PRECEDENTIAL

        UNITED STATES COURT OF APPEALS
             FOR THE THIRD CIRCUIT
                     ______

                       No. 15-2041
                         ______

   GROUP AGAINST SMOG AND POLLUTION, INC.,
                                  Appellant

                             v.

             SHENANGO INCORPORATED
                     ______

      On Appeal from the United States District Court
         for the Western District of Pennsylvania
              (D.C. Civil No. 2:14-cv-00595)
         District Judge: Honorable Cathy Bissoon
                          ______

     Submitted Pursuant to Third Circuit L.A.R. 34.1(a)
                    December 7, 2015

 Before: FUENTES, SHWARTZ, and VAN ANTWERPEN,
                    Circuit Judges

             (Opinion Filed: January 6, 2016)

John K. Baillie, Esq.
Group Against Smog and Pollution, Inc.
5135 Penn Ave.
Pittsburgh, PA 15221
              Counsel for Appellant

Chester R. Babst III, Esq.
James D. Miller, Esq.
Varun Shekhar, Esq.
Babst, Calland, Clements & Zomnir, P.C.
Two Gateway Center, 6th Floor
603 Stanwix Street
Pittsburgh, PA 15222
              Counsel for Appellee

Emily A. Collins, Esq.
Fair Shake Environmental Legal Services
3495 Butler Street, Suite 102
Pittsburgh, PA 15201
              Counsel for Amici Curiae Sierra Club,
              Mountain Watershed Association, Clean Air
              Council, Three Rivers Waterkeeper, and Center
              for Coalfield Justice
                      ______________

                OPINION OF THE COURT
                    ______________


VAN ANTWERPEN, Circuit Judge.

       Group Against Smog and Pollution, Incorporated
(“GASP”) filed suit against Shenango, Incorporated
(“Shenango”) in the U.S. District Court for the Western
District of Pennsylvania pursuant to the citizen suit provision




                              2
of the Clean Air Act (“Act”), 42 U.S.C. § 7604(a)(1). The
District Court granted Shenango’s motion to dismiss for lack
of subject matter jurisdiction, filed pursuant to Federal Rule
of Civil Procedure (“Rule”) 12(b)(1). The District Court
found that the administrative agencies were already
“diligently prosecuting” the Clean Air Act violations alleged
by GASP, and therefore GASP’s action was prohibited by the
diligent prosecution bar of the Act. 42 U.S.C.
§ 7604(b)(1)(B); (App. 13–14). We will affirm the judgment
of the District Court on other grounds, concluding that GASP
has failed to state a claim because administrative agencies
were “diligently prosecuting” the Clean Air Act violations
and that this prosecution “requires compliance” with the Act.
In making this determination, we conclude that the diligent
prosecution bar of the Clean Air Act is not a jurisdictional
limitation and is therefore properly dismissed through a Rule
12(b)(6) motion to dismiss for failure to state a claim upon
which relief may be granted, rather than Rule 12(b)(1).

                              I.

                     INTRODUCTION

      Shenango operates the Neville Island Coke Plant, a
coke manufacturing and by-products recovery facility in
Allegheny County, Pennsylvania.1 (App. 3). The Neville

1
   The Neville Island Coke Plant “performs destructive
distillation of coal to produce metallurgical coke and by-
products such as tar, light oil, sodium phenolate, and
ammonium sulfate. Coke oven gas . . . fuel, which is used to
underfire the coke battery and to fuel the boilers, is also
produced.” (App. 90).




                              3
Island Coke Plant is subject to National Ambient Air Quality
Standards (“NAAQS”) set by the United States
Environmental Protection Agency (“EPA”) pursuant to the
Clean Air Act. 42 U.S.C. §§ 7408–09; (App. 3–4). As part of
the Act’s encouragement of federal cooperation with state and
local governments, Pennsylvania is required to create a “state
implementation plan,” (“SIP”) detailing how it will attain and
maintain the NAAQS. 42 U.S.C. § 7410. Once the EPA
approves the SIP, it becomes binding federal law. 

In Allegheny County, the Commonwealth of Pennsylvania
delegates the authority for enforcing air pollution laws to the
Allegheny County Health Department (“ACHD”). (App. 4).
The ACHD has promulgated emissions standards that are
incorporated in the Pennsylvania SIP and are thereby binding
federal law under the Clean Air Act. See ACHD Rules and
Regulations Art. XXI. Three ACHD regulations are at issue
in this case:

      First, Section 2105.21.b.1 restricts visible
      emissions from any battery of coke ovens to no
      more than five percent . . . of the door areas of
      the operating coke ovens (the “five percent door
      emissions     standard”).     Second,    Section
      2105.21.f.3     prohibits    combustion     stack
      emissions with opacity greater than 20 percent
      for three minutes over a 60 minute period (the
      “20 percent combustion stack opacity
      standard”). Finally, Section 2105.21.f.4
      prohibits combustion stack emissions with
      opacity greater than 60 percent (the “60 percent
      combustion stack opacity standard”).

(App. 4).




                              4
        In 2012, the EPA, the Pennsylvania Department of
Environmental Protection (“DEP”), and the ACHD filed an
action in the U.S. District Court for the Western District of
Pennsylvania against Shenango claiming violations of these
three standards. (App. 4–5). The parties entered into a
Consent Decree to resolve these violations, specifically
addressing the twenty and sixty percent combustion stack
opacity standards. (Id.). The District Court entered final
judgment on this action in 2012 but retained jurisdiction “for
the purpose of modifying, construing and/or enforcing the
rights and obligations of the Parties to this Consent Decree.”
(Id. at 168–69, 174).

       In 2014, GASP sent Shenango a notice of intent to sue,
claiming violations of the same three standards. (Id. at 5). The
ACHD then filed an action against Shenango in the
Allegheny County Pennsylvania Court of Common Pleas, and
the parties entered into a Consent Order and Agreement. (Id.).
This Agreement appears to address the five percent door
emissions standard, as discussed infra, and reaffirms the 2012
Consent Decree’s approach to the twenty and sixty percent
combustion stack opacity standards. (Id.). The Court of
Common Pleas entered final judgment on this action on April
8, 2014. (Id. at 106). The ACHD retained authority with
respect to future violations and “to seek further enforcement
of this Agreement” if Shenango fails to comply. (Id. at 95).
The Consent Order and Agreement was intended to be jointly
terminated by the parties upon Shenango’s compliance with
certain conditions. (Id. at 105–06).

       On May 8, 2014, GASP filed the instant citizen suit
against Shenango in U.S. District Court, again claiming
violations of the same three emissions standards. (Id. at 6, 19–




                               5
29). Shenango moved to dismiss for lack of subject matter
jurisdiction and for failure to state a claim upon which relief
may be granted, pursuant to Rules 12(b)(1) and 12(b)(6). (Id.
at 109–10). The District Court found the issue presented to be
jurisdictional. (Id. at 6). The Court granted Shenango’s
motion to dismiss for lack of subject matter jurisdiction,
finding that GASP could not bring an action because the
ACHD was already “diligently prosecut[ing]” an action in
court against Shenango to require compliance under the Act.
(Id. at 12–14). The Court rejected two arguments raised by
GASP in opposition to the motion to dismiss: (1) that the
Consent Decrees2 do not actually require Shenango to comply
with the standards set forth in the Act; and (2) that the 2014
Consent Order and Agreement was deficient because the
parties failed to provide an opportunity for the public to
intervene or comment on the terms of the order. (Id. at 11–
13). GASP timely appealed. (Id. at 1).

                             II.3

                       DISCUSSION

       GASP raises two arguments on appeal: (1) that the
diligent prosecution bar4 should not apply because no state or

2
 We refer to the 2012 Consent Decree and 2014 Consent
Order and Agreement collectively as the “Consent Decrees.”
3
  The District Court had federal question jurisdiction pursuant
to 28 U.S.C. § 1331 through application of the citizen suit
provision in 42 U.S.C. § 7604(a)(1). We have jurisdiction to
review the final decision of the District Court pursuant to 28
U.S.C. § 1291.




                              6
administrative agency was actively “prosecuting” a civil
action in court at the time GASP filed its present citizen suit;
and (2) that the Consent Decrees from 2012 and 2014 do not
“require compliance” with the Act. (Appellant’s Br. 16–18).
In dealing with these issues we must first determine whether
the diligent prosecution bar is jurisdictional or only a claim-
processing rule. The District Court proceeded assuming the
bar was jurisdictional. (App. 6). We exercise plenary review
over the District Court’s legal conclusions. CNA v. United
States, 

, 139 (3d Cir. 2008).

       A.     Nonjurisdictional Diligent Prosecution Bar

       Amici curiae raise the issue of whether the diligent
prosecution bar is jurisdictional and appropriately decided
through a Rule 12(b)(1) motion to dismiss for lack of subject
matter jurisdiction, or whether the diligent prosecution bar is
nonjurisdictional and should be decided through a Rule
12(b)(6) motion to dismiss for failure to state a claim.5 This

4
  The diligent prosecution bar, discussed infra, is a limitation
on the Act’s citizen suit provision. It provides that a citizen
suit may not be commenced “if the Administrator or State has
commenced and is diligently prosecuting a civil action in a
court of the United States or a State to require compliance
with the standard, limitation, or order.” 42 U.S.C.
§ 7604(b)(1)(B).
5
   While Appellant did not raise this argument and has
consistently proceeded assuming the diligent prosecution bar
is jurisdictional, “federal courts have an independent
obligation to ensure that they do not exceed the scope of their
jurisdiction, and therefore they must raise and decide




                               7
dichotomy is significant, “one of considerable practical
importance for judges and litigants,” as “[b]randing a rule as
going to a court’s subject-matter jurisdiction alters the normal
operation of our adversarial system.” Henderson ex rel.
Henderson v. Shinseki, 

, 434 (2011).6

        The U.S. Supreme Court has noted, “[o]n the subject-
matter jurisdiction/ingredient-of-claim-for-relief dichotomy,
this Court and others have been less than meticulous.”
Arbaugh v. Y & H Corp., 

, 511 (2006). Arbaugh
instructs us that “[i]f the Legislature clearly states that a
threshold limitation on a statute’s scope shall count as
jurisdictional, then courts and litigants will be duly
instructed,” however “when Congress does not rank a
statutory limitation on coverage as jurisdictional, courts
should treat the restriction as nonjurisdictional in 

–16 (footnote omitted). The Court has
described this as a “readily administrable bright line rule.”



jurisdictional questions that the parties either overlook or
elect not to press.” Henderson ex rel. Henderson v. Shinseki,

, 434 (2011) (citation omitted).
6
  The differences between a motion to dismiss for lack of
subject matter jurisdiction and a motion to dismiss for failure
to state a claim include: an objection to subject matter
jurisdiction may be raised at any time, a court may raise
jurisdictional issues sua sponte, and a court may consider
evidence beyond the pleadings such as testimony and
depositions when considering a jurisdictional challenge.
Henderson ex rel 

–35; Gotha v.
United States, 

, 179 (3d Cir. 1997).




                               8
Henderson ex rel. 

(quoting

) (internal quotation marks omitted).

        In Henderson, the Supreme Court distinguished claim-
processing rules, which “seek to promote the orderly progress
of litigation by requiring that the parties take certain
procedural steps at certain specified times,” from
jurisdictional rules, which “govern[] a court’s adjudicatory
capacity, that is, its subject-matter or personal jurisdiction.”

these rules, the pivotal question as it
applies to this case “is whether Congress mandated” the
diligent prosecution bar to be “jurisdictional.” 

no “magic words” Congress must use to express that a
statutory requirement is jurisdictional. 

Instead, we
look “to the condition’s text, context, and relevant historical
treatment” in determining whether the condition is
jurisdictional. Reed Elsevier, Inc. v. Muchnick, 

,
166 (2010); see also Henderson ex rel. 

(stating the Court’s approach in Arbaugh “is suited to
capture Congress’ likely intent and also provides helpful
guidance for courts and litigants, who will be duly instructed
regarding a rule’s nature”) (internal quotation marks omitted).

      Two circuit courts have interpreted Arbaugh in the
context of a diligent prosecution bar in other acts7 and have

7
  While we rely on cases interpreting other environmental
statutes in our present analysis of the Clean Air Act, we note
that the legislative history of these other statutes explains that
their citizen suit provisions and diligent prosecution bars were
“modeled on” the relevant provisions of the Clean Air Act.
See Jeffrey G. Miller, Overlooked Issues in the “Diligent
Prosecution” Citizen Suit Preclusion, 10 Widener L. Rev. 63,




                                9
concluded the bar is nonjurisdictional. Louisiana Envtl.
Action Network v. City of Baton Rouge, 

, 745–49
(5th Cir. 2012) (per curiam) (interpreting the diligent
prosecution bar of the Clean Water Act, 33 U.S.C.
§ 1365(b)(1)(B)); Adkins v. VIM Recycling, Inc., 

, 491–92 (7th Cir. 2011) (interpreting the diligent
prosecution bar of the Resource Conservation and Recovery
Act, 42 U.S.C. § 6972(b)(1)(B)).

        This Court has addressed questions regarding the
diligent prosecution bar, not at issue here, in which the bar
was referenced as jurisdictional. In these cases, we
determined whether the administrative action in question was
taken by a “court” for the purpose of applying the diligent
prosecution bar. Student Pub. Interest Research Grp. of New
Jersey, Inc. v. Fritzsche, Dodge & Olcott, Inc., 

, 1135 (3d Cir. 1985) (“Because we find that the EPA’s
action is not a ‘court’ proceeding (and fails the first prong of
[the citizen suit bar]), we need not address the second issue of
whether      the    consent     order    constitutes    ‘diligent
prosecution.’”); see also Baughman v. Bradford Coal Co.,
Inc., 

, 219 (3d Cir. 1979) (determining that the


69 & n.31 (2003) (collecting cases); see, e.g., Gwaltney of
Smithfield, Ltd. v. Chesapeake Bay Found., Inc., 

,
62 (1987) (explaining that “both the Senate and House
Reports explicitly connected [the citizen suit provision of the
Clean Water Act] to the citizen suit provisions authorized by
the Clean Air Act”). Because the provisions serve a similar
purpose in their respective statutes, courts commonly
consider the interpretation of citizen suit provisions and
diligent prosecution bars in other statutes in deciding the case
at hand. 

& n.32.




                               10
district court had subject matter jurisdiction because the
administrative action in question was not taken by a “court”
under the diligent prosecution bar of the Clean Air Act). We
did not consider in either case whether Congress intended the
bar to be jurisdictional.8

        We conclude that the diligent prosecution bar of the
Clean Air Act is not a jurisdictional limitation. Beginning our
analysis with the text of the statute, the language of the
diligent prosecution bar does not “clearly state[] that a
threshold limitation on [its] scope shall count as
jurisdictional.” 

. The language
Congress used, “No action may be commenced,” is
mandatory, but it is not stated in terms of the court’s
adjudicatory capacity or jurisdiction. 42 U.S.C. § 7604(b); see
Henderson ex rel. 

(explaining
that the Supreme Court has rejected the notion that all
mandatory rules are jurisdictional). Congress could have
expressly made the diligent prosecution bar jurisdictional by
using the word “jurisdiction” or phrasing the language in
terms of the court’s powers. See 

(“[W]hen Congress does not rank a statutory limitation on
coverage as jurisdictional, courts should treat the restriction
as nonjurisdictional in character.”). Shenango has not
identified any specific text in the Act that indicates the
diligent prosecution        language should “count as
jurisdictional.” Beazer E., Inc. v. Mead Corp., 

,


8
  Appellee does not cite cases in which any federal court
engaged in an analysis of the diligent prosecution bar and
concluded that it is a jurisdictional limitation in the vein of
Arbaugh.




                              11
261 (3d Cir. 2008) (quoting requirements of 

–16) (internal quotation marks omitted).

        In Henderson, the Supreme Court held that a 120-day
notice requirement prior to filing an appeal to the Veterans
Court was 

. The Court
interpreted the following statutory language: “In order to
obtain review,” an appropriate person “shall file a notice of
appeal with the Court within 120 days after the date on which
notice of the decision is mailed.” 

(quoting 38
U.S.C. § 7266(a)) (internal quotation marks omitted). The
Court distinguished this from language governing Federal
Circuit review of Veterans Court decisions: “Federal Circuit
review must be obtained within the time and in the manner
prescribed for appeal to United States court of appeals from
United States district courts.” 

U.S.C.
§ 7292(a)) (internal quotation marks omitted). Because timing
requirements for taking an appeal from a district court have
long been considered jurisdictional, this latter language
clearly signaled congressional intent for Federal Circuit
review requirements to be jurisdictional. 

–39; see
Bowles v. Russell, 

, 209–14 (2007) (holding that
statutory time limits for taking an appeal are jurisdictional
based on their “longstanding treatment” as such by the
Supreme Court). The former language, at issue in Henderson,
is not framed in a manner that clearly states its intention to be
jurisdictional or references similar treatment to a clearly
jurisdictional 

. The Clean Air Act
diligent prosecution bar, like the Henderson 120-day notice
requirement, does not reference the court’s jurisdiction in any
way nor is it phrased in a way that clearly suggests it is a
jurisdictional requirement. We agree with the Seventh
Circuit’s interpretation of the citizen suit provision in the




                               12
Resource Conservation and Recovery Act that the “limits on
citizen suits appear in separate provisions that do not ‘speak
in jurisdictional terms or refer in any way to the jurisdiction
of the district courts.’” 

(quoting Zipes
v. Trans World Airlines, Inc., 

, 394 (1982)).9

        The Henderson Court also discussed the placement of
statutory provisions in determining that the notice
requirement in question was 

. The Clean Air Act title for 42 U.S.C. § 7604, “Citizen
suits,” “can aid in resolving an ambiguity in the legislation’s
text.” Immigration & Naturalization Serv. v. Nat’l Ctr. for
Immigrants’ Rights, Inc., 

, 189 (1991). Congress
further titled § 7604(a): “Authority to bring civil action;
jurisdiction,” and § 7604(b): “Notice.” That these subsections
are separately titled suggests they should be considered
separate provisions. Rather than including the diligent
prosecution bar within the exact provision granting
jurisdiction, the diligent prosecution bar is part of this
separate “Notice” provision. The “Notice” provision also
requires the citizen to notify the involved administrative
agencies at least sixty days prior to filing the citizen suit. 42
U.S.C. § 7604(b)(1)(A). This procedural rule is similar to the
claim-processing rule in Henderson. 

(holding that the 120-day notice requirement for filing an
appeal with the Veteran’s Court “does not have jurisdictional

9
   While Appellee appears to object to the approach of
interpreting Arbaugh in the context of an environmental case,
we have already applied Arbaugh in concluding that the “civil
action” requirement of the Comprehensive Environmental
Response, Compensation, and Liability Act of 1980 is not a
jurisdictional threshold. Beazer E., 

–61.




                               13
attributes”).10 The placement of the diligent prosecution bar
within the “Notice” subsection suggests the diligent
prosecution bar is also a claim-processing rule. Louisiana
Envtl. Action 

(“The placement of
the ‘diligent prosecution’ bar in the ‘Notice’ section,
alongside a typical claim-processing rule, suggests that
Congress intended the ‘diligent prosecution’ bar to be a
claim-processing rule.”).

       Our language in Student Public Interest Research
Group and Baughman does not control. Neither case
specifically addresses the question of jurisdiction, but rather
both cases held that the administrative agency involved was
not a “court” for the purpose of applying the diligent
prosecution bar. Student Pub. Interest Research Grp. of New
Jersey, 

; 

.

10
   Appellee relies on Hallstrom v. Tillamook County for the
proposition that “a plaintiff’s failure to abide by the identical
notice requirements under the Resource Conservation and
Recovery Act . . . warranted dismissal for lack of subject
matter jurisdiction.” (Appellee’s Br. 48) (citing 

,
23, 31 (1989)). We believe Appellee’s reliance on this case is
misplaced, as the Hallstrom Court stated, “[t]he parties have
framed the question presented in this case as whether the
notice provision is jurisdictional or procedural. In light of our
literal interpretation of the statutory requirement, we need not
determine whether § 6972(b) is jurisdictional in the strict
sense of the 

. Therefore, the Court did
not determine that this notice provision is jurisdictional. In
fact, Hallstrom was decided before Arbaugh and Henderson,
which themselves further defined the contours of
jurisdictional provisions.




                               14
The approach taken in these cases predates the guidance set
forth in Arbaugh. As the Supreme Court articulated, “the
relevant question here is not” whether the diligent prosecution
bar “itself has long been labeled jurisdictional, but whether
the type of limitation that” the diligent prosecution bar
“imposes is one that is properly ranked as jurisdictional
absent an express designation.” Reed Elsevier, 

.

        In terms of the context of the diligent prosecution bar
and the Supreme Court’s “interpretation of similar
provisions,” the diligent prosecution bar is analogous to other
mandatory, threshold requirements the Supreme Court has
deemed nonjurisdictional in addition to the notice
requirement in Henderson. See 

(holding that the
Copyright Act’s requirement that copyright holders register
their work before suing for copyright infringement is not a
jurisdictional requirement); 

& n.6 (indicating that
the Supreme Court in Jones v. Bock, 

, 216–17
(2007) treated the administrative exhaustion requirement of
the Prison Litigation Reform Act of 1995 as
nonjurisdictional); 

(holding that “a
timely charge of discrimination with the [Equal Employment
Opportunity Commission] is not a jurisdictional prerequisite
to suit in federal court”).

       Appellee presents legislative history in which the word
“jurisdiction” was used in conjunction with the diligent
prosecution bar. See S. Rep. No. 91-1196, at 37 (1970) (“[I]f
the court viewed the agency action as inadequate, it would
have jurisdiction to consider the citizen action
notwithstanding any pending agency action.”). This language
does not convince us that Congress intended the diligent




                              15
prosecution bar to be jurisdictional. It does appear that
Congress intended the diligent prosecution bar to be a
mandatory condition precedent to filing a citizen suit.
Nevertheless as we have discussed, the actual text of the
statute does not reference in any way or clearly suggest its
intention to be jurisdictional, and its placement next to a
claim-processing timing rule suggests it is a nonjurisdictional
requirement. See Reed Elsevier, 

(stating
that the Supreme Court has “treated as nonjurisdictional other
types of threshold requirements that claimants must complete,
or exhaust, before filing a lawsuit”).11

        Congress did not clearly state or mandate that the
diligent prosecution bar of the Clean Air Act “shall count as
jurisdictional.” 

–16. The text and
placement of the specific provision reflect congressional
intent that the limitation is a mandatory claim-processing rule
designed “to promote the orderly progress of litigation” by
ensuring the case is not already being diligently prosecuted.
Henderson ex rel. 

. It is
particularly instructive that the Supreme Court has held
similar mandatory threshold requirements are not
jurisdictional limitations. We therefore conclude that the
diligent prosecution bar of the Clean Air Act is
nonjurisdictional.


11
   There is no historical treatment of the diligent prosecution
bar to discuss because the Supreme Court has not directly
addressed the jurisdictional nature of § 7604(b)(1)(B). Thus,
we lack “a long line of [the Supreme] Court’s decisions” to
instruct our analysis. Henderson ex rel. 

(citations omitted) (internal quotation marks omitted).




                              16
      B.      Analysis

        The Clean Air Act provides that citizens may
commence a civil action on their own behalf against a person
or entity alleged to be in violation of an emission standard or
limitation set forth under the Act. 42 U.S.C. § 7604(a)(1).
This citizen suit provision is subject to an important
limitation, at issue in the present case:

      No action may be commenced—
       ...
      if the Administrator or State has commenced
      and is diligently prosecuting a civil action in a
      court of the United States or a State to require
      compliance with the standard, limitation, or
      order, but in any such action in a court of the
      United States any person may intervene as a
      matter of right.

 

We have commented that there is
“extensive legislative history to establish that Congress
intended citizen suits to both goad the responsible agencies to
more vigorous enforcement of the anti-pollution standards
and, if the agencies remained inert, to provide an alternate
enforcement mechanism.” 

.
However, we have also noted that the “same legislative
history also indicates ‘that Congress intended to provide for
citizens’ suits in a manner that would be least likely to clog
already burdened federal courts and most likely to trigger
governmental action which would alleviate any need for
judicial relief.’” 

of Highland Park v. Train,

, 690–91 (7th Cir. 1975)); see also Gwaltney of
Smithfield, Ltd. v. Chesapeake Bay Found., Inc., 

,




                              17
60 (1987) (“The bar on citizen suits when governmental
enforcement action is under way suggests that the citizen suit
is meant to supplement rather than to supplant governmental
action.”). We consider these policies in assessing the
Appellant’s arguments.

              1.      Standard of Review

       We must decide whether the District Court correctly
determined that GASP could not advance a citizen suit
because of the diligent prosecution bar. We exercise plenary
review over the District Court’s legal conclusions. 

. In so doing, we must ask whether GASP has
failed to state a claim. To survive a 12(b)(6) motion to
dismiss for failure to state a claim,12 “a complaint must
contain sufficient factual matter, accepted as true, to ‘state a
claim to relief that is plausible on its face.’” Ashcroft v. Iqbal,

, 678 (2009) (quoting Bell Atl. Corp. v.
Twombly, 

, 570 (2007)). “In this review, courts
accept all factual allegations as true, construe the complaint in
the light most favorable to the plaintiff, and determine
whether, under any reasonable reading of the complaint, the

12
   Although this case was decided by the District Court as a
12(b)(1) motion to dismiss for lack of subject matter
jurisdiction, consistent with our 

, regarding
the nonjurisdictional nature of § 7604(b), we will decide this
case under 12(b)(6) standards. We note Shenango’s initial
motion to dismiss was based on both 12(b)(1) and 12(b)(6),
and the District Court should have used the 12(b)(6) standard.
We may affirm the judgment of the District Court for any
reason supported by the record. Brightwell v. Lehman, 

, 191 (3d Cir. 2011).




                                18
plaintiff may be entitled to relief.” Eid v. Thompson, 

, 122 (3d Cir. 2014) (quoting Phillips v. Cnty. of
Allegheny, 

, 233 (3d Cir. 2008)) (internal
quotation marks omitted).

          We may review the 2012 Consent Decree and 2014
Consent Order and Agreement in deciding a 12(b)(6) motion
to dismiss for failure to state a claim, as “it is the usual
practice for a court to consider only the allegations contained
in the complaint, exhibits attached to the complaint and
matters of public record.” City of Pittsburgh v. W. Penn
Power Co., 

, 259 (3d Cir. 1998) (citation
omitted); accord Pension Benefit Guar. Corp. v. White
Consol. Indus., Inc., 

, 1196 (3d Cir. 1993).
“Courts have defined a public record, for purposes of what
properly may be considered on a motion to dismiss, to include
. . . letter decisions of government agencies . . . and published
reports of administrative bodies.” Pension Benefit Guar.

(citations omitted); see also Schmidt
v. Skolas, 

, 249 (3d Cir. 2014) (determining that
Securities and Exchange Commission filings are also matters
of public record appropriately considered in reviewing a Rule
12(b)(6) motion to dismiss). Further, courts may consider
exhibits attached to a defendant’s motion to dismiss if it is
“an undisputedly authentic document” and “plaintiff’s claims
are based on the document.” Pension Benefit Guar. 

.

       The 2012 Consent Decree and 2014 Consent Order
and Agreement are public records as they are court decisions
and final judgments. Further, the 2014 Consent Order and
Agreement was an exhibit attached to the complaint. Portions
of the 2012 Consent Decree were attached to the complaint,




                               19
but the full document was only attached to the defendant’s
motion to dismiss. The 2012 Consent Decree is undisputedly
authentic as neither party nor the District Court has
questioned its authenticity. GASP’s claims were based on the
Consent Decree, specifically GASP’s contention that the
2012 Consent Decree does not require compliance with the
Act. Our reliance on these Consent Decrees in the context of
a Rule 12(b)(6) motion is appropriate.

              2.     Were the agencies “prosecuting” an
action?

        Appellant argues that the term “prosecuting” in the
diligent prosecution bar “requires an agency enforcement
action to be pending in court if it is to bar a citizen suit.”
(Appellant’s Br. 26). The argument follows that because the
2012 and 2014 civil actions culminated in final judgments,
they were not pending before a court when GASP filed its
citizen suit, and therefore the Consent Decrees from these
actions could not support a diligent prosecution bar. This
issue is one of first impression in this Court. We have little
difficulty in holding that when a state or federal agency
diligently prosecutes an underlying action in court, the
diligent prosecution bar will prohibit citizen suits during the
actual litigation as well as after the litigation has been
terminated by a final judgment, consent decree, or consent
order and agreement. In addition, when a state or federal
agency diligently pursues an ongoing consent decree that may
be modified by the parties and enforced by the agency, the
diligent prosecution bar will prohibit citizen suits. We note
that the parties in the present case were still able to modify or
enforce the 2012 Consent Decree and 2014 Consent Order
and Agreement and the District Court correctly found that the




                               20
ACHD was “diligently prosecuting” the case by taking
actions that furthered the goals of these Consent Decrees,
which was compliance with the regulations.

         In addition, case law from other circuit courts supports
the proposition that if the underlying case was diligently
pursued, the diligent prosecution bar will apply even though
an agency has entered into a consent decree with a polluter
following a civil or administrative action. See N. & S. Rivers
Watershed Ass’n, Inc. v. Town of Scituate, 

, 556
(1st Cir. 1991) (“The focus of the statutory bar to citizen’s
suits is not on state statutory construction, but on whether
corrective action already taken and diligently pursued by the
government seeks to remedy the same violations as
duplicative civilian action.”); see also Piney Run Pres. Ass’n
v. Cnty. Comm’rs. of Carroll Cnty., Md., 

, 459
(4th Cir. 2008) (stating that “when presented with a consent
decree” following a completed administrative agency
proceeding, “we must be particularly deferential to the
agency’s expertise”); Karr v. Hefner, 

, 1197–
98 (10th Cir. 2007) (determining that a citizen suit was barred
because “the EPA’s prosecution,” a consent decree previously
entered into, “was diligent”); Supporters to Oppose Pollution,
Inc. v. Heritage Grp., 

, 1324 (7th Cir. 1992)
(stating that the diligent prosecution bar in the Resource
Conservation and Recovery Act “permits a follow-on private
suit if the public suit was not prosecuted diligently. But if the
agency prevails in all respects, that is the end . . . .”). Courts
have concluded, in cases similar to ours, that consent decrees
already entered into by administrative agencies and polluting
entities were capable of constituting diligent prosecutions.




                               21
        Within this Circuit, we note that a district court has
determined that the diligent prosecution bar applied to a
consent order in Citizens for Clean Power v. Indian River
Power, LLC, 

, 358 (D. Del. 2009). An
environmental organization sent a notice of intent to sue to
the defendant, prompting the administrative agencies to file
suit against the defendant and propose a consent order. 

On February 13, 2009, the Delaware Superior Court
entered the consent order, and on February 26, 2009, the
organization filed its citizen suit against the same defendant.

The court found that the agency “diligently
prosecuted its suit against defendant, which preclude[ed]
plaintiff’s suit under 42 U.S.C. § 7604(b)(1)(B).” 

        Appellant relies on cases that “employ[] a literal,
inflexible interpretation compelled by the clear and
unambiguous language of the Act.” Friends of Milwaukee’s
Rivers v. Milwaukee Metro. Sewerage Dist., 

,
754 (7th Cir. 2004). The U.S. District Court for the Eastern
District of Texas compared the date the plaintiffs’ complaint
was filed with the date final judgment was entered in the
pending case, finding it “clear the state of Texas was actually
prosecuting [an applicable civil action] on the date the
plaintiffs filed their original complaint.” Glazer v. Am.

13
   In Citizens for Clean Power, the District Court did not
squarely address the present argument of whether
“prosecuting” includes consent decrees from civil actions that
resulted in a final judgment. Just as the District Court in this
case proceeded, the Citizens for Clean Power case impliedly
answered this question affirmatively, evidenced by its
analysis of whether the prosecution was “diligent.” 636 F.
Supp. 2d at 357–58.




                              22
Ecology Envtl. Servs. Corp., 

, 1035 (E.D.
Tex. 1995). Appellant additionally relies on cases from within
this Circuit where a district court applied a literal and
grammatical analysis to conclude a diligent prosecution bar
did not apply. United States v. Sunoco, Inc. 

, 665 (E.D. Pa. 2007) (“The statute speaks in the present
and present perfect tense: it only applies if [the agency] ‘has
commenced’ and ‘is diligently prosecuting’ a civil action in
court; or if it ‘is in litigation’ . . . .”); Pub. Interest Research
Grp. of New Jersey, Inc. v. GAF Corp., 

, 949
(D.N.J. 1991) (stating that the statute “speaks in the present
tense” and it “does not state that a citizen suit is barred if a
state has prosecuted an action with respect to such violations,
although Congress could have easily so provided”).

         We reject cases cited by Appellant which rely on a
literal, inflexible, or grammatical interpretation. We conclude
instead that if a state or administrative agency diligently
prosecuted a suit, the presence of a final judgment, consent
decree, or consent order and agreement will not prevent
application of the diligent prosecution bar.

       The circumstances of this case show ongoing diligent
prosecution. The Consent Decrees provide a means to seek
court intervention in the event of continuing violations. (App.
105–06, 168–69). This provides a speedy and efficient means
to enforce an order mandating compliance with the
regulations without having to initiate a separate lawsuit.
Moreover, the 2012 Consent Decree includes a “Continuing
Jurisdiction” provision, providing that the District Court
“shall retain jurisdiction from the date of entry of this
Consent Decree through the date of termination of this Decree
for the purpose of modifying, construing and/or enforcing the




                                23
rights and obligations of the Parties to this Consent Decree.”
(App. 168). The Decree defines “termination” by requiring
Shenango to file a motion with the Court demonstrating its
compliance with the terms of the Decree. (Id. at 169–70). The
2014 Consent Order and Agreement, in a section titled
“Effective Date and Termination,” states that “[i]t is the
intention of the parties that they will move jointly to
terminate this Agreement” either three years from the
effective date of the Agreement, or once Shenango
demonstrates sufficient compliance with the terms of the
Order and Agreement, whichever is sooner. (Id. at 105–06).
No such motion was filed when GASP filed its citizen suit.
The ACHD also retains its authority “to seek further
enforcement of this Agreement in the event Shenango fails to
successfully comply with its terms and conditions.” (Id. at
95). Both the 2012 Consent Decree and 2014 Consent Order
and Agreement utilize ongoing monitoring and recording of
Shenango’s emissions, as well as allow ACHD the right to
inspect Shenango’s facilities or record emissions. (Id. at 99–
101) (2014 Consent Order and Agreement); (Id. at 130–33,
145–46) (2012 Consent Decree).

       It is undisputed by their own terms that the 2012
Consent Decree and 2014 Consent Order and Agreement
were still in effect when GASP filed its citizen suit.
Therefore, although the actions culminated in final
judgments, the principal enforcement mechanism against
Shenango for these Clean Air Act violations remained in
place.

       We are reminded that the legislative history of the
citizen suit provision of the Clean Water Act suggests that
“the citizen suit is meant to supplement rather than to




                             24
supplant governmental action.” Gwaltney of Smithfield, 

. Legislative history surrounding the citizen suit
provision of the Clean Water Act provides that “[t]he
Committee intends the great volume of enforcement actions
be brought by the State” and that the citizen suit is
appropriate only “if the Federal, State, and local agencies fail
to exercise their enforcement responsibility.” S. Rep. No. 92-
414, at 64 (1971); Gwaltney of Smithfield, 

.

       Appellant is correct that no circuit court has squarely
addressed whether the term “prosecuting” in the diligent
prosecution bar of the Clean Air Act requires an agency
enforcement action to be pending in court when the citizen
suit is filed. Courts have impliedly answered this question
through their decisions on whether to enforce a diligent
prosecution bar when faced with a recent consent decree. Our
decision hinges on the circumstances of this case and the
ongoing vitality of these Consent Decrees, specifically the
parties’ ability to modify or enforce the terms of the Consent
Decrees.

            3.     Does       the     prosecution     “require
compliance” with the Act?

       The Clean Air Act states that diligent prosecution must
“require compliance with the standard, limitation, or order” of
the Act. 42 U.S.C. § 7604(b)(1)(B). We note that the
government’s prosecution is entitled to great deference. 

(quoting Williams Pipe Line Co. v. Bayer
Corp., 

, 1324 (S.D. Iowa 1997)); Friends of
Milwaukee’s 

; see also N. & S. Rivers
Watershed Ass’n, 

(“Where an agency




                              25
has specifically addressed the concerns of an analogous
citizen’s suit, deference to the agency’s plan of attack should
be particularly favored.”). The question of whether the
prosecution is diligent is related to the question of whether
the prosecution requires compliance with the Act, as both
involve the merits of the alleged prosecution. Therefore, we
are mindful that “when presented with a consent decree we
must be particularly deferential to the agency’s expertise.”
Piney Run Pres. 

.

       GASP alleges that the 2012 Consent Decree and 2014
Consent Order and Agreement do not require compliance
with the Act with respect to the twenty and sixty percent
combustion stack opacity requirements and the five percent
door emissions violations. GASP further argues that because
Shenango has continued to violate these provisions since the
effective date of the Consent Decree and Consent Order and
Agreement the Consent Decrees do not require compliance
with the Act. We agree with the District Court that “[o]n
balance, the 2012 and 2014 [Consent Decrees] demonstrate
that the ACHD is in the process of diligently prosecuting and
enforcing the same violations alleged in the instant lawsuit.”
(App. 9).

       We first consider the contention that the ACHD’s
actions in 2012 and 2014 do not require compliance with the
sixty percent and twenty percent combustion stack opacity
requirements. The 2012 Consent Decree addresses these
violations. In a section titled “Compliance With Applicable
Laws,” the Decree states that “[n]othing contained in this
Consent Decree shall be construed to relieve Defendant of
obligations to comply with all applicable federal, state, and
local regulations, statutes, and laws, including but not limited




                              26
to” the Clean Air Act, the Pennsylvania SIP, and the ACHD
Rules and Regulations. (App. 164). This Consent Decree
specifically requires compliance with both the twenty percent
and sixty percent combustion stack opacity standards:

       Defendant shall not operate, or allow to be
       operated, any battery of coke ovens at the
       Facility in such manner that, at any time,
       emissions from any coke oven battery
       combustion stack at the Facility (including
       emissions from the COB S-1 combustion
       stack):
        ...
       b.      equal or exceed any opacity of 20% for a
       period or periods aggregating in excess of three
       (3) minutes in any 60 minute period; or
       c.      equal or exceed any opacity of 60% at
       any time.

(App. 126–27). The Decree was still effective when GASP
filed its citizen suit, as the District Court retained jurisdiction.
(App. 168).

       We next consider GASP’s contention that the Consent
Decrees do not require compliance with the five percent door
emissions standard. The 2014 Consent Order and Agreement
addresses the five percent door emissions violations. The
Consent Order and Agreement states that “the ACHD has
found and determined . . . . [e]xcess visible emissions from
the door areas of Battery S-1 in violation of Section
2105.21.b.1,” which is the five percent door emissions
standard of the ACHD Rules and Regulations. (App. 4, 89–
90). In addition to assessing a civil penalty for these




                                27
violations, the Agreement set forth measures to address the
five percent door emissions violations, “to enhance the
control of . . . coke oven door emissions” and implement
“[d]oor inspection procedures [that] have been revised to
include a door change-out program of 1 to 2 doors/week.”
(App. 94, 102). This Agreement was still effective when
GASP filed its citizen suit and the ACHD retained the
authority “to seek further enforcement of this Agreement.”
(App. 95, 105–06).

        The 2012 Consent Decree and 2014 Consent Order
and Agreement adequately set forth ACHD’s approach with
respect to these three Clean Air Act violations at issue with
Shenango which include monitoring the violator, providing
for penalties in the event of violations, and requiring the
violator to bear the cost of improvement. Concluding that this
approach does not require compliance with the Act when the
Consent Decrees specifically reference and address these
three violations would question the agency’s expertise and
contradict the accepted practice of giving deference to the
diligence of the agency’s prosecution. GASP’s apparent
dissatisfaction with the 2012 Consent Decree led to a
subsequent civil action and the 2014 Consent Order and
Agreement. Taken together, these Consent Decrees address
GASP’s contentions. “Merely because the State may not be
taking the precise action Appellant wants it to or moving with
the alacrity Appellant desires does not entitle Appellant to
injunctive relief.” N. & S. Rivers Watershed Ass’n, 

. Therefore, we will affirm the District Court’s
finding that ACHD’s diligent prosecution “requires
compliance” with the Act.

                             III.




                             28
                        SUMMARY

       In deciding this case, we have determined that the
diligent prosecution bar of the Clean Air Act is a claim-
processing rule, not a jurisdictional limitation, and should
have been dealt with under Rule 12(b)(6) rather than Rule
12(b)(1). GASP has failed to state a cause of action in its
citizen suit because of the diligent prosecution bar. The
ACHD diligently prosecuted the same three Clean Air Act
violations GASP now attempts to litigate. The ACHD entered
into a Consent Decree and Consent Order and Agreement
with Shenango which were still in effect when GASP filed its
citizen suit. ACHD’s prosecution requires compliance with
the Act. We hold that when a state or federal agency
diligently prosecutes an underlying action in court, the
diligent prosecution bar will prohibit citizen suits during the
actual litigation as well as after the litigation has been
terminated by a final judgment, consent decree, or consent
order and agreement. In addition, when a state or federal
agency diligently pursues an ongoing consent decree that may
be modified by the parties and enforced by the agency, the
diligent prosecution bar will prohibit citizen suits.

       Accordingly, we will affirm the District Court’s Order
granting Shenango’s motion to dismiss, albeit for somewhat
different reasons.




                              29