                                                                  FILED
                                                      United States Court of Appeals
                                     PUBLISH                  Tenth Circuit

                    UNITED STATES COURT OF APPEALS             April 10, 2020

                                                         Christopher M. Wolpert
                                 TENTH CIRCUIT               Clerk of Court


JON C. CALDARA; BOULDER RIFLE
CLUB, INC.; GENERAL COMMERCE,
LLC; TYLER FAYE; MARK RINGER,

      Plaintiffs - Appellants,
v.                                               No. 18-1421

CITY OF BOULDER; JANE S.
BRAUTIGAM, in her official capacity as
City Manager of the City of Boulder;
GREGORY TESTA, in his official
capacity as Chief of Police of the City of
Boulder; and JOHN DOES 1-10,

      Defendants - Appellees,

AARON BROCKETT, in his official
capacity as Mayor Pro Tem of the City of
Boulder; CYNTHIA A. CARLISLE, in
her official capacity as Boulder City
Council Member; JILL ADLER GRANO,
in her official capacity as Boulder City
Council Member; and JOHN DOES 1-10;
SUZANNE JONES, in her official
capacity of Mayor of the City of Boulder;
LISA MORZEL, in her official capacity
of Boulder City Council Member;
MIRABAI KUK NAGLE, in her official
capacity as Boulder City Council
Member; SAMUEL P. WEAVER, in his
official capacity as Boulder City Council
Member; ROBERT YATES, in his
official capacity as Boulder City Council
Member; MARY D. YOUNG, in her
  official capacity as Boulder City Council
  Member,

         Defendants.



                     Appeal from the United States District Court
                             for the District of Colorado
                         (D.C. No. 18-cv-1211-MSK-MEH)


Cody J. Wisniewski, Mountain States Legal Foundation (Zhonette M. Brown, Mountain
States Legal Foundation, with him on the briefs), Lakewood, Colorado, for Plaintiffs-
Appellants.

Robert Reeves Anderson, Arnold & Porter Kaye Scholer, Denver, Colorado (Timothy R.
MacDonald, Evan M. Rothstein, and Patrick B. Hall, Arnold & Porter Kaye Scholer,
Denver, Colorado; and Thomas A. Carr and Luis A. Toro, Boulder City Attorney’s
Office, Boulder, Colorado, with him on the brief), for Defendants-Appellees.


Before HARTZ, SEYMOUR, and MATHESON, Circuit Judges.


SEYMOUR, Circuit Judge.



       Plaintiffs are citizens of the City of Boulder and entities with various interests in

the sale or possession of firearms within the city. They filed suit against the City of

Boulder and several of its officials, alleging that Boulder City Ordinances 8245 and 8259

violate the U.S. Constitution, the Colorado State Constitution, and Colorado state

statutes, Colo. Rev. Stat. §§ 29-11.7-102 & 103. The district court abstained and stayed

the proceedings pending resolution of the state law preemption question in state court.




                                              2
Caldera v. City of Boulder, 341 F. Supp. 3d 1241 (D. Colo. 2018). Plaintiffs appeal, and

we affirm.

                                              I.

         On May 15, 2018, the Boulder City Council unanimously passed Ordinance 8245

(“the ordinance”),1 which amended the Boulder Revised Code to prohibit the sale or

possession of “assault weapons”2 and large-capacity ammunition magazines within the


1
  Subsequent to passing Ordinance 8245, the City of Boulder enacted Ordinance 8259 on
June 19, 2018, which amends and clarifies some of the provisions of Ordinance 8245.
The district court found that Ordinance 8259 did not “fundamentally change the thrust of
the prior Ordinance” and plaintiffs do not appeal that finding. Caldera v. City of Boulder,
341 F. Supp. 3d 1241, 1242 (D. Colo. 2018). All references to “the ordinance” are to
Ordinance 8245 with the 8259 changes included.
2
    The ordinance provides the following definition for “assault weapon”:
     (a) All semi-automatic center-fire rifles that have the capacity to accept a detachable
         magazine and that have any of the following characteristics:
         (1) A pistol grip or thumbhole stock.;
         (2) A folding or telescoping stock; or
         (3) Any protruding grip or other device to allow the weapon to be stabilized with
             the non-trigger hand.
     (b) All semi-automatic center-fire pistols that have any of the following
         characteristics:
         (1) Have the capacity to accept a magazine other than in the pistol grip; or
         (2) Have a secondary protruding grip or other device to allow the weapon to be
           stabilized with the non-trigger hand.
     (c) All semi-automatic shotguns that have any of the following characteristics:
         (1) A pistol grip or thumbhole stock;
         (2) Any feature capable of functioning as a protruding grip that can be held by the
           non-trigger hand;
         (3) A folding telescoping stock;
         (4) A fixed magazine capacity in excess of 5 rounds; or
         (5) The capacity to accept a detachable magazine.
     (d) Any firearm which has been modified to be operable as an assault weapon as
         defined herein.
     (e) Any part or combination of parts designed or intended to convert a firearm into an
         assault weapon, including any combination of parts from which an assault weapon
                                               3
City of Boulder. The ordinance also raises the legal age for possession of firearms from

eighteen to twenty-one. The City of Boulder is a home-rule municipality under the

Colorado Constitution, which grants Boulder the authority to pass ordinances in “local

and municipal matters” that supersede “any law of the state in conflict therewith.” Colo.

Const. art. XX, § 6. Boulder passed the ordinance pursuant to its home-rule authority

under the Colorado Constitution.

       Plaintiffs filed this law suit challenging the ordinance under Colorado state law

and the U.S. Constitution. They contend the ordinance is preempted by Colo. Rev. Stat.

§§ 29-11.7-102 & 103. Section 29-11.7-102 limits the information that local

governments may retain about guns and gun owners. Section 29-11.7-103 provides that

“[a] local government may not enact an ordinance, regulation, or other law that prohibits

the sale, purchase, or possession of a firearm that a person may lawfully sell, purchase, or

possess under state or federal law.” Plaintiffs also contend the ordinance violates the

First, Second, Fifth, and Fourteen Amendments to the U.S. Constitution, as well as

provisions of the Colorado Constitution.

       Shortly after plaintiffs filed this action, other individuals and entities filed suit in

state court in Boulder County challenging this same ordinance. Chambers v. City of

Boulder, No. 2018-CV-30581 (Colo. D. Ct., Boulder Cty. filed June 14, 2018)



       may be readily assembled if those parts are in the possession or under the control
       of the same person.

   Aplt. App. at 45.

                                               4
(Complaint at 1). Because of the uncertain state law issue in this case, the district court

here decided to abstain under the Supreme Court’s precedent in Railroad Commission of

Texas v. Pullman Co., 312 U.S. 496 (1941). The district court stayed federal proceedings

pending a determination by the Colorado state court as to whether the ordinance is

preempted by Colorado statutes §§ 29-11.7-102 & 103. Plaintiffs appeal the district

court’s determination.

                                            II.

       Plaintiffs argue that the district court erred in abstaining under Pullman. The

Pullman doctrine is a “narrow exception” to the federal courts’ general duty to decide

cases and “is used only in exceptional circumstances.” Kan. Judicial Review v. Stout,

519 F.3d 1107, 1119 (10th Cir. 2008) (citation omitted). The policy underlying Pullman

abstention is that federal courts should avoid “premature constitutional adjudication,”

Babbitt v. United Farm Workers Nat’l Union, 442 U.S. 289, 306 (1979) (citation

omitted), and the risk of rendering advisory opinions, Moore v. Sims, 442 U.S. 415, 428

(1979) (“[T]he Pullman concern [is] that a federal court will be forced to interpret state
law without the benefit of state-court consideration and . . . render[ ] the federal-court

decision advisory and the litigation underlying it meaningless.”) (citation omitted).

Pullman avoids “federal-court error in deciding state-law questions antecedent to federal

constitutional issues,” by allowing for parties to adjudicate disputes involving “unsettled

state-law issues” in state courts. Arizonans for Official English v. Arizona, 520 U.S. 43,

76 (1997).



                                              5
       In reviewing the district court’s decision to abstain under Pullman, we first

“review de novo whether the requirements for Pullman abstention have been met.” Kan.

Judicial Review, 519 F.3d at 1114–15 (citation omitted). This is so because “[t]he

question of the clarity of state law is essentially legal in nature.” Vinyard v. King, 655

F.2d 1016, 1019 (10th Cir. 1981) (citation omitted).

       If we determine that the requirements for abstention under Pullman are met, we

then review for abuse of discretion the district court’s decision to abstain. See Harman v.

Forssenius, 380 U.S. 528, 534 (1965) (“In applying the doctrine of abstention, a federal

district court is vested with discretion to decline to exercise or to postpone the exercise of

its jurisdiction in deference to state court resolution of underlying issues of state law.”)

(citation omitted); see also Vinyard, 655 F.2d at 1018 (“[If] the particular case falls

within the ambit of Pullman . . . , [the court] must then make a discretionary

determination . . . as to whether abstention is in fact appropriate.”) (citation omitted).

Abuse of discretion occurs “only when [the district court] makes a clear error of

judgment, exceeds the bounds of permissible choice, or when its decision is arbitrary,

capricious or whimsical, or results in a manifestly unreasonable judgment.” Liberty Mut.

Fire Ins. Co. v. Woolman, 913 F.3d 977, 990 (10th Cir. 2019) (internal quotation marks

and citation omitted). We apply these principles to plaintiffs’ claims on appeal.

                                           A.

       Plaintiffs contend the requirements for Pullman abstention are not satisfied. We

have recognized three requirements that must be met to justify abstention under Pullman:



                                                6
       (1) an uncertain issue of state law underlies the federal constitutional claim;
       (2) the state issues are amenable to interpretation and such an interpretation
       obviates the need for or substantially narrows the scope of the
       constitutional claim; and (3) an incorrect decision of state law by the
       district court would hinder important state law policies.

Lehman v. City of Louisville, 967 F.2d 1474, 1478 (10th Cir. 1992) (citation omitted).

       A complex issue of state law underlies the federal constitutional claims in this

case. Both sides agree that the Boulder City Ordinance conflicts with Colorado statutes

§§ 29-11.7-102 & 103. As the district court recognized, however, the statutes “rub[] up

against Art. XX, Section 6 of the Colorado constitution,” which grants municipalities

regulatory authority over the General Assembly in matters of local and municipal concern

(referred to as the “home rule” provision). Caldera, 341 F. Supp. 3d at 1244. In a home-

rule jurisdiction where “a home rule ordinance . . . and a state statute conflict with respect

to a local matter, the home rule provision supersedes the conflicting state

provision.” City & Cty. of Denver v. State, 788 P.2d 764, 767 (Colo. 1990) (citation

omitted). On the other hand, municipal ordinances that deal with matters of statewide

concern and conflict with state law are preempted, unless otherwise authorized by the

constitution or state statute. Id. Finally, in “matters of mixed local and state concern, a

charter or ordinance provision of a home rule municipality may coexist with a state

statute as long as there is no conflict, but in the event of a conflict the state statute

supersedes the conflicting [ordinance] provision.” Id.

       The determinative issue therefore is whether the challenged provisions of the

Boulder City Ordinance regulate matters of purely local or statewide concern, or a mix of

both. That issue implicates state, not federal law, and is uncertain under Colorado law.

                                                7
The question, as far as we are aware, has been addressed only one time by Colorado state

courts, see City & Cty. of Denver v. State, No. 03-CV-3809, 2004 WL 5212983 (Colo. D.

Ct., Denver Cty. Nov. 5, 2004). There, the City of Denver had in place several

ordinances restricting the sale and use of firearms in Denver city limits. Id. at *1. The

City sought a declaratory judgment that the ordinances were not preempted by recently

passed state statutes that “identif[ied] control of firearms as a state interest,” 3 or

alternatively that the Colorado statutes were unconstitutional under the home rule

amendment to the extent that they preempt local laws. Id. The district court considered

each provision individually to determine whether the provision regulated matters of

“purely local, purely state or mixed concern,” and concluded that several provisions

related to matters of purely local concern. Id. at *2, *15–17. The State appealed the

decision to the Colorado Supreme Court, which split evenly on the issue of whether the

ordinances were preempted, thereby affirming the decision of the Denver District Court.4

State v. City & Cty. of Denver, 139 P.3d 635, 636 (Colo. 2006) (3-3 decision, J. Eid not

participating).

       Plaintiffs maintain that the first Pullman factor is not satisfied because the

Colorado district court decision in City & Cty. of Denver provides certainty in addressing




3
 The statutes at issue in City and County of Denver were also Colo. Rev. Stat.
§§ 29-11.7-102 & 103.
4
  Colorado Appellate Rule 35(b) provides that “[w]hen the supreme court acting en banc
is equally divided in an opinion, the judgment being appealed will stand affirmed.”

                                                8
the issue.5 They contend that “trial court interpretations . . . constitute a ruling on a

question of state law that is binding on [the Court].” City of Houston v. Hill, 482 U.S.

451, 470 (1987) (quotation marks and citation omitted). In Hill, the plaintiff filed a civil

rights action after he was arrested several times for violating a city ordinance that

proscribed “interrupt[ing] any policeman in the execution of his duty” and he was

subsequently acquitted. Id. at 454–55. The district court held that the ordinance had not

been unconstitutionally applied. When the Court of Appeals declined to abstain and held

en banc that the statute was overbroad, Hill v. City of Houston, 789 F.2d 1103, 1113 (5th

Cir. 1986), the city appealed. The Supreme Court denied abstention under Pullman based

upon the fact that the Houston Municipal Courts had applied the city ordinance on

numerous occasions. Hill, 482 U.S. at 469–70. The Court held that the ordinance was

overbroad. Id. at 467.

       Unlike in Hill, however, the Colorado Supreme Court previously had occasion to

review the issue on appeal here and split evenly in response. See City & Cty. of Denver,

139 P.3d at 636. In these circumstances, we agree with the district court that “it is hard to

conceive of a more potent way of demonstrating” uncertainty under Pullman than “the




5
  Plaintiffs also assert that the district court should not have engaged in the Pullman
analysis without a more thorough factual record in order “to determine the extent of the
issues in the case and to frame which issues, if any, require abstention.” Aplt. Rep. Br.
at 34. We are not persuaded that Pullman requires the district court to engage in the
examination of state law that it has determined to leave to the state courts. Further, the
factual record before the district court was sufficient to establish which issues required
abstention in this case and the extent of those issues.

                                               9
state’s highest court split[ting] evenly on a question of law.” Caldera, 341 F. Supp. 3d

at 1245.

       The state law issue in this case is not only uncertain but also potentially decisive.

The second Pullman factor presents “the pivotal question in determining whether

abstention is appropriate”: is the statute “fairly subject to an interpretation which will

render unnecessary or substantially modify the federal constitutional question.” Hill, 482

U.S. at 468 (quotation marks and citation omitted). The answer here is clearly yes: if the

state court were to conclude that the Colorado statutes preempt the Boulder ordinance,

there would be no need for us to resolve the federal constitutional questions. Plaintiffs do

not allege any impediment to bringing their preemption claim in state court. Even if the

state court does not hold that each provision of the ordinance is preempted by the statute,

its potential determination that some of the provisions are preempted would substantially

narrow the scope of the constitutional analysis in federal court. Thus, the second

Pullman factor is satisfied in this case and weighs in favor of abstention.

       The third Pullman factor is also satisfied because the case implicates state rights

and a decision by this court would risk intrusion into important state functions. In

making this determination, we afford deference to the district court’s assessment. As we

recognized in Vinyard;

       The appraisal of whether an erroneous federal court determination of state
       law would have a disruptive effect on state policies is more discretionary in
       character than the determination of the clarity of state law, and greater
       deference will be generally accorded to a district court’s appraisal if it is
       adequately explained.

655 F.2d at 1020 (quotation marks and citation omitted).

                                              10
       The Supreme Court has found the third Pullman factor to be satisfied where “the

dispute in its broad reach involves a question as to whether a city has trespassed on the

domain of a State.” City of Chicago v. Fieldcrest Dairies, 316 U.S. 168, 172 (1942). In

Fieldcrest Dairies, milk sellers sued after being denied a permit to sell milk in paper

cartons due to a city ordinance which required that milk products sold in quantities less

than one gallon be “delivered in standard milk bottles.” Id. at 169. Subsequently, Illinois

passed the Illinois Milk Pasteurization Plant Law, which regulated single service and

paper milk containers and “reserve[d] to cities, villages and incorporated towns the power

to regulate the distribution . . . of pasteurized milk” so long as the regulation did not

violate the act. Id. at 170 (internal quotation marks omitted). The Seventh Circuit held

that the ordinance’s prohibition of single-service containers was void as it violated the

public policy of the state expressed in the statute and suggested in dictum that the

ordinance was unconstitutional. Fieldcrest Dairies v. City of Chicago, 122 F.2d 132, 139




                                              11
(7th Cir. 1941). The Supreme Court reversed on the ground that Pullman abstention was

required. Fieldcrest Dairies, 316 U.S. at 171. The Court reasoned that “Illinois has the

final say as to the meaning of the ordinance in question” as well as “the final word on the

alleged conflict between the ordinance and the state Act.” Id. at 171–72. The Court

determined that the constitutional issue raised “may not survive the litigation in the state

courts” and explained that the wisdom in abstention is that it “avoid[s] the waste of a

tentative decision and any needless friction with state policies.” Id. at 172, 173

(quotation marks and citation omitted). As in Fieldcrest Dairies, there is a concern in the

present case as to “the appropriate relationship between federal and state authorities

functioning as a harmonious whole.” Id. at 172–73. Indeed, the district court rightly

determined that federalism interests are salient in this case. Caldera, 341 F. Supp. 3d

at 1246.

       The deciding court in the present case must balance two competing state policy

choices. First, the state legislature has expressed a strong interest in uniform firearm

regulation. See Colo. Rev. Stat. § 29-11.7-101 (explaining that “[i]nconsistency among

local governments of laws regulating the possession and ownership of firearms results in

persons being treated differently under the law solely on the basis of where they reside”).

On the other hand, the Colorado Constitution grants regulatory power to municipalities

under the home rule provision. See Colo. Const. art. XX., § 6. We agree with the district

court that an “incorrect prediction” as to “the correct interpretation of C.R.S.

§ 29.11.7-103 and Art. XX, Section 6 of the Colorado constitution will necessarily

disrupt an important state interest” in decisively balancing these state policies. Caldera,

                                             12
341 F. Supp. 3d at 1246. Thus, all three Pullman factors are satisfied and weigh in favor

of abstention in this case.

                                           B.

       Because we have determined that all Pullman factors are present, we now review

the district court’s abstention determination for abuse of discretion. See Harman, 380

U.S. at 534; see also Vinyard, 655 F. 2d at 1018. The decision whether to abstain is a

“discretionary exercise of a court’s equity powers.” Baggett v. Bullitt, 377 U.S. 360, 375

(1964). The consideration of “the nature of the constitutional deprivation alleged and the

probable consequences of abstaining” are part of the assessment in determining whether

to abstain under Pullman. Harman, 380 U.S. at 537. In deciding whether to abstain, a

court considers “the delays inherent in the abstention process and the danger that valuable

federal rights might be lost in the absence of expeditious adjudication in the federal

court.” Harris Cty. Comm’rs Court v. Moore, 420 U.S. 77, 83 (1975).

       Plaintiffs argue abstention in this case is improper because it chills the exercise of

their fundamental constitutional right to keep and bear arms.6 But the Supreme Court has

not recognized a categorical rule against abstention in cases involving constitutional

rights. See Moore v. Sims, 442 U.S. 415, 434–35 (1979) (ordering abstention in a child-

welfare case involving due process rights); see also Reetz v. Bonzannich, 397 U.S. 82



6
  For the first time at oral argument, plaintiffs also argued that abstention was
inappropriate because they are seeking damages under 42 U.S.C. § 1983. Because
“issues may not be raised for the first time at oral argument,” we do not consider this
argument. Dodds v. Richardson, 614 F.3d 1185, 1208 (10th Cir. 2010).

                                             13
(1970) (requiring abstention despite Fourteenth Amendment challenge). Moreover,

consideration of the nature of the right and the chilling effect of abstention is a secondary

assessment to determining whether the Pullman requirements are met. See Harman, 380

U.S. at 535–37 (assessing the nature of the right and the consequences of abstaining only

after determining that the statute was “clear and unambiguous” and therefore did not

meet the requirements of Pullman).7

       Plaintiffs also argue that abstention causes a lengthy delay before the

constitutional issues are adjudicated and, as a result, they will be deprived of their Second

Amendment rights for an extended period. We have recognized that certification is

preferable to abstention as a means of avoiding delay. Kan. Judicial Review, 519 F.3d

at 1119. The district court provided the parties with the option to certify the state law



7
  Notably, in each Supreme Court case cited by plaintiffs to support their chilling
argument, the Court determined that at least one of the Pullman factors was not satisfied.
See Hill, 482 U.S. at 471 (concluding that the “ordinance is neither ambiguous nor
obviously susceptible of a limiting construction”); Zwickler v. Koota, 389 U.S. 241, 249
(1967) (“[W]e have here no question of a construction of [the statute] that would avoid or
modify the constitutional question.”) (quotation marks omitted); Dombrowski v. Pfister,
380 U.S. 479, 490–91 (1965) (denying abstention where state law was not uncertain
because “the conduct charged in the indictments is not within the reach of an acceptable
limiting construction” of the statute, and statutes were invoked in bad faith to discourage
civil rights activities); Harman, 380 U.S. at 536 (stating that no “provision in the
legislation . . . leaves reasonable room for a construction by the [state] courts which
might avoid in whole or in part the necessity for federal constitutional adjudication, or at
least materially change the nature of the problem”) (citation omitted); and Baggett, 377
U.S. at 375–78 (denying abstention on the grounds that there was not an uncertain issue
of state law that “turn[s] upon a choice between one or several alternative meanings of a
state statute” but rather “an indefinite number” of interpretations and therefore, a
construction of the statute by the state court would not avoid or alter the constitutional
issue).

                                             14
questions to the Colorado Supreme Court, but the parties were unable to reach an

agreement to pursue that path. Caldera, 341 F. Supp. 3d at 1248. Moreover, the

Supreme Court has “regularly ordered abstention” when a case is “pending in state court

that will likely resolve the state-law questions underlying the federal claim.” Moore, 420

U.S at 83. Because there is a case involving substantially identical issues8 pending in

state court, the concern as to delay is mitigated. See Chambers v. City of Boulder, No.

2018-CV-30581 (Colo. D. Ct, Boulder Cty. filed June 14, 2018).

       Accordingly, we hold that the district court properly abstained as “appropriate

regard for the rightful independence of state governments reemphasize[s] that it is a wise

and permissible policy for the federal chancellor to stay his hand in absence of an

authoritative and controlling determination by the state tribunals.” Fieldcrest Dairies,

316 U.S. at 172 (quotation marks and citation omitted).

       We AFFIRM.




8
  The Chambers lawsuit raises only state law challenges to the ordinance and does not
include the federal constitutional challenges included in this case.

                                            15
