusion that “at the summary judgment
stage, this as well as other evidence in the record . . . suffices
to raise a genuine issue of material fact as to whether there
was a ‘policy, plan, or a pervasive pattern’ of misconduct.” Id.
at 690.

  On November 6, 2001, appellants moved to amend their
complaint to substitute defendants and to assert a claim for
       ROSENBAUM v. CITY AND COUNTY OF SAN FRANCISCO        4697
damages by Livingston involving similar circumstances.
Aside from granting the substitution of defendants, the district
court denied the motion to amend because an additional dam-
ages claim under new factual allegations was unduly delayed
and would have prejudiced the City.

   At a bench trial in December of 2002, based on the parties’
stipulation the district court determined at the outset that the
following claims remained: (1) an equal protection claim
based on the manner in which the City issued permits and
enforced permit requirements for amplified sound; (2) a First
Amendment claim based on viewpoint discrimination (or
“heckler’s veto”) in the City’s issuance of permits and
enforcement of permit requirements; (3) a First Amendment
claim of prior restraint in the alleged denial of permits based
on appellants’ past non-compliance with loudspeaker permit
restrictions; (4) a First Amendment claim based on the City’s
application of California Penal Code § 415; (5) a claim under
42 U.S.C. § 1983 based on the above-described alleged con-
stitutional violations; and (6) a claim under article I, sections
1, 2 and 4 of the California Constitution, also based on viola-
tions of rights to free speech and religion.

   Before the district court issued its disposition, appellants
moved on April 27, 2004 under Federal Rule of Civil Proce-
dure 15(b) (“Rule 15”) to expand their claims to encompass
events occurring after the filing of their complaint, which the
City opposed. In post-trial motions, appellants also sought to
introduce additional incidents that allegedly occurred as late
as November 8, 2002. Thus, appellants contended that the
actionable conduct began as early as May 28, 1990 and con-
tinued through November 8, 2002.

   The district court issued a Memorandum of Decision on
January 12, 2005. As a threshold issue, the district court con-
sidered the issue raised in appellants’ Rule 15 motion whether
numerous incidents alleged to have occurred between appel-
lants and the San Francisco police after the August 9, 1996
4698   ROSENBAUM v. CITY AND COUNTY OF SAN FRANCISCO
filing of the complaint could be included within the scope of
actionable conduct. In particular, appellants had previously
alleged in a declaration filed in opposition to the City’s
motion for summary judgment that, beginning on October 11,
1996 and ending on October 31, 1998, they endured addi-
tional encounters with the police that resulted in the police
“shutting down” appellants’ use of unpermitted amplified
sound, while the police allegedly acquiesced in other
instances of unpermitted or excessively loud sound amplifica-
tion by similarly situated loudspeaker users, i.e. small musical
groups and individual performers in addition to promoters of
larger events.

   The district court first narrowed the scope of actionable
conduct under the statute of limitations. The district court
determined that the appropriate statute of limitations period
for claims under 42 U.S.C. § 1983 and the California Consti-
tution was one year because this period paralleled the limita-
tions period for personal injury suits in California at the time
of relevant conduct under section 340(3) of the California
Code of Civil Procedure. See Wilson v. Garcia, 471 U.S. 261,
275-76 (1985) (holding state statute of limitations period for
personal injury suit applies to constitutional claims under
§ 1983). Under this authority, the district court determined
that claims based on events prior to September 19, 1995 were
time-barred.

   As for post-complaint events, the district court first
observed that in appellants’ November 2001 motion to amend
the complaint, appellants made no effort to supplement the
complaint for the purpose of alleging expanded claims based
on incidents alleged to have occurred after the filing of the
complaint, and that they waited to move expressly to add fac-
tual allegations to encompass post-complaint events until
April 27, 2004. The district court held that under Rule 15 the
City had neither expressly, nor impliedly, consented to such
an expansion of claims based on post-complaint factual alle-
gations. In light of our decision in Rosenbaum II, however,
         ROSENBAUM v. CITY AND COUNTY OF SAN FRANCISCO                  4699
where we held genuine issues of material fact existed as to
appellants’ constitutional claims in part in reliance on facts
alleged after the complaint was filed, the district court
declined to speculate whether we had decided which events fit
within the scope of conduct under the complaint. Leaving the
question unanswered, the district court addressed appellants’
claims first based solely on alleged conduct between Septem-
ber 19, 1995 and August 9, 1996, and in the alternative, based
on alleged post-complaint conduct included in appellants’
opposition to the City’s motion for summary judgment that
we considered in Rosenbaum II. In any event, the district
court considered evidence of all incidents, irrespective of date
of occurrence, to the extent it bore on any alleged pattern or
policy of police misconduct.

   Under both the narrow and the expanded scope of conduct
as described above, the district court rejected all appellants’
claims. This timely appeal followed.

                                     II

  We first address what conduct may be considered action-
able under the complaint. The City seeks to limit the scope of
actionable conduct to events that transpired between Septem-
ber 1995 and September 1996 based on the district court’s rul-
ings on the statute of limitations and the denial of appellants’
motion on April 27, 2004 under Rule 15(b).3 In their reply
  3
    The City argues first that we should not pass on this question because
appellants waived these issues by not challenging either the statute of limi-
tations ruling or the Rule 15(b) ruling in their opening appellate brief.
“[W]e will not ordinarily consider matters on appeal that are not specifi-
cally and distinctly argued in appellant’s opening brief” unless one of
three exceptions applies: (1) “for good cause shown,” (2) when the issue
“is raised in the appellee’s brief,” or (3) “if the failure to raise the issue
properly did not prejudice the defense of the opposing party.” See Koerner
v. Grigas, 328 F.3d 1039, 1048-49 (9th Cir. 2003) (internal quotation
marks and citation omitted). Here, although the appellants initially did not
contest the district court’s rulings on these matters, the City raised the
scope of conduct issue in its brief and the appellants responded in their
reply brief. Accordingly, we exercise discretion to address the issue.
4700   ROSENBAUM v. CITY AND COUNTY OF SAN FRANCISCO
brief, appellants contend that the district court erred in deny-
ing the April 27, 2004 motion and limiting the scope of
actionable conduct to events that occurred before the filing of
the complaint because we considered post-complaint events in
Rosenbaum II.

   We review the district court’s order denying a Rule 15(b)
motion to amend the complaint to conform the pleadings to
the evidence for an abuse of discretion. See Madeja v. Olym-
pic Packers, LLC, 310 F.3d 628, 635 (9th Cir. 2002).

  Rule 15(b) provides in pertinent part:

    When issues not raised by the pleadings are tried by
    express or implied consent of the parties, they shall
    be treated in all respects as if they had been raised
    in the pleadings. Such amendment of the pleadings
    as may be necessary to cause them to conform to the
    evidence and to raise these issues may be made upon
    motion of any party at any time, even after judg-
    ment; but failure so to amend does not affect the
    result of the trial of these issues.

See Fed. R. Civ. P. 15(b); see also Idaho Plumbers and Pipe-
fitters Health and Welfare Fund v. Mechanical Contractors,
Inc., 875 F.2d 212, 214-15 (9th Cir. 1989) (“We treat issues
tried by the express or implied consent of the parties as raised
in the pleadings, even if the parties made no formal amend-
ment.”).

   In Patelco Credit Union v. Sahni, we rejected the argument
that certain evidence adduced at trial without objection effec-
tively amended the defendant’s answer to include a statute of
limitations defense. 262 F.3d 897, 907 (9th Cir. 2001). “While
it is true that a party’s failure to object to evidence regarding
an unpleaded issue may be evidence of implied consent to a
trial of the issue, it must appear that the party understood the
evidence was introduced to prove the unpleaded issue.” Id.
        ROSENBAUM v. CITY AND COUNTY OF SAN FRANCISCO              4701
(internal quotation marks omitted); see also Consol. Data
Terminals v. Applied Digital Data Sys., Inc., 708 F.2d 385,
396 (9th Cir. 1983) (“An adverse party cannot be expected to
object to the introduction of evidence that is only tangentially
related to the issues actually pleaded prior to trial unless the
party has notice that the evidence is being introduced as proof
on some other unpleaded issue.”).

   [1] Here, the district court did not abuse its discretion in
concluding that the City had not impliedly consented to try
appellants’ claims based on post-complaint conduct simply
because the City referred to events in 1997 and 1998 in
responding to appellants’ opposition to summary judgment.
As the district court correctly found, the thrust of the City’s
motion for summary judgment pertained to its argument that
Livingston and Rosenbaum lacked standing to assert claims
for injunctive relief because they could not demonstrate a
threat of future harm where “over a three year period, plain-
tiffs obtained loudspeaker permits for at least seventy-eight
events; during 1998 alone, plaintiff received permits for
twenty-five events.” See Def. Mot. for Summ. J., Nov. 16,
1998, at 11. To the extent appellants referenced post-
complaint events in their opposition to summary judgment,
the district court concluded that such additional factual allega-
tions “reasonably would have been understood . . . to be in
response to the City’s argument.” Also, the City objected at
trial to any evidence referring to post-complaint events as
irrelevant, and the district court permitted the evidence only
for the limited purpose of showing a pattern or practice of dis-
crimination required for injunctive relief. The district court
did not abuse its discretion under Patelco Credit because
there was no indication that appellants introduced the numer-
ous post-complaint events for any purpose other than to refute
the City’s claim of insufficient threat of future harm in light
of its assertion that permits had been issued to appellants dur-
ing 1998.4
  4
   Our decision in Rosenbaum II viewed in context reinforces the district
court’s conclusion. When we referred to Livingston’s arrest on February
4702     ROSENBAUM v. CITY AND COUNTY OF SAN FRANCISCO
   [2] Because appellants do not explicitly contest the district
court’s proper statute of limitations ruling, the scope of
actionable conduct begins with events that occurred as of Sep-
tember 1995. Because the district court did not abuse its dis-
cretion in narrowing the scope of actionable conduct to events
alleged in the complaint, we do not consider events after Sep-
tember 19, 1996, except as relevant to any alleged policy or
pattern of police misconduct that would warrant injunctive
relief.

                                    III

   We review constitutional issues de novo. See Buono v. Nor-
ton, 371 F.3d 543, 548 (9th Cir. 2004). A district court’s
determinations on mixed questions of law and fact that impli-
cate constitutional issues are similarly reviewed de novo.
Cogswell v. City of Seattle, 347 F.3d 809, 813 (9th Cir. 2003).
Where, however, the application of the law to the facts
requires an inquiry that is “essentially factual,” we review for
clear error, see Zivkovic v. S. Cal. Edison Co., 302 F.3d 1080,
1088 (9th Cir. 2002), with exception of issues arising under
the First Amendment, where we conduct an independent
review of the facts. See Tucker v. California Dep’t of Educ.,
97 F.3d 1204, 1209 n.2 (9th Cir. 1996).

                                    IV

  In their equal protection challenge under the Fourteenth
Amendment, Rosenbaum and Livingston assert: (1) that they
were denied permits where similarly situated applicants

22, 1997, and to several permit denials between March 14, 1997 and Sep-
tember 16, 1997, we did so to support our conclusion that the district court
erroneously granted summary judgment where these alleged post-
complaint events created genuine issues of material fact in regard to the
issue whether the City exhibited a policy or pervasive pattern of improper
selective enforcement that might warrant injunctive relief. See Rosenbaum
II, 8 Fed. Appx. at 690.
         ROSENBAUM v. CITY AND COUNTY OF SAN FRANCISCO                4703
received permits; (2) that, irrespective of whether they
received a permit for sound amplification, the City police
“shut down” their amplified speech whereas other similarly
situated groups (mainly street musicians), permitted or not,
were left unmolested to engage in sound amplification.

   A government entity has discretion in prosecuting its crimi-
nal laws, but enforcement is subject to constitutional con-
straints. See Wayte v. United States, 470 U.S. 598, 608 (1985).5
To prevail on its claim under the equal protection clause of
the Fourteenth Amendment, a plaintiff must demonstrate that
enforcement had a discriminatory effect and the police were
motivated by a discriminatory purpose. Id. at 608. “To estab-
lish a discriminatory effect . . . , the claimant must show that
similarly situated individuals . . . were not prosecuted.”
United States v. Armstrong, 517 U.S. 456, 465 (1996). To
show discriminatory purpose, a plaintiff must establish that
“the decision-maker . . . selected or reaffirmed a particular
course of action at least in part ‘because of,’ not merely ‘in
spite of,’ its adverse effects upon an identifiable group.”
Wayte, 470 U.S. at 610 (internal citation omitted).

   In addition to the showing of discriminatory purpose and
effect, plaintiffs seeking to enjoin alleged selective enforce-
ment must demonstrate the police misconduct is part of a
“policy, plan, or a pervasive pattern.” See Thomas v. County
of Los Angeles, 978 F.2d 504, 509 (9th Cir. 1993); see also
id. at 508 (“A state law enforcement agency may be enjoined
from committing constitutional violations where there is proof
that officers within the agency have engaged in a persistent
  5
    In the seminal case Yick Wo v. Hopkins, 118 U.S. 356, 374 (1886), the
Supreme Court considered an equal protection claim by Chinese nationals
who operated laundry businesses in San Francisco that met with all public
health requirements, yet the Chinese nationals were still found to have vio-
lated city ordinances and fined. The Supreme Court held that no reason for
this discrimination existed except hostility to the petitioners’ race and
nationality, which violated the Fourteenth Amendment’s guarantee of
equal protection under the law. Id.
4704   ROSENBAUM v. CITY AND COUNTY OF SAN FRANCISCO
pattern of misconduct.”); Easyriders Freedom F.I.G.H.T. v.
Hannigan, 92 F.3d 1486, 1500 (9th Cir. 1996) (requiring
plaintiffs to establish more than repeated incidents of miscon-
duct). Notwithstanding the availability of injunctive relief,
declaratory relief may be appropriate where a plaintiff making
a facial or as-applied constitutional attack “demonstrates a
genuine threat of enforcement of a disputed state criminal
statute.” Steffel v. Thompson, 415 U.S. 452, 475 (1974).

                                A

   As for appellants’ argument urging that there was selective
issuance of permits, appellants alleged in their complaint the
following instances within the statute of limitations period
where they were either denied a permit or issued a permit
with restrictions: (1) In February 1996, the City granted two
permits for the intersection of Fifth and Market Streets, with
the restriction that the speaker be turned away from Market
Street; and in March 1996, the City denied Livingston four
permit applications for the same intersection. (2) On April 26,
1996, appellants were denied three permits requested for May
4, 11 and 25, 1996 at the corner of Fifth and Market Streets
and a resubmitted request for 989 Market Street. (3) On July
1, 1996, appellants received permits for July 20 and August
17, 1996 at 835 Market Street, with the limitation that appel-
lants could not use more than two loudspeakers of no more
than 50-watt capacity each.

   [3] “The first step in equal protection analysis is to identify
the [city’s] classification of groups. . . . Once the plaintiff
establishes governmental classification, it is necessary to
identify a ‘similarly situated’ class against which the plain-
tiff’s class can be compared.” Freeman v. City of Santa Ana,
68 F.3d 1180, 1187 (9th Cir. 1995) (internal quotation marks
omitted). Appellants argue that the district court erroneously
rejected appellants’ alleged control group—any group or indi-
vidual, permitted or non-permitted, that appellants observed
using amplified sound.
       ROSENBAUM v. CITY AND COUNTY OF SAN FRANCISCO       4705
   [4] Appellants’ control group theory is unconvincing. In
their focus on selective enforcement, appellants appear not to
recognize the district court’s distinction between its analysis
of alleged equal protection violations based respectively on
permit issuance and permit enforcement. Appellants in their
complaint refer only to large permitted events that apparently
were allowed to continue despite excessive volume and some
noise complaints by appellants—the Cinco de Mayo Celebra-
tion on May 5, 1996; the “KFOG Sky Concert” on May 11,
1996; the “Making Waves” musical heritage festival on June
21, 1996; and the Gay Pride Celebration on June 30, 1996. As
for permit issuance, the district court correctly held that a
proper control group would have been smaller groups that
applied for permits for sound amplification at similar times
and locations. By contrast, appellants’ undifferentiated control
group of permitted and non-permitted groups, large and small,
using amplified sound was not comparable because these
groups were not similarly situated because of their varying
characteristics. Because appellants did not identify a bona fide
control group, they cannot demonstrate a discriminatory effect
in the City’s issuance of permits for amplified sound.

                               B

   As for appellants’ argument that they were shut down while
others were unmolested in selective enforcement of S.F.P.C.
§ 47.2, appellants alleged in their complaint that the City
police in some manner “shut down” appellants’ use of ampli-
fied sound on six occasions: (1) On February 2, 1996, at 9:00
p.m., the police stopped appellants’ use of their 9-watt “maxi
mouse” amplifier at Haight and Ashbury Streets based on an
alleged violation of the noise ordinance. (2) On March 9,
1996, at 12:15 p.m., Livingston was cited for a noise violation
under S.F.P.C. § 47.2 and the outreach rally that had received
a permit was discontinued because the investigating officer
purportedly could hear the sound from over 250 feet of the
attendant audience. (3) On March 29, 1996, at 9:45 p.m. at
Haight and Masonic Streets, the police stopped the unpermit-
4706   ROSENBAUM v. CITY AND COUNTY OF SAN FRANCISCO
ted use of the “maxi mouse” amplifier in response to a citizen
complaint and threatened to arrest Livingston if the unpermit-
ted activity continued. (4) Similarly, on April 13, 1996, at
5:00 p.m. at Clement and Tenth Streets, two officers threat-
ened to cite appellants for excessive sound during unpermitted
activity. (5) On August 2, 1996, Rosenbaum was cited for
excessive noise during unpermitted use of the “maxi mouse”
amplifier in response to a citizen complaint where the com-
plainant supposedly had been heckling Rosenbaum before-
hand. (6) On August 9, 1996, at 9:25 p.m. on Broadway and
Columbus Streets, Livingston was arrested for violating
S.F.P.C. § 47.2 and § 415 of the California Penal Code.

   Appellants argue that the district court erred in adjudicating
their equal protection claims by not acknowledging similarly
situated groups—“small un-permitted groups . . . allowed to
engage in amplified speech activities”—and by requiring that
appellants prove that the City had a discriminatory intent.
Both theories are unavailing.

   Appellants’ first argument is not supported by the district
court’s actual finding. The district court stated that “various
street musicians and other entertainers whom plaintiffs
observed using amplified sound . . . without police interfer-
ence . . . [were] comparable for purposes of equal protection
analysis.” (emphasis added). In regard to identifying the con-
trol group for purposes of selective enforcement, the district
court did not err. Appellants’ claim that the district court erred
in applying the wrong legal standard, namely that the City
was motivated by a “discriminatory intent,” is similarly belied
by the district court’s emphasis on the discriminatory effect
and purpose test in Wayte, 470 U.S. 598, and its conclusion
that appellants did not establish that the City engaged in “pur-
poseful discrimination based on the content of plaintiffs’ mes-
sage.” The district court correctly identified the proper control
group and applied the correct legal standard for selective
enforcement analysis.
       ROSENBAUM v. CITY AND COUNTY OF SAN FRANCISCO        4707
   [5] To the extent appellants claim an equal protection viola-
tion because large, permitted events were allowed to continue
despite noise complaints, whereas appellants’ activities were
restricted or terminated in some manner in response to com-
plaints, this claim, too, is unavailing. The district court cred-
ited evidence introduced by the City that two different
divisions of the San Francisco Police Department are charged
with permit issuance and enforcement of the municipal noise
ordinances respectively, each with distinct standards and
objectives: permits are issued in light of time, place and man-
ner criteria whereas permit enforcement is complaint-based.
Aside from anecdotal testimony by Rosenbaum and Living-
ston that they complained about “loud” music featured at
these larger events, appellants did not produce evidence
regarding restrictions on these permits, or whether these
permit-holders violated any conditions of their respective per-
mits. Without proof of permit violation, the fact that appel-
lants may have complained without police response is not
dispositive of any discriminatory effect. Moreover, the fact
that officers “shut down” appellants’ four instances of unper-
mitted activity based on citizen complaints does not reflect
discriminatory enforcement because the police may legiti-
mately respond to citizen complaints and stop excessive
amplified sound, especially if unpermitted, under S.F.P.C.
§§ 43, 47.2, and 49. In light of these distinct noise enforce-
ment modes, and the differences in event size, the district
court permissibly could conclude that the City did not engage
in a pattern of selective noise ordinance enforcement based on
the conduct alleged in the complaint.

   [6] An examination of the events alleged to have occurred
post-complaint also does not reveal any pattern of discrimina-
tory noise ordinance enforcement aimed at appellants. To
conclude that such a pattern existed, appellants would have to
present evidence of a pervasive policy of selective enforce-
ment with respect to the control group of individuals or small
groups engaged in unpermitted sound amplification.
4708     ROSENBAUM v. CITY AND COUNTY OF SAN FRANCISCO
   In addition to showing that officers within the agency have
engaged in a persistent pattern of misconduct, see Hannigan,
92 F.3d at 1500, “[l]iability may attach to a municipality only
where the municipality itself causes the constitutional viola-
tion through ‘execution of a government’s policy or custom,
whether made by its lawmakers or by those whose edicts or
acts may fairly be said to represent official policy.’ ” Ulrich
v. City and County of San Francisco, 308 F.3d 968, 984 (9th
Cir. 2002) (quoting Monell v. Dep’t of Soc. Serv., 436 U.S.
658, 694 (1978)). In a Monell claim, there are three ways to
show a policy or custom of a municipality: (1) by showing “a
longstanding practice or custom which constitutes the ‘stan-
dard operating procedure’ of the local government entity”; (2)
“by showing that the decision-making official was, as a matter
of state law, a final policymaking authority whose edicts or
acts may fairly be said to represent official policy in the area
of decision”; or (3) “by showing that an official with final
policymaking authority either delegated that authority to, or
ratified the decision of, a subordinate.” Ulrich, 308 F.3d at
984-85 (internal quotation marks and citations omitted).

   The district court found that there was no discriminatory
effect on the following evidence: (1) Appellants’ “maxi-
mouse” loudspeaker required a permit, which the police only
irregularly enforced against the appellants and similarly situ-
ated musicians and performers. (2) Under the expanded chro-
nology of reviewable events, the district court addressed a
variety of musical groups who were, with one exception,6
playing without permits at different times and places than appel-
lants.7 (3) Police asked appellants to turn down their loud-
  6
    The exception concerned only one incident where appellants’ non-
permitted activities prompted an admonishment, but a performer named
Emerson did not receive a similar warning, among the four incidents
where appellants’ and Emerson’s activities coincided at Taylor and Jeffer-
son Streets from the afternoon to early evening hours on February 8 and
22, 1997, March 22, 1997, and April 12, 1997. The district court ruled that
appellants did not prove discriminatory effect based on a single incident.
  7
    The district court determined that appellants were told by police to stop
preaching with amplified sound or to turn down the volume on the follow-
        ROSENBAUM v. CITY AND COUNTY OF SAN FRANCISCO              4709
speaker at Fisherman’s Wharf when no other similarly
situated groups were playing music. Under these findings, the
evidence suggests no pattern of selective enforcement.

   In regard to discriminatory effect, it must be first recog-
nized as a general matter that during the approximate seven-
year period covered under the complaint and afterward, appel-
lants were often unmolested in using sound equipment to
preach the Christian gospel, whether their activities were per-
mitted or not.8 According to Livingston’s own testimony,
appellants were able to perform on many occasions from 1995
to 1997 in well-populated San Francisco neighborhoods using
a 9-watt “maxi-mouse” amplifier without police interference.
This admission suggests that appellants were regularly
allowed to preach using non-permitted sound amplification.

   Evidence relied on by appellants also supports this conclu-
sion. For instance, appellants point to incidents on June 1 and
November 6, 1999, at Powell and Market Streets, where
appellants complained about a small protest group using a 10-
watt loudspeaker without a permit, but the police allowed the
protest to continue. Appellants contend that this type of post-
complaint police inaction showed the City’s pattern of selec-
tive enforcement; however, when viewed in light of appel-
lants’ own admission that they also were regularly allowed to
continue unpermitted activity, their claim of selective enforce-
ment is undercut. Second, in the vast majority of instances,

ing dates and locations: October 11, 1997 at 9:40 p.m. at Broadway and
Columbus Avenue; January 9, 1997 at 5:20 p.m. on Haight Street near
Ashbury Street; February 22, 1997 at 7:00 p.m. on Market Street near
Grand Avenue; and June 26, 1998 at 9:30 p.m. at Taylor and Jefferson
Streets.
  8
    In support of the conclusion that there was a general acceptance of
appellants’ ministries in San Francisco, the City issued nine permits in
October-December 1995; fifteen permits in 1996; twenty-five permits in
1997; twenty-six permits in 1998; three permits in 1999; forty-seven per-
mits in 2000; forty-four permits in 2001, and thirty-one permits in 2002.
4710     ROSENBAUM v. CITY AND COUNTY OF SAN FRANCISCO
appellants made no showing that they were using amplified
sound at the same time and/or location as comparable perform-
ers.9

   [7] As for discriminatory purpose, the City produced evi-
dence that police were responding to citizen complaints or
were alerted to appellants’ illegal activities (whether permit-
ted or not) because of the excessive noise. Evidence at trial
revealed only a few occasions where appellants were using
amplified sound and complained about other small groups
also engaged in sound amplification in the same vicinity. For
example, appellants claim that on August 6, 1996 the police
failed to cite Reckless Records, a record store that purportedly
played loud music to disturb plaintiffs. While it is true that
police issued no citation, police did admonish the record store
and ordered it to turn down the music. Moreover, in the single
post-complaint incident where appellants were preaching
without permitted sound amplification at the same time and
location as the performer Emerson, police ordered appellants
to stop on one occasion but took no action against Emerson
because he was not playing when police arrived.10 Appellants’
claim that police should have remained on the scene due to a
likelihood that Emerson would play again is unreasonable
given the low law enforcement priority at issue.
  9
    For instance, appellants cite the testimony of Carl Friedrich, a business
manager at Pier 41, who stated that between 1991 and 1997 he complained
approximately twenty times that rock music was being played, but no
police arrived. However, the potency of this testimony with respect to the
claimed discriminatory effect is substantially weakened by the fact that
appellants did not allege that they also were active at Pier 41 on these
occasions.
   10
      Appellants claim that the district court improperly disregarded two
other incidents of alleged disparate treatment involving their use of ampli-
fied speech coincident with Emerson’s street performances, on June 26,
1998 and January 19, 2001, where appellants were “shut down” but Emer-
son was purportedly allowed to continue. The district court did not commit
clear error in dismissing the significance of these incidents because there
was insufficient evidence that Emerson was playing when the police
arrived.
         ROSENBAUM v. CITY AND COUNTY OF SAN FRANCISCO                   4711
   [8] Appellants’ claimed acts of selective enforcement did
not have a discriminatory effect. There was likewise no evi-
dence to suggest that any action or non-action by the police
was taken “because of . . . its adverse effects upon [the] iden-
tifiable group.”11 Wayte, 470 U.S. at 610. Even if we were to
credit the few instances of arguable non-enforcement against
similarly situated groups, a pattern or policy of discrimination
is not established by these few instances over the entire period
where appellants frequently conducted outreach with both
permitted and unpermitted amplified sound, and police have
discretion to determine the appropriate level of enforcement.
See Hannigan, 92 F.3d at 1500 (requiring plaintiffs to estab-
lish more the repeated incidents of misconduct sufficient for
injunctive relief). Appellants’ claim for injunctive relief is
also flawed because of a lack of evidence that the City had a
standard operating procedure or policy directed by an official
with final policy-making authority. See Ulrich, 308 F.3d at
984-85. We affirm the district court in denying appellants’
equal protection claims.

                                      V

   Appellants advance three main theories in claiming that the
City engaged in viewpoint discrimination in violation of the
First Amendment. First, appellants argue that the City gave
effect to an improper “heckler’s veto” when officers
  11
     Due to the absence of a discriminatory effect or purpose, appellants’
claim that the district erred in not applying strict scrutiny is meritless.
Strict scrutiny only applies once a law is determined to be discriminatory.
See Doe v. Kamehameha Schools/Bernice Pauahi Bishop Estate, 470 F.3d
827, 837-39 (9th Cir. 2006) (discussing type and nature of discrimination
that triggers strict scrutiny review). Likewise, appellants’ assertion that the
district court improperly applied rational basis review is also baseless. The
district court made passing reference to “rational basis” only to reject any
implied equal protection claim that the permitting ordinance was passed
to discriminate against appellants as a discrete class. See Village of Wil-
lowbrook v. Olech, 528 U.S. 562 (2000) (recognizing equal protection vio-
lation where ordinance is targeted at single individual because state action
is arbitrary and irrational).
4712    ROSENBAUM v. CITY AND COUNTY OF SAN FRANCISCO
responded to noise complaints initiated by citizens who dis-
agreed with the content of appellants’ Christian message.
Appellants contend that the district court erred in examining
the enforcing officer’s state of mind to reject discriminatory
intent. Second, appellants contend that the district court erred
in rejecting viewpoint discrimination because the City exer-
cised unbridled discretion in issuing permits and because the
City used the grounds of excessive volume as a pretext for
denying loudspeaker permits where the actual basis was the
content of appellants’ Christian message. Third, appellants
argue that the district court erred in finding probable cause to
arrest appellants under California Penal Code § 415 for “dis-
turbing the peace,” where the motivation implied was dis-
agreement with the content of appellants’ speech.

   “Discrimination against speech because of its message is
presumed to be unconstitutional.” Rosenberger v. Rector &
Visitors of the Univ. of Va., 515 U.S. 819, 828 (1995). Sec-
tions 43 and 47.2 of the San Francisco Police Code, which
jointly comprise the statutory framework governing eligibility
for loudspeaker permits, are facially valid as a content-neutral
time, place, and manner restriction.12 See Faith Ctr. Church
Evangelistic Ministries v. Glover, No. 05-16132, 2007 WL
703599, at *12 (9th Cir. Mar. 9, 2007) (“Content-neutral
restrictions that regulate the time, place, and manner of
speech are permissible so long as they are ‘narrowly tailored
to serve a significant government interest, and [they] leave
open ample alternative channels of communication.’ ”) (alter-
ation in the original) (quoting Perry Educ. Ass’n v. Perry
Local Educators’ Ass’n, 460 U.S. 37, 45 (1983)). Despite the
neutral content of a statute on its face, however, a statute as-
applied may be constitutionally infirm if its enforcement is
based on viewpoint discrimination. See Kuba v. 1-A Agric.
Ass’n, 387 F.3d 850, 856 (9th Cir. 2004) (“An as-applied
  12
   In fact, after the City successfully moved for partial summary judg-
ment, appellants’ claim of facial invalidity was dismissed on June 15,
1998.
       ROSENBAUM v. CITY AND COUNTY OF SAN FRANCISCO       4713
challenge alleges that the restriction on speech is unconstitu-
tional as applied to the litigant’s particular speech activity,
even though the law may be capable of valid application to
others.”) (internal quotation marks omitted). “ ‘Content dis-
crimination’ occurs when the government ‘choos[es] the sub-
jects’ that may be discussed, while ‘viewpoint discrimination’
occurs when the government prohibits ‘speech by particular
speakers,’ thereby suppressing a particular view about a sub-
ject.” Giebel v. Sylvester, 244 F.3d 1182, 1188 (9th Cir. 2001)
(alteration in the original) (quoting Perry Educ. Ass’n, 460
U.S. at 59 (Brennan, J., dissenting)). It should be underscored,
however, that “[a] regulation that serves purposes unrelated to
the content of expression is deemed neutral, even if it has an
incidental effect on some speakers or messages but not oth-
ers.” Ward v. Rock against Racism, 491 U.S. 781, 791
(1989).

                               A

   Appellants argue that the City applied an improper “heck-
ler’s veto” when, in regulating amplified speech under
S.F.P.C. § 47.2, police officers responded to complaints by
citizens who disagreed with the content of appellants’ Chris-
tian message.

   [9] A “heckler’s veto” is an impermissible content-based
speech restriction where the speaker is silenced due to an
anticipated disorderly or violent reaction of the audience. See
Brown v. Louisiana, 383 U.S. 131, 133 n.1 (1966); see also
Forsyth County v. Nationalist Movement, 505 U.S. 123, 137
(1992) (invalidating ordinance that allowed county adminis-
trator to adjust parade permit fees based on anticipated cost of
security). In Forsyth County, Chief Justice Rehnquist pointed
to the risk of a “heckler’s veto” where a permittee might be
subject to higher fees because of higher security costs associ-
ated with a hostile crowd. Id. at 142 (Rehnquist, J., dissent-
ing).
4714   ROSENBAUM v. CITY AND COUNTY OF SAN FRANCISCO
   [10] Appellants’ “heckler’s veto” claim here is miscon-
ceived. The district court concluded that the City’s permitting
procedures and enforcement criteria were not motivated by
fear of any hostile or unruly reaction by citizens who com-
plained about appellants’ activities. Testimony at trial indi-
cated only two incidents within the scope of actionable
conduct where citizen complainants may have responded to
appellants’ Christian message when making noise complaints:
(1) On August 2, 1996, a complainant allegedly yelled at
appellants that “Christians are child molesters,” before lodg-
ing a complaint that appellants were disturbing the peace. (2)
On August 9, 1996, a complainant purportedly argued with
SOS Ministries members and expressed anti-Christian views
prior to calling the police. As to these specific exchanges
between appellants and citizen complainants, appellants do
not allege whether any complainant mentioned any anti-
Christian sentiments when filing the complaint. Moreover, to
follow appellants’ logic and impute the view of the complain-
ant to the investigating officer would lead to an absurd result:
In the event a bystander was provoked by the content of a par-
ticular message and complained, the speaker could theoreti-
cally amplify that message at an intolerable volume with
impunity because the enforcement of the complaint would
automatically be transformed into a First Amendment viola-
tion. As such, we reject appellants’ theory. Absent some gen-
uine nexus between a complainant’s subject-matter
disagreement and the basis for the investigation of the com-
plaint by authorities, appellants cannot prevail on a “heckler’s
veto” claim of viewpoint discrimination.

   [11] Here, the district court’s findings after bench trial
rejected such a nexus. The district court found the testimony
of the responding officers to be credible that they were
responding only to noise complaints. The district court cor-
rectly concluded that there was no “heckler’s veto” because
appellants did not demonstrate with any evidence that the San
Francisco police officers who responded to these specific inci-
dents, or any incidents more generally, knew about, agreed
       ROSENBAUM v. CITY AND COUNTY OF SAN FRANCISCO        4715
with or adopted any views of the complainants. To the con-
trary, the record is clear that officers responding to these two
incidents instructed appellants to lower the volume, which
would have allowed appellants to express their Christian
views; when they refused, however, the officers were again
dispatched to control the unreasonably loud speech in
response to citizen complaints. The district court also credited
police officer testimony that when appellants were told to stop
the non-permitted amplified speech that was excessively loud,
investigating officers regularly informed appellants that they
could continue to preach, albeit without amplification. This
reinforces the conclusion that the City was concerned about
unacceptable noise levels and not with the content of appel-
lants’ Christian message.

                               B

   Appellants claim that the district court erred in not address-
ing their claim of unbridled discretion, which appellants con-
tend allowed the City to engage in viewpoint discrimination.
Appellants also contend that because no volume specification
was called for on permit applications, evidence that police
officers were responding to excessive noise is pretextual and
betrays viewpoint discrimination.

   [12] “The principal inquiry in determining content neutral-
ity, in speech cases generally and in time, place, or manner
cases in particular, is whether the government has adopted a
regulation of speech because of disagreement with the mes-
sage it conveys.” Ward, 491 U.S. at 791. An ordinance that
affords city officials unbridled discretion to determine
whether or not to enforce limitations on First Amendment
activity may support the inference of viewpoint discrimina-
tion. See City of Lakewood v. Plain Dealer Publ’g Co., 486
U.S. 750, 757 (1988). As noted above, however, “[a] regula-
tion that serves purposes unrelated to the content of expres-
sion is deemed neutral, even if it has an incidental effect on
4716   ROSENBAUM v. CITY AND COUNTY OF SAN FRANCISCO
some speakers or messages but not others.” Ward, 491 U.S.
at 791.

   In pressing their theory that the City fell prey to viewpoint
discrimination due to its alleged exercise of unbridled discre-
tion, appellants rely on our decision in American Jewish
Cong. v. City of Beverly Hills, 90 F.3d 379 (9th Cir. 1996).
In that case, we considered a claim under the Establishment
Clause of the First Amendment where defendant city gener-
ally proscribed erection of unattended displays on public
property, with a single exception that permitted the presence
of a 27-foot menorah during the Chanukah season. Id. at 380-
81. When the city denied permits to two applicants, who were
respectively seeking to create a “winter solstice” scene and
plant a Latin cross on public property, we concluded that the
unique exception to allow the menorah violated the Establish-
ment Clause because it demonstrated a preference for the
Jewish religion, see id. at 383, and because the ordinance
vested city officials with unbridled discretion. Id. at 384
(“The City may not have a general policy banning unattended
private displays, but, on an ad hoc basis with no standards to
guide it, choose one religious group and permit it to erect a
display while denying all other groups permission to erect dis-
plays.”). In American Jewish Congress, we held that the “ad
hoc and structureless nature of the City’s permitting process
leaves open the possibility of improper discrimination by the
City.” Id. at 385.

   [13] Contrary to appellants’ contentions, under S.F.P.C.
§ 43, the police commissioner has guided discretion to issue
permits for amplified sound for a variety of purposes includ-
ing public affairs interests. Applicants must designate time,
location and purpose of the permit, see § 43(c), and are
expressly subject to conditions under S.F.P.C. §§ 47.2 and 49.
Section 47.2 prohibits amplified sound from being “unreason-
ably loud [and] raucous” and sets forth the temporal restric-
tion that amplified sound is permitted only between 9:00 a.m.
and 10:00 p.m. and the spatial restriction that amplified sound
        ROSENBAUM v. CITY AND COUNTY OF SAN FRANCISCO          4717
cannot be audible from 250 feet of the broadcast area. See
S.F.P.C. §§ 47.2(2), (5) and (7). In pertinent part, § 49 also
prohibits “amplification of sound or human voice in such a
manner as to produce raucous noises or . . . disturb the peace,
quiet and comfort of persons in the neighborhood or with vol-
ume louder than . . . necessary for convenient hearing.” See
S.F.P.C. § 49.

   [14] In denying appellants permits, the City based its deci-
sion on the fact that the proposed use of amplified sound was
unsuitable for the area covered by the requested permit under
several statutory criteria. For instance, in the Notice of Deci-
sion on May 23, 1996 denying appellants’ permit application,
the hearing officer noted citizens’ complaints that they were
being subjected to excessive volumes that disrupted busi-
nesses during the day and disturbed residents with children in
the evening because of the unreasonably loud volume. The
hearing officer also cited repeated direct requests by citizens
to Livingston and Rosenbaum to reduce their sound levels.
Moreover, the hearing officer credited police statements that
appellants routinely could be heard at a distance of more than
250 feet from the sound source. Finally, the hearing officer
found that appellants were often unwilling to reach an accom-
modation with these area residents. As such, the City hearing
officer denied the permit application because people near the
proposed gatherings were being “subjected to unreasonably
loud music and human speech.” See Notice of Decision, May
23, 1996. Appellants adduced no evidence that City officials
were otherwise motivated in denying permits. Finally, as dis-
cussed in the context of appellants’ equal protection claim, the
charge of unbridled discretion is weakened by the fact that on
many occasions they applied for and received permits at this
and other sites.13
  13
    The City issued nine permits in October-December 1995 and fifteen
permits in 1996.
4718   ROSENBAUM v. CITY AND COUNTY OF SAN FRANCISCO
   Appellants also assert a claim of pretext that the police rou-
tinely requested or forced appellants to cease their permitted
amplified speech based on excessive noise, although, accord-
ing to appellants, the City had no grounds to do so because
appellants never requested a particular volume level when
applying for a permit. As an initial matter, this factual claim
is inaccurate because permits issued under S.F.P.C. § 47(a)(9)
are subject to the requirement that applicants indicate “maxi-
mum sound-producing power” in terms of specific wattage for
the loudspeaker to be used, see S.F.P.C. § 47(a)(9), and the
record contains numerous permit applications that uniformly
request that the applicant indicate a specific wattage. Appel-
lants’ argument here suffers from lacking specificity since
they have not cited to any particular permit where they did not
indicate a volume level. More importantly, whether permitted
or not, users of amplified sound are subject to general regula-
tions that “amplified human speech . . . shall not be unreason-
ably loud, raucous, jarring or disturbing to persons of normal
sensitiveness within the area of audibility.” S.F.P.C.
§ 47.2(5), unless specifically granted permission otherwise
(e.g. for larger events). This evidence defeats appellants’
claim of pretext.

   [15] Because §§ 47 and 47.2 condition both the issuance of
sound permits and the use of sound amplification, it is evident
that the City did not have unbridled discretion. The Notices
of Decision during the relevant period provide content-neutral
justifications for appellants’ denied permits, and appellants do
not facially attack the governing framework for permit issu-
ance under S.F.P.C. §§ 43, 47 and 47.2.

                               C

   Appellants’ third theory of viewpoint discrimination is that
the City made no legitimate showing of probable cause when
citing Livingston and Rosenbaum under California Penal
Code § 415 for “maliciously and willfully” disturbing others.
The absence of probable cause, continues appellants’ argu-
        ROSENBAUM v. CITY AND COUNTY OF SAN FRANCISCO                4719
ment, demonstrates that the City sought to suppress appel-
lants’ religious message.14

   [16] California Penal Code § 415 provides in pertinent part
that “[a]ny person shall be punished . . . who maliciously and
willfully disturbs another person by loud and unreasonable
noise.” Cal. Pen. Code § 415(2). As the district court found,
“[t]he words ‘malice’ and ‘maliciously’ import a wish to vex,
annoy, or injure another person, or an intent to do a wrongful
act, established either by proof or presumption of law.” See
Cal. Pen. Code § 7. In In re Brown, the California Supreme
Court clarified the meaning of willful disturbance: “The use
of the human voice to disturb others by the mere volume of
the sound when there is no substantial effort to communicate
or when the seeming communication is used as a guise to
accomplish the disruption may be prohibited [under § 415].”
9 Cal. 3d 612, 621 (1973). Although the California Supreme
Court concluded in that case that anti-war protesters who car-
ried picket signs, shouted obscenities, and shook their fists at
riot police could not be arrested under § 415 because their
actions did not pose a clear and present danger of inciting oth-
ers to violence, the holding was not absolute such “that sec-
tion 415 may never be applied to loud shouting and cheering.”
Id.

   [17] In Knox v. Southwest Airlines, we recognized the con-
stitutional principle that “[t]he First Amendment does not pre-
vent enforcement of disorderly conduct statutes so long as
they are not vague or applied to curb protected speech.” 124
F.3d 1103, 1109 (9th Cir. 1997) (alteration in original) (hold-
ing officer’s motive for the arrest could not be resolved on
summary judgment) (internal quotation marks omitted).
  14
     We review the district court’s finding of probable cause de novo, see
United States v. Nava, 363 F.3d 942, 944 (9th Cir. 2004); however, histor-
ical facts are reviewed for clear error. See United States v. Vesikuru, 314
F.3d 1116, 1122 (9th Cir. 2002).
4720   ROSENBAUM v. CITY AND COUNTY OF SAN FRANCISCO
   Here, appellants alleged in their complaint two separate
incidents where they contend that they were cited under § 415
without probable cause. The district court made the following
findings about the incidents:

    At the time of the citation [on August 2, 1996],
    plaintiff Rosenbaum was using amplified sound in a
    mixed residential/commercial neighborhood after
    9:00 p.m. He did not have a permit to use amplified
    sound. Officer Mark Landon, a police officer on
    vehicle patrol, heard the sound from a block away
    with his windows closed, responded and asked
    Rosenbaum to turn the sound down. Approximately
    fifteen minutes later, Officer Landon was dispatched
    on a noise complaint, at which time the complainant,
    Joe Narvik, signed a citizen’s arrest card. Narvik
    reported that Rosenbaum was keeping his children
    awake and had refused to turn the sound down when
    Narvik requested that he do so.

    At approximately 9:30 p.m. [on August 9, 1996], at
    Broadway and Columbus Avenue, Livingston was
    preaching using amplification and had no permit for
    such amplification. Officer Milan Kangrga, on patrol
    in the North Beach area, responded to a noise com-
    plaint and requested that Livingston turn down his
    sound, which he did. Officer Kangrga returned,
    again in response to a noise complaint, at which time
    the volume was loud, and the complainant, Harry
    Wamack, who, by his address as indicated in the
    police report, resides near that intersection, signed a
    citizen’s arrest card. There is no indication of any
    encounter between the complainant and Livingston
    in this instance, however, or of the particular manner
    in which the complainant’s peace was disturbed.
    Nevertheless, given Livingston’s lack of permit, his
    knowledge of a complaint, and his increasing the
    volume of his amplifier to a high level once the
       ROSENBAUM v. CITY AND COUNTY OF SAN FRANCISCO          4721
    police had left the scene, it cannot be said that Offi-
    cer Kangrga had no reasonable cause to believe Liv-
    ingston did so not to communicate but rather to
    annoy the individual who had seen fit to report him.

   [18] “The test for probable cause is whether facts and cir-
cumstances within the officers’ knowledge are sufficient to
warrant a prudent person, or one of reasonable caution, to
believe, in the circumstances shown, that the suspect has com-
mitted, is committing or is about to commit an offense.”
Menotti v. City of Seattle, 409 F.3d 1113, 1149 (9th Cir. 2005)
(internal quotation marks omitted). Although it is not disposi-
tive, the City introduced testimony that under an informal pol-
icy, its police officers have probable cause to believe a
speaker “maliciously and willfully” caused a “loud and unrea-
sonable” noise for purposes of § 415 where (1) a citizen has
been unreasonably disturbed by sound volume, and is willing
to sign a citizen’s arrest form to that effect; and (2) the police
have cause to believe that the person who is the source of the
sound knows that he or she is too loud, but refuses to turn
down the volume. Under the test we enunciated in Menotti, to
sustain the implied claim that the City officers subjected
appellants to viewpoint discrimination due to the alleged cita-
tion without probable cause, the question is whether a prudent
person in the position of the officers who cited appellants
would have believed that appellants were committing the
offense of disturbing the peace under § 415, with the requisite
specific intent to annoy. We conclude that city police here had
probable cause.

   As for the August 2, 1996 citation, the district court reason-
ably inferred that Rosenbaum had not adequately lowered the
volume of his loudspeakers despite Officer Landon’s admon-
ishment, because the volume remained sufficiently loud to
rouse a neighborhood resident to complain and sign a citizen
arrest form. Testimony to bolster appellants’ contention here
that Rosenbaum turned off one of his loudspeakers, and
turned down the second loudspeaker, was not so credible as
4722   ROSENBAUM v. CITY AND COUNTY OF SAN FRANCISCO
to overcome the inference that his purpose was to annoy Nar-
vik, who, according to the investigating officer, had also
requested that Rosenbaum reduce the volume. See Anderson
v. City of Bessemer, 470 U.S. 564, 573 (1985) (recognizing
that trial court’s credibility findings are subject to clear error
and deserve special deference). Rosenbaum’s amplified
speech was loud enough to draw Officer Landon to the scene
twice within fifteen minutes. There was no clear error in the
district court’s determination that Rosenbaum’s amplified
sound remained at an unreasonable volume despite police
warnings, from which we may conclude that Officer Landon
had probable cause to issue a citation under § 415.

   The circumstances surrounding the August 9, 1996 citation
also support probable cause for a violation of § 415. Here,
Officer Kangrga similarly was twice called to the location
where Livingston was engaged in unpermitted amplified
speech. Appellants’ assertion that no evidence was submitted
that Livingston actually “increased” the volume is immaterial
in light of Officer Kangrga’s testimony. According to Officer
Kangrga, Livingston disregarded the initial warning and
maintained his volume at an unreasonably loud level so as to
prompt another complaint. Because Livingston was on notice
after the first warning that his volume was excessive, the dis-
trict court could draw the permissive inference that Living-
ston’s intent was to annoy or vex. No more is required to
make a valid showing of probable cause.

   Because both incidents of citation under § 415 were legiti-
mately based on probable cause, the district court correctly
rejected appellants’ implied viewpoint discrimination claim.
Moreover, the district court was also correct that even if prob-
able cause were lacking, these two isolated incidents do not
amount to a pattern or policy of abusive citation under § 415,
given that two unrelated individuals prompted the complaints
and two different officers responded. There was no evidence
that the citations were coordinated by an overarching and
improper policy or directive. See Ulrich, 308 F.3d at 984.
         ROSENBAUM v. CITY AND COUNTY OF SAN FRANCISCO                  4723
   [19] Because the district court’s findings of probable cause
for enforcement of the noise ordinance against appellants is
supported by evidence in the record, we affirm the district
court’s rejection of the viewpoint discrimination claims.15

                                     VI

   Appellants argue that the City engaged in unconstitutional
prior restraint in rejecting several permit applications based
on appellants’ non-compliance with conditions attached to
sound permits issued in the past.16

   [20] Laws that impose a prior restraint on the free exercise
of speech have been disfavored as tantamount to censorship.
See Near v. Minnesota, 283 U.S. 697, 713 (1931). In Fer-
nandes v. Limmer the Fifth Circuit espoused the broad princi-
ple that a “[d]enial of a permit for prior violations
unquestionably entails a total abridgement of a citizen’s right
to use the forum . . . .” 663 F.2d 619, 632 (5th Cir. Unit A
Dec. 1981). In that case, the Fifth Circuit confronted a local
ordinance governing literature distribution and fund solicita-
tion at the Dallas-Fort Worth Airport, which provided, inter
  15
      We conclude that declaratory relief is unnecessary because it would
“neither serve a useful purpose in clarifying and settling the legal relations
in issue nor terminate the proceedings and afford relief from the uncer-
tainty and controversy faced by the parties.” See United States v. Washing-
ton, 759 F.2d 1353, 1357 (9th Cir. 1985).
   16
      Appellants assert this claim generally without any reference to partic-
ular permit denials or dates when the denials might have occurred. While
appellants cite a variety of exhibits in the briefing, these exhibits are not
tied to specific motions the district court reviewed. Nor do appellants
include in their Excerpts of Record copies of any particular Notices of
Decision documenting the City’s permit denials. The City, for its part,
included in the Supplemental Excerpts of Record copies of Notices of
Decision for March 23, 1996; November 8, 1996; March 17, 1997; April
1, 1997; April 7, 1997; June 25, 1997; and September 23, 1997. Because
the district court correctly limited actionable conduct to that alleged in the
complaint, and our appellate review is similarly limited, we consider only
evidence of the May 23, 1996 denial.
4724    ROSENBAUM v. CITY AND COUNTY OF SAN FRANCISCO
alia, that permits could be withheld in the event “ ‘the Appli-
cant or any agent or representative of the Applicant . . . has
previously violated . . . Regulations of the Dallas-Fort Worth
Regional Airport Board, or has violated any of the terms and
provisions of any prior Permit.’ ” Id. (quoting local ordi-
nance) (alteration in original). Because this statutory subsec-
tion effected a categorical denial of permits for prospective
activity based solely on the fact of prior violations, the Fifth
Circuit invalidated the ordinance on grounds of prior restraint.
Id.; see also Kunz v. New York, 340 U.S. 290, 293 (1951)
(holding denial of permit to engage in outdoor religious activ-
ity based on earlier revocation of speech permit, where
administrative officer had unbounded discretion, was imper-
missible prior restraint).

   The City relies on a Notice of Decision, issued on May 23,
1996, that upheld the denial of appellants’ application for an
amplified sound permit proposed for five days in March of
1996 at the intersection of Fifth and Market Streets.17 A hear-
ing was held on May 8, 1996, at which Sergeant Terence Col-
lins (head of the Permit Section) reviewed letters written by
proponents and opponents of appellants’ use of amplified
speech, in addition to hearing live public comment.

   Among other evidence, the hearing officer considered the
testimony of Officer Dan Gallagher. Officer Gallagher ini-
tially denied the March 1996 applications, and, in the preced-
ing months, had fielded complaints from frustrated citizens
who disparaged appellants’ use of excessively loud speech
and music, and a purported lack of cooperation from represen-
tatives of the SOS Ministries who, when asked, refused to
  17
     From the appellants’ briefing, it is evident that appellants decry as
prior restraint some aspects of the decision-making process evinced in the
March 23, 1996 Notice of Decision. Also, appellants in their complaint
alleged the March 1996 permit denials as actionable conduct. To this
extent, then, the May 23, 1996 Notice of Decision is an emblematic
instance of the challenged City conduct.
        ROSENBAUM v. CITY AND COUNTY OF SAN FRANCISCO          4725
lower their loudspeaker volume. Officer Gallagher also testi-
fied that business owners in the vicinity complained that they
could clearly hear appellants’ sound inside their establish-
ments. Officer Gallagher further testified that he had frequent
occasions to warn appellants about their excessive sound that
violated § 47.2(7) (prohibiting sound that is audible beyond
250 feet of its source), and that he ultimately sent appellants
a letter informing them that they would not receive permits if
they failed to comply with permit conditions that the volume
be maintained at a reasonable level. Finally, Officer Gallagher
recounted that at an outreach gathering in the area on March
2, 1996, the City’s Noise Abatement Unit received complaints
that required a police response. On March 9, 1996, the date
on which the last previous permit was issued, Officer Gal-
lagher noted that police were on hand to monitor appellants’
use of sound and reported that the speech and music could be
heard up to 400 feet away, which again spurred complaints to
the Noise Abatement Unit.

   The hearing officer reviewed letters and heard comment by
various neighborhood civic and business associations who
similarly expressed frustration with appellants’ persistently
loud amplified speech and music. These association represen-
tatives mentioned that their members’ businesses were dis-
rupted and residents were subject to loud volumes in the late
evening when children were trying to sleep. In the case of an
assistant manager of the City’s Visitor’s Information Center,
the hearing officer heard that many visitors, some of whom
could not speak English well, were unable to communicate
effectively because of appellants’ use of amplified sound. In
addition to recounting a few alleged incidents of being base-
lessly “shut down,” Rosenbaum testified that the problem was
not the level of sound, but rather “members of the homosex-
ual community who oppose him.”18
  18
    Appellants’ on-going presence in some City neighborhoods caused a
controversy because some gay members of the community and others
4726    ROSENBAUM v. CITY AND COUNTY OF SAN FRANCISCO
   [21] Appellants are correct that in the May 23, 1996 Notice
of Decision, the City cited prior instances in 1995 and early
1996 where plaintiffs were unwilling to comply with permit
conditions as part of its grounds for denial. However, this can-
not be viewed in isolation. Aside from the past violations,
what is plain from the varied public comments documented in
the Notice of Hearing was that appellants’ persistent use of
unreasonably loud amplified speech and music was disruptive
to both businesses and residents at the specified location, the
intersection of Fifth and Market Streets. The hearing officer
considered not only the misconduct inherent in the past viola-
tions, but also previous instances where plaintiffs received
permits in March 1996 despite the widespread complaints in
order to provide an “opportunity to reduce the volume of
amplified sound in an effort to co-exist with the businesses in
the area.”19 Despite this acknowledged accommodation, more
complaints from the business community ensued describing
the appellants’ unwillingness to lower the volume and the
appellants’ occasional abusive response when asked to do so
by fellow citizens. The hearing officer’s consideration of the
past misconduct was thus aimed at determining the compati-
bility of the amplified speech and music with the various

were angered by what they perceived to be an “anti-gay” message in some
of appellants’ Christian outreach. However, there is no evidence in the
Notice of Decision that local residents or business owners offering public
comment focused their opposition on appellants’ allegedly “anti-gay”
message or that Sergeant Collins gave any weight to any animosity
between the SOS Ministries and certain gay community members.
   19
      In a Notice of Decision, dated November 8, 1996, plaintiffs were
denied a permit based on similar considerations about persistent noise
complaints and unwillingness to comply with admonitions to lower the
volume, i.e. appellants’ “spirit of non-cooperation.” In this instance, the
hearing officer denied the permit because “amplified sound in the densely
populated neighborhood of Sixth and Market Streets would have a nega-
tive impact and be in conflict with the production at the Golden Gate The-
ater.” Even this denial contained an invitation to reach an accommodation
whereby plaintiffs could use a 9-watt bullhorn.
       ROSENBAUM v. CITY AND COUNTY OF SAN FRANCISCO          4727
interests in the proposed permit area, not the mere fact of any
past violation.

   In this light, appellants’ reliance on the Fifth Circuit’s deci-
sion in Limmer is inapt. The categorical permit ineligibility at
issue in Limmer is different from the guided discretion exer-
cised under § 47.2 to deny some of appellants’ applications.
See Cox v. New Hampshire, 312 U.S. 569, 576 (1941). In
Cox, the Supreme Court rejected a prior restraint claim by
Jehovah’s Witnesses who chose to march without a parade
permit because the city could legitimately enforce a permit
requirement as a generally applicable condition for public
gatherings where it did not otherwise control or suppress the
distribution of literature, the display of placards or individual
oration. 312 U.S. at 576 (“If a municipality has authority to
control the use of its public streets for parades or processions,
as it undoubtedly has, it cannot be denied authority to give
consideration, without unfair discrimination, to time, place
and manner in relation to the other proper uses of the
streets.”).

   In the successful facial challenge in Limmer, the impermis-
sible prior restraint was effectuated because under no circum-
stances could an applicant purge the taint of a previous
violation. In sharp contrast, the evidence here supports the
finding that the City police and its citizens engaged in an on-
going negotiation with appellants to reach accommodation
despite the widely complained-of noise violations under
§ 47.2. Unlike in Limmer, where the Fifth Circuit rejected the
unequivocal “once a sinner, always a sinner” effect of the
Dallas-Fort Worth ordinance, see 663 F.2d at 632 (internal
quotation marks and citation omitted), appellants here were
afforded opportunities to redeem past misconduct and bring
their use of amplified sound into reasonable cooperation with
other neighborhood activities at the proposed permit site.

  The Supreme Court decision in Kunz, 340 U.S. 290, on
which appellants also rely, is inapposite. In Kunz, the defen-
4728   ROSENBAUM v. CITY AND COUNTY OF SAN FRANCISCO
dant city revoked a Baptist minister’s permit to hold an out-
door public meeting because he had in the past violated a
New York statute forbidding the ridicule and denunciation of
other religions. Id. at 292. The Supreme Court held that the
permit denial due to a past violation of this statute was uncon-
stitutional prior restraint because “the ordinance does not
specify this as a ground for permit revocation.” Id.; see also
id. at 294 (“[W]e have consistently condemned licensing sys-
tems which vest in an administrative official discretion to
grant or withhold a permit upon broad criteria unrelated to
proper regulation of public places.”).

   [22] Here, the hearing officer’s reference to appellants’ past
violations in context do not show an absolute prohibition
based on past violation, but rather that the City hearing officer
sought to balance, within constitutional bounds, the compet-
ing interests at the proposed permit location. In doing so, the
hearing officer reasonably surmised from the instances of past
misconduct, on-going complaints, and appellants’ apparent
recalcitrance that the proposed amplified sound activity was
unsuitable for the location and incompatible with other neigh-
borhood activities. Unlike in Kunz, the City here did not
deprive appellants of permits based on an arbitrary application
of an unrelated statute. In contrast to Limmer, moreover, no
provision of the City’s permitting scheme called for a
mechanical rejection of appellants’ permit application because
of past violation of the noise ordinance. Rather, the City’s
refusal to issue permits in these limited instances was guided
by conditions enumerated under S.F.P.C. § 47.2 (e.g. the 250-
foot distance requirement), which, unlike the unrelated statute
in Kunz, is expressly cross-referenced in S.F.P.C. § 43, the
provision that governs permit issuance. Finally, as we noted
previously, the fact that appellants received permits at differ-
ent city locations reinforces the hearing officer’s finding that
it was the proposed location in the March 1996 permit appli-
cations, and not the content of appellants’ message, that was
unsuitable. As in Cox, the City was within its police power to
deny permits that might seriously interfere with its streets, see
       ROSENBAUM v. CITY AND COUNTY OF SAN FRANCISCO        4729
312 U.S. at 575, and did not engage in unconstitutional prior
restraint.

                              VII

   Appellants contend that the district court erred in not apply-
ing a substantive analysis of their free speech claims under
article 1, section 2(a) of the California Constitution, which, in
appellants’ view, provides more expansive rights than federal
protections, including a burden on the state to prove that the
speech activity was “incompatible” with the public forum. In
failing to show incompatibility, appellants argue, the City did
not prove that amplified speech by Livingston and Rosen-
baum “blocked the sidewalks, caused congestion or otherwise
interfered with the use of the public forum . . . .” See App. Br.
at 24. While acknowledging the asserted broader freedoms
under article 1, section 2(a) of the California Constitution, the
district court found, without further substantive analysis, “no
reason” to conclude that appellants demonstrated a violation
of state constitutional rights.

   [23] Article 1, section 2(a) of the California Constitution
guarantees that “[e]very person may freely speak, write and
publish his or her sentiments on all subjects.” Cal. Const. art.
I, § 2(a). “The California Supreme Court has recognized that
the California Constitution is ‘more protective, definitive and
inclusive of rights to expression and speech’ than the First
Amendment to the United States Constitution.” Glendale
Assocs., Ltd. v. NLRB, 347 F.3d 1145, 1154 (9th Cir. 2003)
(quoting Robins v. Pruneyard Shopping Ctr., 23 Cal. 3d 899,
908, 910 (1979), aff’d, 447 U.S. 74 (1980)). Despite this
greater expansiveness of speech rights, article 1, section 2(a)
tolerates content neutral speech restriction commensurate with
the First Amendment. See, e.g., Pruneyard Shopping Ctr., 23
Cal. 3d at 909 (recognizing such permissible restrictions
under California Constitution). In the context of amplified
sound regulation, time-place-manner restrictions also apply
under California law. See Wollam v. City of Palm Springs, 59
4730   ROSENBAUM v. CITY AND COUNTY OF SAN FRANCISCO
Cal. 2d 276, 278 (1963) (holding that blanket prohibition
against the use of a stationary sound truck exceeded its justifi-
cation under time, place and manner restriction because the
outright ban was not limited to the elimination of loud or rau-
cous noise or necessary for the prevention of traffic hazards).

   Here, appellants’ contention that their repeated use of
amplified sound at excessive volume did not interfere with the
public forum is unavailing. As discussed above, the City’s
Permit Section was presented with ample evidence from busi-
nesses and residents in the area around Fifth and Market
Streets and elsewhere that the excessive volume was destruc-
tive to commerce, interfered with residents’ ability to sleep,
was often audible from more than 250 feet of the performance
site in violation of § section 47.2(7) and prompted widespread
complaints.

   [24] In contrast to Pruneyard Shopping, regulation under
S.F.P.C. § 47.2 did not prohibit all speech activities, as appel-
lants were informed that they could continue to preach if they
would lower the volume of their loudspeakers. More impor-
tantly, unlike the blanket prohibition invalidated in Wollam,
§§ 47 and 47.2 incorporate reasonable enforcement limita-
tions such as maintaining reasonable volume levels, distance
requirements, specifying wattage and imposing bans only on
amplification before 9:00 a.m. and after 10:00 p.m. See
S.F.P.C. §§ 47(a) and 47.2. The consequences of amplifica-
tion at excessive volume is a genuine form of “interference”
with the public forum even if it did not block traffic or cause
congestion. As such, enforcement of the time, place and man-
ner restriction under S.F.P.C. §§ 43 and 47.2 to curb appel-
lants’ use of amplified sound at excessive volumes did not run
afoul of the California Constitution.

                              VIII

  In conclusion, San Francisco’s enforcement of its noise
abatement ordinance, in its permitting and its law enforce-
       ROSENBAUM v. CITY AND COUNTY OF SAN FRANCISCO        4731
ment activities, did not violate the federal constitutional guar-
antee of equal protection of the laws, or its protection of First
Amendment rights. Similarly, San Francisco’s enforcement of
its noise restrictions against appellants did not offend the Cal-
ifornia Constitution.

  AFFIRMED.
