               IN THE SUPREME COURT OF IOWA
                              No. 15–1942

                           Filed May 12, 2017

                        Amended July 13, 2017

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

      Appellees,

vs.

GRAIN PROCESSING CORPORATION,

      Appellant.



      Appeal from the Iowa District Court for Muscatine County,
Thomas G. Reidel, Judge.


      Defendant appeals district court ruling certifying case as a class
action.      DISTRICT    COURT      CLASS    CERTIFICATION        ORDER
AFFIRMED.


      Michael R. Reck, Mark McCormick, Charles F. Becker, and
Kelsey J. Knowles of Belin McCormick, P.C., Des Moines; Steven J.
Havercamp and Eric M. Knoernschild of Stanley, Lande & Hunter, P.C.,
Muscatine;    and   Joshua     B.   Frank    of   Baker   Botts   L.L.P.,
Washington, D.C., for appellant.


      Sarah E. Siskind and Scott A. Entin of Miner, Barnhill & Galland,
P.C., Madison, Wisconsin; James C. Larew of Larew Law Office,
Iowa City; and Claire M. Diallo of Browne, Diallo & Roy, LLP,
Princeton Junction, New Jersey, for appellees.
                                      2

WATERMAN, Justice.

      In this appeal, we must decide whether the district court abused

its discretion by certifying this case as a class action. The plaintiffs are

residents of Muscatine, Iowa, who live near a corn wet milling plant. The

plaintiffs allege air pollution from the plant interferes with the use of

their property. They have filed this lawsuit alleging state common law

and statutory claims based on nuisance, trespass, and negligence

theories. In a prior appeal, we held their claims were not preempted by

the Federal Clean Air Act (CAA). Freeman v. Grain Processing Corp., 848

N.W.2d 58, 94 (Iowa 2014).         On remand, the district court, over

defendant’s   objections,   granted   the   plaintiffs’   motion   for   class

certification and divided the class into two subclasses. For the reasons

explained below, we affirm the class certification order.

      I. Background Facts and Proceedings.

      Grain Processing Corporation (GPC) has operated its corn wet

milling facility in Muscatine since 1943, converting corn kernels into

products for commercial and industrial use.       On April 23, 2012, eight

Muscatine residents living near GPC filed a putative class action on

behalf of “themselves and others who have resided within one and one-

half miles from the perimeter” of GPC’s facility within the preceding five

years, an estimated 4000 residents. Their petition provides this overview

of their claims:

      The plaintiffs allege the corn wet milling operation at GPC’s
      facility creates hazardous by-products and harmful
      chemicals, many of which are released directly into the
      atmosphere. . . . 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
                                     3
      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.

Id. at 63–64. The plaintiffs limited their damage claims to loss of use and

enjoyment of property, foregoing claims for diminution in value or

personal injury.

      GPC moved for summary judgment, asserting plaintiffs’ common

law and statutory claims were preempted by the CAA and Iowa Code

chapter 455B (2011), Iowa’s counterpart to the CAA.         GPC’s motion

alternatively argued the lawsuit raised nonjusticiable political questions.

The district court granted GPC’s motion for summary judgment based on

preemption and the political-question doctrine. The district court relied

on a key federal preemption decision that subsequently was reversed on

appeal.   On our review, we concluded the plaintiffs’ claims were not

preempted or barred by the political-question doctrine. Id. at 83–85, 88–

89, 93–94.    We reversed the summary judgment and reinstated the

lawsuit against GPC, relying in part on the new federal appellate decision

filed after the district court’s ruling.    See id. at 65 n.2 & 94.    We

remanded the case to the district court.

      A. Plaintiffs’ Motion for Class Certification. The plaintiffs

moved for class certification after remand.          GPC resisted class

certification on several grounds.          The plaintiffs argued common

questions of law and fact predominated over individual claims—a

fundamental requirement for class certification.      Common questions

included “whether GPC violated its duty of care, whether the haze, odor,

and smoke emitted from GPC [were] the product of negligence, and

whether such emissions constituted negligence or unlawful trespass.”

The plaintiffs proposed a plan for adjudicating their claims.    The plan
                                       4

focused on three prongs: GPC’s common course of conduct, proof of

harm, and calculation of damages.

      First, the plaintiffs proposed to show GPC’s common course of

conduct in knowingly creating a nuisance.           They pointed to internal

emails indicating GPC was aware of the pollution and the need to update

equipment to improve air quality. For example, in 2008, Derek Biggs,

GPC’s plant manager, emailed coworkers observing, “At times when I was

there, the parking lot and south end of Muscatine [were] covered in a

haze, and if we had that odor, haze, etc. in Washington, we would have

serious problems with the locals.” Mick Durham, GPC’s environmental

director, received an email in 2010 from Kurt Levetzow, an employee of

the Department of Natural Resources (DNR) who stated he was “amazed

at a bluish colored haze that was leaving GPC’s property and blanketing

the residential neighborhood across from the plant.” A 2012 email from

Bill Chrisman, GPC senior process engineer, to Durham disclosed that

over one weekend the facility’s dryers caused “the neighborhood [to be]

so smoky across the street that it was fairly hard to see, not to mention

breathe.”     GPC engineers described the dryers as “antiquated,”

“deteriorating,” “run down,” and “older higher polluting.”

      The plaintiffs proposed to prove that GPC delayed fixing the

problems by choosing to focus its resources elsewhere. Technologies to

reduce emissions were available but not implemented at GPC’s

Muscatine plant. The plaintiffs characterized this common proof as the

“most significant portion of the trial,” stating,

            Whether it be a class case or an individual trial, there
      is going to be a lot of evidence, a significant amount of
      evidence regarding the culpability of GPC’s conduct. That
      evidence will be the same, over and over again, for every
      single class member. Regardless if this case is tried once or
      tried hundreds or thousands of times, the same witnesses,
                                      5
        the same documents will be testified about, the same issues
        [will be presented].

The plaintiffs noted, “[T]hese conditions and GPC’s knowledge of them
are facts and evidence that reside at the heart of every class member’s

claims.”

        In the second phase, the plaintiffs proposed to focus on proof of

harm: that every resident within one-and-a-half miles suffered a

nuisance.     The plaintiffs would offer three categories of evidence.   The

first addressed causation; it “revolve[d] around GPC’s public admissions

that its operation had been causing the smoke, the odor and the haze

that had concerned the Muscatine community for years.”

        The next addressed harms suffered by the residents. The plaintiffs

proposed to offer testimony from twenty to thirty “normal” persons living

within the class boundaries, describing the common character of the

harm.      The plaintiffs submitted over 100 declarations from residents.

Most described the smell emitted from the GPC plant as “burned corn” or

“rotten eggs.” Many mentioned dust-like particles accumulating on their

lawns and homes.         Sometimes the dust was white or gray, and

sometimes it was darker. Most declarations indicated the smell or ash

happened daily or nearly every day and mentioned symptoms of burning

eyes and irritated sinuses. Many said they could not open windows or

enjoy the outdoors due to the smell and dust. The plaintiffs alleged these

declarations, together with residents’ testimony, met the objective

standard for nuisance: that normal persons in the community found the

conditions offensive, annoying, or intolerable. The plaintiffs stated,

               Plaintiffs are prepared to present testimony from
        normal persons from all over the class area who regard
        GPC’s pollution as definitely offensive, seriously annoying or
        intolerable. Whether they are, in fact, normal persons living
        in the community will be a jury question. But if so, and if
        the jury credits their testimony, it will establish that GPC
                                     6
      created a nuisance at their properties, and if in every portion
      of the class area normal persons testify that they
      experienced a nuisance, then it is permissible for a jury to
      infer that a nuisance has been suffered throughout the class
      area.

GPC could then present conflicting testimony from other residents within

the class boundaries who did not experience similar harm or were not

bothered by the emissions.

      The final type of evidence plaintiffs intended to offer was air

modeling data from Dr. Paul Rosenfeld.          Dr. Rosenfeld plotted the

dispersion of three types of emissions: volatile organic compounds

(VOCs), particulate matter (PM10), and sulfur dioxide. These emissions

were proxies for odor, smoke, and haze, respectively. Dr. Rosenfeld used

AERMOD, an EPA-approved modeling algorithm that accounts for wind

direction, wind speed, temperature, humidity, precipitation, and certain

obstructions to estimate where the wind blew particles from GPC.

Dr. Rosenfeld’s model revealed pollutant concentrations and variations

over time across the class area.         He also developed a “wind rose”

analysis, based on the sixteen cardinal wind directions, which he used to

quantify the amount of time each property received “direct hits,” or was

downwind from, the emissions.         Dr. Rosenfeld’s data showed “the

presence of the same pollutants frequently and repeatedly on every

property in the class, and . . . the presence of those pollutants at

properties closely surrounding the properties of the testifying normal

persons.”    At the class certification hearing, the plaintiffs’ counsel

explained,

             And if you look at this, what you don’t see, Your
      Honor, is during the hour of 5:00 to 6:00 a.m., a single
      solitary orange little cloud only covering the red cross that is
      Ms. Mockmore’s property. What you do see is that when
      GPC’s soup of pollutants are blown at Ms. Mockmore’s
      property, all of the other parcels and properties in close
                                      7
      proximity to Ms. Mockmore’s are similarly hit by GPC’s soup
      of pollutants.
            And the Mockmore’s property is not isolated in this
      observation, Your Honor. And this is important because this
      is why it supports the inference that we’re asking the jury to
      make in this case, that when Ms. Mockmore or this normal
      person or that normal person testifies about his or her
      experience with GPC’s pollutants . . . it is a reasonable
      inference for the jury to infer that similar properties in close
      proximity experience a similar nuisance[.]

“All of this evidence in combination, these three categories of evidence,”

the plaintiffs argued, “will support a reasonable inference by the jury that

the nuisance conditions existed on every property in the class area.”

      Finally, for the third phase of the plaintiff’s proposed trial strategy,

the plaintiffs suggested a formula for calculating damages. Initially, they

proposed using a simple per diem formula, in which the jury would

assess a per-hour amount ($10 to $15) for the time each resident lived in

the area.   Alternatively, the plaintiffs proposed another, more exacting

formula in which the jury’s assigned baseline per-hour value would be

multiplied by each property’s “direct hit” hours and prorated based on

each property’s pollutant concentration.             Pollution concentration,

plaintiffs argued, could be calculated as follows:

      The formula takes the average concentrations of each of
      [VOCs, PM10s, and sulfur dioxide] present on each parcel
      and then sums them up to arrive at a property-specific
      concentration total and to determine how that compares to
      the total concentrations of the hardest hit property. And we
      refer to the hardest hit property as the baseline for all
      others. The formula divides the concentration total for each
      property into the . . . baseline total.

Plaintiffs acknowledged that because the model measures only the

amount of time a property is hit by emissions, lower concentration totals

may measure emissions that residents would not notice. It would be left

for the court and jury to identify what total concentration level, if any,

constituted a nuisance.    The plaintiffs admitted this formula does not
                                     8

account for time class members spent asleep or away from their

property, but asserted the formula was permitted under our caselaw

allowing approximation of damages.

      To the extent issues remained concerning individual damages, the

plaintiffs contended these issues could be litigated during a “claims

administration process typical to class actions.”     During this process,

individual factors such as tenure of the residents and proximity to other

sources of pollution could be addressed.

      B. GPC’s Resistance to Certification. GPC argued the residents’

claims were inherently individual, and as such, individual issues

predominated over those common to the class. GPC pointed to variances

in testimony submitted by the residents. For example, their descriptions

of GPC’s emissions differed, such as “yellow dust,” “syrupy, sticky

residue,” “similar to pencil shavings,” “sticky, brownish tan particulates,”

“small black pellets like peppercorns,” or “dust that looks like fur.” Some

residents had moved into the neighborhood with knowledge of the

emissions, while others were unaware before moving. The neighbors had

lived in the area for varying periods, some moving to the area after the

lawsuit was filed and others living there for over fifty years. Some stated

they may have received reduced pricing on their homes because of the

pollution.     Some lived closer to other emission sources, such as a

wastewater treatment plant or railroad. GPC identified seven residents

(out of over 100 declarants) who stated they never had been prevented

from doing anything outdoors because of the smells or emissions. Even

these residents, however, acknowledged the prevalent odor in their

neighborhood from GPC’s facility.     The individual issues, GPC argued,

necessitated    a   property-by-property,   person-by-person   analysis   to

determine whether GPC’s conduct created a nuisance.
                                     9

      GPC also resisted the residents’ phased trial strategy. Specifically,

GPC objected to the use of lay testimony to infer classwide harm. GPC

noted a class action must “rise or fall” with the named plaintiffs.

Allowing the jury to infer, from representative testimony, conditions on

surrounding properties, GPC argued, would impermissibly alleviate each

resident’s burden to prove nuisance on his or her property. Moreover,

using inferences would mask individual issues, hindering individual

defenses and thereby depriving GPC of due process.

      GPC submitted expert testimony criticizing Dr. Rosenfeld’s model

and corresponding allocation of damages.         It alleged the model was

flawed because it combined disparate substances (VOS, PM10, and

sulfur dioxide) to reach an aggregate total, even though properties with

differing concentrations of these substances would experience differing

harms.    The model showed concentration totals on a linear scale,

although testimony established that emissions would not be experienced

linearly. A property with a concentration total of 200 would not suffer

double the lost use of enjoyment as one with 100.          The model only

accounted for wind direction and failed to account for hours during

which the residents were sleeping, on vacation, or otherwise away from

home. Because the model measured emissions hitting the property even

at levels that would not be perceptible, let alone cause compensable

harm, GPC argued the model did not establish a nuisance.           GPC also

noted the residents’ model and formula could not measure any alleged

trespass or negligence by GPC.

      C. The District Court’s Decision.         The district court granted

class certification. Noting its authority to modify or decertify the class at

any time, the district court divided the class into two subclasses, one for

members in close proximity to GPC, and the other for those in peripheral
                                    10

proximity.   The court reasoned that plaintiffs’ air dispersion analysis

“yields results one would expect—properties in close proximity have

comparable ‘Concentration Totals’ and direct-hit hours.”          Therefore,

“named plaintiffs suffer the most comparable harm to absent class

members who live in close proximity, and the closer the proximity the

more analogous the harm.” The court sorted six named plaintiffs into

the close-proximity subclass and two into peripheral proximity.

      The district court further determined that common issues of law

and fact existed and that common issues predominated over individual

ones. Common issues included GPC’s course of conduct, its knowledge

of the pollution, and its level and duration of emissions.     Addressing

GPC’s concerns, the district court, citing Miller v. Rohling, 720 N.W.2d

562 (Iowa 2006), stated,

             Because Iowa measures the existence of nuisance-level
      harm objectively, a nuisance claim brought under Iowa law
      is not inherently individual.      Indeed, Iowa’s objective
      standard renders many of Defendant’s Due Process
      arguments—idiosyncratic sensitivities, physical infirmities,
      life style choices, preferences for use and enjoyment,
      housekeeping habits—immaterial to proving nuisance.
      Further, Iowa’s objective-nuisance standard supports
      Plaintiffs’ plan for presenting the jury with lay testimony
      from witnesses—whom the jury can find are “normal persons
      living in the community”—to prove the class-wide impact of
      the alleged nuisance throughout each subclass area.

             Miller also supports Plaintiffs’ proposed use of
      formulaic damages. Miller upheld the trial court’s formulaic
      use of an identical per hour dollar value for all of the
      plaintiffs notwithstanding differences in their proximity to
      the sources of the pollution. Miller also approved the trial
      court multiplying an identical per hour dollar value by
      sixteen hours a day—because it assumed that “most normal
      people would be out of their home a period of eight hours a
      day.” . . . Miller approving formulaic damages based on
      reasonable inferences and approximation renders more of
      Defendant’s Due Process arguments—each class member
      living in a different proximity to the source of the pollution,
      the varying rate of emission over time, the varying velocity
      and direction of the wind, and the number of hours each
                                      11
         plaintiff was actually or wakefully present at his or her
         property—immaterial to proving nuisance.

The district court concluded, “Due to the remedial nature of our class
action     rules,   the   manageability   concerns   raised   by   Defendant’s

arguments are presently insufficient to deny certification.”

         GPC appealed as of right. See Iowa R. Civ. P. 1.264(3) (“An order

certifying or refusing to certify an action as a class action is

appealable.”).      GPC argues the district court abused its discretion in

certifying the class and that certification infringed upon its due process

rights. We retained the appeal.

      II. Standard of Review.

      “Our review of the district court’s ruling granting or denying

certification of a class is limited because the district court enjoys broad

discretion in the certification of class action lawsuits.” Legg v. W. Bank,

873 N.W.2d 756, 758 (Iowa 2016) (quoting Vos v. Farm Bureau Life Ins.

Co., 667 N.W.2d 36, 44 (Iowa 2003)). We review a district court’s class

certification ruling for abuse of discretion. Id. The district court abuses

its discretion when its “grounds for certifying a class action are clearly

unreasonable.” Id. If the district court “ ‘weigh[ed] and consider[ed] the

factors and [came] to a reasoned conclusion as to whether a class action

should be permitted for a fair adjudication of the controversy,’ we will

affirm.” Anderson Contracting, Inc. v. DSM Copolymers, Inc., 776 N.W.2d

846, 848 (Iowa 2009) (alterations in original) (quoting Luttenegger v.

Conseco Fin. Servicing Corp., 671 N.W.2d 425, 437 (Iowa 2003)). To the

extent GPC argues certification infringes upon its due process right to

present a defense, our review is de novo. Kragnes v. City of Des Moines,

810 N.W.2d 492, 498 (Iowa 2012).
                                       12

      III. Analysis.

      We must decide whether the district court abused its discretion by

certifying this class action. GPC contends that commonality, a question

of law or fact common to the class, is not present as required under Iowa

Rule of Civil Procedure 1.261(2). GPC relatedly argues common issues of

law or fact do not predominate over individual issues, a factor it

contends the district court failed to sufficiently weigh when concluding a

class action should be permitted for the fair and efficient adjudication of

the controversy. See Iowa R. Civ. P. 1.263(1)(e).          We determine that

common issues of law or fact exist and predominate over individual

issues. Finally, GPC argues the certification order violates due process

by interfering with its right to litigate individual defenses. We disagree

and conclude GPC will be able to litigate individual issues. We hold the

district court did not abuse its broad discretion in certifying this class

action.

      A. Whether the District Court Abused Its Discretion by

Certifying the Class Action.          Iowa Rules of Civil Procedure 1.261

through 1.263 govern class actions. Under rule 1.262, the district court

may certify a class action if it finds all of the following:

             a. The requirements of rule 1.261 have been satisfied.
             b. A class action should be permitted for the fair and
      efficient adjudication of the controversy.
            c. The representative parties fairly and adequately will
      protect the interests of the class.

Id. r. 1.262(2).   Rule 1.261 provides parties may sue as a class when

“[t]he class is so numerous . . . that joinder of all members . . . is

impracticable” and “[t]here is a question of law or fact common to the

class.”   Id. r. 1.261(1)–(2).    “A failure of proof on any one of the

prerequisites is fatal to class certification.”     City of Dubuque v. Iowa
                                        13

Trust, 519 N.W.2d 786, 791 (Iowa 1994). But at the class certification

stage, “the proponent’s burden is light.”           Id.   The class action rules

should be “liberally construed and the policy should favor maintenance

of class actions.”      Lucas v. Pioneer, Inc., 256 N.W.2d 167, 175 (Iowa

1977). The goal of the rules is the

      efficient resolution of the claims or liabilities of many
      individuals in a single action, the elimination of repetitious
      litigation and possibly inconsistent adjudications involving
      common questions, related events, or requests for similar
      relief, and the establishment of an effective procedure for
      those whose economic position is such that it is unrealistic
      to expect them to seek to vindicate their rights in separate
      lawsuits.

Comes v. Microsoft Corp., 696 N.W.2d 318, 320 (Iowa 2005) (quoting 7A

Charles Alan Wright, Arthur R. Miller & Mary Kay Kane, Federal Practice

and Procedure § 1754, at 49 (2d ed. 1986) [hereinafter Wright]).

      Rule 1.263(1) lists thirteen factors the district court may consider

in determining whether “the class action should be permitted for the fair

and efficient adjudication of the controversy.” 1 Iowa R. Civ. P. 1.263(1).


      1Rule   1.263(1) provides,
      In determining whether the class action should be permitted for the fair
      and efficient adjudication of the controversy, as appropriately limited
      under rule 1.262(3), the court shall consider and give appropriate weight
      to the following and other relevant factors:
              a. Whether a joint or common interest exists among members of
      the class.
             b. Whether the prosecution of separate actions by or against
      individual members of the class would create a risk of inconsistent or
      varying adjudications with respect to individual members of the class
      that would establish incompatible standards of conduct for a party
      opposing the class.
             c. Whether adjudications with respect to individual members of
      the class as a practical matter would be dispositive of the interests of
      other members not parties to the adjudication or substantially impair or
      impede their ability to protect their interests.
            d. Whether a party opposing the class has acted or refused to act
      on grounds generally applicable to the class, thereby making final
                                         14

These factors “center on two broad considerations: ‘achieving judicial

economy by encouraging class litigation while preserving, as much as

possible, the rights of litigants—both those presently in court and those

who are only potential litigants.’ ”          Vos, 667 N.W.2d at 45 (quoting

Vignaroli v. Blue Cross of Iowa, 360 N.W.2d 741, 744 (Iowa 1985)).

      A key factor is whether “common questions of law or fact

predominate over any questions affecting only individual members.”

Iowa R. Civ. P. 1.263(1)(e). “[T]he language of rule 1.263 indicates the

district court has ‘considerable discretion’ in weighing the factors.”

Anderson Contracting, 776 N.W.2d at 848 (quoting Vignaroli, 360 N.W.2d

at 744). The district court decides what weight, if any, to give each of the

factors and may weigh one factor more heavily than another.                         Id.

_______________________
      injunctive relief or corresponding declaratory relief appropriate with
      respect to the class as a whole.
            e. Whether common questions of law or fact predominate over
      any questions affecting only individual members.
             f. Whether other means of adjudicating the claims and defenses
      are impracticable or inefficient.
             g. Whether a class action offers the most appropriate means of
      adjudicating the claims and defenses.
             h. Whether members who are not representative parties have a
      substantial interest in individually controlling the prosecution or defense
      of separate actions.
             i. Whether the class action involves a claim that is or has been
      the subject of a class action, a government action, or other proceeding.
               j. Whether it is desirable to bring the class action in another
      forum.
               k. Whether management of the class action poses unusual
      difficulties.
               l. Whether any conflict of laws issues involved pose unusual
      difficulties.
              m. Whether the claims of individual class members are
      insufficient in the amounts or interests involved, in view of the
      complexities of the issues and the expenses of the litigation, to afford
      significant relief to the members of the class.
                                            15

“Whether or not we agree with the decision arrived at by the trial court is

not the issue.       The issue is one of abuse of discretion.”         Id. (quoting

Martin v. Amana Refrigeration, Inc., 435 N.W.2d 364, 369 (Iowa 1989)).

The district court has considerable leeway when deciding whether to

certify the class. See, e.g., Legg, 873 N.W.2d at 761–62 (affirming class

certification and noting broad discretion); Kragnes, 810 N.W.2d at 500

(“We find no abuse of the district court’s broad discretion in certifying

and refusing to decertify the class.”); Varner v. Schwan’s Sales Enters.,

Inc., 433 N.W.2d 304, 306 (Iowa 1988) (concluding the district court did

not “abuse[] its discretion in denying certification).

       GPC does not contest numerosity. See Legg, 873 N.W.2d at 759

(noting   numbers        alone    are    dispositive   to   show   numerosity   and

impracticality is presumed if the class has over forty members). Nor does

GPC contest the adequacy of the named plaintiffs to represent the class.

Rather, GPC argues that the district court erred in certifying the class

because the requirement of commonality was not met.                      GPC also

contends individual issues predominate over common questions of law or

fact. We address each argument in turn.

       1. Commonality.         GPC relies on federal authority in arguing the

commonality requirement is lacking here. Iowa’s “rules regarding class

actions[] closely resemble Federal Rule of Civil Procedure 23.” Vos, 667

N.W.2d at 44. We have relied on “federal authorities construing similar

provisions” of the federal rule to interpret our state counterpart. Id. The

federal rule requires “questions of law or fact common to the class.” Fed.

R. Civ. P. 23(a)(2). 2


       2Federal   Rule 23 provides in relevant part,
              (a) Prerequisites. One or more members of a class may sue or be
       sued as representative parties on behalf of all members only if:
                                              16




_______________________
                       (1) the class is so numerous that joinder of all members is
                impracticable;
                        (2) there are questions of law or fact common to the class;
                        (3) the claims or defenses of the representative parties are
                typical of the claims or defenses of the class; and
                        (4) the representative parties will fairly and adequately
                protect the interests of the class.
               (b) Types of Class Actions. A class action may be maintained if
        Rule 23(a) is satisfied and if:
                       (1) prosecuting separate actions by or against individual
                class members would create a risk of:
                                (A) inconsistent or varying adjudications with
                        respect to individual class members that would establish
                        incompatible standards of conduct for the party opposing
                        the class; or
                               (B) adjudications with respect to individual class
                        members that, as a practical matter, would be dispositive
                        of the interests of the other members not parties to the
                        individual adjudications or would substantially impair or
                        impede their ability to protect their interests;
                       (2) the party opposing the class has acted or refused to act
                on grounds that apply generally to the class, so that final
                injunctive relief or corresponding declaratory relief is appropriate
                respecting the class as a whole; or
                        (3) the court finds that the questions of law or fact
                common to class members predominate over any questions
                affecting only individual members, and that a class action is
                superior to other available methods for fairly and efficiently
                adjudicating the controversy. The matters pertinent to these
                findings include:
                                (A) the class members’ interests in individually
                        controlling the prosecution or defense of separate actions;
                               (B) the extent and nature of any litigation
                        concerning the controversy already begun by or against
                        class members;
                               (C)   the    desirability    or   undesirability   of
                        concentrating the litigation of the claims in the particular
                        forum; and
                                  (D) the likely difficulties in managing a class
                        action.
Fed. R. Civ. P. 23(a)–(b).
                                    17

      GPC argues Wal-Mart Stores, Inc. v. Dukes, supports its challenge

to the district court’s determination on commonality. 564 U.S. 338, 349,

131 S. Ct. 2541, 2551 (2011). In Dukes, the plaintiffs sought to certify a

class action of all women employed at Wal-Mart stores nationwide since

1998, alleging Wal-Mart’s promotion policies discriminated on the basis

of sex in violation of Title VII. Id. at 346, 131 S. Ct. at 2549. The Dukes

Court noted commonality “is easy to misread, since ‘[a]ny competently

crafted class complaint literally raises common “questions” ’ ” Id. at 349,

131 S. Ct. at 2551 (quoting Richard A. Nagareda, Class Certification in

the Age of Aggregate Proof, 84 N.Y.U. L. Rev. 97, 131–32 (2009)). But

“[c]ommonality requires the plaintiff to demonstrate that the class

members ‘have suffered the same injury.’ ” Id. at 349–50, 131 S. Ct. at

2551 (quoting Gen. Tel. Co. of Sw. v. Falcon, 457 U.S. 147, 157, 102

S. Ct. 2364, 2370 (1982)). It was not sufficient that class members “have

all suffered a violation of the same provision of law.”    Id. at 350, 131

S. Ct. at 2551. Rather, “claims must depend on a common contention”

of “such a nature that it is capable of classwide resolution—which means

that the determination of its truth or falsity will resolve an issue that is

central to the validity of each one of the claims in one stroke.” Id. To

satisfy the commonality requirement, “ ‘[e]ven a single [common]

question’ will do.” Id. at 359, 131 S. Ct. at 2556 (alteration in original)

(quoting Richard A. Nagareda, The Preexistence Principle and the

Structure of the Class Action, 103 Colum. L. Rev. 149, 176 n.10 (2003)).

      The Dukes Court concluded that no common question of law or

fact was present. Id. at 359, 131 S. Ct. at 2556–57. Unlike an “assertion

of discriminatory bias on the part of the same supervisor,” the class

members
                                     18
      held a multitude of different jobs, at different levels of
      Wal-Mart hierarchy, for variable lengths of time, in 3,400
      stores, sprinkled across 50 states, with a kaleidoscope of
      supervisors (male and female), subject to a variety of regional
      policies that all differed . . . .

Id. at 350, 359–60, 131 S. Ct. at 2551, 2557 (alteration in original)

(quoting Dukes v. Wal-Mart Stores, Inc., 603 F.3d 571, 652 (9th Cir.

2010) (Kozinski, C.J., dissenting)).   The employees failed to identify a

specific employment practice tying together their nationwide claims. Id.

at 357, 131 S. Ct. at 2555.

      By contrast, the district court here found several common

questions of both law and fact. The class includes only “members who

live in the vicinity of Defendant’s Muscatine facility and allegedly suffered

damages from Defendant’s course of conduct.”           GPC engaged in a

common course of conduct regarding all class members.

             Specifically, Defendant operated outdated, high-
      polluting dryers and coal-boilers, with virtually no controls
      to reduce emissions, [which] purportedly released noxious
      smoke and odor and haze into the surrounding
      neighborhoods for years, which caused a class-wide
      nuisance. Almost identical evidence will be required to
      establish the level and duration of Defendant’s emissions,
      the reasonableness of Defendant’s operations, and the
      causal connection, if any, between the injuries allegedly
      suffered and Defendant’s liability.

Although the “nature and amount of damages” may differ for each class

member, the district court concluded, “The central factual basis for all of

Plaintiff’s claims . . . is GPC’s course of conduct and knowledge of its

potential hazards. Thus, Plaintiffs’ theory presents a common nucleus of

operative fact.”   We agree.     All class members allegedly suffered a

common injury—air pollution emanating from GPC that interfered with

the use and enjoyment of their property.

      GPC argues the named plaintiffs did not suffer the same injury as

other class members. “[A] class representative must be part of the class
                                       19

and ‘possess the same interest and suffer the same injury’ as class

members.”     Hammer v. Branstad, 463 N.W.2d 86, 90 (Iowa 1990)

(alteration in original) (quoting E. Tex. Motor Freight Sys., Inc. v.

Rodriguez, 431 U.S. 395, 403, 97 S. Ct. 1891, 1896 (1977)). Initially, the

district court was “not persuaded class representatives ha[d] suffered the

same injury shared by all members of the class.”          The court observed

that Sharon Mockmore, the class member located closest to GPC,

experienced a “concentration total” of 317.21, while Bobbie Lynn

Weatherman, the class member located furthest from GPC, experienced a

“concentration total” of only 71.50.        Thus, “the effects of Defendant’s

emissions at the edge of the class boundary [could not] be inferred from

the testimony of class members living in close proximity to Defendant.”

But the district court resolved that disparity by creating two subclasses,

entitled “close proximity” and “peripheral proximity,” and grouping the

named plaintiffs accordingly. Within these subclasses, the district court

found the named plaintiffs were “ideal representatives for absent class

members who live nearby.” Our rules allow the district court to define

subclasses. Iowa R. Civ. P. 1.262(3)(c) (“If appropriate, the court may do

any of the following: . . . Divide a class into subclasses and treat each

subclass as a class.”).

      Other   courts      applying   equivalent   class   action   rules   have

determined the commonality requirement was met when neighboring

property owners sued a polluter under nuisance or negligence theories.

See Ebert v. Gen. Mills, Inc., 823 F.3d 472, 478 (8th Cir. 2016) (“Here, the

district court recognized that the issues of General Mills’ standardized

conduct of alleged contamination and the remedies sought by the class

are common to all plaintiffs . . . .”); Rowe v. E.I. Dupont De Nemours &

Co., 262 F.R.D. 451, 457 (D.N.J. 2009) (commonality present for
                                        20

nuisance claim alleging groundwater contamination); Collins v. Olin

Corp., 248 F.R.D. 95, 101 (D. Conn. 2008) (finding common questions

existed as to polluter’s course of conduct for contaminated soil and

water); Mejdreck v. Lockformer Co., No. 01 C 6107, 2002 WL 1838141, at

*3 (N.D. Ill. Aug. 12, 2002) (“Plaintiffs allege this contamination

constitutes standardized conduct towards all proposed class members

and there are therefore common questions of law and fact.”); Boggs v.

Divested Atomic Corp., 141 F.R.D. 58, 64 (S.D. Ohio 1991) (stating

plaintiffs had identified common questions of extensiveness of emissions,

what caused them, what precautions were taken, and economic impact

of emissions); Berdysz v. Boyas Excavating, Inc., ___ N.E.3d ___, ___,

2017 WL 632445, at *6 (Ohio Ct. App. Feb. 16, 2017) (finding common

issues and affirming certification in air pollution case).

      We reach the same conclusion under this record and hold the

district court did not abuse its discretion in finding the commonality

requirement was satisfied within the two subclasses.

      2. Predominance. The question of whether common or individual

issues     predominate    has    been   characterized   as     “fairly   complex.”

Vignaroli, 360 N.W.2d at 744.            “Inherent in our inquiry into the

predomination issue is the recognition [that] the class action device is

appropriate only where class members have common complaints that

can   be    presented    by     designated   representatives    in   the   unified

proceeding.”     Id.    Predominance “necessitates a ‘close look’ at ‘the

difficulties likely to be encountered in the management of a class

action.’ ” Vos, 667 N.W.2d at 46 (quoting Rothwell v. Chubb Life Ins. Co.

of Am., 191 F.R.D. 25, 28–29 (D.N.H. 1998)). The predominance inquiry

is “qualitative rather than quantitative”; merely “a common question does

not end the inquiry.”         Ebert, 823 F.3d at 478; see also William B.
                                     21

Rubenstein, Newberg on Class Actions § 4:50 (5th ed.), Westlaw

(database updated Dec. 2016) [hereinafter Newberg].

      Individual claims need not “be carbon copies of each other” to

determine common issues predominate. Vignaroli, 360 N.W.2d at 745.

The test for predominance “is a pragmatic one.” Luttenegger, 671 N.W.2d

at 437.

      When common questions represent a significant aspect of the
      case and they can be resolved for all members of the class in
      a single adjudication, there is a clear justification for handling
      the dispute on a representative rather than an individual
      basis. . . . [C]ourts have held that a [class action] can be
      brought . . . even though there is not a complete identity of
      facts relating to all class members, as long as a “common
      nucleus of operative facts” is present. . . .
             The common questions need not be dispositive of the
      entire action. In other words, “predominate” should not be
      automatically equated with “determinative” or “significant.”
      Therefore, when one or more of the central issues in the action
      are common to the class and can be said to predominate, the
      [class] action will be considered proper.

Id. (alterations in original) (quoting Wright § 1778, at 528–33). “A claim

will meet the predominance requirement when there exists generalized

evidence which proves or disproves an element on a simultaneous, class-

wide basis, since such proof obviates the need to examine each class

member’s individual position.” Vos, 667 N.W.2d at 45 (quoting Cope v.

Metro. Life Ins. Co., 696 N.E.2d 1001, 1004 (Ohio 1998)).

      The district court issued a forty-seven-page ruling, with eleven

pages addressing predominance. See Anderson Contracting, 776 N.W.2d

at 849 (noting the thoroughness of the district court’s ruling).

Ultimately, the district court determined,

      While variations in the individual damage claims are likely to
      occur and other sources of emissions may pose unusual
      difficulties, common questions of law or fact regarding
      Defendant’s liability predominate over questions affecting
      only individual class members such that the subclasses
                                      22
      should be permitted for the fair and efficient adjudication of
      this controversy.

The district court also addressed the other factors considered under rule
1.263(1).

              One of the purposes of class action procedures “is to
      provide small claimants an economically viable vehicle for
      redress in court.” [Martin], 435 N.W.2d at 366. . . . Given
      the complexities of the liability issue and the expenses of this
      litigation, the claims of individual class members are
      insufficient in the amounts or interests involved to afford
      significant relief to the proposed subclass members without
      certification of the subclasses. Finally, class action will
      establish Defendant’s liability in a single proceeding for
      thousands of Muscatine residents.             This will avoid
      unacceptable costs and repetition for both parties.

In Comes, we emphasized the district court’s broad discretion to weigh

the thirteen factors in deciding class certification.

      In most cases some of the thirteen factors [regarding the fair-
      and-efficient-administration-of-justice     test]   will   weigh
      against certification and some will weigh in favor. It is for
      the trial court, employing its broad discretion, to weigh the
      competing factors and determine whether a class action will
      provide a fair and efficient adjudication of the controversy.
      Thus, even if [defendant] is correct in its assertion four of the
      factors weigh against certification, that does not preclude the
      court from certifying the class action if, in its opinion, those
      factors are outweighed by other factors supporting
      certification.

Comes, 696 N.W.2d at 322 (quoting Howe v. Microsoft Corp., 656 N.W.2d

285, 289 (N.D. 2003)).
      “Further, a safety net is provided for cases in which certification is

improvidently granted: the court may decertify the class at a later time.”

Id. at 324; see also Vos, 667 N.W.2d at 54–55 (affirming district court’s

decision to decertify class because individual issues predominated). Or

the district court may bifurcate the trial into separate phases for liability

and damages. See Hammer, 463 N.W.2d at 88; see also Newberg § 10:6
                                     23

(“[A] common use of bifurcation . . . is to try liability issues to a jury

before damages . . . .”). When

      defendant’s activities present a “common course of conduct”
      so that the issue of statutory liability is common to the class,
      the fact that damages . . . may vary for each party does not
      require that the class action be terminated.

Legg, 873 N.W.2d at 759–60 (alterations in original) (quoting Luttenegger,

671 N.W.2d at 437).

      “Certification of a class action does not depend on a determination

of whether the plaintiffs will ultimately prevail on the merits.” Vos, 667

N.W.2d at 45. However, determining whether the requirements for class

certification are met “will entail some overlap with the merits of the

plaintiff’s underlying claim. That cannot be helped.” Dukes, 564 U.S. at

351, 131 S. Ct. at 2551.     Nonetheless, we decline to “engage in free-

ranging merits inquiries at the certification stage.” Amgen Inc. v. Conn.

Ret. Plans & Trust Funds, 568 U.S. 455, 466, 133 S. Ct. 1184, 1194–95

(2013).    The merits should be analyzed only to the extent relevant in

determining whether the rules have been satisfied. Id. at 466, 133 S. Ct.

at 1195.

      We begin, as the district court did, with the plaintiffs’ first cause of

action, nuisance. See Newton v. Merrill Lynch, Pierce, Fenner & Smith,

Inc., 259 F.3d 154, 172 (3d Cir. 2001) (“To determine whether the claims

alleged by the putative class meet the requirements for class certification,

we must first examine the underlying cause of action . . . .”).           The

legislature has defined nuisance as “[w]hatever is injurious to health,

indecent, or unreasonably offensive to the senses, or an obstruction to

the free use of property, so as essentially to interfere unreasonably with

the comfortable enjoyment of life or property.”       Iowa Code § 657.1(1)

(2015).     Under section 657.2(1), “occasioning noxious exhalations,
                                    24

unreasonably offensive smells, or other annoyances, [which] becomes

injurious and dangerous to the health, comfort, or property of individuals

or the public” constitute a nuisance. Id. § 657.2(1).

      The nuisance statute does not supersede common law nuisance.

See Freeman, 848 N.W.2d at 67. Rather, statutory nuisance claims are

“supplemented by common law principles governing private nuisances.”

Perkins v. Madison Cty. Livestock & Fair Ass’n, 613 N.W.2d 264, 271

(Iowa 2000). We have defined a common law nuisance as “an actionable

interference with a person’s interest in the private use and enjoyment of

the person’s land.” Id. (quoting Weinhold v. Wolff, 555 N.W.2d 454, 459

(Iowa 1996)).

            Whether a lawful business is a nuisance depends on
      the reasonableness of conducting the business in the
      manner, at the place, and under the circumstances in
      question. Thus the existence of a nuisance does not depend
      on the intention of the party who created it. Rather, it
      depends on the following three factors: priority of location,
      the nature of the neighborhood, and the wrong complained
      of.

Id. (quoting Weinhold, 555 N.W.2d at 459).         Alleged nuisances are

assessed under an “objective, normal-person” standard.       Id.   “Thus, if

‘normal persons living in the community would regard the invasion in

question as definitely offensive, seriously annoying or intolerable’ then

the invasion is significant enough to constitute a nuisance.” Id. (quoting

Weinhold, 555 N.W.2d at 459).

      Whether a nuisance exists is a factual inquiry. Patz v. Farmegg

Prods., Inc., 196 N.W.2d 557, 561 (Iowa 1972). To recover against GPC,

the plaintiffs must establish common facts as to “priority of location, the

nature of the neighborhood [involving common proof assessing the

locale], and the wrong complained of.” Perkins, 613 N.W.2d at 271.
                                          25

       At oral argument and in their appellate brief, the plaintiffs

conceded priority of location favored GPC as to all class members. GPC’s

operations commenced in 1943, and in the words of plaintiffs’ counsel, a

resident would have had to be “living under a rock” not to know of GPC’s

activities in the neighborhood. The plaintiffs have also eliminated many

individual issues by confining their claims to property damages without

claiming diminution in value or alleging personal injury claims.                   Any

class member may opt out. 3            See Iowa R. Civ. P. 1.267(1) (allowing

putative class member to “elect to be excluded” unless he or she is a

class representative, there has been an affirmative finding under rule

1.263(a), (b), or (c), or a counterclaim has been asserted against the

member).

       Because the “normal person” standard is an objective one, any

idiosyncratic sensitivity, physical infirmities, lifestyle choices, preferences

for use and enjoyment, or housekeeping habits are immaterial to proving

whether defendant’s conduct created a nuisance. See, e.g., Miller, 720

N.W.2d at 569 (awarding damages despite witness testimony emissions

were “not that bothersome”). Objective standards more readily present

common questions than subjective standards. See Amgen, 568 U.S. at

459, 133 S. Ct. at 1191. In Amgen, the United States Supreme Court

evaluated whether the objective element of “materiality” was a common



       3Indeed,   at least seventeen individual class-member plaintiffs have filed
expedited civil actions. See Pl.’s Appl. for Interlocutory Appeal, Wittenberg v. Grain
Processing Corp., No. 17–0058 (filed Jan. 12, 2017) (six individuals); Pl.’s Appl. for
Interlocutory Appeal, Tate v. Grain Processing Corp., No. 17–0062 (filed Jan. 12, 2017)
(eleven individuals). These expedited civil actions allege property and medical damages,
while the Freeman class members have limited damages to lost use and enjoyment. The
individual plaintiffs stated they chose the expedited civil action forum because of the
opportunity to have cases resolved more expeditiously than a class claim. See Iowa R.
Civ. P. 1.281(4)(b) (“Unless that court otherwise orders for good cause shown, expedited
civil actions must be tried within one year of filing.”).
                                      26

or individual question when deciding whether to certify a class action

alleging securities fraud.

      Because materiality is judged according to an objective
      standard,       the     materiality     of     Amgen’s      alleged
      misrepresentations and omissions is a question common to
      all members of the class. . . . The alleged misrepresentations
      and omissions, whether material or immaterial, would be so
      equally for all investors composing the class. As vital, the
      plaintiff class’s inability to prove materiality would not result
      in individual questions predominating. Instead, a failure of
      proof on the issue of materiality would end the case, given
      that materiality is an essential element of the class members’
      securities-fraud claims. As to materiality, therefore, the
      class is entirely cohesive: It will prevail or fail in unison.

Id. Similarly, if the residents fail to demonstrate that a normal person in

the locality would find the conditions existing throughout the subclass

area “definitely offensive, seriously annoying or intolerable,” then the

residents will fail to meet their burden, and the claim will fail. Weinhold,

555 N.W.2d at 459 (quoting Restatement (Second) of Torts § 821F cmt. d,

at 106 (1979)).

      Given the plaintiffs’ showing that the three factors—priority of

location, the nature of the neighborhood, and the wrong complained of—

are objective, common factors, it appears the factual determination of

whether a nuisance exists is capable of being made on a classwide basis.

      GPC argues Perkins is fatal to class certification because it applied

a   property-by-property     determination   to   resolve   nuisance   claims,

showing that individual issues will predominate over common questions.

613 N.W.2d at 273 (“We examine each plaintiff’s claim independently of

the other plaintiffs’ claims so that a plaintiff’s claim will succeed or fail

on the basis of that plaintiff’s particular circumstances.”). We disagree

that Perkins requires reversal. In Perkins, neighboring property owners

brought a nuisance action in equity against operators of a figure-eight
                                    27

auto racetrack built on the county fairgrounds. Id. at 268. The plaintiffs

all lived in their homes nearby before the racetrack was built and thus

had priority of location. Id. at 271–72. Races occurred seven nights a

year. Id. at 272. The district court denied recovery, finding “ ‘the seven

time invasion’ did not rise to the level of a nuisance.” Id. at 272–73. We

applied de novo review and affirmed as to three of the property owners

located between 975 and 1150 feet from the track. Id. at 273–74. But

we reversed as to one plaintiff who lived adjacent to the fairgrounds and

whose yard was seventy-seven feet from the racetrack. Id. at 274. She

testified the pit area, located on her property line, was “extremely noisy”

and that “[l]ights, noise, dust, smoke and exhaust fumes emanate from

the track and pit area directly onto [her] property, including the house.”

Id. We found she proved her nuisance claim while the other property

owners (who lived the length of three to four football fields away) did not.

Id.

       Perkins is distinguishable. It was not a class action. We reviewed

the evidence de novo to decide the merits of the nuisance claims. Id. at

267. By contrast, we are reviewing here the district court’s procedural

ruling on class certification for abuse of discretion.   The merits of the

nuisance claims will be decided at trial. The district court appropriately

divided the case into two subclasses, based on the distance from the

source of the alleged nuisance.       Moreover, Perkins did not involve

negligence claims in which the reasonableness of the defendant’s

conduct is an issue common to all the neighboring property-owner

plaintiffs.

       Negligence and nuisance are distinct theories. Dalarna Farms v.

Access Energy Coop., 792 N.W.2d 656, 659 (Iowa 2010). We explained
                                     28

the distinction between the two in Bormann v. Board of Supervisors,

stating,

       Negligence is a type of liability-forming conduct, for example,
       a failure to act reasonably to prevent harm. In contrast,
       nuisance is a liability-producing condition. Negligence may
       or may not accompany a nuisance; negligence, however, is
       not an essential element of nuisance. If the condition
       constituting the nuisance exists, the person responsible for
       it is liable for resulting damages to others even though the
       person acted reasonably to prevent or minimize the
       deleterious effect of the nuisance.

584 N.W.2d 309, 315 (Iowa 1998) (citations omitted).        In other words,

nuisance is a condition, not an act or failure to act by the party

responsible. See id.

       [T]he true distinction between negligence and nuisance is
       that “to constitute a nuisance ‘there must a degree of danger
       (likely to result in damage) inherent in the thing itself,
       beyond that arising from a mere failure to exercise ordinary
       care.’ ”

Dalarna Farms, 792 N.W.2d at 659 (quoting Martins v. Interstate Power

Co., 652 N.W.2d 657, 661 (Iowa 2002)).

       Under both nuisance and negligence theories, the harm caused by

the defendant’s conduct is relevant.      In Martins, the plaintiffs claimed

electrical transmission lines emitted stray voltage, harming dairy cows on

an adjoining farm and reducing milk production. 652 N.W.2d at 659.

Stray voltage was an “inherent part of supplying electricity,” but problems

in electrical systems could increase its frequency.     Id. at 662 (quoting

Peter G. Yelkovac, Homogenizing the Law of Stray Voltage: An Electrifying

Attempt to Corral the Controversy, 28 Val. U. L. Rev. 1111, 1112–13

(1994)). To constitute a nuisance, we pointed out the “degree of danger

likely to result in damages must be inherent in the thing itself.” Id. at

664.   We concluded “[e]xcessive stray voltage from an electric utility

resulting in damage to a dairy herd [met] that test.”        Id.   Assessing
                                         29

whether GPC’s conduct created an inherent risk of danger will be a

common legal question affecting both the plaintiffs’ nuisance (the

resulting condition) and negligence (the reasonableness of the conduct)

claims.

       In addition, the plaintiffs’ negligence claims will require evidence of

GPC’s course of conduct, its duty of care and corresponding breach, and

its knowledge of the harms caused. Raas v. State, 729 N.W.2d 444, 447

(Iowa 2007) (noting to establish claim of negligence plaintiffs must show

“a duty of care,” a breach of duty, that the breach “was a proximate

cause of their injuries,” and damages).              The plaintiffs plan to offer

evidence GPC could have upgraded its coal-burning equipment with

cleaner burning, natural gas-fired equipment earlier, and had it done so,

much of the air pollution would have been avoided. Whether GPC acted

unreasonably by delaying that equipment upgrade appears to be a

common issue.

       Proving trespass will involve similar common evidence, such as

whether harms can be attributed to GPC and whether emissions

interfered with the residents’ exclusive land possession. See Freeman,

848 N.W.2d at 67 (addressing cases deciding whether air pollution

constituted a trespass). GPC’s arguments against certifying these claims

go to the merits. 4

       Class action treatment appears to be the most efficient way to

resolve these issues. See Iowa R. Civ. P. 1.263(1)(g) (instructing court to

consider whether class action “offers the most appropriate means of

adjudicating the claims and defenses”).             Moreover, the complexity of


       4For example, GPC asserts that no physical invasion is shown by Dr. Rosenfeld’s
model, that GPC did not cause the physical invasion because testing of residue revealed
it was from another source, and that even nonnegligently run mills produce emissions.
                                      30

these questions may hinder the ability of some class members to get

relief due to the expense of expert testimony. Id. r. 1.263(1)(m) (directing

consideration of “[w]hether the claims of the individual class members

are insufficient in the amounts or interests involved, in view of the

complexities of the issues and the expenses of litigation, to afford

significant relief to the members of the class”). The district court acted

within its discretion in concluding that individual differences among

class members were not fatal to class certification.

      GPC    contends    individual   issues   of   causation   and   injury

predominate over common questions.             We disagree.      Contesting

causation, GPC notes some class members live closer to other industrial

sources of pollution, specifically the active railroad tracks or the sewage

treatment plant.     But the industrial character of the surrounding

neighborhood does not preclude a finding of nuisance. See Gacke v. Pork

Xtra, L.L.C., 684 N.W.2d 168, 180 (Iowa 2004) (affirming finding of

nuisance from hog confinement facility, even though it was a “customary

enterprise in the neighborhood”); Bates v. Quality Ready-Mix Co., 261

Iowa 696, 704, 154 N.W.2d 852, 858 (1967) (affirming nuisance finding

even though in commercial area). We also observe there was testimony

indicating residents could distinguish between odors attributed to GPC

and the sewage plant. See Olden v. LaFarge Corp., 383 F.3d 495, 508

(6th Cir. 2004) (affirming certification when plaintiffs could show injury

from contaminants directly attributable to defendant, despite other

industrial sources in area).

      We also do not see an issue in the plaintiffs’ use of representative

testimony to show classwide harm. In Tyson Foods, Inc. v. Bouaphakeo,

the Supreme Court addressed whether representative evidence could be

used in proving harm to employees. 577 U.S. ___, ___, 136 S. Ct. 1036,
                                    31

1046 (2016). Employees alleged a violation of the Fair Labor Standards

Act (FLSA) when an employer refused to compensate them for time

donning and doffing protective clothing. Id. at ___, 136 S. Ct. at 1042.

Because there were no records of time actually spent donning and doffing

and time varied among employees, plaintiffs relied on a representative

sample to allow an expert to compute the average time spent. Id. at ___,

136 S. Ct. at 1043. The employer moved to set aside the jury verdict,

arguing that the variation in donning and doffing time required

individual inquiries preventing certification. Id. at ___, 136 S. Ct. at

1044. Under the FLSA, an employee bringing an individual claim was

permitted to establish hours worked by producing sufficient evidence to

permit a “just and reasonable inference.” Id. at ___, 136 S. Ct. at 1047

(quoting Anderson v. Mt. Clemens Pottery Co., 328 U.S. 680, 687, 66

S. Ct. 1187, 1192 (1946), superseded by statute as recognized in Integrity

Staffing Sols., Inc. v. Busk, 574 U.S. ___, 135 S. Ct. 513 (2014)). As such,

the Court concluded class action plaintiffs could use a representative

sample to provide a reasonable inference of classwide harm. Id.

      Similarly, the typical method of proving the objective “normal

person in the community” standard for nuisance is to present

representative, lay testimony from members of the community that they

were disturbed by the condition. See Gacke, 684 N.W.2d at 180 (“The

testimony of the plaintiffs and of the witnesses they presented convinced

the court that normal persons would be and were substantially annoyed

. . . .”); Weinhold, 555 N.W.2d at 460 (stating that lay witnesses

presented from surrounding farms established offensiveness to persons

of “ordinary sensibilities”); Bates, 261 Iowa at 702, 154 N.W.2d at 857

(“Other witnesses living in the vicinity testified to the noises and being
                                    32

disturbed by operation of the plant.”).     This is the method of proof

proposed by the plaintiffs.

      Moreover, we have previously approved the use of a formula

employing reasonable inferences to calculate nuisance damages. Miller,

720 N.W.2d at 569. In Miller, neighbors claimed the defendants’ grain-

harvesting activities constituted a nuisance.      Id. at 566.   Testimony

confirmed that the defendants’ “emissions during harvest season were so

pervasive that they blanketed not only the plaintiffs’ vehicles and

personal property located outside their residences, but also filtered into

the interior of the plaintiffs’ homes.” Id. at 569. Awarding damages for

loss of enjoyment during harvest season, the district court used a

per diem formula, compensating the plaintiffs at the rate of “$6 per hour

for 16 hours a day for 90 days a year.”      Id. at 570.    The defendants

argued this calculation was in error, as “each plaintiff lived in different

proximity to the defendants’ property and was impacted differently by the

defendants’ grain storage activities.”     Id. at 571.     In addition, the

per diem formula did not account for hours each individual plaintiff may

not have been present at the property.      Id.   We upheld the per diem

calculation. Id. We noted,

      If the record is uncertain and speculative whether a party
      has sustained damages, the fact finder must deny recovery.
      But if the uncertainty is only in the amount of damages, a
      fact finder may allow recovery provided there is a reasonable
      basis in the evidence from which the fact finder can infer or
      approximate the damages.

Id. at 572 (emphasis added) (quoting Sun Valley Iowa Lake Ass’n v.

Anderson, 551 N.W.2d 621, 641 (Iowa 1996)). On this basis, we affirmed

the district court’s calculation, but reduced the damages of two plaintiffs:

one because she did not primarily reside on the property and the other

because she had negotiated for a lesser rent price because of the
                                      33

nuisance.    Id. at 571–72.     So long as the residents establish the

emissions constituted a nuisance on each property (fact of harm),

reasonable inferences may be used to approximate damages. See id.

      GPC argues that class certification will deny it the fair opportunity

to contest whether individual homeowners have suffered injury or

damage.     We disagree.    The plaintiffs have proposed a formula for

damages. GPC can contest the appropriateness of that formula before

the jury. If a special jury verdict is entered approving this formula and

that verdict is supported by substantial evidence, then potentially this

formula can be used in subsequent claims administration by the court

while preserving GPC’s due process and jury trial rights. If no damage

formula is approved, then there would have to be subsequent individual

trials on damages. Either way, GPC’s rights would be protected.

      A possibility that the class includes some uninjured residents will

not bar certification at this time.    Requiring plaintiffs to show every

member of the class was exposed to contaminants at a high enough level

to be considered a nuisance would “ask[] the court to make a class-

certification ruling based on the merits of the case, something we have

uniformly rejected.”   Comes, 696 N.W.2d at 325 (declining to require

plaintiffs prove “each class member actually paid some portion of a

passed-on overcharge” in an antitrust claim). Evidence plaintiffs suffered

contamination at sufficient levels to recover for nuisance “goes to proof of

damages, rather than to common liability issues.”         Luttenegger, 671

N.W.2d at 440 (holding that court did not have to make case-by-case

determination of whether fee charged was improper at certification

stage).   “[T]he fact that a potential class action involves individual

damage claims does not preclude certification when liability issues are

common to the class.” Id. (quoting Iowa Trust, 519 N.W.2d at 792).
                                      34

         GPC’s objections at this stage to Dr. Rosenfeld’s model are likewise

unavailing.      Assertions that “methods are flawed and incapable of

calculating injury and damages to the class as a whole constitute[] a

challenge going directly to the merits of the case and should not be

resolved at this preliminary stage.” Anderson Contracting, 776 N.W.2d at

855. At the certification stage, “[c]alculations need not be exact”; they

must simply “be consistent” with liability, making just and reasonable

inferences that are not speculative. Comcast Corp. v. Behrend, 569 U.S.

___, ___, 133 S. Ct. 1426, 1433 (2013).       Moreover, GPC’s defense that

Dr. Rosenfeld’s study is “unrepresentative or inaccurate” is “itself

common to the claims made by all class members.” Bouaphakeo, 577

U.S. at ___, 136 S. Ct. at 1047.

         Class certification is supported by many cases applying equivalent

rules.     In Sterling v. Velsicol Chemical Corporation, the United States

Court of Appeals for the Sixth Circuit addressed the propriety of a class

action in a mass tort case alleging strict liability, common law negligence,

trespass, and nuisance theories. 855 F.2d 1188, 1194 (6th Cir. 1988).

The defendant allegedly deposited ultrahazardous material into a landfill,

polluting groundwater used by neighboring residents. Id. at 1193. In

affirming class certification, the Sixth Circuit stated,

         In complex, mass, toxic tort accidents, where no one set of
         operative facts establishes liability, no single proximate
         cause equally applies to each potential class member and
         each defendant, and individual issues outnumber common
         issues, the district court should properly question the
         appropriateness of a class action for resolving the
         controversy. However, where the defendant’s liability can be
         determined on a class-wide basis because the cause of the
         disaster is a single course of conduct which is identical for
         each of the plaintiffs, a class action may be the best suited
         vehicle to resolve such a controversy.
                In the instant case, each class member lived in the
         vicinity of the landfill and allegedly suffered damages as a
                                     35
      result of ingesting or otherwise using the contaminated
      water.    Almost identical evidence would be required to
      establish the level and duration of chemical contamination,
      the causal connection, if any, between the plaintiffs’
      consumption of the contaminated water and type of injuries
      allegedly suffered, and the defendant’s liability.

Id. at 1197.

      Other federal courts have affirmed class certification in tort actions

brought by neighboring property owners over pollution to avoid the

“duplicative litigation” of individual lawsuits. Gintis v. Bouchard Transp.

Co., 596 F.3d 64, 67 (1st Cir. 2010); see Olden, 383 F.3d at 508

(affirming certification based in part on “common argument that the

class’s properties are regularly covered in cement dust, causing minor

property damage”); Mejdreck v. Met-Coil Sys. Corp., 319 F.3d 910, 911

(7th Cir. 2003) (affirming certification because “[t]he questions whether

Met-Coil leaked TCE in violation of law and whether the TCE reached the

soil and groundwater beneath the homes of the class members are

common to all the class members”); Navelski v. Int’l Paper Co., ___

F. Supp. 3d ___, ___, 2017 WL 1132569, at *18 (N.D. Fla. Mar. 25, 2017)

(affirming certification of nuisance and negligence claims from dam

collapsing “[b]ecause in this case, every aspect of liability can be resolved

on a classwide basis, it would be neither efficient nor fair to anyone,

including Defendant, to hold over 300 trials to hear the same evidence

and decide the same liability issues”); Mejdreck, 2002 WL 1838141, at *7

(stating “it would be wholly inefficient to try thousands of separate cases

that would allege the same misconduct and provide the same proof of

such” in negligence and nuisance pollution claims); LeClercq v.

Lockformer Co., No. 00 C 7164, 2001 WL 199840, at *7 (N.D. Ill. Feb. 28,

2001) (noting proof “would be identical” as to “history of operations, the

spillage, the impact on the land, soil, and water, [and] possible remedies”
                                      36

and “[r]epetitive discovery for individual cases on the same core issues

would be wasteful”); Cook v. Rockwell Int’l Corp., 181 F.R.D. 473, 480 (D.

Colo. 1998) (“Significant elements of Plaintiffs’ case in chief . . . will be

presented through the testimony of five experts.        This testimony will

apply to the classes as a whole.”); Boggs, 141 F.R.D. at 67 (“If these

claims were tried separately, the amount of repetition would be

manifestly unjustified.    To the extent that each claim of each plaintiff

depends upon proof concerning the history of operations at the plant, the

nature, timing, extent and cause of emissions, . . . that proof would be

virtually identical in each case.”); Bates v. Tenco Servs., Inc., 132 F.R.D.

160, 164 (D.S.C. 1990) (“The common questions in this suit will be the

cause of the ground water contamination, the defendants’ liability, and

the alleged effects of jet fuel contamination on the neighborhood and the

people who have lived there.”); Wehner v. Syntex Corp., 117 F.R.D. 641,

645 (N.D. Cal. 1987) (“Significant judicial economies are served by trying

the common issues [of contamination].”); cf. Jackson v. Unocal Corp., 262

P.3d 874, 890 (Colo. 2011) (en banc) (concluding, in a state court case,

common     issues   of    asbestos   contamination   predominated    despite

individual damages issues); 7-Eleven Inc. v. Bowens, 857 N.E.2d 382,

395 (Ind. Ct. App. 2006) (“Although these concerns [of individual issues]

may be legitimate, we cannot conclude that they outweigh the economies

of time, effort, and expense that will be achieved by allowing the class

action to proceed on the issues defined by the trial court.”); Claborne v.

Hous. Auth. of New Orleans, 165 So. 3d 268, 284 (La. Ct. App. 2015) (“We

also recognize that the risk in trying some 2900 individual cases could

result in non-uniformity and inconsistent adjudications on the common

issues.”); Doyle v. Fluor Corp., 199 S.W.3d 784, 789–90 (Mo. Ct. App.

2006) (“Although individual questions of damages or individual defenses
                                           37

may remain after the common issues here are resolved, the need for

individualized proof . . . does not defeat the predominance of the common

issues.”); Freeman v. Blue Ridge Paper Prods., Inc., 229 S.W.3d 694, 706

(Tenn. Ct. App. 2007) (concluding class action is superior because of

single course of conduct).

       Still other courts have declined to certify a class action for

nuisance claims because of the individualized nature of determining

contamination on each property. See Gates v. Rohm & Haas Co., 655

F.3d 255, 272 (3d Cir. 2011) (“[G]iven the potential difference in

contamination on the properties, common issues do not predominate.”);

Powell v. Tosh, No. 5:09-CV-00121, 2013 WL 4418531, at *8 (W.D. Ky.

Aug. 2, 2013) (“[E]ach Plaintiff’s experience as to the intensity and

duration (or lack thereof) of the hog odor is susceptible to marked

variation.       Further, each named Plaintiff’s . . . property is situated

uniquely with respect to the barns in question.”); Fisher v. Ciba Specialty

Chems. Corp., 238 F.R.D. 273, 307 (S.D. Ala. 2006) (“[B]oth the existence

of contamination and the risk of future contamination will have to be

proven on a property-by-property basis.”); see also Ga.-Pac. Corp. v.

Carter, 265 S.W.3d 107, 114 (Ark. 2007) (“[I]t is evident, from the

property owners’ claims and from the sheer nature of a claim for private

nuisance, that individual issues exist in the instant case as to whether

and to what extent Georgia-Pacific’s operation of its waste water

treatment     system      caused     consequences        to,   and    constituted     an

unreasonable interference with, the property owners’ use and enjoyment

of their property.”). 5


       5Courts  have also declined to certify nuisance pollution cases when the plaintiffs
failed to show a method of proving classwide harm. See, e.g., Burkhead v. Louisville Gas
& Elec. Co., 250 F.R.D. 287, 299 (W.D. Ky. 2008) (“Plaintiffs have alleged that
Defendant’s operations result in extensive emissions, but what remains missing is any
                                           38

       GPC relies on a decision by the Eighth Circuit filed after the class

certification order here. See Ebert, 823 F.3d at 475, 481. In Ebert, the

district court certified a class action against General Mills brought by

neighboring property owners arising from groundwater contamination.

Id. at 476.      The defendant had disposed of hazardous chemicals by

burying perforated drums of trichloroethylene (TCE) on its land. Id. at

475.     “[T]he plaintiffs claim[ed] . . . TCE vapors migrated into the

surrounding residential area, threatening the health of the residents and

diminishing the value of their property.” Id. The Eighth Circuit panel

agreed the “standardized conduct of alleged contamination and the

remedies sought by the class are common to all plaintiffs.” Id. at 478.

Yet the appellate court reversed the certification order after concluding

that individual issues predominated:

       To resolve liability there must be a determination as to
       whether vapor contamination, if any, threatens or exists on
       each individual property as a result of General Mills’ actions,
       and, if so, whether that contamination is wholly, or actually,
       attributable to General Mills in each instance. Accordingly,
       accompanying a determination regarding General Mills’
       actions, there likely will be a property-by-property
       assessment of additional upgradient (or other) sources of
       contamination, whether unique conditions and features of
       the property create the potential for vapor intrusion, whether
       (and to what extent) the groundwater beneath a property is
       contaminated, whether mitigation has occurred at the
       property, or whether each individual plaintiff acquired the
       property prior to or after the alleged diminution in value.

Id. at 479.
_______________________
evidence that the cause of the entire class’s damages could be determined in a single
proceeding.”); St. Joe Co. v. Leslie, 912 So. 2d 21, 24 (Fla. Dist. Ct. App. 2005)
(“Appellees failed to prove how the class representatives could prove their own . . .
nuisance claims, thereby proving the claims of the unnamed members.”); Ga.-Pac.
Consumer Prods., LP v. Ratner, 762 S.E.2d 419, 423 (Ga. 2014) (reversing order to
certify air pollution class because members had not presented “evidence by which the
plaintiffs might be able to prove [harm] on a classwide basis” such as scientific evidence
about how much pollution moved through the air). By contrast, the plaintiffs here have
offered expert testimony and a common method for proving their claims against GPC.
                                        39

      Ebert is distinguishable. Tracking the migration of contaminated

groundwater in that case involved more complex variables than GPC’s

smokestack pollution blanketing its Muscatine neighborhood with

airborne particulates.        And the Ebert plaintiffs sought recovery for

diminution in property values, raising valuation issues unique to each

property. Id. at 479; see also Mel Foster Co. Props., Inc. v. Am. Oil Co.,

427 N.W.2d 171, 176 (Iowa 1988) (noting measure of damages in

nuisance case for diminution of value is “the market value of [the]

property immediately before contamination and the market value of that

property after the contamination”). By contrast, the class members here

are not seeking recovery for any reduction in their property values, but

rather for their shared experiences with GPC’s smoke, odor, and dust.

      We hold that the district court did not abuse its discretion in

rejecting GPC’s predominance objection to class certification. Our class

action rules do not require that the residents present “common proof on

each element of the claim. Rather, we have repeatedly noted that the

existence   of   individual    issues   is   not   necessarily   fatal   to   class

certification.” Comes, 696 N.W.2d at 322 (quoting Howe, 656 N.W.2d at

289). Individual issues concerning contamination from other sources or

the amount of chemicals present on a particular property may affect

damage calculations, but such concerns do not overwhelm common

issues of liability. GPC’s priority of location is conceded, and common

proof will be required on GPC’s course of conduct, its emissions during

the relevant time period, its knowledge of emissions, and at what level

emissions interfere with a normal person in the community’s enjoyment

of his or her property. These common questions of liability are at the

heart of the residents’ claims.
                                    40

      B. Whether Certifying the Class Offends Due Process. We next

address GPC’s contention that the class certification violates its due

process rights.    “Civil litigation deprives the litigants of property—the

plaintiff of her chose in action, the defendant of money damages if it

loses—and thus must accord the litigants due process of law.” Newberg

§ 11:21 (footnote omitted).   “A defendant in a class action has a due

process right to raise individual challenges and defenses to claims, and a

class action cannot be certified in a way that eviscerates this right or

masks individual issues.” Carrera v. Bayer Corp., 727 F.3d 300, 307 (3d

Cir. 2013).

      Extrapolation raises due process concerns because it
      provides a full trial, and opportunity to be heard, for some
      plaintiffs but not for others and, correlatively, because it
      enables the defendant to contest damages through
      individualized affirmative defenses against some plaintiffs
      but not all.

Newberg § 11:21.

      GPC asserts the residents’ plan to extrapolate harm to surrounding

properties from testimony of twenty to thirty representative class

members violates due process by masking individual issues. GPC argues

it must be allowed to pursue individual factors that might reduce certain

class members’ damages, such as the members’ knowledge of the air

pollution upon moving to the community. GPC relies on In re Fibreboard

Corp., 893 F.2d 706 (5th Cir. 1990).     In Fibreboard, the district court

certified a class of over 3000 asbestos claims.    Id. at 707.   To assess

damages, it proposed to try a small, limited segment of claims in full,

then extrapolate from those individualized awards to an omnibus award

for the class.    Id. at 708–09.   From those witnesses, the jury would

extrapolate damages to the class as a whole.       Id. at 709.   The Fifth

Circuit, in granting mandamus to prevent trial, recognized that such
                                     41

extrapolation violated the defendant’s rights by masking differences in

causation, types of injury, fact of injury, and exposure. Id. at 711.

      Fibreboard is inapposite. In Fibreboard, the claims presented were

more diverse than here.     Plaintiffs suffered different personal injuries,

from different causes, over different periods of time. Here, the residents

are not claiming personal injuries.    Rather, they seek recovery for the

loss of use and enjoyment of their property caused by GPC’s emissions.

The district court has not limited the number of witnesses GPC can

present, nor its exploration of individual defenses.

      Moreover, the Supreme Court has indicated inferences from

representative proof are permissible in certain circumstances. In Dukes,

the Court rejected the use of testimony from a sample of 120 Wal-Mart

employees because it found all members of the class were not similarly

situated   and   the   plaintiffs   lacked   evidence   the   sample    was

representative. 564 U.S. at 367, 131 S. Ct. at 2561. But five years later,

in Bouaphakeo, the Court allowed representative evidence compiled by

an expert to establish employee’s average donning and doffing time. 577

U.S. at ___, 136 S. Ct. at 1044–45. Explaining this difference, the Court

stated,

      The underlying question in Wal-Mart, as here, was whether
      the sample at issue could have been used to establish
      liability in an individual action. Since the Court held that
      the employees were not similarly situated, none of them
      could have prevailed in an individual suit by relying of
      depositions detailing the ways in which other employees
      were discriminated against by their particular store
      managers. . . .
             In contrast, the study here could have been sufficient
      to sustain a jury finding as to hours worked if it were
      introduced in each employee’s individual action. While the
      experiences of the employees in Wal-Mart bore little
      relationship to one another, in this case each employee
      worked in the same facility, did similar work, and was paid
      under the same policy. . . . [U]nder these circumstances the
                                    42
      experiences of a subset of employees can be probative as to
      the experiences of all of them.

Id. at ___, 136 S. Ct. at 1048.        We have allowed testimony from
community residents in nuisance actions to prove the “normal person”

standard.    The plaintiffs plan to call witnesses from throughout the

neighborhood.    GPC is free to call additional witnesses.     As we have

already discussed, this class action can proceed in a manner that

preserves GPC’s due process rights to contest harm and damages

suffered by individual class members.

      If proof of individual defenses becomes unmanageable, the district

court has discretion to bifurcate the trial, create additional subclasses,

or decertify the class.

      [B]ifurcation enables the common issue of liability to be
      resolved in an aggregate proceeding but reserves the
      assessment of individual damages for some subsequent,
      more individualized processing. Courts have therefore held
      that bifurcation assists certification by responding to due
      process concerns.

Newberg § 11:10 (footnote omitted). At this stage of the case, GPC has

not shown the class certification order violates its due process rights.

      IV. Disposition.

      For these reasons, we affirm the district court’s order certifying

this class action.

      DISTRICT COURT CLASS CERTIFICATION ORDER AFFIRMED.

      All justices concur except Appel, J., who concurs specially.
                                     43

                             #15–1942, Freeman v. Grain Processing Corp.

APPEL, Justice (concurring specially).

      I concur in the generally thorough majority opinion in this case. I

write separately, however, to emphasize the difference between Iowa law

and federal law on the question of class certification.

      Iowa is one of two states that have adopted a version of the

Uniform Class Actions Act.      Thomas D. Rowe, Jr., State and Foreign

Class-Actions Rules and Statutes: Differences from—and Lessons for?—

Federal Rule 23, 35 W. St. U. L. Rev. 147, 150 (2007).          One of the

purposes of the Uniform Class Actions Act was to create a more generous

standard for class certification because “federal courts have severely

restricted the availability of class actions in their forum.” Irving Scher,

Opening State Courts to Class Actions: The Uniform Class Actions Act, 32

Business Lawyer 75, 86 (1976).        Consistent with the Uniform Class

Actions Act upon which they are based, Iowa courts have consistently

stated “[o]ur class-action rules are remedial in nature and should be

liberally construed to favor the maintenance of class actions.” Comes v.

Microsoft Corp., 696 N.W.2d 318, 320 (Iowa 2005); accord Anderson

Contracting, Inc. v. DSM Copolymers, Inc., 776 N.W.2d 846, 848 (Iowa

2009); Lucas v. Pioneer, Inc., 256 N.W.2d 167, 175 (Iowa 1977). In light

of this legislative history and our caselaw, federal class action precedent

is of limited value in determining class certification under Iowa law.
