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 lawsuit1 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 byproducts 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-andbuggy 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. Envt’l 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 wellestablished 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, 82 

U.S.L.W. 3459 (U.S. Apr. 21, 2014) (No.13–0842).

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 preemption 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).

 5The Federal 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 commonlaw 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 instate 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-ofstate 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 sourcestate 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 pollutionaffected 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 445B. 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. 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, 825 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 longdistance 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.