                IN THE SUPREME COURT OF IOWA
                               No. 13–0723

                           Filed June 13, 2014


LAURIE FREEMAN, SHARON MOCKMORE, BECCY BOYSEL, GARY D.
BOYSEL, LINDA L. GOREHAM, GARY R. GOREHAM, KELCEY
BRACKETT, and BOBBIE LYNN WEATHERMAN,

      Appellants,

vs.

GRAIN PROCESSING CORPORATION,

      Appellee.


      Appeal from the Iowa District Court for Muscatine County, Mark J.

Smith, Judge.



      Appellants assert the district court improperly granted summary

judgment.    DISTRICT COURT JUDGMENT REVERSED AND CASE

REMANDED.



      Sarah E. Siskind, Barry J. Blonien and David Baltmanis of Miner,
Barnhill & Galland, P.C., Madison, Wisconsin, Andrew L. Hope of Hope

Law Firm, P.L.C., West Des Moines, James C. Larew and Claire M. Diallo

of Larew Law Office, Iowa City, for appellants.



      Michael R. Reck, Mark McCormick, Charles F. Becker, Kelsey J.

Knowles of Belin McCormick, P.C., Des Moines, Steven J. Havercamp

and Eric M. Knoernschild of Stanley, Lande & Hunter, P.C., Muscatine,

Joshua B. Frank and Charles A. Loughlin of Baker Botts L.L.P.,

Washington, D.C., for appellee.
                                   2

      Joshua T. Mandelbaum, Des Moines, and Howard A. Learner,

Chicago, Illinois, for amici curiae Environmental Law & Policy Center and

Iowa Environmental Council.

      Ronald A. May of Gomez, May LLP, Davenport, James L. Huffman,

Portland, Oregon, Scott A. Shepard, Chicago, Illinois, Roger E. Meiners,

Arlington, Texas, and Andrew Morriss, Tuscaloosa, Alabama, for amicus

curiae Property and Environment Research Center.

      Sarah E. Crane of Davis Brown Law Firm, Des Moines, and

Richard O. Faulk of Hollingsworth LLP, Washington, D.C., for amici

curiae National Association of Manufacturers, Council of Industrial

Boiler Owners, National Shooting Sports Foundation, Inc., National

Mining Association, Nuclear Energy Institute, Inc., and Textile Rental

Services Association of America.
                                         3

APPEL, Justice.

       Eight residents of Muscatine filed a lawsuit 1 on behalf of

themselves and other similarly situated Muscatine residents against

Grain Processing Corporation (GPC), which operates a local corn wet

milling facility. The residents claim the operations at GPC’s facility cause

harmful pollutants and noxious odors to invade their land, thereby

diminishing the full use and enjoyment of their properties. They base

their claims on common law and statutory nuisance as well as the

common law torts of trespass and negligence.                 The residents seek

certification of the lawsuit as a class action, damages for the lost use and

enjoyment of their properties, punitive damages, and injunctive relief.

       Prior to class certification, GPC moved for summary judgment.

GPC asserted the residents’ common law and statutory claims were

preempted by the Federal Clean Air Act (CAA), 42 U.S.C. §§ 7401–7671q

(2012).   In the alternative, GPC claimed the common law claims were

preempted by Iowa Code chapter 455B (2013), which is the state

statutory companion to the CAA. Finally, GPC argued the issues raised

by the residents amounted to political questions involving complex policy

and economic issues that cannot and should not be resolved by the

judicial process.

       The district court granted summary judgment in favor of GPC on

all three theories and dismissed the lawsuit. The residents appeal. For

the reasons expressed below, we reverse the judgment of the district

court and remand the case for further proceedings.




        1Plaintiffs filed an “Amended Class Action Petition” on March 19, 2013, which

will hereinafter be referred to as the petition.
                                      4

       I. Factual and Procedural Background.

       The eight individually named plaintiffs all reside within one and

one-half miles of GPC’s facility in Muscatine. They seek to represent a

class described as follows:       “All Muscatine residents (other than

Defendant and its affiliates, parents, or subsidiaries) who have resided

during the damages period within 1.5 [miles] of the perimeter of

Defendant’s facility located at 1600 Oregon St., Muscatine, Muscatine

County, Iowa.”

       According to the petition, GPC conducts corn wet milling

operations at its Muscatine facility. The plaintiffs assert wet milling is a

production method and process that transforms corn kernels into

products for commercial and industrial use.        The plaintiffs allege the

corn wet milling operation at GPC’s facility creates hazardous by-

products and harmful chemicals, many of which are released directly

into the atmosphere.    The plaintiffs allege these by-products include:

particulate matter, volatile organic compounds including acetaldehyde

and other aldehydes, sulfur dioxide, starch, and hydrochloric acid. They

assert the polluting chemicals and particles are blown from the facility

onto nearby properties.      They note particulate matter is visible on

properties, yards, and grounds and various chemical pollutants are also

present. Compounding these adverse effects, according to the plaintiffs,

GPC has used, continues to use, and has failed to replace its worn and

outdated technology with available technology that would eliminate or

drastically reduce the pollution.     The plaintiffs assert these emissions

have    caused   them   to   suffer   persistent   irritations,   discomforts,

annoyances, inconveniences, and put them at risk for serious health

effects.
                                      5

      The plaintiffs generally allege three claims against GPC: nuisance,

negligence, and trespass.        With regard to the nuisance claim, the

plaintiffs contend GPC’s use of its facility constitutes a nuisance under

the common law and Iowa Code chapter 657, which provides a statutory

framework for nuisance claims. They assert that GPC has operated its

facility in a manner that unreasonably interferes with the reasonable use

and enjoyment of their properties.

      The plaintiffs also assert they have been harmed by GPC’s

negligence.   They claim GPC failed to exercise reasonable care in its

operations by causing or permitting hazardous substances to be released

at the facility; failing to follow accepted industry standards with respect

to maintaining its operation; failing to exercise reasonable and prudent

care in their operations; and failing to implement, follow, and enforce

proper operations and safety procedures. The plaintiffs further rely on

res ipsa loquitor, arguing the release of the toxic substances would not

ordinarily occur in the absence of GPC’s negligence, and, the acts or

omissions of the equipment and personnel that led to the toxic releases

were under GPC’s control at all relevant times.

      Finally, the plaintiffs claim GPC’s operations constitute a past and

continuing trespass.    They allege GPC, intentionally, purposefully, or

with substantial knowledge that harm would result, contacted the

properties of the plaintiffs and the class without their consent, resulting

in the lost use and enjoyment of their properties. The plaintiffs assert

GPC’s contact with their properties constitutes a tortious physical

intrusion on their properties.

      GPC sought to bring an end to the litigation by filing a motion for

summary judgment.        First, GPC claimed the CAA’s comprehensive

regulatory framework preempted the plaintiffs’ causes of action. Second,
                                     6

GPC claimed Iowa Code chapter 455B, which regulates emissions,

preempted the plaintiffs’ claims.        Finally, GPC asserted the case

presented a nonjusticiable political question because a lawsuit impacting

facility emissions lacks judicially discoverable and manageable standards

for resolving the issues.

      Resisting the motion for summary judgment, the plaintiffs

emphasized that under the CAA, states are allowed to impose stricter

standards than those imposed by federal law.           The plaintiffs noted

nothing in the language of Iowa Code chapter 455B repealed chapter 657

related to nuisance claims and, in any event, their common law claims

were not inconsistent or irreconcilable with chapter 455B. Finally, the

plaintiffs asserted courts routinely hear complex nuisance, negligence,

and trespass cases and, as a result, there was no basis in the federal

political question doctrine to decline to hear the case.

      The district court first considered whether the CAA preempted the

plaintiffs’ claims and concluded the CAA established a comprehensive

regulatory scheme that displaced state law. In reaching this result, the

district court noted that in American Electric Power Co. v. Connecticut

(AEP), the United States Supreme Court held the CAA displaced “any

federal common law right to seek abatement of carbon-dioxide emissions

from fossil-fuel fired power plants.” 564 U.S. ___, ___, 131 S. Ct. 2527,

2537, 180 L. Ed. 2d 435, 447 (2011). While the district court recognized

the AEP Court did not consider the question of whether the CAA

preempted state law claims, the district court cited lower federal court

authority concluding the CAA also preempted state law claims. See Bell

v. Cheswick Generating Station (Bell I), 903 F. Supp. 2d 314, 315–16, 322

(W.D. Pa. 2012) (concluding the CAA preempted state common law

nuisance, negligence, trespass, and strict liability claims), rev’d 734 F.3d
                                          7

188, 190 (3d Cir. 2013); 2 Comer v. Murphy Oil USA, Inc. (Comer I), 839 F.

Supp. 2d 849, 865 (S.D. Miss. 2012) (extending the reasoning of AEP to

state   law   claims     after   characterizing     them     as    turning   on    the

reasonableness of emissions, a determination entrusted to Congress);

United States v. EME Homer City Generation L.P., 823 F. Supp. 2d 274,

297 (W.D. Pa. 2011) (holding the CAA is a comprehensive regulatory

scheme that preempted a common law public nuisance claim).

        Adopting the reasoning of these authorities, the district court

noted Congress had entrusted to the EPA and parallel state agencies the

authority to regulate air emissions, and the CAA had established a

method of citizen input in its rulemaking process. The district court held

that to have a jury make a judgment about the reasonableness of GPC’s

emissions would invade the authority Congress vested in the EPA and

state environmental authorities.         The district court further noted GPC

was already the subject of an enforcement action by state regulators

under the CAA and that the plaintiffs’ actions in this case would conflict

with these enforcement procedures.

        For largely the same reasons, the district court concluded state

environmental statutes and regulations under Iowa Code chapter 455B

preempted the plaintiffs’ common law claims.                      The district court

reasoned that controversies related to air emissions were to be

determined by state regulators, not by judges and juries in common law

actions.

        Finally, the district court also agreed with GPC’s position that the

questions raised in the litigation amounted to political questions not


       2The Third Circuit heard the appeal after the district court ruled on the motion

for summary judgment in this case.
                                     8

amenable to resolution by the judiciary in a lawsuit. Citing Comer I, the

district court noted a court or jury lacks judicially discoverable and

manageable standards for resolving the complex environmental issues

and would be forced to make policy determinations weighing the costs

and benefits of GPC’s facility to the surrounding community. See 839 F.

Supp. 2d at 864 (“It is unclear how this Court or any jury, regardless of

its level of sophistication, could determine whether the defendants’

emissions unreasonably endanger the environment or the public without

making policy determinations that weigh the harm caused by the

defendants’ actions against the benefits of the products they produce.”).

      This court retained the plaintiffs’ appeal.

      II. Standard of Review.

      The standard of review for rulings on motions for summary

judgment is for correction of legal errors. Stevens v. Iowa Newspapers,

Inc., 728 N.W.2d 823, 827 (Iowa 2007). The standard applies when the

material facts are not disputed or the appeal turns on questions of

statutory interpretation.   See State v. Spencer, 737 N.W.2d 124, 128

(Iowa 2007); Krause v. Krause, 589 N.W.2d 721, 724 (Iowa 1999).

      III. Discussion of Preemption Under the CAA.

      A. Overview of Common Law and Statutory Approaches to

Environmental Protection.

      1. Introduction. In the law, as in life, in order to know where you

are, you need to know where you have been.          We therefore begin our

discussion of the issues posed in this case with an overview of the law of

environmental protection.      This background will give us a better

understanding of the historical and legal context in which the issues in

this case arise. In particular, the historical and legal context will shed
                                            9

light on the degree to which the passage of the CAA impacts the

traditional role of state law in environmental regulation.

       2. Traditional remedies for environmental harm: the common law.

The common law provided the first means of attempting to control

environmental        pollution.      Tort    claims    challenging      environmental

pollution can be traced back to at least the seventeenth century to

William Aldred’s Case, (1611) 77 Eng. Rep. 816, 9 Co. Rep. 57a (K.B.),

where the court held odor from the defendant’s hog lot was a nuisance.

See 1 John H. Wigmore, Select Cases on the Law of Torts 569–71 (1912);

Jason J. Czarnezki & Mark L. Thomsen, Advancing the Rebirth of

Environmental Common Law, 34 B.C. Envtl. Aff. L. Rev. 1, 3 & n.14

(2007) [hereinafter Czarnezki]. Despite its ancient origin, most American

environmental caselaw dates to the late nineteenth and twentieth

centuries after the Industrial Revolution. See Czarnezki, 34 B.C. Envtl.

Aff. L. Rev. at 3.

       The     primary      common       law     theories     seeking     redress     for

environmental harms were nuisance, 3 negligence, trespass, and strict

liability. See 1 Linda A. Malone, Environmental Regulation of Land Use

§ 10:2, at 10-7, 10-8.1 (2013) [hereinafter Malone]. In the United States,
many pollution cases invoking these common law theories have been

brought over the years, with mixed results. See, e.g., id. § 10:2, at 10-9

n.8, 10-12 n.19 (collecting cases involving trespasses committed in the



       3The common law distinguishes between private and public nuisances. See
Czarnezki, 34 B.C. Envtl. Aff. L. Rev. at 4. A private nuisance is a tort arising from the
unreasonable “invasion of another’s interest in the private use and enjoyment of land.”
Restatement (Second) of Torts § 821D, at 100 (1979). A public nuisance arises from “an
unreasonable interference” with a public right. Id. § 821B(1), at 87. A public nuisance
does not necessarily involve interference with the use and enjoyment of land. Id.
§ 821B cmt. h, at 93.
                                     10

air space above land and nuisance cases involving odors in the air and

smoke, dust, or gas emissions). See generally Andrew Jackson Heimert,

Keeping Pigs Out of Parlors: Using Nuisance Law to Affect the Location of

Pollution, 27 Envtl. L. 403, 406–08 & n.7 (1997) (providing a brief history

of nuisance actions from as early as the twelfth century to the early

twentieth century); Julian Conrad Juergensmeyer, Control of Air Pollution

Through the Assertion of Private Rights, 1967 Duke L.J. 1126, 1130–48

(1967) (summarizing cases involving trespass, negligence, and nuisance

claims in the air pollution context); Harold W. Kennedy and Andrew G.

Porter, Air Pollution: Its Control and Abatement, 8 Vand. L. Rev. 854, 854–

64 (1954–1955) (citing numerous common law cases seeking remedies in

the context of air pollution); Roger Meiners & Bruce Yandle, Common

Law and the Conceit of Modern Environmental Policy, 7 Geo. Mason L.

Rev. 923, 926–46 (1999) (giving overview of common law tradition and

identifying nuisance as the “backbone” of common law environmental

litigation). The availability of nuisance theory to address environmental

harms was endorsed by the Restatement (Second) of Torts, which

includes sections on both public nuisance and private nuisance.        See

Restatement (Second) of Torts §§ 821B–821E, at 87–104. According to

one commentator, nuisance theory “has hung on from its horse-and-

buggy origins” and “continues to be the fulcrum of what is called today

environmental law.” 1 William H. Rodgers, Jr., Environmental Law: Air

and Water § 1.1, at 3 (1986); id. § 2.1, at 29.

      Nuisance theory has been recognized in Iowa for decades and has

been utilized to address environmental problems.      See, e.g., Kriener v.

Turkey Valley Cmty. Sch. Dist., 212 N.W.2d 526, 535–36 (Iowa 1973)

(noxious odor from sewage facility amounts to private nuisance); Ryan v.

City of Emmetsburg, 232 Iowa 600, 601–03, 4 N.W.2d 435, 437–38 (1942)
                                    11

(private nuisance arising from sewer system).        See generally Ronald

Sorenson, The Law of Nuisance in Iowa, 12 Drake L. Rev. 107 (1962–

1963). For instance, in Bowman v. Humphrey, the plaintiff landowner

successfully sued a creamery on a nuisance theory for depositing refuse

in a running stream that injured the lower riparian owner.        132 Iowa

234, 235–36, 243, 109 N.W. 714, 714–15, 717 (1906).           Similarly, in

Higgins v. Decorah Produce Co., plaintiffs successfully claimed that a

poultry and produce plant was a nuisance and obtained a court order

that certain sanitary measures be taken to reduce the odor. 214 Iowa

276, 283–84, 242 N.W. 109, 112–13 (1932).

      In addition to common law nuisance, the Iowa legislature has

enacted a statutory nuisance claim in Iowa Code chapter 657. See Iowa

Code § 657.1. We have long held that the statutory nuisance provisions

of Iowa Code chapter 657 do not modify the common law of nuisance but

supplement it. See, e.g., Miller v. Rohling, 720 N.W.2d 562, 567 (Iowa

2006); Perkins v. Madison Cnty. Livestock & Fair Ass’n, 613 N.W.2d 264,

271 (Iowa 2000); Bates v. Quality Ready-Mix Co., 261 Iowa 696, 703, 154

N.W.2d 852, 857 (1967).

      In addition to nuisance claims, parties seeking redress for

environmental harms have also pleaded common law claims of

negligence and trespass. See Malone § 10:2, at 10-7, 10-8.1. Negligence

claims ordinarily require conduct that falls below a standard of care

established for others against unreasonable risk of harm. Id. § 10:2, at

10-8.1; see also Sterling v. Velsicol Chem. Corp., 647 F. Supp. 303, 316–

17 (W.D. Tenn. 1986) (involving common law negligence claim in

connection with closure of chemical waste burial site), aff’d in part, rev’d

in part, 855 F.2d 1188 (6th Cir. 1988); Patrick v. Sharon Steel Corp., 549

F. Supp. 1259, 1261, 1269 (N.D. W. Va. 1982) (holding negligence claim
                                     12

arising from air pollution raises question of fact for jury); Conrad v. Bd. of

Supervisors, 199 N.W.2d 139, 140 (Iowa 1972) (involving negligence

claim arising from pollution of a farm pond); Bloodgood v. Organic Techs.

Corp., No. 99–0755, 2001 WL 98656, at *1 (Iowa Ct. App. Feb. 7, 2001)

(involving negligence claim, inter alia, arising from operation of a

compost facility); Schlichtkrull v. Mellon-Pollock Oil Co., 152 A. 832, 832

(Pa. 1930) (involving negligence claim arising from injuries resulting from

pollution of house well).

      Trespass ordinarily requires a showing of actual interference with a

party’s exclusive possession of land including some observable or

physical invasion. See Ryan, 232 Iowa at 603, 4 N.W.2d at 438 (noting

distinction between trespass and nuisance); see also Borland v. Sanders

Lead Co., 369 So. 2d 523, 525 (Ala. 1979) (trespass involving lead

particulates and sulfoxide deposits); Lunda v. Matthews, 613 P.2d 63,

65–66 (Or. Ct. App. 1980) (trespass caused by dust); Bradley v. Am.

Smelting & Ref. Co., 709 P.2d 782, 784, 792 (Wash. 1985) (holding

intentional deposit of microscopic particulates from copper smelter could

give rise to trespass claim).   Perhaps the most cited, relatively recent,

trespass cases in the air pollution context arise from fluoride emissions

in Washington and Oregon.       See generally Lampert v. Reynolds Metals

Co., 372 F.2d 245 (9th Cir. 1967); Reynolds Metals Co. v. Lambert, 316

F.2d 272, rev’d in part 324 F.2d 465 (9th Cir. 1963); Arvidson v.

Reynolds Metals Co., 236 F.2d 224 (9th Cir. 1956); Fairview Farms, Inc.

v. Reynolds Metals Co., 176 F. Supp. 178 (D. Or. 1959); Martin v.

Reynolds Metals Co., 342 P.2d 790, 791 (Or. 1959).

      As with nuisance claims, these common law causes of action have

a deep legal tradition that find their roots well into the past and extend to

the present day.     See Patrick J. Kelley, Restating Duty, Breach, and
                                          13

Proximate Cause in Negligence Law: Descriptive Theory and the Rule of

Law, 54 Vand. L. Rev. 1039, 1056–63 (2001); George E. Woodbine, The

Origins of the Action of Trespass, 34 Yale L.J. 343, 343–44 (1925); George

E. Woodbine, The Origins of the Action of Trespass, 33 Yale L.J. 799, 799–

800 (1924).

      3. Advent of the “age of statutes.” 4             While state common law

actions to address environmental problems may be well-established,

reliance solely on common law to control pollution proved inadequate.

Because the common law only settled disputes on a case-by-case basis,

coverage was hit and miss. Further, bringing common law actions was

expensive, and many potential plaintiffs simply could not afford to bring

actions against well-heeled defendants.             In addition, requirements of

standing, causation, and proof of damages often made success in

common law actions difficult. See Malone § 10:2, at 10-19. Finally, the

1960s and 1970s saw dramatic increases in the amount and extent of

pollution.      Through broadcast television, viewers watched as the

Cuyahoga River caught fire, acid rain poured on the Northeast region,

and many American cities experienced severe smog. See Lowell E. Baier,

Reforming the Equal Access to Justice Act, 38 J. Legis. 1, 12–13 (2012)

(describing “[e]nvironmental disasters in the 1960’s and 1970’s . . . [that]

gave rise to . . . environmentalism”).

      As a result, the 1960s and 1970s saw the development of

significant statutory approaches to pollution. See Arnold W. Reitze, Jr.,

The Legislative History of U.S. Air Pollution Control, 36 Hous. L. Rev. 679,

696–711 (1999) [hereinafter Reitze]. The CAA was originally enacted in

1963. Id. at 698. It has since been substantially amended numerous

      4See   generally Guido Calabresi, A Common Law for the Age of Statutes (1982).
                                    14

times. See Arnold W. Reitze Jr., A Century of Air Pollution Control Law:

What’s Worked; What’s Failed; What Might Work, 21 Envtl. L. 1549,

1588–1612 (1991); Reitze, 36 Hous. L. Rev. at 699, 702–29.

       Each subsequent amendment increased the scope and complexity

of the effort to control air pollution. See Reitze, 36 Hous. L. Rev. at 699–

729. In particular, in 1990 Congress enacted major amendments to the

CAA.   See Craig N. Oren, The Clean Air Act Amendments of 1990:           A

Bridge to the Future?, 21 Envtl. L. 1817, 1817, 1828, 1832 (1991). As

noted by one commentator, since 1970, “the EPA has created a vast

regulatory structure to control the emission of air pollutants, including

technological standards, health standards, risk levels, and enforcement

provisions, completely transforming what was once the province of state

law.” Alexandra B. Klass, State Innovation and Preemption: Lessons from

State Climate Change Efforts, 41 Loy. L.A. L. Rev. 1653, 1686 (2008).

       The CAA is undoubtedly complex. By way of general overview, the

CAA embraces what has been called a “cooperative federalism” model.

See Bell v. Cheswick Generating Station (Bell II), 734 F.3d 188, 190 (3d

Cir. 2013) (“[The CAA] employs a ‘cooperative federalism’ structure under

which the federal government develops baseline standards that the states

individually implement and enforce.”).      With respect to ambient air

quality, the CAA directs the EPA to set national ambient air quality

standards (NAAQS) for pollutants in ambient air considered harmful to

the public health and welfare. See 42 U.S.C. § 7409(a)–(b). The NAAQS

are further divided into primary NAAQS and secondary NAAQS.              Id.

§ 7409(b).   The primary NAAQS are intended to protect public health,

while the secondary NAAQS are intended to protect the surrounding

environment.   Id.   They are often, though not always, the same. See,

e.g., 40 C.F.R. pt. 50 (2013); U.S. Envtl. Prot. Agency, National Ambient
                                     15

Air Quality Standards (NAAQS), http://www.epa.gov/air/criteria.html

(last updated Dec. 14, 2012) (chart detailing primary and secondary

NAAQS levels).     States are required to develop state implementation

plan(s) (SIP) that employ pollution reduction methods to meet the

NAAQS.    Id. § 7410(a)(1).   The states, however, are free to adopt more

stringent requirements if they choose to do so. Id. § 7416. Each state’s

SIP must include a mandatory permitting program for all stationary

sources limiting the amounts and types of emissions each source is

allowed to discharge.    Id. § 7661a(d)(1).   Before new construction or

modifications may be made to a source of emissions, the SIP must

provide for “written notice to all nearby States the air pollutions levels of

which may be affected by such source at least sixty days prior to the date

on which commencement of construction is to be permitted.”                Id.

§ 7426(a)(1)(B).   See generally North Carolina ex rel. Cooper v. Tenn.

Valley Auth. (TVA), 615 F.3d 291, 299–300 (4th Cir. 2010) (providing

overview of the CAA’s management of emissions through NAAQS, SIP,

permit programs, and 42 U.S.C. § 7426(a)(1)); Her Majesty the Queen v.

City of Detroit, 874 F.2d 332, 335 (6th Cir. 1989) (describing basic

requirements for SIP, including permit programs).

      4. Differences between common law and regulatory regimes. The

CAA and Iowa Code chapter 455B address the overall quality of air that

we all breathe and provide a regulatory framework focused on prevention

of pollution through emissions standards designed to protect the general

public. While civil money penalties may be imposed for violations of the

CAA, the CAA does not provide damage remedies to harmed individuals.

See 42 U.S.C. § 7604. In contrast, the common law focuses on special

harms to property owners caused by pollution at a specific location. See

Alice Kaswan, The Domestic Response to Global Climate Change: What
                                          16

Role for Federal, State, and Litigation Initiatives?, 42 U.S.F. L. Rev. 39,

102–03 (2007). As a result, through common law actions, victims may

obtain compensatory damages, punitive damages, and injunctive relief.

See id.    In sum, statutes deal with general emissions standards to

prospectively    protect       the    public,    while    common        law     actions

retrospectively focus on individual tort remedies for owners of real

property in particular locations for actual harms.                      As noted by

commentators:

      [C]ommon law controls are based on property rights, are
      location specific, and provide remedies to rightholders for
      real harms. Federal regulation, on the other hand, is all
      encompassing,      provides   no    specific  protection   to
      rightholders, and offers no remedies for damages that
      rightholders may sustain . . . [t]he two approaches are truly
      different and therefore, cannot be compared as though they
      were quite similar.

Roger E. Meiners, Stacie Thomas, & Bruce Yandle, Burning Rivers,

Common Law, and Institutional Choice for Water Quality, in The Common

Law and the Environment: Rethinking the Statutory Basis for Modern

Environmental Law 54, 78 (Roger E. Meiners & Andrew P. Morriss eds.,

2000); see also 6 Frank P. Grad, Treatise on Environmental Law § 18.02,
at 18-5 (2001) [hereinafter Grad] (“A rather clear division of labor has

developed between litigation to protect the public interest under federal

and state statutory law, and the protection of individual, private interests

through common law, frequently tort actions.”); Daniel P. Selmi &

Kenneth A. Manaster, State Environmental Law § 2:2, at 2-12 to 2-13

(2012)    [hereinafter   Selmi]      (noting    that   even   citizen   suits    under

environmental statutes do not ordinarily provide a damage remedy and

that injunctive relief in common law actions can take into account

specific facts of the case).
                                    17

      The differences in the statutory and common law regimes are

demonstrated by what must be shown to establish a violation. A party

seeking to establish a violation of the statutory regime does not need to

demonstrate the presence of a nuisance. See, e.g., Pottawattamie County

v. Iowa Dep’t of Envtl. Quality, 272 N.W.2d 448, 454 (Iowa 1978) (holding

violation of fugitive-dust rule does not require showing of public

nuisance).   Conversely, many cases have held that a party seeking to

show a nuisance is not required to show a violation of some other law.

See, e.g., Galaxy Carpet Mills, Inc. v. Massengill, 338 S.E.2d 428, 429

(Ga. 1986) (permitting nuisance action related to pollution caused by

coal-fired boilers even though owner had obtained environmental

permits); Urie v. Franconia Paper Corp., 218 A.2d 360, 362–63 (N.H.

1966) (permitting private nuisance action for pollution even though

defendant complied with state environmental laws); Tiegs v. Watts, 954

P.2d 877, 883–84 (Wash. 1998) (finding defendant could be held liable

for nuisance even though defendant had permit from department of

ecology). See generally 58 Am. Jur. 2d Nuisances § 395, 873–74 (2012)

(“A governmental license does not carry with it immunity for private

injuries that may result directly from the exercise of the powers and

privileges conferred.”). Similarly, compliance with statewide air pollution

regulations does not shield a defendant from trespass liability.         Cf.

Borland, 369 So. 2d at 526–27 (holding compliance with Alabama’s air

pollution control law does not shield a defendant from trespass liability).

      Thus, a property owner seeking full compensation for harm related

to the use and enjoyment of property at a specific location must resort to

common law or state law theories to obtain a full recovery.         Cf. Md.

Heights Leasing, Inc. v. Mallinckrodt, Inc., 706 S.W.2d 218, 221–22, 224,

226 (Mo. Ct. App. 1985) (discussing available damages and relief for
                                     18

claims based on nuisance, negligence, and trespass theories).              In

addition, the common law offers the prospect of creative remedies, such

as paying for clean-up costs or creation of a common law fund for

compensation or restoration. See Czarnezki, 34 B.C. Envtl. Aff. L. Rev.

at 27–35.

      B. Positions of the Parties.

      1. Plaintiffs. The plaintiffs begin their attack on the district court’s

ruling by suggesting that we are required to approach the issue of federal

preemption of state law with skepticism.          They point to the well-

established history of common law claims. They further note that several

statutory provisions of the CAA demonstrate that Congress did not

intend to preempt state common law actions. Turning to the caselaw,

the plaintiffs argue that the reasoning in International Paper Co. v.

Ouellette, 479 U.S. 481, 107 S. Ct. 805, 93 L. Ed. 2d 883 (1987), is

applicable here and not the reasoning in AEP.

      The plaintiffs note that there is no express preemption of state law

causes of action in the CAA. As a result, any preemption of state law

arises by implication only.     According to the plaintiffs, such implied

preemption is strongly disfavored and ordinarily to be avoided unless

absolutely necessary. Cf. Rice v. Santa Fe Elevator Corp., 331 U.S. 218,

230, 67 S. Ct. 1146, 1152, 91 L. Ed. 1447, 1459 (1947) (“[W]e start with

the assumption that the historic police powers of the States were not to

be superseded by the Federal Act unless that was the clear and manifest

purpose of Congress.”).

      Citing the language of the CAA, the plaintiffs note that the “any

measures” clause demonstrates that the states retain broad authority

over air pollution.   Specifically, the any measures clause states: “[t]he

reduction or elimination, through any measures, of the amount of
                                     19

pollutants produced or created . . . and air pollution control [measures]

at its source is the primary responsibility of States and local

governments.” 42 U.S.C. § 7401(a)(3) (emphasis added). The plaintiffs

contend that the plain language of the statute authorizes the states to

reduce pollution through any measures, which include nuisance and

common law claims.

      The plaintiffs next draw our attention to the “citizens’ rights”

savings clause in the CAA, which in relevant part provides:

             Nothing in this section shall restrict any right which
      any person (or class of persons) may have under any statute
      or common law to seek enforcement of any emission
      standard or limitation or to seek any other relief (including
      relief against the Administrator or a State agency).

Id. § 7604(e). The plaintiffs argue that the language of the citizens’ rights

savings clause demonstrates congressional intent not to preempt state

statutory or common law claims related to air pollution.

      The plaintiffs further cite another savings clause in the CAA

entitled “Retention of State authority,” which in relevant part provides:

             Except as otherwise provided . . .      nothing in this
      chapter shall preclude or deny the right       of any State or
      political subdivision thereof to adopt or      enforce (1) any
      standard or limitation respecting emissions    of air pollutants
      or (2) any requirement respecting control or   abatement of air
      pollution . . . .

Id. § 7416. The plaintiffs contend that the retention of state authority

savings clause demonstrates congressional intent to allow state statutory

or common law causes of action respecting emissions of air pollutants.

      The plaintiffs find support for their position in caselaw.         The

plaintiffs focus our attention on Ouellette.      In Ouellette, a class of

property owners on the Vermont side of Lake Champlain alleged the

discharge of pollutants into the lake by a paper mill located in New York
                                      20

constituted a continuing nuisance under Vermont common law.               479

U.S. at 483–84, 107 S. Ct. at 807, 93 L. Ed. 2d at 891. The defendant

maintained that the lawsuit was preempted by the Clean Water Act

(CWA), 33 U.S.C. §§ 1251–1387 (2010). Id. at 484, 107 S. Ct. at 807, 93

L. Ed. 2d at 892.

      Like the CAA, the CWA contains two savings clauses. The “citizen

suit” savings clause of the CWA provides: “Nothing in this section shall

restrict any right which any person (or class of persons) may have under

any statute or common law to seek enforcement of any effluent standard

or limitation or to seek any other relief . . . .” 33 U.S.C. § 1365(e).

      The CWA also has a “states’ rights” savings clause, which provides:

            Except as expressly provided in this chapter, nothing
      in this chapter shall (1) preclude or deny the right of any
      State or political subdivision thereof or interstate agency to
      adopt or enforce (A) any standard or limitation respecting
      discharges of pollutants, or (B) any requirement respecting
      control or abatement of pollution; . . . or (2) be construed as
      impairing or in any manner affecting any right or jurisdiction
      of the States with respect to the waters (including boundary
      waters) of such States.

Id. § 1370.

      The Supreme Court in Ouellette concluded that while a Vermont

common law nuisance claim could not be brought against a New York

paper mill, the plaintiffs could bring a nuisance claim under New York

common law. 479 U.S. at 497–500, 107 S. Ct. at 814–16, 93 L. Ed. 2d at

900–02. While the plaintiffs recognize that Ouellette was a case brought

under the CWA, see id. at 483, 107 S. Ct. at 807, 93 L. Ed. 2d at 891,

they claim that the reasoning of the case is fully applicable to cases

brought under the CAA in light of the similarity of structure and

language of the two statutes. See Bell II, 734 F.3d at 195 (“[A] textual
                                     21

comparison of the two savings clauses [in the CAA and CWA] at issue

demonstrates there is no meaningful difference between them.”).

      The plaintiffs further argue that Congress knew how to preempt

state laws when it so desired. The CAA expressly preempts state law in

some areas, for example, with respect to new motor vehicle emissions,

fuel additives, and aircraft emissions. See 42 U.S.C. § 7543(a) (motor

vehicles); id. § 7545(c)(4)(A) (fuel or fuel additives); id. § 7573 (aircraft

emissions).

      The plaintiffs argue the district court erred in relying on AEP

instead of Ouellette.   In AEP, the Supreme Court held that the CAA

preempted potential claims under federal common law. 564 U.S. at ___,

131 S. Ct. at 2537, 180 L. Ed. 2d at 447. The plaintiffs argue that the

separation of powers question presented in determining whether a

federal statute preempts federal common law is fundamentally different

from the federalism question raised in determining whether a federal

statute preempts state common law. They note that AEP itself recognizes

the distinction. See 564 U.S. at ___, 131 S. Ct. at 2535–37, 2540, 180

L. Ed. 2d at 445–47, 450–51. The plaintiffs claim that AEP does not alter

the basic teaching of Ouellette and does not represent a shift in the

Supreme Court’s approach to federal preemption issues.

      In support of their position, the plaintiffs cite two circuit court

cases decided after AEP. First, the plaintiffs cite Bell II, where the Court

of Appeals for the Third Circuit reversed a case on appeal that was cited

by GPC and relied upon extensively by the district court, Bell I. See Bell

II, 734 F.3d at 190. In Bell II, the Third Circuit followed Ouellette and

held that the CAA did not preempt state common law claims in the

source state.   734 F.3d at 196–97.       Second, the plaintiffs note that a

similar result with similar reasoning was obtained in the Court of
                                   22

Appeals for the Second Circuit in In re Methyl Tertiary Butyl Ether (MTBE)

Prods. Liab. Litig., 725 F.3d 65, 96–103 (2d Cir. 2013), cert. denied, ___

U.S. ___, 134 S. Ct. 1876, 188 L. Ed. 2d 912 (2014).

      2.     GPC.   In response, GPC notes that the CAA preempts

nonsource-state statutory law and federal common law. AEP, 564 U.S.

at ___, 131 S. Ct. at 2540, 180 L. Ed. 2d at 447; TVA, 615 F.3d at 296. It

invites us to take the next step and hold that the CAA also preempts

source-state common law and statutory private actions.

      GPC recognizes that in Ouellette, dictum indicates that the CWA

did not preempt source-state common law.       See 479 U.S. at 497, 107

S. Ct. at 814, 93 L. Ed. 2d at 900. But GPC suggests that events since

Ouellette was decided have driven the law in a different direction.

Specifically, GPC points to amendments enacted to the CAA in 1990 and

the recent decision of the United States Supreme Court in AEP.

      GPC’s narrative emphasizes that in 1990, three years after

Ouellette was decided, Congress enacted the Clean Air Act Amendments

of 1990, Pub. L. No. 101-549, 104 Stat. 2399 (1990). Characterizing the

amendments as “extensive,” GPC notes that, among other things, the

amendments      required   the   EPA    Administrator    to   conduct   “a

comprehensive analysis of the impact of this chapter on the public

health, economy, and environment of the United States.”          42 U.S.C.

§ 7612(a).   Further, in conducting the analysis, Congress required the

Administrator to consider the effects of the CAA on “employment,

productivity, cost of living, economic growth, and the overall economy of

the United States.” Id. § 7612(c). GPC asserts that the Clean Air Act

Amendments of 1990 triggered a “regulatory tsunami” in environmental

regulations, including the requirement that the EPA regulate carbon

dioxide and other “greenhouse” gases. See Massachusetts v. EPA, 549
                                      23

U.S. 497, 528, 127 S. Ct. 1438, 1459, 167 L. Ed. 2d 248, 274 (2007)

(holding that “the [CAA] authorizes EPA to regulate greenhouse gas

emissions from new motor vehicles in the event that it forms a ‘judgment’

that such emissions contribute to climate change”). GPC seeks to escape

the power of the 1987 language in Ouellette by urging this court to

examine the CAA as it exists today.

      Looking at the CAA today, GPC argues that AEP, and not Ouellette,

is the most authoritative case from the Supreme Court. In reaching the

conclusion that the CAA preempted federal common law, the AEP Court

emphasized the first decider under the CAA is an expert administrative

agency involved in the balancing of complex factors. 564 U.S. at ___, 131

S. Ct. at 2539, 180 L. Ed. 2d at 449. According to the AEP Court, such

complex judgments are better left to an expert agency rather than

individual district court judges who “lack the scientific, economic, and

technological resources an agency can utilize” in deciding such issues.

564 U.S. at ___, 131 S. Ct. at 2539–40, 180 L. Ed. 2d at 450. While GPC

recognizes that the narrow issue in AEP was whether federal common

law was preempted by the CAA, see id. at ___, 131 S. Ct. at 2532, 180

L. Ed. 2d at 442, GPC argues that the reasoning in AEP on the federal

common law preemption issue applies fully to the question of whether

the CAA preempts state law, see id. at ___, 131 S. Ct. at 2537–38, 180

L. Ed. 2d at 447–48.

      Casting a somewhat broader argument, GPC argues that common

law and statutory actions such as those brought by the plaintiffs

interfere with both the goals and method embraced by the CAA in

regulating air pollution.   According to GPC, interference with either is

grounds for preemption. Geier v. Am. Honda Motor Co., 529 U.S. 861,

881, 120 S. Ct. 1913, 1925, 146 L. Ed. 2d 914, 932 (2000) (holding
                                        24

claims   are    preempted        when    they   are     “ ‘an   obstacle    to   the

accomplishment and execution of’ . . . important means-related federal

objectives” (quoting Hines v. Davidowitz, 312 U.S. 52, 67, 61 S. Ct. 399,

404, 85 L. Ed. 581, 587 (1941))); Ouellette, 479 U.S. at 494, 107 S. Ct. at

813, 93 L. Ed. 2d at 898 (“A state law also is pre-empted if it interferes

with the methods by which the federal statute was designed to reach

[the] goal [of eliminating water pollution].”).

      With respect to goals, GPC argues that allowing the plaintiffs’

causes   of    action   to    proceed   would   upset     the   balance    between

environmental     protection     and    economic      disruption   that    Congress

authorized the EPA to determine. See AEP, 564 U.S. at ___, 131 S. Ct. at

2539, 180 L. Ed. 2d at 449 (noting “[t]he [CAA] entrusts such complex

balancing to EPA”).          GPC maintains that the EPA has established a

balanced approach to require transition to lower emitting equipment only

when modification, replacement, or construction occurs.              In this case,

GPC claims that plaintiffs, among other things, are seeking to require

GPC to install new equipment and take other equipment offline even

though the EPA has not imposed a similar requirement.                       Such a

requirement is contrary to Goodell v. Humboldt County, 575 N.W.2d 486,

500–01 (Iowa 1998), where we observed that a local law that would in

effect prohibit what state law permitted could give rise to conflict

preemption.

      GPC also asserts that the goal of certainty is undermined by

allowing the plaintiffs’ claims to proceed. GPC relies on TVA, in which

the Court of Appeals for the Fourth Circuit considered whether public

nuisance claims related to air pollution could go forward. 615 F.3d at

296. The TVA court noted the complex balancing entrusted to the EPA,

the comprehensive nature of the regulation, the scientific complexity of
                                    25

many of the issues, and the reliance interests and expectations of

enterprises that have complied with the CAA regulatory requirements,

and reasoned that “individual states [should not] be allowed to supplant

the cooperative federal-state framework that Congress through the EPA

has refined over many years.” Id. at 298–301. The TVA court noted that

if nuisance suits were brought across the country, they would threaten

to “overturn the carefully enacted rules governing airborne emissions”

and “it would be increasingly difficult for anyone to determine what

standards govern.” Id. at 298.

      GPC also asserts that private common law and state statutory

actions would interfere with the law’s method of achieving its goal and

should therefore be preempted.     See Ouellette, 479 U.S. at 494, 107

S. Ct. at 813, 93 L. Ed. 2d at 898.      GPC argues the CAA provides a

method for individuals to participate in decision making through the

rulemaking process.    According to GPC, a citizen cannot sidestep that

process by bringing common law claims.

      GPC further claims that the CAA amounts to a comprehensive

scheme that occupies the entire regulatory field. It notes that Congress

and the EPA have pervasively regulated the area of clean air and, relying

on TVA, GPC argues that field preemption is an alternative route to

affirm the district court. See 615 F.3d at 303.

      Last, GPC attacks the plaintiffs’ statutory analysis of the CAA.

With respect to the retention of state authority savings clause, GPC notes

that it allows a “[s]tate or political subdivision thereof to adopt or

enforce” more stringent regulations. See 42 U.S.C. § 7416. GPC asserts

that by its plain language, the retention of state authority savings clause

does not authorize private common law or statutory causes of action, but

only the imposition of more stringent standards by state or subdivision
                                    26

regulators.   See 42 U.S.C. § 7602(d) (defining state); United States v.

Amawi, 552 F. Supp. 2d 679, 680 (N.D. Ohio 2008) (holding the judiciary

is not a state or political subdivision); Haudrich v. Howmedica, Inc., 642

N.E.2d 206, 209–10 (Ill. App. Ct. 1994) (same). GPC also argues that the

CWA has stronger language than the retention of state authority savings

clause of the CAA. In the CWA, Congress provided that nothing in the

chapter shall “be construed as impairing or in any manner affecting any

right or jurisdiction of the States with respect to the waters . . . of such

States.”   33 U.S.C. § 1370.   GPC notes that Congress did not include

similar language in the CAA.

      In any event, GPC argues that while a savings clause might

prevent field preemption, it does not prevent conflict preemption.      See

Geier, 529 U.S. at 869, 120 S. Ct. at 1919, 146 L. Ed. 2d at 924; Pokorny

v. Ford Motor Co., 902 F.2d 1116, 1125 (3d Cir. 1990). Moreover, GPC

asserts that the express language of the citizens’ rights savings clause is

limited to “this section,” see 42 U.S.C. § 7604(e); Iowa Code § 455B.11,

and, as a result, other sections of the CAA are not impacted by the

savings clause and may preempt state common law and statutory claims.

      C. Analysis of CAA Preemption.

      1.   Introduction to federal preemption concepts.   GPC claims that

the CAA preempts state common law actions.         The concept of federal

preemption is based upon the Supremacy Clause of the United States

Constitution. Under the Supremacy Clause,

      [the] Constitution, and the Laws of the United States . . .
      shall be the supreme Law of the Land; and the Judges in
      every State shall be bound thereby, any Thing in the
      Constitution or Laws of any State to the Contrary
      notwithstanding.
                                     27

U.S. Const. art. VI, cl. 2.    The question of whether a federal statute

preempts state common law is one of federal law and we are bound by

the decisions of the United States Supreme Court in the area.

      Under the Supremacy Clause, whether Congress sought to override

or preempt any inconsistent state law turns on congressional intent.

Medtronic, Inc. v. Lohr, 518 U.S. 470, 485, 116 S. Ct. 2240, 2250, 135 L.

Ed. 2d 700, 715–16 (1996). “Congress may indicate pre-emptive intent

through a statute’s express language or through its structure and

purpose.” Altria Grp., Inc. v. Good, 555 U.S. 70, 76, 129 S. Ct. 538, 543,

172 L. Ed. 2d 398, 405 (2008); accord Scott Gallisdorfer, Clean Air Act

Preemption of State Common Law: Greenhouse Gas Nuisance Claims After

AEP v. Connecticut, 99 Va. L. Rev. 131, 140 (2013) [hereinafter

Gallisdorfer].

      Implied preemption falls into two categories: conflict preemption

and field preemption.     Conflict preemption occurs when a state law

“actually conflicts” with a federal law, especially where it is impossible for

a party to comply with both state and federal requirements. See English

v. Gen. Elec. Co., 496 U.S. 72, 79, 100 S. Ct. 2270, 2275, 110 L. Ed. 2d

65, 74 (1990).    A variant of conflict preemption, obstacle preemption,

may be found where “state law stands as an obstacle to the

accomplishment and execution of the full purposes and objectives of

Congress.” See Caleb Nelson, Preemption, 86 Va. L. Rev. 225, 228–29,

265 (2000) (internal quotation marks omitted). Field preemption occurs

where the federal law so thoroughly occupies the field that Congress left

no room for state law. Cipollone v. Liggett Grp., Inc., 505 U.S. 504, 516,

112 S. Ct. 2608, 2617, 120 L. Ed. 2d 407, 423 (1992); Gallisdorfer, 99

Va. L. Rev. at 141.
                                    28

      The Supreme Court, however, has been particularly reluctant to

find federal preemption of state law in areas where states have

traditionally exercised their police power.   In Rice, the Supreme Court

noted that preemption analysis begins “with the assumption that the

historic police powers of the States [are] not to be superseded by the

Federal Act unless that was the clear and manifest purpose of Congress.”

331 U.S. at 230, 67 S. Ct. at 1152, 91 L. Ed. at 1459.        Further, the

Supreme Court has emphasized that “when the text of an express pre-

emption clause is susceptible of more than one plausible reading, courts

ordinarily ‘accept the reading that disfavors pre-emption.’ ” Altria Grp.,

555 U.S. at 77, 129 S. Ct. at 543, 172 L. Ed. 2d at 406 (quoting Bates v.

Dow Agrosciences LLC, 544 U.S. 431, 449, 125 S. Ct. 1788, 1801, 161 L.

Ed. 2d 687, 706 (2005)).

      2.   Traditional application of federal common law or state law

causes of action to environmental claims. When dealing with interstate

pollution, federal common law provided the rule of decision in a number

of early cases.   Prior to the recent AEP ruling in the Supreme Court,

federal common law was utilized in numerous water pollution cases. As

noted above, state claims of nuisance, negligence, and trespass are

traditional causes of action that have been utilized in a wide variety of

environmental contexts. Plainly, the existence of common law causes of

action to address pollution has been part of the “historic police powers”

of the states. See Huron Portland Cement Co. v. City of Detroit, 362 U.S.

440, 442, 80 S. Ct. 813, 815, 4 L. Ed. 2d 852, 855 (1960) (noting the

authority of states “to free from pollution the very air that people breathe

clearly falls within the exercise of even the most traditional concept of

what is compendiously known as the police power”).
                                    29

      3.   Clean water precedents related to preemption of federal and

state common law claims. We begin our discussion of CAA preemption

with an overview of clean water cases both prior to and after the passage

of the CWA. These cases are instructive because of their discussion of

the intergovernmental complexities surrounding pollution cases and

because of the similarities in language and structure between the CWA

and the CAA.      In particular, the cases demonstrate the important

distinction between whether a federal statute extinguishes federal

common law, and whether a federal statute preempts state common law.

      We begin our survey by noting the state of the law prior to the

enactment of the CWA. Prior to the 1970s, the Supreme Court held that

federal common law governed the use and misuse of interstate water.

See, e.g., Hinderlider v. La Plata River & Cherry Creek Ditch Co., 304 U.S.

92, 110, 58 S. Ct. 803, 811, 82 L. Ed. 1202, 1212 (1938); Missouri v.

Illinois, 200 U.S. 496, 518–20, 26 S. Ct. 268, 268–69, 50 L. Ed. 572,

577–78 (1906).

      In 1971, the Supreme Court suggested in dicta, however, that an

interstate dispute between a state and a private company should be

resolved by reference to state nuisance law.      See Ohio v. Wyandotte

Chems. Corp., 401 U.S. 493, 498 n.3, 91 S. Ct. 1005, 1009 n.3, 28

L. Ed. 2d 256, 263 n.3 (1971) (“[A]n action such as this, if otherwise

cognizable in federal district court, would have to be adjudicated under

state law.”). Thus, in the early 1970s, it was uncertain whether plaintiffs

seeking to attack pollution in the waterways could bring their claims

under federal common law or state common law.

      In 1972, the United States Supreme Court decided Illinois v. City of

Milwaukee (Milwaukee I), 406 U.S. 91, 92 S. Ct. 1385, 31 L. Ed. 2d 712

(1972). The case arose when Illinois moved for leave to file an original
                                        30

action in the Supreme Court to enjoin Milwaukee from discharging

sewage into Lake Michigan. Id. at 93, 92 S. Ct. at 1387–88, 31 L. Ed. 2d

at 717. The Supreme Court concluded that Illinois could bring a claim

under federal common law to abate a public nuisance in interstate or

navigable waters. Id. at 106–07, 92 S. Ct. at 1394–95, 31 L. Ed. 2d at

725–26.       The Supreme Court, however, foreshadowed the future and

noted that “[i]t may happen that new federal laws and new federal

regulations may in time pre-empt the field of federal common law of

nuisance.” Id. at 107, 92 S. Ct. at 1395, 31 L. Ed. 2d at 725.

       With respect to state common law, the Milwaukee I Court

suggested that it was displaced by federal legislation and federal common

law at least with respect to sources located in another state.                 The

Milwaukee I Court noted that:

       [f]ederal common law and not the varying common law of the
       individual States is . . . entitled and necessary to be
       recognized as a basis for dealing in uniform standard with
       the environmental rights of a State against improper
       impairment by sources outside its domain.

Id. at 107 n.9, 92 S. Ct. at 1395 n.9, 31 L. Ed. 2d at 726 n.9 (emphasis

added) (quoting Texas v. Pankey, 441 F.2d 236, 241 (10th Cir. 1971)).

       In 1972, Congress adopted the CWA. 5            33 U.S.C. §§ 1251–1387

(2012). The CWA contains a “citizen suit” savings clause in its remedies

section, which provides:

       Nothing in this section shall restrict any right which any
       person (or class of persons) may have under any statute or
       common law to seek enforcement of any effluent standard or
       limitation or to seek any other relief (including relief against
       the Administrator or a State agency).



       5TheFederal Water Pollution Control Act of 1948 was significantly reorganized
and expanded, and as amended became commonly known as the CWA.
                                       31

Id. § 1365(e).   The Senate Public Works Committee report in 1971

suggested that the citizen suit savings clause would specifically preserve

any rights or remedies under any other law. See S. Rep. No. 92-414, at

81 (1971), reprinted in 1972 U.S.C.C.A.N. 3668, 3746.

      The CWA also contains a “states’ rights” savings clause, which

states: “[e]xcept as expressly provided . . . nothing in this chapter shall

. . . be construed as impairing or in any manner affecting any right or

jurisdiction of the States with respect to the waters (including boundary

waters) of such States.” 33 U.S.C. § 1370.

      Finally, the CWA contains a “primary responsibilities and rights”

provision. The primary responsibilities and rights provision declares that

“[i]t is the policy of the Congress to recognize, preserve, and protect the

primary responsibilities and rights of States to prevent, reduce, and

eliminate pollution.” Id. § 1251(b).

      After the enactment of the CWA, the Supreme Court decided City of

Milwaukee v. Illinois (Milwaukee II), 451 U.S. 304, 101 S. Ct. 1784, 68 L.

Ed. 2d 114 (1981). This case arose out of the ongoing efforts of Illinois,

and later Michigan, to abate sewage discharges from the city of

Milwaukee allegedly in violation of federal common law. Id. at 308–10,

101 S. Ct. at 1788–89, 68 L. Ed. 2d at 120–22.        The Supreme Court

granted certiorari to consider the effect of the CWA on the federal

common law cause of action recognized by Milwaukee I. Milwaukee II,

451 U.S. at 307–08, 101 S. Ct. at 1787, 68 L. Ed. 2d at 120.

      In Milwaukee II, the Supreme Court, consistent with its prediction

in Milwaukee I, held in light of the passage of the CWA, federal common

law related to pollution of the waterways was preempted. Milwaukee II,

451 U.S. at 317–19, 101 S. Ct. at 1792–93, 68 L. Ed. 2d at 126–28.
                                   32

Speaking for a six-member majority, Justice Rehnquist observed in a

footnote that:

      the question whether a previously available federal common-
      law action has been displaced by federal statutory law
      involves an assessment of the scope of the legislation and
      whether the scheme established by Congress addresses the
      problem formerly governed by federal common law.

Id. at 315 n.8, 332, 101 S. Ct. at 1792 n.8, 1800, 68 L. Ed. 2d at 125

n.8, 136. The Milwaukee II Court concluded that:

      Congress has not left the formulation of appropriate federal
      standards to the courts through application of often vague
      and indeterminate nuisance concepts and maxims of equity
      jurisprudence, but rather has occupied the field through the
      establishment of a comprehensive regulatory program
      supervised by an expert administrative agency.

Id. at 317, 101 S. Ct. at 1792, 68 L. Ed. 2d at 126. The Court noted:

      Not only are the technical problems difficult—doubtless the
      reason Congress vested authority to administer the Act in
      administrative agencies possessing the necessary expertise—
      but the general area is particularly unsuited to the approach
      inevitable under a regime of federal common law [that would
      generate] ‘sporadic’ [and] ‘ad hoc’ [approaches to pollution
      control].

Id. at 325, 101 S. Ct. at 1796–97, 68 L. Ed. 2d at 131 (quoting S. Rep.

No. 92-414, at 95).

      The Milwaukee II Court, however, was careful to distinguish

between federal common law and state common law. See id. at 310 n.4,

329, 101 S. Ct. at 1789 n.4, 1798, 68 L. Ed. 2d at 122 n.4, 134. While

the Supreme Court declared that federal common law was displaced by

the CWA, it expressly declined to consider whether plaintiffs could bring

a claim under state common law. Id. at 310 n.4, 101 S. Ct. at 1789 n.4,

68 L. Ed. 2d at 122 n.4. In this regard, the Court noted:

      It is one thing . . . to say that States may adopt more
      stringent limitations through state administrative processes,
      or even that States may establish such limitations through
                                    33
      state nuisance law, and apply them to in-state discharges. It
      is quite another to say that the States may call upon federal
      courts to employ federal common law to establish more
      stringent standards applicable to out-of-state dischargers.

Id. at 327–28, 101 S. Ct. at 1798, 68 L. Ed. 2d at 133.

      Upon remand, the Court of Appeals for the Seventh Circuit in

Illinois v. City of Milwaukee (Milwaukee III), considered whether the CWA

precluded application of one state’s common law against a pollution

source located in a different state. 731 F.2d 403, 406 (7th Cir. 1984).

The Seventh Circuit in Milwaukee III concluded that such state common

law was preempted.     Id. at 410–11.    The Seventh Circuit was careful,

however, to distinguish an effort to apply a state’s common law against a

polluter located outside the state and a common law claim against an in-

state polluter.   See id. at 414.   The Seventh Circuit noted that an

approach that allowed the application of state common law against an

out-of-state polluter could lead to confusion, as a single source might be

subject to different and conflicting state common law in a number of

surrounding states, thereby leading to a “chaotic confrontation between

sovereign states.” Id. Yet, the Seventh Circuit recognized that the citizen

suit savings clause preserved a right under state common law to obtain

enforcement or prescribed standards or limitations against an in-state

polluter. Id. at 413–14. The Supreme Court denied certiorari. 469 U.S.

1196, 105 S. Ct. 980, 83 L. Ed. 2d 981 (1985).

      In 1987, the Supreme Court returned to the subject area in

Ouellette. In Ouellette, a class of property owners on the Vermont side of

Lake Champlain alleged that a paper mill located in New York discharged

pollutants into the lake and constituted a nuisance under Vermont law.

479 U.S. at 483–84, 107 S. Ct. at 807, 93 L. Ed. 2d at 891. International

Paper Co. moved for summary judgment, claiming that the CWA
                                    34

preempted state common law claims under Milwaukee III. Ouellette, 479

U.S. at 484–85, 107 S. Ct. at 808–09, 93 L. Ed. 2d at 892–93.          The

federal district court denied summary judgment, citing the citizen suit

savings clause and the states’ rights savings clause of the CWA. Id. at

485, 107 S. Ct. at 808, 93 L. Ed. 2d at 892–93.         The district court

reasoned that state common law actions to redress interstate water

pollution could be maintained under the law of the state where the injury

occurred. Id. at 486, 107 S. Ct. at 808–09, 93 L. Ed. 2d at 893.

      In Ouellette, the Supreme Court reversed the district court. See id.

at 487, 101 S. Ct. at 809, 93 L. Ed. 2d at 893. The Supreme Court held

that the CWA preempted state nuisance actions to the extent that state

law applied to an alleged out-of-state polluter. Id. at 493–94, 107 S. Ct.

at 812–13, 93 L. Ed. 2d at 897–98. The Ouellette Court recognized that

states play a significant role in the protection of their own natural

resources, that the CWA permits the EPA to delegate to a state the

authority to administer permit programs with respect to certain sources

of pollution within the state, and that a state may require discharge

limitations more stringent than those required by the EPA. Id. at 489–

90, 107 S. Ct. at 810, 93 L. Ed. 2d at 895.

      Nonetheless, the Ouellette Court noted that with respect to out-of-

state sources, the affected state’s role is limited to the opportunity to

object to the proposed standards of a federal permit in a public hearing.

Id. at 490, 107 S. Ct. at 810–11, 93 L. Ed. 2d at 895. A state, however,

does not have the authority to block the issuance of a permit with which

it may be dissatisfied. Id. at 490, 107 S. Ct. at 811, 93 L. Ed. 2d at 896.

In short, the state “may not establish a separate permit system to

regulate an out-of-state source.” Id. at 491, 107 S. Ct. at 811, 93 L. Ed.

2d at 896.   The Ouellette Court noted that allowing affected states to
                                    35

impose separate discharge standards on a single “point source” would

interfere with the carefully devised regulatory system established by the

CWA. Id. at 493, 107 S. Ct. at 812, 93 L. Ed. 2d at 898.

      While the Ouellette Court held that the plaintiffs could not impose

Vermont law on the out-of-state polluter, it emphasized that the Vermont

residents were not without a remedy. Id. at 497, 107 S. Ct. at 814, 93

L. Ed. 2d at 900. According to the Ouellette Court, the citizen suit and

states’ rights savings clauses, jointly referred to by the Court as the

“saving clause,” preserves actions not incompatible with the CWA and

“nothing in the Act bars aggrieved individuals from bringing a nuisance

claim pursuant to the law of the source State.” Id.

      The Ouellette Court offered three reasons why an action brought

against International Paper Co. under New York nuisance law would not

frustrate the goals of the CWA.    First, the Ouellette Court noted that

imposing a source state’s law does not affect the balance among federal,

source-state, and affected-state interests, particularly in light of the

specific authorization that allows source states to impose stricter

standards.   Id. at 498–99, 107 S. Ct. at 815, 93 L. Ed. 2d at 901.

Second, the Ouellette Court noted that restricting common law actions to

those of the source state “prevents a source from being subject to an

indeterminate number of potential regulations.” Id. at 499, 107 S. Ct. at

815, 93 L. Ed. 2d at 901. Finally, the Ouellette Court noted that states

may be expected to take into account their own nuisance laws in setting

permit requirements. Id.

      Thus, under the CWA cases, a clear pattern emerges.        Federal

common law over pollution of interstate waterways is now preempted in

light of the comprehensive nature of the CWA and the expertise vested in

the EPA and state agencies to solve complex problems involved in
                                   36

environmental issues. State law claims against out-of-state sources are

preempted because they would be inconsistent with the regulatory

framework created by the CWA and would create chaos by imposing

multiple regulatory schemes on a single source. State law claims against

in-state sources of pollution, however, are saved by the citizen suit

savings clause, the states’ rights savings clause, and other provisions of

the CWA and are consistent with the principle that states may impose

limitations on pollution more stringent than required by federal law. As

a result, state common law claims against an in-state source are not

preempted by the CWA.

      4.   CAA precedent.      The Supreme Court has not recently

considered the scope of preemption of state common law under the CAA.

We begin our discussion, however, with an important Supreme Court

case that teed up the issue.     In Massachusetts, the Supreme Court

considered a claim brought by a group of private organizations that filed

a rulemaking petition asking the EPA to regulate greenhouse gas (GHG)

emissions from new motor vehicles under the CAA. 549 U.S. at 505, 127

S. Ct. at 1446, 167 L. Ed. 2d at 260.      After an extensive notice and

comment period, the EPA entered an order denying the rulemaking. Id.

at 511, 127 S. Ct. at 1449–50, 167 L. Ed. 2d at 263–64.        The EPA’s

stated reasons for denial were that the CAA did not authorize the EPA to

issue mandatory regulations to address global climate change and that

even if it did, it would be unwise to issue such regulations at this time.

Id. at 511, 127 S. Ct. at 1450, 167 L. Ed. 2d at 264.       The Court of

Appeals for the D.C. Circuit denied a petition to review the denial of

rulemaking. Id. at 511, 127 S. Ct. at 1451, 167 L. Ed. 2d at 265.

      The Supreme Court reversed. Id. at 535, 127 S. Ct. at 1463, 167

L. Ed. 2d at 278.     It held that the EPA did have authority to set
                                   37

emissions standards and had offered no reasonable explanation for its

failure to promulgate rules. 549 U.S. at 528, 534, 127 S. Ct. at 1459,

1463, 167 L. Ed. 2d at 274, 278.

      After Massachusetts, the EPA began to incrementally regulate

aspects of GHG emissions.      See Gallisdorfer, 99 Va. L. Rev. at 131.

Environmental groups were unsatisfied with the pace of EPA regulation,

however, and began to file actions seeking injunctive caps on GHG

emissions under a public nuisance theory.       See id.   Often, plaintiffs

seeking to increase environmental protection from GHG emissions

proceeded on a federal common law theory. Id.

      In 2011, however, the Supreme Court decided AEP, in which eight

states, New York City, and three nonprofit land trusts, brought an action

seeking to enjoin GHG emissions from four private companies and the

Tennessee Valley Authority. See 564 U.S. at ___, 131 S. Ct. at 2532, 180

L. Ed. 2d at 442. Because the EPA began regulating GHG emissions as a

result of the Massachusetts case during the pendency of the lawsuit, the

question arose as to whether the action of the EPA “displaced” the federal

common law that was traditionally regarded as a source of law for

interstate nuisance actions. See id. at ___, 131 S. Ct. at 2533–35, 180

L. Ed. 2d at 442–45.

      In language similar to that used in Milwaukee II, the Supreme

Court held that the CAA displaced federal common law with respect to

GHG emissions. AEP, 564 U.S. at ___, 131 S. Ct. at 2537, 180 L. Ed. 2d

at 447. The Supreme Court concluded that the CAA directly addressed

the question because “air pollutants” were subject to regulation under

the CAA and “air pollutants” clearly included GHG emissions. Id. at ___,

131 S. Ct. at 2532–33, 180 L. Ed. 2d at 442–43.
                                          38

       The Supreme Court in AEP, however, only held that federal

common law regarding “air pollutants” was displaced by the CAA. Id. at

___, 131 S. Ct. at 2537, 180 L. Ed. 2d at 447. The Court declined to

reach the state law nuisance claims because they had not addressed the

issue on appeal. Id. at ___, 131 S. Ct. at 2540, 180 L. Ed. 2d at 450–51.

The AEP Court noted, however, that “[l]egislative displacement of federal

common law does not require the same sort of evidence . . . demanded

for preemption of state law.” Id. at ___, 131 S. Ct. at 2537, 180 L. Ed. 2d

at 447 (quoting Milwaukee II, 451 U.S. at 317, 101 S. Ct. at 1792, 68 L.

Ed. 2d at 126) (internal quotation marks omitted).

       As previously noted, after AEP, two federal appellate courts

considered whether the CAA preempted state law in the source state.

See Bell II, 734 F.3d at 190, cert. denied, 82 U.S.L.W. 3531 (U.S. June 2,

2014) (No. 13–1013) (concluding that state law claims are not

preempted); MTBE Prods. Liab. Litig., 725 F.3d at 96–103 (finding that

source-state common law claims are not preempted under the CAA).

       One federal district court, however, came to a different conclusion.

In Comer I, a federal district court found that state common law claims

brought by property owners against several oil companies, coal

companies,      electric   companies,      and     chemical     companies,      whose

emissions allegedly contributed to global warming were preempted by the

CAA. 839 F. Supp. 2d at 865. 6




        6On appeal, the case was reversed by a panel of the Court of Appeals for the

Fifth Circuit. Comer v. Murphy Oil USA, Inc. (Comer II), 585 F.3d 855, 859, 878–80 (5th
Cir. 2009). However, in an unusual result, a petition for rehearing en banc was granted
and then dismissed for a lack of quorum, with the result that the district court opinion
stood. See Comer v. Murphy Oil USA, Inc., 598 F.3d 208, 210 (5th Cir.), dismissed on
reh’g, 607 F.3d 1049, 1055 (5th Cir. 2010).
                                     39

      Prior to AEP, federal caselaw on the question of CAA preemption of

source-state common law was mixed.         In Her Majesty the Queen, the

Court of Appeals for the Sixth Circuit held that Canadian officials could

seek to enjoin construction of a Michigan trash incinerator under

Michigan law because of the alleged lack of air pollution control

equipment, even though the facility had already received a CAA permit.

874 F.2d at 342–44. Similarly, in Gutierrez v. Mobil Oil Corp., a federal

district court held that plaintiffs could proceed on source-state common

law claims alleging defendant negligently maintained storage facilities for

various fuels. 798 F. Supp. 1280, 1281 (W.D. Tex. 1992).

      However, in TVA, the Fourth Circuit reviewed a district court order

granting an injunction at the behest of the State of North Carolina

requiring the immediate installation of emissions controls at four

Tennessee Valley Authority generating plants located in Alabama and

Tennessee. 615 F.3d at 296. The injunction was based upon the district

court’s determination that the plants were a public nuisance under the

law of the affected state, North Carolina.     Id.   The estimated cost of

compliance with the order was uncertain, but North Carolina admitted

that the cost would be in excess of one billion dollars. Id. at 298.

      The Fourth Circuit reversed. Id. at 312. The Fourth Circuit found

that the litigation amounted to a collateral attack on the process chosen

by Congress to establish appropriate standards and grant permits for the

operation of power plants. See id. at 302. The Fourth Circuit stressed

that an “injunction-driven demand” for artificial changes was likely to be

inferior to a system-based analysis of what changes would do the most

good. Id. Yet, the Fourth Circuit did not hold that Congress had entirely

preempted the field of emissions regulation. Id. Instead, each case had

to be considered on a case-by-case basis to determine “ ‘if it interferes
                                          40

with the methods by which the federal statute was designed to reach [its]

goal.’ ” Id. at 303 (alteration in original) (quoting Ouellette, 479 U.S. at

494, 107 S. Ct. at 813, 93 L. Ed. 2d at 898).              While the TVA court

expressly disapproved of the application of the law of the affected state as

contrary to Ouellette, TVA, 615 F. 3d at 308–09, the court further found

“it would be difficult to uphold the injunctions because [the Tennessee

Valley        Authority’s]   electricity-generating   operations   are   expressly

permitted by the states in which they are located,” id. at 309.

         5. Discussion. All parties agree that nothing in the CAA expressly

preempted the nuisance and common law actions presented in this case.

Therefore, the question of whether the CAA preempted the claims in this

case must rely on an implied preemption theory based upon either field

preemption or conflict preemption.

         a.    Field preemption.    We begin our discussion by noting that a

party seeking to use implied field preemption to oust state law causes of

action that have been traditionally part of the police power of the states

faces an uphill battle. See Huron, 362 U.S. at 442, 80 S. Ct. at 815, 4

L. Ed. 2d at 855 (noting the authority of states “to free from pollution the

very air that people breathe clearly falls within the exercise of even the

most traditional concept of what is compendiously known as the police

power”). Congress unquestionably has the power to preempt local law

when it acts on federal concerns and may expressly do so. To imply the

ousting of traditional state law remedies such as nuisance by implication

in a federal statute, though not impossible, seems at least improbable in

most cases. In the case of the CAA, state regulation of pollution sources

through source-state-law actions had to have been something of an

obvious, yet unaddressed, issue when the statute was drafted.                  To

suggest that Congress indirectly removed the state’s ability to address
                                     41

these environmental concerns with state law actions seems, on the

surface at least, rather unlikely.   At a minimum, to find implied field

preemption, we think there should be powerful textual authority or

structural issues that drive us in this counterintuitive direction.

       When we look at the text of the CAA, we find language that tends

to support the conclusion that Congress did not impliedly oust the state

law actions of the source state. The any measures clause, the retention

of state authority savings clause, and the citizens’ rights savings clause

strongly suggest that Congress did not seek to preempt, but to preserve,

state law claims.    See 42 U.S.C. §§ 7401(a)(3), 7416, 7604(e).          The

citizens’ rights savings clause expressly states that the ability to bring

actions under the CAA does not preempt common law rights.              See 42

U.S.C. § 7604(e). While the term “requirements” in the retention of state

authority savings clause is perhaps indefinite, most courts that have

considered the question have concluded that the term includes common

law duties. See, e.g., Riegel v. Medtronic, Inc., 552 U.S. 312, 323–24, 128

S. Ct. 999, 1007–08, 169 L. Ed. 2d 892, 902–03 (2008); Cipollone, 505

U.S. at 521–22, 112 S. Ct. at 2620, 120 L. Ed. 2d at 426.

       GPC suggests that allowing state law actions based on source-state

law will undercut the structure of the CAA.       We think not.       The CAA

statute was structured to promote cooperative federalism.         Under the

cooperative federalism approach, the states were given the authority to

impose stricter standards on air pollution than might be imposed by the

CAA.    See Bell II, 734 F.3d at 197–98.     In short, Congress expressly

wanted the CAA to be a floor, but not a ceiling, on air pollution control.

A similar conclusion has been reached by the Second, Third, and Sixth

Circuits. Id. at 194–98; MTBE Prods. Liab. Litig., 725 F.3d at 96–103;

Her Majesty the Queen, 874 F.2d at 342–44.
                                    42

      GPC further suggests that because air pollution matters involve

complex questions requiring the balancing of economic and social

benefits and harms, controversies over source-state pollution are best

left to administrative agencies and the rulemaking process.       Further,

GPC makes an appeal that there should be a uniform approach to these

questions.   This argument may have some policy appeal, but it runs

against the grain of bilateral cooperative federalism manifest in the any

measures clause, the retention of state authority savings clause, and the

citizens’ rights savings clause of the CAA. See 42 U.S.C. §§ 7401(a)(3),

7416, 7604(e).

      GPC supports its argument with citation to language in AEP and

Comer I.     But GPC and some of the authority upon which it relies

conflate the issue of displacement of federal common law with the

somewhat related but distinct issue of preemption of state common law.

We think two takeaway points from the Supreme Court’s caselaw are (1)

the question of displacement of federal common law is different than the

question of preemption of state law actions, and (2) the standard for

displacement of federal common law is different than the standard for

preemption of state law.       Further, in considering the issues of

displacement of federal common law under the CWA and the CAA, the

Supreme Court has not had to consider the statutory language in the

CAA suggesting a congressional intent to not preempt state law.

      GPC’s argument that it will be subject to multiple regulators is also

insufficient for us to find that all state law actions based upon source-

state law are preempted because Congress occupied the field.          With

respect to this argument, it is important to remember the distinction in

Ouellette and Milwaukee II between preemption of the law of a source

state from the preemption of the law of the pollution-affected state.
                                   43

Ouellette, 479 U.S. at 491–94, 107 S. Ct. at 811–13, 93 L. Ed. 2d at 896–

98; Milwaukee II, 451 U.S. at 327–28, 101 S. Ct. at 1798, 68 L. Ed. 2d at

132–33.   Allowing claims to go forward based on the law of the state

merely affected by pollution could cause real structural problems as a

multistate polluter could be subject to the laws of many states, which

could impose contradictory and confusing legal requirements.          The

thrust of the Ouellette and Milwaukee II decisions is that allowing

common law claims from all affected states would create chaos and

cannot be allowed.

      It is critical, however, to distinguish between efforts to apply the

law of the source state and efforts to apply the law of the pollution-

affected state. In this case we deal with a claim that seeks to regulate

pollution based on the law of the source state. This is precisely the kind

of cooperative federalism anticipated by the statute. GPC is not subject

to a dozen or more regulatory regimes, but only two. The notion that a

person must comply with parallel state and federal law requirements that

may not be uniform is not new to the law. As recognized in Ouellette, on

the one hand, state “nuisance law may impose separate standards and

thus create some tension with the permit system,” but, on the other

hand, “the restriction of suits to those brought under source-state

nuisance law prevents a source from being subject to an indeterminate

number of potential regulations.” Id. at 499, 107 S. Ct. at 815, 93 L. Ed.

2d at 901.

      The conclusion that source-state common law claims are not

preempted by the CAA is endorsed by treatise writers. See Grad § 18.02,

at 18-4 to 18-5 (“Despite the overriding emphasis on federal and state

statutes in the field of environmental law, common law remedies, even

those old fashioned causes of trespass and nuisance, remain viable
                                   44

causes of action.”); Malone § 10:2, at 10-7 n.1 (“[S]tate common law

theories of liability were not preempted by the [CAA].”); 1 William H.

Rodgers,    Environmental   Law    §    3:1(A)(1)   (2013),   available   at

www.westlaw.com (“[T]here is no question that nuisance law that was

preserved has remained vibrant and serviceable.”).

      GPC seeks to avoid the teaching of Milwaukee II and Ouellette by

suggesting that while state common law actions might not have been

originally preempted by the CAA when Milwaukee II and Ouellette were

decided, the Clean Air Act Amendments of 1990 and the dramatic growth

in the complexity of clean air regulation now give rise to conflict

preemption.    According to GPC, this increasingly complex web of

regulation was recognized in AEP, where the Supreme Court emphasized

the complexity of environmental regulation and the difficulties of

balancing competing interests in the formulation of environmental policy.

See 564 U.S. at ___, 131 S. Ct. at 2539, 180 L. Ed. 2d at 449–50.

      This argument has been zealously advanced by GPC and has some

appeal.    There is no question that the federal regulatory framework

under the CAA is increasingly complicated. It is important in our view,

however, not to conflate increased complexity with the issue of conflict

preemption. Notwithstanding the increased complexity, the cooperative

federalism framework and the notion that states may more stringently

regulate remains a hallmark of the CAA.

      Further, state common law and nuisance actions have a different

purpose than the regulatory regime established by the CAA. The purpose

of state nuisance and common law actions is to protect the use and

enjoyment of specific property, not to achieve a general regulatory

purpose. It has long been understood that an activity may be entirely

lawful and yet constitute a nuisance because of its impairment of the use
                                    45

and enjoyment of specific property. See Galaxy Carpet Mills, 338 S.E.2d

at 429–30; Urie, 218 A.2d at 362; Tiegs, 954 P.2d at 883–84.           We

therefore decline to conclude that the increased complexity of the CAA

has categorically elbowed out a role for the state nuisance and common

law claims presented here.

      b. Conflict preemption. GPC presents yet another refinement of its

argument. While it may be that Congress has not impliedly occupied the

field, case-by-case conflict preemption may arise in light of the dense

federal regulations.   In other words, while it may not be possible to

declare that Congress has preempted source-state law in all cases

involving emissions regulation, it has in cases that amount to a collateral

attack on the NAAQS, SIP, and permitting method established by

Congress under the CAA.

      In support of this argument, GPC cites TVA. As noted above, in

TVA the Fourth Circuit reversed an order granting injunctive relief to the

State of North Carolina in a public nuisance action challenging the

pollution from power plants located in Alabama and Tennessee.          615

F.3d at 296.   The Fourth Circuit noted that it was estimated that the

equipment modification ordered by the district court could cost in excess

of one billion dollars.   Id. at 298.    The Fourth Circuit held that the

injunction requiring extensive changes to equipment based on a public

nuisance theory conflicted with the CAA where the existing equipment

had been approved under the CAA regulatory framework. See id. at 302–

03.

      The approach of TVA has not been uniformly embraced in the

federal courts. The conflict preemption analysis in TVA seems contrary

to the approach of the Third Circuit in Bell II, 734 F.3d at 193–98

(finding “nothing in the [CAA] to indicate that Congress intended to
                                     46

preempt source state common law tort claims.”), and the Second Circuit

in MTBE Products Liability Litigation, 725 F.3d at 95–104 (finding “[s]tate

law [in the case] neither ‘penalizes what federal law requires’ nor ‘directly

conflicts’ with federal law” and therefore the impossibility preemption

defense did not overcome the presumption against preemption).             Cf.

Merrick v. Diageo Americas Supply, Inc., No. 3:12-CV-334-CRS, 2014 WL

1056568, at *5–8 (W.D. Ky. Mar. 19, 2014) (disagreeing with TVA and

following Bell II and MTBE Products Liability Litigation).

      While we understand the reasoning in TVA, we do not think it

provides a basis for summary judgment in this case. The plaintiffs seek

damages related to specific properties at specific locations allegedly

caused by a specific source.     Of course, the plaintiffs must prevail on

issues of substantive liability that the district court has not had occasion

to address and are not before us now. If the plaintiffs do prevail on the

merits, however, any remedy involving damages or remediation would

simply not pose the kind of conflict with the permitting process that the

sweeping injunction in TVA presented. See id. at 301–06. Any impact on

the regulatory regime would be indirect and incidental. As a result, we

conclude that conflict preemption with the CAA does not apply to a

private lawsuit seeking damages anchored in ownership of real property.

See Bell II, 734 F.3d at 189–90 (allowing private property owners’ claims

for nuisance, negligence, and trespass based on facility’s flying ash and

unburned by-products to go forward); Bennett v. Mallinckrodt, Inc., 698

S.W.2d 854, 862 (Mo. Ct. App. 1985) (“States may be preempted from

setting their own emissions standards, but they are not preempted from

compensating injured citizens.”).

      With respect to the question of whether injunctive relief would

conflict with the CAA, we do not find this issue ripe at this time. Even
                                     47

TVA indicates that conflict preemption analysis is not subject to

sweeping generalities and must be done on a case-by-case basis.         See

615 F.3d at 302–03.        We simply cannot evaluate the lawfulness of

injunctive relief that has not yet been entered. Such an evaluation must

await the development of a full record and the shaping of any injunctive

relief by the district court.

      IV. Discussion of Preemption by Iowa Code Chapter 455B.

      A. Positions of the Parties.

      1. Plaintiffs.   The plaintiffs attack the district court’s ruling on

preemption under Iowa Code chapter 455B in several ways.                The

plaintiffs note that Iowa Code chapter 455B, like the CAA, has a citizens’

rights savings clause, which provides: “[t]his section does not restrict any

right under statutory or common law of a person or class of person to . . .

seek other relief permitted under the law.”     Iowa Code § 455B.111(5).

The plaintiffs contend the language simply means what it says and

allows the statutory and common law claims they have brought in this

case, which should be considered “other relief permitted under the law.”

      With respect to common law claims, the plaintiffs assert because

there is no express preemption in Iowa Code chapter 455B, the

defendants must rely on implied preemption.           Implied preemption,

however, is found only where “ ‘imperatively required,’ ” Fabricius v.

Montgomery Elevator Co., 254 Iowa 1319, 1322, 121 N.W.2d 361, 362

(1963) (quoting Bradshaw v. Iowa Methodist Hosp., 251 Iowa 375, 388,

101 N.W.2d 167, 174 (1960)). The plaintiffs maintain that preemption

here is not “imperatively required,” as the common law claims specifically

address harms to property, while the regulatory framework in Iowa Code

chapter 455B addresses more general harms caused by pollution. The

plaintiffs assert that Iowa caselaw supports this proposition.          See
                                    48

Simpson v. Kollasch, 749 N.W.2d 671, 674 (Iowa 2008) (indicating

compliance with environmental regulation is not a defense to a nuisance

claim, though it may be evidence of whether defendant’s conduct is a

nuisance); Gerst v. Marshall, 549 N.W.2d 810, 813–15 (Iowa 1996)

(involving common law claims brought along with claims under chapter

455B).

      The plaintiffs further note that their nuisance claim is based in

part on Iowa Code chapter 657, which provides a general framework for

bringing statutory nuisance claims in Iowa. In order to find that Iowa

Code chapter 455B preempts the statutory provisions of Iowa Code

chapter 657, the plaintiffs maintain that the two statutes must be

“irreconcilably repugnant.”   State v. Rauhauser, 272 N.W.2d 432, 434

(Iowa 1978). The plaintiffs argue that far from being irreconcilable, the

statutes may be harmonized by interpreting Iowa Code chapter 455B’s

citizens’ rights savings clause as allowing statutory nuisance actions that

may result in stricter control of pollution. Further, plaintiffs emphasize

that claims under the nuisance statute protect against harms to specific

property, while chapter 455B more generally protects the public from air

pollution.   Because the statutes address different types of harms and

interests, the plaintiffs contend there can be no preemption of nuisance

claims arising from Iowa Code chapter 455B.

      Further, the plaintiffs note that the legislature has expressly

provided that certain types of statutes do preempt statutory nuisance

actions. Specifically, Iowa Code sections 657.1(2) and 657.11(1) provide

that nuisance claims related to electrical utilities and animal feeding

operations are preempted from further regulation through statutory

nuisance claims. The plaintiffs press the point that the legislature knew

how to preempt certain types of environmental claims from nuisance
                                    49

actions but did not extend preemption to the plaintiffs’ claims in this

case.

        Finally, the plaintiffs claim that if Iowa Code chapter 455B

preempted state common law claims, a serious constitutional issue

would be present.     They note, for instance, we have held that giving

farms immunity from nuisance suits may deprive one of the use and

enjoyment of property and amount to an unconstitutional “taking” of

property without due compensation.         Gacke v. Pork Xtra, L.L.C., 684

N.W.2d 168, 172–74 (Iowa 2004); Bormann v. Bd. of Supervisors, 584

N.W.2d 309, 320–21 (Iowa 1998).          To the extent there is any doubt

regarding the proper interpretation of Iowa Code chapter 455B, it should

be interpreted in a fashion to avoid the constitutional problem. Dalarna

Farms v. Access Energy Coop., 792 N.W.2d 656, 663–64 (Iowa 2010).

        2. GPC. Because state law preemption is substantively identical to

federal conflict and field preemption, GPC incorporates its arguments

regarding federal preemption on the question of whether Iowa Code

chapter 455 preempted the common law claims in this case.            GPC,

however, presents some refinements based upon its analysis of the Iowa

caselaw.

        First, GPC points out that in order for state law to preempt

common law claims based on field preemption, it is not necessary that it

be impossible to reconcile the statute with the common law claims. GPC

argues that in Northrup v. Farmland Industries, Inc., we found that the

Iowa Civil Rights Act was the exclusive remedy for wrongful discharge

based on disability without a finding of impossibility. See 372 N.W.2d

193, 197 (Iowa 1985).      Further, GPC argues that an action becomes

irreconcilable with state law by imposing requirements beyond what the

state law proscribes. For instance, in Baker v. City of Iowa City, we held
                                    50

that an ordinance allowing claims against employers with fewer than four

employees was irreconcilable with the Iowa Civil Rights Act, which

provided claims could only be brought against employers with four or

more employees. 750 N.W.2d 93, 101–02 (Iowa 2008).

      Second, building on Northrup and Baker, GPC asserts that the

common law claims in this case go beyond the state law framework in

chapter 455 by circumventing the state’s emissions regulation and

permitting process and by potentially imposing new standards without

the scientific expertise and extensive rulemaking process employed by

the state environmental regulators.       GPC argues that the court could

order GPC to use certain processes or install new pollution control

equipment,   which    could    conflict   with   environmental   regulatory

requirements imposed on it by the Iowa Department of Natural

Resources (DNR) or the EPA and further upset the delicate balance

achieved through the regulatory process.

      Therefore, GPC argues that if the plaintiffs prevail in their common

law claims, GPC could end up in an intolerable catch-22 situation. For

instance, GPC suggests that the state court in the common law actions

might order a remedy that the DNR refuses to approve. In this setting,

GPC would be forced to either comply with the district court order and

defy the DNR, or vice versa.     Or, the DNR could, after careful study,

ultimately approve court-ordered changes to its operations as a result of

the common law claims, but the necessary approvals might not be

obtained quickly enough for timely compliance with the court’s mandate.

GPC argues this kind of trouble was addressed in Goodell, where the

court noted that imposition of local requirements in excess of state law

requirements could lead to preemption.           575 N.W.2d at 501 (“Any

attempt by a local government to add to those requirements would
                                    51

conflict with the state law, because the local law would in effect prohibit

what the state law permits.”).

      B.   Analysis of Iowa Code Chapter 455B Preemption.              The

precise question here is whether Iowa Code chapter 455B impliedly

conflicts with and thus preempts a statutory claim for nuisance under

Iowa Code chapter 657 and common law claims of nuisance, trespass,

and negligence.    With respect to one statute impliedly preempting

another, we have       understandingly been quite demanding.           The

legislature is presumed to know the existing state of the law when the

new statute is enacted. Jahnke v. Incorporated City of Des Moines, 191

N.W.2d 780, 787 (Iowa 1971). In the absence of any express repeal, the

new provision is presumed to accord with the legislative policy embodied

in prior statutes. See Ruth Fisher Elementary Sch. Dist. v. Buckeye Union

High Sch. Dist., 41 P.3d 645, 648 (Ariz. Ct. App. 2002). When prior and

later statutes deal with the same subject matter, although in apparent

conflict, they should as far as reasonably possible be construed in

harmony with each other to allow both to stand and be given force and

effect. See Polk Cnty. Drainage Dist. Four v. Iowa Natural Res. Council,

377 N.W.2d 236, 241 (Iowa 1985). While we recognize the possibility of

an implied repeal, such action is permitted only where the statutes

“cover the same subject matter,” are “irreconcilably repugnant,” and

implied repeal is “absolutely necessary.” Rauhauser, 272 N.W.2d at 434.

While the issue in this case does not require a complete repeal of Iowa

Code chapter 657, we think the Rauhauser test remains applicable where

a party seeks to nullify application of a preexisting statute to a specific

circumstance.

      With respect to whether a statute abrogates common law, the test

is somewhat similar.    We have declared that absent express statutory
                                    52

language, a party seeking to demonstrate that a statute impliedly

overrides common law must show that this result is “imperatively

required.” See, e.g., Rieff v. Evans, 630 N.W.2d 278, 286 (Iowa 2001);

Collins v. King, 545 N.W.2d 310, 312 (Iowa 1996). While the question of

whether the CAA preempts state common law is a question of federal law,

whether chapter 455B impliedly repeals or overrides common law is a

question of state law.

      There is no definitive Iowa case dealing with the question of

whether nuisance or common law claims may go forward in light of the

provisions of Iowa Code chapter 455B. In Gerst, a plaintiff raised parallel

common law claims along with a citizen-action claim under Iowa Code

chapter 455B.    549 N.W.2d at 813.      We were not asked, however, to

decide whether the nuisance and common law claims were extinguished

by Iowa Code chapter 455B.

      Nonetheless, we do have instructive caselaw. We have made clear

that a lawful business, properly conducted, may still be a nuisance. For

instance, in Simpson we noted in the context of the proposed

construction of a hog-confinement facility that compliance with DNR

regulations was not a defense to a nuisance action. 749 N.W.2d at 672,

674. We noted that “ ‘a lawful business, properly conducted, may still

constitute a nuisance if the business interferes with another’s use of his

own property.’ ” Id. at 674 (quoting Weinhold v. Wolff, 555 N.W.2d 454,

461 (Iowa 1996)).    Our approach is consistent with the law in other

jurisdictions. See, e.g., Flo-Sun, Inc. v. Kirk, 783 So. 2d 1029, 1036 (Fla.

2001) (holding “something may legally constitute a public nuisance . . .

although it may technically comply with existing pollution laws”); Biddix

v. Henredon Furniture Indus., Inc., 331 S.E.2d 717, 724 (N.C. Ct. App.

1985) (noting that the North Carolina Clean Water Act does not preempt
                                     53

common law claims); Gonzalez v. Whitaker, 643 P.2d 274, 278 (N.M. Ct.

App. 1982) (holding state environmental statutes do not preempt

common law claims). See generally, Selmi § 10:26, at 10-56, 57.

       We do not see enforcement of nuisance and other common law

torts in this case as inconsistent with the regulatory framework

established by chapter 455B.       As indicated above, the nuisance and

common law actions in this case are based on specific harms to the use

and enjoyment of real property that are different from the public interest

generally in controlling air pollution.     We thus think the principles

articulated in Van Baale v. City of Des Moines, 550 N.W.2d 153, 156

(Iowa 1996) (“Where the legislature has provided a comprehensive

scheme for dealing with a specified kind of dispute, the statutory remedy

provided is generally exclusive.” (quoting IA C.J.S. Actions § 14 n.55

(1985))), and Northrup, 372 N.W.2d at 197 (holding remedy provided

under Iowa Civil Rights Act “is exclusive”), are inapplicable. In short, we

think Iowa Code chapter 455B did not impliedly repeal application of

Iowa Code chapter 657 to air pollution claims or preempt Iowa common

law.

       With respect to remedies, GPC speculates that the district court

could enter a remedy that conflicts with Iowa Code chapter 455B. As a

result, GPC argues that the nuisance and common law claims should not

be allowed to go forward.     Any consideration of this possibility at this

stage of the litigation, however, is premature. GPC has not demonstrated

that the district court sitting in equity cannot fashion equitable relief that

is consistent with Iowa Code chapter 455B. Specifically, to the extent

the district court orders equitable relief, any such relief may be

conditioned upon obtaining regulatory approvals required under Iowa

Code chapter 455B. Or, equitable relief may require development of a
                                      54

common     fund   to     promote   clean up   that   does   not   impact the

requirements of Iowa Code chapter 455B at all. In any event, we decline

to speculate at this stage about the possible legal issues that may be

raised by the granting of any injunctive relief in this case.

      V. Discussion of Political Question Doctrine.

      A. Positions of the Parties.

      1.   Plaintiffs.    The plaintiffs argue that the political question

doctrine does not serve as an impediment to their statutory and common

law claims. The plaintiffs note that political questions ordinarily involve

questions for which there is a demonstrable constitutional commitment

to other branches of government. The plaintiffs note that in Des Moines

Register & Tribune Co. v. Dwyer, this court held the Iowa Constitution

had “a textually demonstrable constitutional commitment” to the Iowa

Senate of the power to establish its rules of proceedings. 542 N.W.2d

491, 496 (Iowa 1996).       Unlike Dwyer, the plaintiffs argue, there is no

demonstrable constitutional commitment involved in this case. Indeed,

Congress has expressly authorized statutory and common law actions

under state law.       A state court deciding directly authorized litigation

would not be expressing a lack of respect for Congress or any other

coordinate branch of government.

      The plaintiffs recognize that one of the criteria identified in Baker

v. Carr and other political question doctrine cases is “a lack of judicially

discoverable and manageable standards for resolving [the issue].” 369

U.S. 186, 217, 82 S. Ct. 691, 710, 7 L. Ed. 2d 663, 686 (1962). The

plaintiffs agree that this case may involve social and economic issues to

some extent, but that is in the nature of environmental litigation.

According to the plaintiffs, courts have been deciding nuisance cases for

years without invoking the political question doctrine. See, e.g., Comer v.
                                      55

Murphy Oil USA, Inc. (Comer II), 585 F.3d 855, 869–76 (5th Cir. 2009),

reh’g granted, 598 F.3d 208, 210 (5th Cir.), dismissed on reh’g for lack of

quorum, 607 F.3d 1049, 1055 (5th Cir. 2010); Connecticut v. Am. Elec.

Power Co., 582 F.3d 309, 321–32 (2d Cir. 2009) (lower court decision

preceding AEP), rev’d on other grounds, 564 U.S. ___, 131 S. Ct. 2527,

180 L. Ed. 2d 435 (2011). This case is no more complex than thousands

of other cases involving medical malpractice, copyright infringement, or

patent protection.      The plaintiffs argue that the political question

doctrine does not permit a court to avoid a dispute merely because it

presents complex or technical factual issues that the court “would gladly

avoid.” Zivotofsky ex rel. Zivotofsky v. Clinton, ___ U.S. ___, ___, 132 S.

Ct. 1421, 1427, 182 L. Ed. 2d 423, 429 (2012) (quoting Cohens v.

Virginia, 19 U.S. (6 Wheat.) 264, 404, 5 L. Ed. 257, 291 (1821)).

        Finally, on the question of whether the case is impossible to decide

“without an initial policy determination of a kind clearly for nonjudicial

discretion,” Baker, 369 U.S. at 217, 82 S. Ct. at 710, 7 L. Ed. 2d at 686,

the plaintiffs contend the fact that the court or jury may have to

determine     what   conduct   is   reasonable   does   not   amount   to   a

nonjusticiable question. They cite McMahon v. Presidential Airways, Inc.,

where the court noted that in “an ordinary tort suit, there is no

‘impossibility of deciding without an initial policy determination of a kind

clearly for nonjudicial discretion.’ ”     502 F.3d 1331, 1365 (11th Cir.

2007) (quoting Baker, 369 U.S. at 217, 82 S. Ct. at 710, 7 L. Ed. 2d at

686).

        2. GPC.   GPC claims that this case presents textbook political

questions. No judge or jury could decide the claims, according to GPC,

without balancing economic benefits against the harms caused by air

pollution. It notes, for instance, that the balance between environmental
                                    56

goals and economic growth involves a conflict between pollution control

and new jobs. See Chevron, U.S.A., Inc. v. Natural Res. Def. Council, Inc.,

467 U.S. 837, 852 n.25, 104 S. Ct. 2778, 2786 n.25, 81 L. Ed. 2d 694,

708 n.25 (1984). GPC asserts that this balancing of interests is best left

to the political branches of government.      Allowing the statutory and

common law claims to go forward, according to GPC, would amount to a

collateral attack on the elaborate system created by Congress that will

risk results that undermine the system’s clarity and legitimacy.        TVA,

615 F.3d at 301, 304.

      B. Analysis of Political Question Doctrine.

      1.   Overview of political question doctrine.   The federal political

question doctrine arises largely from the United States Supreme Court

case of Baker. In that case, the United States Supreme Court laid out six

considerations for determining whether a political question was present:

      [(1)] a textually demonstrable constitutional commitment of
      the issue to a coordinate political department; or [(2)] a lack
      of judicially discoverable and manageable standards for
      resolving it; or [(3)] the impossibility of deciding without an
      initial policy determination of a kind clearly for nonjudicial
      discretion; or [(4)] the impossibility of a court’s undertaking
      independent resolution without expressing lack of the
      respect due coordinate branches of government; or [(5)] an
      unusual need for unquestioning adherence to a political
      decision already made; or [(6)] the potentiality of
      embarrassment from multifarious pronouncements by
      various departments on one question.
369 U.S. at 217, 82 S. Ct. at 710, 7 L. Ed. 2d at 686.

      The high-water mark of the federal political question doctrine

appears to be matters involving foreign affairs, determinations of the

propriety of congressional enactments, and matters related to the

legislative process. See, e.g., Nixon v. United States, 506 U.S. 224, 226,

236–38, 113 S. Ct. 732, 734, 739–40, 122 L. Ed. 2d 1, 7, 13–14 (1993);
                                    57

Goldwater v. Carter, 444 U.S. 996, 1002–06, 100 S. Ct. 533, 536–38, 62

L. Ed. 2d 428, 430–32 (1979) (Rehnquist, J., concurring in judgment).

      The federal political question doctrine has been the subject of

extensive commentary. Some question whether there is any legitimate

basis for it. See Louis Henkin, Is There a “Political Question” Doctrine?,

85 Yale L.J. 597, 600 (1976) (“[T]here may be no doctrine requiring

abstention from judicial review of ‘political questions.’ ”); Martin H.

Redish, Judicial Review and the “Political Question,” 79 Nw. U. L. Rev.

1031, 1031 (1984) (noting commentators have “disagreed about [the

federal political question doctrine’s] wisdom and validity”).        Other

commentators have defended the federal political question doctrine. See

J. Peter Mulhern, In Defense of the Political Question Doctrine, 137 U. Pa.

L. Rev. 97 (1988).

      It has also been observed that since Baker, the doctrine has fallen

into disuse in the United States Supreme Court. See Rachel E. Barkow,

More Supreme than Court?: The Fall of the Political Question Doctrine and

the Rise of Judicial Supremacy, 102 Colum. L. Rev. 237, 263 (2007).

Since Baker, the federal political question doctrine has been invoked

successfully in only three cases. See Vieth v. Jubelirer, 541 U.S. 267,

281, 124 S. Ct. 1769, 1778, 158 L. Ed. 2d 546, 560 (2004) (holding

gerrymanding claim nonjusticiable); Nixon, 506 U.S. at 226, 113 S. Ct. at

734, 122 L. Ed. 2d at 7 (concluding question whether the Senate rule

regarding impeachment is constitutional is nonjusticiable); Gilligan v.

Morgan, 413 U.S. 1, 5–6, 10, 93 S. Ct. 2440, 2443, 2446, 37 L. Ed. 2d

407, 413, 415 (1973) (holding determination of adequacy of national

guardsmen training exclusively vested in Congress).     Even   if   one   is

inclined to adopt a political question doctrine of some kind, there is a

question of scope. The six considerations listed by Justice Brennan in
                                         58

Baker, see 369 U.S. at 217, 82 S. Ct. at 710, 7 L. Ed. 2d at 686, are both

opaque and elastic. Some commentators advocate consideration of all of

them, usually in descending order of importance as recognized by the

plurality opinion in Vieth, see 541 U.S. at 278, 124 S. Ct. at 1776, 158 L.

Ed. 2d at 558. Others urge a narrower approach through what has been

termed the “classical” model, which emphasizes, if not requires, a

constitutionally based commitment of power to another branch of

government.    See Amelia Thorpe, Tort-Based Climate Change Litigation

and the Political Question Doctrine, 24 J. Land Use & Envtl. L. 79, 80

(2008). It is important to note, however, that the United States Supreme

Court has made clear that the federal political question doctrine does not

apply to state courts. See Goldwater, 444 U.S. at 1005 n.2, 100 S. Ct. at

538 n.2, 62 L. Ed. 2d at 430 n.2 (Rehnquist, J., concurring) (“This Court,

of course, may not prohibit state courts from deciding political questions,

any more than it may prohibit them from deciding questions that are

moot, so long as they do not trench upon exclusively federal questions of

foreign policy.” (Citation omitted.)).

      Whether and to what extent state courts should adopt the federal

political question doctrine is a question of some controversy.         Several

decades ago, Oregon Supreme Court Justice Hans Linde remarked that

“there are hardly any state analogues to the self-imposed constraints on

justiciability, ‘political questions,’ and the like.” Hans A. Linde, Judges,

Critics, and the Realist Tradition, 82 Yale L. J. 227, 248 (1972). While

Linde’s observation may be overstated, Helen Hershkoff has noted that

state courts do tend to hear an array of questions that would be

considered nonjusticiable in federal court.         See Helen Hershkoff, State

Courts and the “Passive Virtues”: Rethinking the Judicial Function, 114

Harv. L. Rev. 1833, 1863 (2001).              Two former state supreme court
                                       59

justices have observed the significant differences between separation of

powers under state constitutions as compared to under the Federal

Constitution.    See Christine M. Durham, The Judicial Branch in State

Government: Parables of Law, Politics, and Power, 76 N.Y.U. L. Rev. 1601,

1603 (2001) (“State constitutions have a tradition independent of federal

law in the allocation of power among the branches of state government

and in their development and understanding of republican principles.”);

Ellen A. Peters, Getting Away from the Federal Paradigm: Separation of

Powers in State Courts, 81 Minn. L. Rev. 1543, 1558 (1997) (“State courts

are regularly called upon to enforce state constitutional obligations that,

for sound reasons of federalism, federal courts have declined to enforce.”

(Footnote omitted.)). If so, the federal political question doctrine might

have limited value for state courts.
      In some state courts, the doctrine seems to be met with some
skepticism.     See Backman v. Secretary, 441 N.E.2d 523, 527 (Mass.
1982) (“[W]e have never explicitly incorporated the [political question]
doctrine into our State jurisprudence . . . . [T]his court has an obligation
to adjudicate claims that particular actions conflict with constitutional
requirements.”).     Other state courts, however, have cited federal
precedent solely as if the doctrine were binding on state courts, mixed
federal and state cases without any clear delineation, and even simply
used the label “political question” without meaningful case citation or
analysis. See Christine M. O’Neill, Closing the Door on Positive Rights:
State Court Use of the Political Question Doctrine to Deny Access to
Educational Adequacy Claims, 42 Colum. J.L. & Soc. Probs. 545, 560–76
(2009) (categorizing cases according to citation methodology).
      The political question doctrine has rarely provided the basis for a
holding in our cases.     One exception is Dwyer, a case in which we
                                    60

considered whether the Iowa Senate’s policy on release of certain long-
distance phone records fell within the constitutionally granted power to
the Senate to determine its own rules of proceedings.      542 N.W.2d at
493.     We held that because of the demonstrable constitutional
commitment to the Senate of the power to make its own rules in article
III, section 9 of the Iowa Constitution, the lawsuit filed by the newspaper
to obtain the records raised a nonjusticiable political question.    Id. at
494, 501.
       Similarly, in State ex rel. Turner v. Scott, we considered an action
brought by the attorney general to remove Scott from his Senate seat.
269 N.W.2d 828, 828 (Iowa 1978). Relying upon article III, section I of
the Iowa Constitution (which vests authority upon each house to judge
the qualifications of its own members) we held that the case presented a
political question that should be resolved by the Senate. Id. at 830–31.
The holdings in Dwyer and Scott are consistent with the narrower
classical model of the political question doctrine, which focuses on the
textually demonstrable constitutional commitment of decision-making
power to another branch of government, the first Baker factor, 369 U.S.
at 217, 82 S. Ct. at 710, 7 L. Ed. 2d at 686.
       As is often the case, however, the plaintiffs do not question
whether the political question doctrine applies in state court and whether
we should adopt a political question doctrine for Iowa that departs from
the federal approach. In somewhat similar circumstances, where a party
does not suggest a different standard under Iowa law, we adopt for the
purposes of the case the federal standard, reserving the right to apply the
standard differently than under the federal cases. See, e.g., State v.
Becker, 818 N.W.2d 135, 150 (Iowa 2012) (“Even where a party has not
provided a substantive standard independent of federal law, we reserve
the right to apply the standard presented by the party in a fashion
                                     61

different than the federal cases.”); NextEra Energy Res. LLC v. Iowa Utils.
Bd., 815 N.W.2d 30, 45 (Iowa 2012) (“Even in cases where a party has
not suggested that our approach under the Iowa Constitution should be
different from that under the Federal Constitution, we reserve the right to
apply the standard in a fashion at variance with federal cases under the
Iowa Constitution.”); State v. Oliver, 812 N.W.2d 636, 650 (Iowa 2012);
State v. Bruegger, 773 N.W.2d 862, 883 (Iowa 2009); In re Det. of
Hennings, 744 N.W.2d 333, 338–39 (Iowa 2008). We reserve the right to
apply the federal standards differently because the six factors in Baker
are not clearly defined and are open-ended. As a result, within the Baker
framework, there is a wide range of permissible analysis on each of the
factors.   We therefore proceed to utilize the federal Baker approach,
reserving the right to apply these standards in a fashion different from
federal precedent.
      2. Discussion. From any perspective, it is clear that there is no
textual constitutional commitment of the issues raised in this case to
another branch of government. The first and most important factor of
the Baker formula is thus plainly not present and cuts markedly against
any application of the political question doctrine here. See Klinghoffer v.
S.N.C. Anchille Lauro Ed Altri-Gestione Motonave Achille Lauro in
Amministrazione Straordinaria, 937 F.2d 44, 49 (2d Cir. 1991) (“Although
no one factor is dispositive, Justice Brennan, the author of Baker, has
suggested that the first [factor] . . . is of particular importance . . . [and
the absence of this factor] strongly suggests that the political question
doctrine does not apply.” (Citation omitted.)).
      We now move to the second factor, namely, a lack of judicially
discoverable and manageable standards to resolve the issues. Tort law,
however, including the law of nuisance, has evolved over the centuries.
The law has devised a number of doctrinal approaches to accommodate
                                     62

difficulties in proof associated with complex environmental and toxic tort
cases.     See Benjamin Ewing & Douglas A. Kysar, Prods and Pleas:
Limited Government in an Era of Unlimited Harm, 121 Yale L.J. 350, 370
(2011). As a result, the United States Supreme Court has never found a
lack of judicially manageable standards in a tort suit involving private
parties. Id. at 412. The caselaw generally stands for the proposition that
actions for damages are relatively immune to efforts to dismiss based
upon the political question doctrine. See, e.g., Gordon v. Texas, 153 F.3d
190, 195 (5th Cir. 1998) (“Monetary damages might but typically do not
require courts to dictate policy . . . nor do they constitute a form of relief
that is not judicially manageable.”); Koohi v. United States, 976 F.2d
1328, 1332 (9th Cir. 1992) (“Damage actions are particularly judicially
manageable.”); Barasich v. Columbia Gulf Transmission Co., 467 F. Supp.
2d 676, 679–80, 683 (E.D. La. 2006) (holding demand for damages
justiciable); Mallinckrodt, Inc., 706 S.W.2d at 221 (“[I]ndividual tort
recoveries . . . are not precluded by the political question doctrine.
Appellants are not trying to establish standards that conflict with
legislative determinations; they are seeking compensation for injuries.”
(Citation omitted.)).
         To the extent the science is obscure and complex, the burden of
proof of all elements of causation remains on the plaintiffs. The mere
fact that a case is complex does not satisfy this factor. As noted by the
Second Circuit in AEP, courts have successfully adjudicated complex
common law public nuisance claims for more than a century. Am. Elec.
Power Co., 582 F.3d at 326; Alperin v. Vatican Bank, 410 F.3d 532, 552
(9th Cir. 2005) (noting the political question doctrine does not arise
because the case “is unmanageable in the sense of being large,
complicated, or otherwise difficult to tackle from a logistical standpoint”).
                                      63

      Turning to the third factor, there is no need for an initial policy
determination by another branch of government.          Indeed, the tort law
itself represents an initial policy determination, namely, that certain
plaintiffs who demonstrate necessary harm to the use and enjoyment of
their real property may be entitled to damages and injunctive relief. See
Am. Elec. Power Co., 582 F.3d at 331; McMahon, 502 F.3d at 1364–65;
Klinghoffer, 937 F.2d at 49 (“The fact that the issues before us arise in a
politically charged context does not convert what is essentially an
ordinary tort suit into a non-justiciable political question.”).
      With these major factors removed, the remaining factors generally
fall out of the equation. None of the remaining Baker factors are very
strong in any approach to the political question doctrine and they
certainly do not provide a basis for nonjusticiability in this case.
      As is apparent from the above analysis, none of the Baker factors
apply in this case with much force. We therefore conclude that this case
is not subject to dismissal under the political question doctrine.
      VI. Conclusion.
      For all of the above reasons, we conclude that the plaintiffs’ claims
in this case are not preempted by the CAA, are not preempted by Iowa
Code chapter 455B, and are not subject to dismissal by operation of the
political question doctrine.    Our rulings on these issues, of course,
express no view on the appropriateness of class certification or on the
underlying merits of the plaintiffs’ claims.     We do conclude, however,
that GPC was not entitled to summary judgment.              As a result, the
judgment of the district court is reversed and the case is remanded for
further proceedings.
      DISTRICT      COURT       JUDGMENT        REVERSED           AND   CASE
REMANDED.
      All justices concur, expect Mansfield, J., who takes no part.
