                FOR PUBLICATION

  UNITED STATES COURT OF APPEALS
       FOR THE NINTH CIRCUIT


IN RE VOLKSWAGEN “CLEAN                  No. 18-15937
DIESEL” MARKETING, SALES
PRACTICES, AND PRODUCTS                    D.C. No.
LIABILITY LITIGATION,                   3:15-md-02672-
                                             CRB

THE ENVIRONMENTAL PROTECTION
COMMISSION OF HILLSBOROUGH                 OPINION
COUNTY, Florida; SALT LAKE
COUNTY,
              Plaintiffs-Appellants,

                 v.

VOLKSWAGEN GROUP OF AMERICA,
INC.; AUDI OF AMERICA, LLC;
PORSCHE CARS NORTH AMERICA,
INC.; ROBERT BOSCH, LLC; ROBERT
BOSCH GMBH,
              Defendants-Appellees.


      Appeal from the United States District Court
        for the Northern District of California
      Charles R. Breyer, District Judge, Presiding
2               IN RE VOLKSWAGEN LITIGATION

             Argued and Submitted August 6, 2019
                     Anchorage, Alaska

                         Filed June 1, 2020

        Before: Richard C. Tallman, Sandra S. Ikuta,
            and N. Randy Smith, Circuit Judges.

                      Opinion by Judge Ikuta


                            SUMMARY*


                  Clean Air Act / Preemption

    The panel affirmed in part, and reversed in part, the
district court’s dismissal of complaints brought by two
counties against Volkswagen after it installed defeat devices
in new cars, and subsequently modified those devices post
sale, for the purpose of evading compliance with federally
mandated emission standards.

    Volkswagen settled the Environmental Protection Agency
(“ EPA”)’s criminal and civil actions for over $20 billion, but
failed to obtain a release of liability from state and local
governments. In this action, two counties sought to impose
penalties for violation of their laws prohibiting tampering
with emission control systems. The district court held that
the counties’ actions were preempted by the Clean Air Act.


    *
      This summary constitutes no part of the opinion of the court. It has
been prepared by court staff for the convenience of the reader.
              IN RE VOLKSWAGEN LITIGATION                    3

    The panel agreed with the district court that the Clean Air
Act expressly preempted state and local government efforts
to apply anti-tampering laws to pre-sale vehicles. The panel
disagreed with the district court’s ruling that the Clean Air
Act impliedly preempted state authority to enforce anti-
tampering laws against post-sale vehicles. The panel held
that the Clean Air Act did not prevent the two counties here
from enforcing their regulations against Volkswagen for post-
sale vehicles.

    The panel rejected Volkswagen’s assertions that the
counties’ anti-tampering rules were preempted under ordinary
preemption principles. First, Volkswagen argued that
Congress intended to give the EPA exclusive oversight over
post-sale compliance with emission standards on a model-
wide basis, and the counties’ anti-tampering rules posed an
obstacle to this goal. The panel saw no indication that
Congress intended to preempt state and local authority to
enforce anti-tampering rules on a model-wide basis. Second,
Volkswagen argued that the Clean Air Act’s penalty
provision, 42 U.S.C. § 7524, showed that Congress struck a
balance of interests with respect to the imposition of
penalties, and this balance would be disturbed if states could
impose their own penalties for tampering with post-sale
vehicles.      The panel held that the Clean Air Act’s
cooperative federalism scheme, its express preservation of
state and local police powers post sale, and the complete
absence of a congressional intent to vest in the EPA the
exclusive authority to regulate every incident of post-sale
tampering raised the strong inference that Congress did not
intend to deprive the EPA of effective aid from local officers
to combat tampering with emission control systems.
4            IN RE VOLKSWAGEN LITIGATION

                        COUNSEL

Peter K. Stris (argued), Stris & Maher LLP, Los Angeles,
California, for Plaintiffs-Appellants.

W. Daniel “Dee” Miles III, H. Clay Barnett, and Archie I.
Grubb II, Beasley Allen Crow Methvin Portis & Miles P.C.,
Montgomery, Alabama; Luis Martinez-Monfort, Gardner
Brewer Martinez-Monfort P.A., Tampa, Florida; Thomas L.
Young, Law Office of Thomas L. Young P.A., Tampa,
Florida; for Plaintiff-Appellant Environmental Protection
Commission of Hillsborough County.

Bridget K. Romano, Deputy District Attorney, Office of the
Salt Lake County District Attorney, Salt Lake City, Utah;
Colin P. King and Paul M. Simmons, Dewsnup King Olsen
Worel Havas Mortensen, Salt Lake City, Utah; for Plaintiff-
Appellant Salt Lake County.

Robert J. Giuffra, Jr. (argued), Sharon L. Nelles, David M.J.
Rein, and Matthew A. Schwartz, Sullivan & Cromwell LLP,
New York, New York; for for Defendants-Appellees
Volkswagen Group of America, Inc. and Audi of America,
LLC.

Cari K. Dawson, Alston & Bird LLP, Atlanta, Georgia, for
Defendant-Appellee Porsche Cars North America, Inc.

Carmine D. Boccuzzi, Jr., Cleary Gottlieb Steen & Hamilton
LLP, New York, New York; Matthew D. Slater, Cleary
Gottlieb Steen & Hamilton LLP, Washington, D.C.; for
Defendant-Appellee Robert Bosch, LLC and Robert Bosch
GMBH.
             IN RE VOLKSWAGEN LITIGATION                5

Richard W. Mithoff, Sherie Potts Beckham, and Warner V.
Hocker, Mithoff Law, Houston, Texas; Russell S. Post and
Owen J. McGovern, Beck Redden LLP, Houston, Texas;
Benny Agosto, Jr. and Muhammad S. Aziz, Abraham
Watkins Nichols Sorrels Agosto & Friend, Houston, Texas;
Debra Tsuchiyama Baker, Earnest W. Wotring, John Muir,
and David George, Baker & Botring LLP, Houston, Texas;
Vince Ryan, Robert Soard, Terence L. O’Rourke, and Rock
W.A. Owens, Office of the Harris County Attorney, Houston,
Texas; for Amicus Curiae Harris County, Texas.

Jonathan S. Martel, Arnold & Porter Kaye Scholer LLP,
Washington, D.C.; S. Zachary Fayne, Arnold & Porter Kaye
Scholer LLP, San Francisco, California; Sarah Grey, Arnold
& Porter Kaye Scholer LLP, Denver, Colorado; Steven P.
Lehotsky and Michael B. Schon, U.S. Chamber Litigation
Center, Washington, D.C.; for Amici Curiae Alliance of
Automobile Manufacturers Inc., Association of Global
Automakers, and Chamber of Commerce of the United States
of America.
6                IN RE VOLKSWAGEN LITIGATION

                              OPINION

IKUTA, Circuit Judge:

    Volkswagen,1 a car manufacturer, installed defeat devices
in new cars for the purpose of evading compliance with
federally mandated emission standards, and subsequently
updated the software in those cars so the defeat devices would
do a better job of avoiding and preventing compliance.2
Volkswagen settled EPA’s criminal and civil actions for over
$20 billion dollars—but failed to obtain a release of liability
from state and local governments at the same time. When
two counties sought to impose additional penalties for
violation of their laws prohibiting tampering with emission
control systems, Volkswagen persuaded the district court that
these claims were preempted by the Clean Air Act.

    We agree with the district court only in part. We agree
that the Clean Air Act expressly preempts state and local
government efforts to apply anti-tampering laws to pre-sale
vehicles.3 But we disagree with the district court’s ruling that

    1
      We use “Volkswagen” to refer to the parent company, Volkswagen
Aktiengesellschaft (“Volkswagen AG”) and its several subsidiaries,
including Volkswagen Group of America, Inc. (“Volkswagen USA”),
Audi of America, LLC (“Audi”), and Porsche Cars North America, Inc.
(“Porsche”).
    2
      The following background facts are taken from the “Statement of
Facts,” to which Volkswagen stipulated pursuant to its plea agreement
with the federal government. See United States v. Volkswagen AG,
No. 16-cr-20394-SFC-APP-8, Dkt. 68 (E.D. Mich. Mar. 10, 2017).
    3
      We likewise agree with the district court that the Clean Air Act does
not expressly preempt the application of state and local anti-tampering
laws to post-sale vehicles.
              IN RE VOLKSWAGEN LITIGATION                    7

the Clean Air Act impliedly preempts state authority to
enforce anti-tampering laws against post-sale vehicles. In
other words, the Clean Air Act does not prevent the two
counties here from enforcing their regulations against
Volkswagen for tampering with post-sale vehicles.

    We base this conclusion on Supreme Court precedent. A
“high threshold must be met if a state law is to be preempted
for conflicting with the purposes of a federal Act.” Chamber
of Commerce of U.S. v. Whiting, 563 U.S. 582, 607 (2011)
(citation omitted). Volkswagen has not met that high
threshold here. The text and structure of the Clean Air Act do
not indicate any congressional intent to prohibit states from
enforcing anti-tampering laws in this context. Moreover, the
regulation of air pollution for health and welfare purposes
“falls within the exercise of even the most traditional concept
of what is compendiously known as the police power,” Huron
Portland Cement Co. v. Detroit, 362 U.S. 440, 442 (1960), so
we must “assume that ‘the historic police powers of the
States’ are not superseded ‘unless that was the clear and
manifest purpose of Congress,’” Arizona v. United States,
567 U.S. 387, 400 (2012) (citation omitted). No such purpose
exists here.

    We acknowledge that our conclusion—that the Clean Air
Act does not prevent the two counties from enforcing their
regulations against Volkswagen for tampering with post-sale
vehicles—may result in the imposition of unexpected (and
enormous) liability on Volkswagen. But that result is caused
by the unusual and perhaps unprecedented situation before us.
In drafting the Clean Air Act, Congress apparently did not
contemplate that a manufacturer would intentionally tamper
with the emission control systems of its vehicles after sale in
order to improve the functioning of a device intended to
8               IN RE VOLKSWAGEN LITIGATION

deceive the regulators. In other words, Volkswagen faces
liability due to the straightforward application of the Clean
Air Act and the preemption doctrine to its unexpected and
aberrant conduct. We may not strain to give Volkswagen the
equivalent of a release from state and local liability (which it
did not secure for itself) by engaging in a “freewheeling
judicial inquiry into whether a state statute is in tension with
federal objectives; such an endeavor would undercut the
principle that it is Congress rather than the courts that pre-
empts state law.” Whiting, 563 U.S. at 607 (internal
quotation marks and citation omitted).4

                                    I

    Under Title II, Part A of the Clean Air Act of 1990
(CAA),5 car manufacturers cannot sell new motor vehicles in
the United States unless the vehicles comply with federal

    4
       In view of the federal government’s central role in bringing
comprehensive civil and criminal enforcement actions against
Volkswagen and ultimately obtaining a $20 billion settlement, and given
that “the agency’s own views should make a difference” on the question
of federal preemption, Williamson v. Mazda Motor of Am., Inc., 562 U.S.
323, 335 (2011) (citation omitted), we asked the Solicitor General of the
United States and the EPA for their views on whether the CAA preempts
a state or its political subdivision from enforcing state or local anti-
tampering laws with respect to post-sale vehicles and whether their
agreements to settle their federal claims against Volkswagen were
intended to foreclose subsequent state or local civil financial penalties.
Envtl. Prot. Comm’n of Hillsborough Cty. v. Volkswagen Grp. of Am.,
Inc., No. 18-15937, Dkt. 64 (9th Cir. Aug. 22, 2019). The federal
government elected not to provide its opinion on these issues to aid us in
addressing these significant questions. Id., Dkt. 70 (Nov. 4, 2019).
    5
      Title II of the CAA governs “Emission Standards for Moving
Sources.” 42 U.S.C. §§ 7521–7590. Part A of this title governs “Motor
Vehicle Emission and Fuel Standards.” §§ 7521–7554.
                  IN RE VOLKSWAGEN LITIGATION                        9

emission standards, including standards for the emission of
nitrogen oxide (NOx). See 42 U.S.C. §§ 7521, 7525. The
CAA gives the Environmental Protection Agency (EPA) the
authority to establish emission standards for new motor
vehicles, § 7521(a)(1), and administer a certification program
to ensure compliance with those standards, § 7525. To obtain
a certificate of conformity from the EPA, a manufacturer
must submit an application to the EPA; the application must
be submitted for each model year and it must include (among
other things) test results from standardized federal emission
tests that demonstrate compliance with the applicable
emission standards. See 40 C.F.R. §§ 86.1843-01, 86.1844-
01, 86.1848-01. The CAA also governs the use of emission
control devices. 42 U.S.C. § 7521(a)(4)(A). A device “that
reduces the effectiveness of the emission control system
under conditions which may reasonably be expected to be
encountered in normal vehicle operation and use” is called a
“defeat device,” 40 C.F.R. § 86.1803-01,6 and is prohibited,
see 42 U.S.C. § 7522(a)(3)(B).

                                    A

    In 1998, the EPA established new federal emission
standards for light duty vehicles, the type of vehicles at issue




    6
        40 C.F.R. § 86.1803-01 provides:

          Defeat device means an auxiliary emission control
          device (AECD) that reduces the effectiveness of the
          emission control system under conditions which may
          reasonably be expected to be encountered in normal
          vehicle operation and use, unless: [listing exceptions].
10              IN RE VOLKSWAGEN LITIGATION

here,7 including stricter NOx emission standards.
Manufacturers were required to comply with the new
standards beginning with model year 2007 vehicles.
Volkswagen concluded that some of its diesel engine vehicles
would not be able to meet the heightened NOx emission
standards while still operating at a performance level that
could attract customers. Therefore, beginning in 2006,
Volkswagen employees developed and installed two defeat
devices that would enable its diesel engine vehicles to pass
federal emission tests, even though the vehicles could not
actually meet the NOx emission standards while being driven
on the street.

    Volkswagen installed different defeat devices in vehicles
with a 2.0 liter diesel engine (the “2.0 Liter Vehicles”) and
vehicles with a 3.0 liter diesel engine (the “3.0 Liter
Vehicles”). The defeat device in the 2.0 Liter Vehicles
comprised software designed to recognize whether the
vehicle was undergoing federal emission testing on a
dynamometer8 or was being driven on the road. When the
software detected that the vehicle was being tested, the
vehicle performed in “dyno mode,” i.e., in compliance with
federal NOx emission standards. Otherwise, the vehicle
would operate in “street mode,” which substantially reduced
the effectiveness of the vehicle’s emission control system.



     7
       “Light-duty vehicle means a passenger car or passenger car
derivative capable of seating 12 passengers or less.” 40 C.F.R. § 86.082-
2.
     8
      A “dynamometer” is an instrument that measures the power output
of an engine. Dynamometer, Webster’s Third New International
Dictionary 711 (2002) (“an apparatus for measuring mechanical power (as
of an engine, an electric motor, or a draft animal)”).
              IN RE VOLKSWAGEN LITIGATION                  11

When in street mode, the vehicle’s NOx emissions were up
to 35 times higher than federal standards.

    The defeat device installed in the 3.0 Liter Vehicles was
also designed to recognize when the vehicle was undergoing
emission testing, but rather than cause the vehicle to switch
between dyno mode and street mode, the defeat device
injected varying amounts of a solution, AdBlue, into the
exhaust system. When the vehicle was being tested, the
defeat device would inject high amounts of AdBlue, reducing
NOx emissions below federal standards. When the vehicle
was being driven on the street, the defeat device would inject
less AdBlue, causing NOx emissions to exceed federal
standards.

    Between 2009 and 2015, Volkswagen installed these
defeat devices in approximately 585,000 new motor vehicles
that were sold in the United States. During this period,
Volkswagen deliberately misled the EPA by concealing the
defeat devices and certifying that the vehicles complied with
federal NOx emission standards. Unaware of Volkswagen’s
deception, the EPA issued certificates of conformity for these
vehicles in each model year. Volkswagen also misled
consumers by marketing the vehicles as “clean diesel” and
“environmentally-friendly,” despite knowing that the vehicles
“were intentionally designed to detect, evade and defeat U.S.
emissions standards.”

    Around 2012, consumers who purchased a 2.0 Liter
Vehicle began reporting hardware failures. In investigating
these failures, Volkswagen engineers theorized that the defeat
device failed to switch into street mode when the vehicle was
being driven on the street. Because the 2.0 Liter Vehicles
were not designed to comply with NOx emission standards
12            IN RE VOLKSWAGEN LITIGATION

except during the short periods of testing, the Volkswagen
engineers suspected that the hardware failures were caused by
the increased stress on the exhaust system from being driven
too long in compliance with NOx standards, i.e., in dyno
mode.

    To prevent such hardware failures, Volkswagen
developed two software updates for the 2.0 Liter Vehicles.
The first software update would decrease stress on the
exhaust system by causing the vehicle to start in street mode
rather than dyno mode; the second update would improve
emission-testing detection by adding a “steering wheel angle
recognition” feature. If a vehicle’s steering wheel was
stationary, the updated software would recognize that the
vehicle was being tested and the engine would switch to dyno
mode. But if the updated software detected that the steering
wheel was turning, it would allow the engine to operate in
street mode.

     Volkswagen began installing the updated software in new
2.0 Liter Vehicles in 2014. The same year, Volkswagen took
the following steps for its post-sale 2.0 Liter Vehicles. First,
it issued voluntary recalls and installed the software fixes
without revealing their purpose. Second, it updated the
software when customers brought their cars in for normal
maintenance, again without revealing the purpose of the
software updates. In each scenario, Volkswagen deceptively
told EPA regulators and American consumers that the
software updates were intended to improve the operation of
the 2.0 Liter Vehicles.

    An independent study soon revealed that certain
Volkswagen vehicles emitted air pollutants at concentrations
“of up to approximately 40 times the permissible limit.” The
                IN RE VOLKSWAGEN LITIGATION                           13

EPA commenced an investigation. In August 2015, a
Volkswagen whistleblower informed federal regulators about
the defeat device in the 2.0 Liter Vehicles. Eventually,
Volkswagen disclosed the entire scheme affecting both the
2.0 and 3.0 Liter Vehicles to federal regulators.

    The EPA subsequently issued notices of violation and
filed civil and criminal actions against Volkswagen for
violating the CAA. In the civil action, the EPA charged
Volkswagen with installing a defeat device on new motor
vehicles, in violation of 42 U.S.C. § 7522(a)(3)(B), and
tampering with emission control systems, in violation of
§ 7522(a)(3)(A), among other things. In the criminal action,
the EPA charged Volkswagen with conspiracy, 18 U.S.C.
§ 371, obstruction of justice, § 1512(c), and introducing
imported merchandise into the United States by means of
false statements, § 542.

    Volkswagen pleaded guilty to the criminal charges and
agreed to pay a $2.8 billion fine to the United States.
Pursuant to the plea agreement, Volkswagen stipulated to a
detailed statement of facts regarding the defeat devices and
agreed not to “contest the admissibility of, nor contradict”
those stipulated facts “in any proceeding.” The plea
agreement did not give Volkswagen “any protection against
prosecution” from state or local governments.

    Volkswagen also settled the civil CAA claims, entering
into three consent decrees with the United States.9 Other than


    9
      California was a party to both the first and second consent decrees.
At the time, California was authorized to “adopt and enforce” its own
“standards relating to control of emissions from new motor vehicles.”
42 U.S.C. § 7507; see also § 7543(b). But see The Safer Affordable Fuel-
14               IN RE VOLKSWAGEN LITIGATION

California (which entered into the first and second consent
decrees), no other state or local government released
Volkswagen from liability. To the contrary, each state
expressly reserved its ability to sue Volkswagen for
damages.10 In total, Volkswagen’s liability exceeded
$20 billion.

                                     B

    While the EPA was litigating its civil and criminal actions
against Volkswagen, a number of states and counties brought
separate lawsuits against the company for violating state and
local laws that prohibit tampering with vehicle emission
control systems.

    In 2016, the Multidistrict Litigation (MDL) judicial panel
transferred these actions to the district court for the Northern




Efficient (SAFE) Vehicles Rule Part One: One National Program, 84 Fed.
Reg. 51310 (Sept. 27, 2019) (withdrawing the waiver previously provided
to California for certain emission standards, as applied to new motor
vehicles). Under this grant of authority, California, like the United States,
brought claims for injunctive relief against Volkswagen, alleging
violations of California environmental and unfair competition laws.
     10
       Specifically, each state expressly reserved its right “to seek fines or
penalties” against Volkswagen in connection with being named a
beneficiary of a trust created by Volkswagen to help reduce the NOx
emissions caused by Volkswagen’s noncompliant vehicles. In re
Volkswagen “Clean Diesel” Mktg., Sales Practices, & Prods. Liab. Litig.,
No. 3:15-md-02672, Dkt. 2103-1, App’x D-3 at 2 (N.D. Cal. Apr. 16,
2018).
                 IN RE VOLKSWAGEN LITIGATION                              15

District of California.11 In 2017, the district court granted
Volkswagen’s motion to dismiss a suit brought by Wyoming,
holding that the state’s claim that Volkswagen violated
Wyoming law by installing the defeat device in new motor
vehicles was preempted by the CAA. See In re Volkswagen
“Clean Diesel” Mktg., Sales Practices, & Prods. Liab. Litig.,
264 F. Supp. 3d 1040, 1052–57 (N.D. Cal. 2017). In light of
the district court’s ruling, several local governments amended
their respective complaints to allege facts relating not only to
Volkswagen’s installation of the defeat device in new motor
vehicles (i.e., pre-sale conduct), but also to Volkswagen’s
modification to the defeat device in used vehicles (i.e., post-
sale conduct).

    Two of these complaints, one from Salt Lake County,
Utah, and one from Hillsborough County, Florida,
(collectively, the “Counties”) are before us on appeal.

     Salt Lake County sued Volkswagen in Utah state court.
In its third amended complaint, Salt Lake County alleged that
Volkswagen’s installation of and modification to the defeat
devices violated Utah’s anti-tampering regulation, which


    11
       On December 8, 2015, pursuant to 28 U.S.C. § 1407, the MDL
judicial panel transferred 63 actions relating to Volkswagen’s defeat
device as MDL No. 2672 to the Northern District of California for
coordinated pretrial proceedings. The MDL judicial panel noted that any
other related actions were potential tag-along actions. See Rule 1.1(h),
Rules of Procedure of the United States Judicial Panel on Multidistrict
Litigation (“‘Tag-along action’ refers to a civil action pending in a district
court which involves common questions of fact with either (1) actions on
a pending motion to transfer to create an MDL or (2) actions previously
transferred to an existing MDL, and which the Panel would consider
transferring under Section 1407.”). To date, the MDL judicial panel has
transferred over 1,500 actions as tag-along actions.
16               IN RE VOLKSWAGEN LITIGATION

provides: “[n]o person shall remove or make inoperable the
[emission control] system or device or any part thereof,
except for the purpose of installing another [emission control]
system or device, or part thereof, which is equally or more
effective in reducing emissions from the vehicle to the
atmosphere.” Utah Admin. Code R. 307-201-4.12 The
complaint alleged that Volkswagen violated this regulation by
installing defeat devices in new vehicles to render the
emission control systems inoperable, and by modifying the
software in post-sale vehicles to enhance the defeat devices’
capabilities. The penalty for violating Utah’s anti-tampering
regulation is up to $5,000 per violation, with each day of
violation constituting a separate offense. Utah Code Ann.
§ 19-1-303(1)(a), (3). The complaint also brought common
law claims for intentional misrepresentation and nuisance.
Volkswagen removed the Salt Lake County action to federal
court.

    The Environmental Protection Commission of
Hillsborough County (EPC), Florida, filed an action against
Volkswagen in Florida district court. EPC’s first amended
complaint alleged that Volkswagen violated two of the
county’s anti-tampering and defeat device regulations, which
provide that “[n]o person shall tamper, cause, or allow the
tampering of the emission control system of any motor
vehicle,” and no person shall “manufacture, install, sell or
advertise for sale, devices to defeat or render inoperable any
component of a motor vehicle’s emission control system.”


     12
       See also Utah Code Ann. § 26A-1-123(1)(a) (“It is unlawful for any
person, association, or corporation, and the officers of the association or
corporation to violate state laws or any lawful notice, order, standard, rule,
or regulation issued under state laws or local ordinances regarding public
health or sanitation.”).
                IN RE VOLKSWAGEN LITIGATION                          17

Rules of Envtl. Prot. Comm’n of Hillsborough Cty., Rule 1-
8.05(1), (6).13 The complaint alleged that Volkswagen
violated these provisions by installing defeat devices in new
vehicles, and by tampering with the emission control systems
of used vehicles registered in the county through a program
of field fixes and recall campaigns. The penalty for violating
Hillsborough County’s anti-tampering and defeat device
regulation is up to $5,000 per violation, with each day of
violation constituting a separate offense. See Hillsborough
County Environmental Protection Act, Fla. Laws 84-446
§ 17(2) (as amended by Fla. Laws 87-495 (2005)).

    The Counties’ claims were transferred to the district court
presiding over the MDL as tag-along actions. Volkswagen
moved to dismiss the Counties’ claims for failure to state a
claim. The district court granted the motion. It first
determined that, on their face, the Counties’ anti-tampering
rules applied to Volkswagen’s conduct in installing and
subsequently enhancing the defeat devices. Volkswagen does
not challenge this conclusion.

    Nevertheless, the district court dismissed the Counties’
actions with prejudice. It held that the Counties’ claims, as
applied to new vehicles, were preempted by § 209 of the
CAA, which precludes state and local governments from
adopting or attempting to enforce “any standard relating to

    13
       As used in the Hillsborough County regulations, “emission control
system” means “the devices and mechanisms installed as original
equipment at the time of manufacture . . . for the purpose of reducing or
aiding in the control of emissions,” Rules of Envtl. Prot. Comm’n of
Hillsborough Cty., Rule 1-8.03(2)(b), and “tampering” means “the
intentional inactivation, disconnection, removal or other modification of
a component or components of the emission control system resulting in it
being inoperable,” id., Rule 1-8.03(2)(h).
18            IN RE VOLKSWAGEN LITIGATION

the control of emissions from new motor vehicles or new
motor vehicle engines.” 42 U.S.C. § 7543(a). As to post-sale
vehicles, the district court concluded that the CAA preempts
the Counties’ anti-tampering rules because Volkswagen made
post-sale software changes on a model-wide basis and
Congress intended for model-wide tampering to be regulated
exclusively by the EPA.

    On appeal, the Counties argue that the CAA does not
preempt their claims for either pre-sale or post-sale vehicles.

    We have jurisdiction under 28 U.S.C. § 1291. We review
the district court’s preemption analysis de novo. Ting v.
AT&T, 319 F.3d 1126, 1135 (9th Cir. 2003).

                              II

    The question on appeal is whether the Counties’
regulations imposing penalties for tampering with emission
control systems in motor vehicles are expressly or impliedly
preempted by the CAA’s motor vehicle emission standards.
We begin with the framework for considering whether
Congress has preempted (or displaced) state law. The
Supremacy Clause provides that federal law “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.” U.S. Const. art.
VI, cl. 2. “The Clause provides a ‘rule of decision’ for
determining whether federal or state law applies in a
particular situation.” Kansas v. Garcia, 140 S. Ct. 791, 801
(2020) (quoting Armstrong v. Exceptional Child Ctr., Inc.,
575 U.S. 320, 324 (2015)). The basic principle is as follows:
“If federal law imposes restrictions or confers rights on
private actors and a state law confers rights or imposes
              IN RE VOLKSWAGEN LITIGATION                    19

restrictions that conflict with the federal law, the federal law
takes precedence and the state law is preempted.” Id.
(internal quotation marks omitted) (quoting Murphy v. Nat’l
Collegiate Athletic Ass’n, 138 S. Ct. 1461, 1480 (2018)).

    Congress may expressly preempt state law by enacting a
clear statement to that effect. Id. “If the statute contains an
express pre-emption clause, the task of statutory construction
must in the first instance focus on the plain wording of the
clause, which necessarily contains the best evidence of
Congress’ pre-emptive intent.” CSX Transp., Inc. v.
Easterwood, 507 U.S. 658, 664 (1993).

    Congress may also preempt state law implicitly. In
discerning whether there is implied preemption, our analysis
“must be guided by two cornerstones of . . . pre-emption
jurisprudence.” Wyeth v. Levine, 555 U.S. 555, 565 (2009).
“First, ‘the purpose of Congress is the ultimate touchstone in
every pre-emption case.’” Id. (quoting Medtronic, Inc. v.
Lohr, 518 U.S. 470, 485 (1996)). We must find such a
purpose “grounded ‘in the text and structure of the statute at
issue.’” Garcia, 140 S. Ct. at 804 (quoting CSX Transp., Inc.,
507 U.S. at 664). “Second, in all pre-emption cases . . . we
start with the assumption that the historic police powers of
the States” are not preempted “unless that was the clear and
manifest purpose of Congress.” Wyeth, 555 U.S. at 565
(alteration adopted and internal quotation marks omitted)
(quoting Lohr, 518 U.S. at 485). Both of these cornerstones
support the same analytic approach: “a high threshold must
be met” before a court will conclude that a federal law has
impliedly preempted a state law. Whiting, 563 U.S. at 607
(citation omitted).
20            IN RE VOLKSWAGEN LITIGATION

    The Supreme Court has articulated two
circumstances—referred to as “field preemption” and
“conflict preemption”—where Congress’s implicit intent to
preempt state law clears that high threshold. First, “when
federal law occupies a ‘field’ of regulation ‘so
comprehensively that it has left no room for supplementary
state legislation,’” Murphy, 138 S. Ct. at 1480 (quoting R.J.
Reynolds Tobacco Co. v. Durham Cty., 479 U.S. 130, 140
(1986)), a court may infer that Congress intended to preempt
state law.

     Second, when a state law “actually conflicts with federal
law,” English v. Gen. Elec. Co., 496 U.S. 72, 79 (1990),
either because “compliance with both state and federal law is
impossible,” or because “the state law ‘stands as an obstacle
to the accomplishment and execution of the full purposes and
objectives of Congress,’” Oneok, Inc. v. Learjet, Inc.,
575 U.S. 373, 377 (2015) (quoting California v. ARC Am.
Corp., 490 U.S. 93, 100–01 (1989)), a court may again
conclude that Congress implicitly intended to preempt state
law. To evaluate a claim based on the second type of conflict
preemption—referred to as “obstacle preemption”—a court
must identify the “full purposes and objectives” of the federal
law from “the text and structure of the statute at issue.”
Garcia, 140 S. Ct. at 804 (quoting CSX Transp., Inc.,
507 U.S. at 664). “The Supremacy Clause gives priority to
‘the Laws of the United States,’” not the priorities and
preferences of federal officers, id. at 807, or the “unenacted
approvals, beliefs, and desires” of Congress, P.R. Dep’t of
Consumer Affairs v. Isla Petroleum Corp., 485 U.S. 495, 501
(1988).

   The Supreme Court has found obstacle preemption in
only a small number of cases. First, where the federal
              IN RE VOLKSWAGEN LITIGATION                   21

legislation at issue involved a “uniquely federal area[] of
regulation,” the Court has inferred a congressional intent to
preempt state laws “that directly interfered with the operation
of the federal program.” Whiting, 563 U.S. at 604. Such
unique federal areas include exercising foreign affairs
powers, Crosby v. Nat’l Foreign Trade Council, 530 U.S.
363, 373–74 (2000), sanctioning fraud on a federal agency,
Buckman Co. v. Plaintiffs’ Legal Comm., 531 U.S. 341, 353
(2001), and regulating maritime vessels, United States v.
Locke, 529 U.S. 89, 97 (2000). Second, the Court has
inferred that Congress made “a considered judgment” or “a
deliberate choice” to preclude state regulation when a federal
enactment clearly struck a particular balance of interests that
would be disturbed or impeded by state regulation. Arizona,
567 U.S. at 405. Thus, a state law imposing criminal
penalties on aliens who sought or engaged in unlawful
employment “would interfere with the careful balance struck
by Congress,” because “Congress made a deliberate choice
not to impose criminal penalties” for the same conduct. Id.
at 405, 406; see also Geier v. Am. Honda Motor Co., 529 U.S.
861, 879–81 (2000) (holding that certain federal safety
regulations “deliberately sought a gradual phase-in” of
airbags to give manufacturers more time and increase public
acceptance, and that state tort law requiring the immediate
installation of airbags would have “stood as an obstacle” to
the phase-in program “that the federal regulation deliberately
imposed”); Int’l Paper Co. v. Ouellette, 479 U.S. 481, 494,
497 (1987) (holding that the federal statute’s comprehensive
regulation “carefully addressed” the “balance of public and
private interests,” giving rise to the inference that Congress
did not intend to “tolerate common-law suits that have the
potential to undermine this regulatory structure”). Where
Congress has determined the appropriate balance, state
regulation involving a different method of enforcement may
22            IN RE VOLKSWAGEN LITIGATION

upset that balance and be displaced by federal law even where
the state “attempts to achieve one of the same goals as federal
law.” Arizona, 567 U.S. at 406.

    Absent such circumstances, the Supreme Court has
frequently rejected claims of obstacle preemption. For
instance, the Court does not infer Congress intended to
preempt state enactments merely because they overlap with
a federal act. “Our federal system would be turned upside
down if we were to hold that federal criminal law preempts
state law whenever they overlap, and there is no basis for
inferring that federal criminal statutes preempt state laws
whenever they overlap.” Garcia, 140 S. Ct. at 806.

    This analysis is equally applicable in the civil context,
especially when the federal statute expressly or impliedly
preserves state laws that might overlap with a federal statute.
See Whiting, 563 U.S. at 607. The Court gives great weight
to Congress’s inclusion of a provision preserving states’
enforcement authority. In Williamson, for instance, the Court
concluded that a federal statute giving manufacturers a choice
to select a less effective car safety device did not preempt a
state tort suit that could require the manufacturer to select a
more effective device. 562 U.S. at 332–36. The Court
reasoned that because Congress included “a statutory saving
clause” preserving state remedies, it foresaw “the likelihood
of a continued meaningful role for state tort law.” Id. at 335.
Similarly, in Whiting, the Court concluded that federal law
preempting “any State or local law imposing civil or criminal
sanctions” on employers who hire “unauthorized aliens,” did
not impliedly preempt an Arizona law that authorized (and
sometimes required) the suspension or revocation of an
employer’s business license if the employer knowingly or
intentionally employed unauthorized aliens. 563 U.S. at 587.
              IN RE VOLKSWAGEN LITIGATION                   23

The Court held that there was no express preemption, because
the state law fell “comfortably within the saving clause.” Id.
at 596. The Court likewise concluded there was no implied
preemption of the Arizona law, because where “Congress
specifically preserved such authority for the States, it stands
to reason that Congress did not intend to prevent the States
from using appropriate tools to exercise that authority.” Id.
at 600–01.

    Although a saving clause raises the inference that
Congress did not intend to preempt state law, the existence of
a saving clause does not “foreclose or limit the operation of
ordinary pre-emption principles” that are “grounded in
longstanding precedent.” Geier, 529 U.S. at 869, 874; see
also Buckman, 531 U.S. at 352 (broadening Geier’s specific
holding to apply to all saving clauses). We may not interpret
a saving clause as preserving a state law that would so
conflict and interfere with a federal enactment that it would
defeat the federal law’s purpose or essentially nullify it;
rather, such a state law is preempted under ordinary
preemption principles. Said otherwise, we infer that
Congress did not intend the saving provisions in a federal law
to be interpreted in a way that causes the federal law “to
defeat its own objectives, or potentially, as the Court has put
it before, to destroy itself.” Geier, 529 U.S. at 872 (internal
quotation marks and citation omitted). But this unremarkable
principle means only that a court must interpret a saving
clause as it would any statutory language: giving effect to its
plain language and meaning in a way that best comports with
the statute as a whole. See FDA v. Brown & Williamson
Tobacco Corp., 529 U.S. 120, 133 (2000) (explaining that
courts must interpret statutes “as a symmetrical and coherent
regulatory scheme . . . and fit, if possible, all parts into an
harmonious whole” (citation and quotation marks omitted));
24            IN RE VOLKSWAGEN LITIGATION

see also A. Scalia & B. Garner, Reading Law: The
Interpretation of Legal Texts 180 (2012) (“[T]here can be no
justification for needlessly rendering provisions in conflict if
they can be interpreted harmoniously.”).

                              III

   We apply these principles to the question whether the
Counties’ anti-tampering rules are preempted.

                               A

    Some background is helpful to put our interpretation of
the CAA and its relationship with states’ laws and police
powers into context. The CAA is a joint venture, one that
makes “the States and the Federal Government partners in the
struggle against air pollution.” Gen. Motors Corp. v. United
States, 496 U.S. 530, 532 (1990). The basic division of
responsibility in Title II of the CAA reflects the cooperative
federalism principles that have long informed this nation’s air
pollution control laws. See Comm. for a Better Arvin v. EPA,
786 F.3d 1169, 1173 (9th Cir. 2015) (“[T]he CAA has
established a uniquely important system of cooperative
federalism in the quest for clean air.”); GenOn REMA, LLC
v. EPA, 722 F.3d 513, 516 (3d Cir. 2013) (“This ‘cooperative
federalism’ structure is a defining feature of the [CAA].”).
Prior to 1955, the regulation of air pollution was the sole
responsibility of the states as a matter of public health, and
the states enacted various regulations pursuant to their
historic police powers. See Arthur C. Stern, History of Air
Pollution Legislation in the United States, 32 J. Air Pollution
Control Ass’n 44, 44, 47 (1982); see also, e.g., 1947 Cal.
Stat. 1640; 1911 Iowa Acts 27; 1887 Minn. Special Laws
623. The federal government first partnered with the states
               IN RE VOLKSWAGEN LITIGATION                     25

in the fight against air pollution in 1955, enacting the Air
Pollution Control Act and espousing a national policy “to
preserve and protect the primary responsibilities and rights of
the States and local governments in controlling air pollution.”
Act of July 14, 1955, Pub. L. No. 84-159, 69 Stat. 322, 322
(1955). In 1963, Congress enacted the first version of the
CAA, Act of Dec. 17, 1963, Pub. L. No. 88-206, 77 Stat. 392
(1963), which was “[b]uilt on a scheme of ‘cooperative
federalism,’” MacClarence v. EPA, 596 F.3d 1123, 1125 (9th
Cir. 2010).

    The current version of the CAA recognizes “that air
pollution prevention . . . and air pollution control at its source
is the primary responsibility of States and local
governments.” 42 U.S.C. § 7401(a)(3). In regard to air
pollution from motor vehicles, Congress has taken a stronger
lead in enforcing emission standards. Nevertheless, it has
consistently preserved the legitimacy of state regulations. For
instance, although Congress displaced state emission
standards for new motor vehicles in 1967, see Air Quality Act
of 1967, Pub. L. No. 90-148, § 208(a), 81 Stat. 485, 501
(1967); Clean Air Amendments of 1970, Pub. L. No. 91-604,
§ 8(a), 84 Stat. 1676, 1694 (1970), it has maintained a
substantial role for states in post-sale implementation and
enforcement ever since, see 42 U.S.C. §§ 7416, 7543(d); see
also Ashoff v. City of Ukiah, 130 F.3d 409, 412–13 (9th Cir.
1997) (describing how the CAA’s citizen suit provision
enables citizens to “sue on the basis of more stringent state
standards”). In sum, the regulation of air pollution falls
within the historic police powers of the states, see Huron
Portland Cement Co., 362 U.S. at 442, and the modern CAA
maintains a cooperative federalism approach, see Gen.
Motors Corp., 496 U.S. at 532.
26           IN RE VOLKSWAGEN LITIGATION

                              B

     We now turn to the relevant text of the CAA. Under Title
II, Part A of the CAA, the federal government has authority
to establish “standards applicable to the emission of any air
pollutant from . . . new motor vehicles.” 42 U.S.C.
§ 7521(a)(1). This includes the authority to set emission
limits for air pollutants, § 7521(b), and to promulgate
standards governing the use of emission control devices,
§ 7521(a)(4)(A). Failure to comply with the CAA and
regulatory emission standards for new motor vehicles can
result in civil penalties, criminal penalties, or both. See
§§ 7413(c), 7524.

    The CAA expressly preempts certain state and local laws
regulating emissions from new motor vehicles. Under
§ 209(a) of the CAA:

       No State or any political subdivision thereof
       shall adopt or attempt to enforce any standard
       relating to the control of emissions from new
       motor vehicles or new motor vehicle engines
       subject to this part. No State shall require
       certification, inspection, or any other approval
       relating to the control of emissions from any
       new motor vehicle or new motor vehicle
       engine as condition precedent to the initial
       retail sale, titling (if any), or registration of
       such motor vehicle, motor vehicle engine, or
       equipment.

42 U.S.C. § 7543(a). A “new motor vehicle” is “a motor
vehicle the equitable or legal title to which has never been
transferred to an ultimate purchaser,” § 7550(3), in other
              IN RE VOLKSWAGEN LITIGATION                    27

words, a pre-sale vehicle. Although the CAA does not define
a “standard relating to the control of emissions,” the Supreme
Court has provided a definition. See Engine Mfrs. Ass’n v.
South Coast Air Quality Mgmt. Dist., 541 U.S. 246, 252–53
(2004) (“South Coast”). In South Coast, the Court first
turned to the dictionary to define “standard” as “that which ‘is
established by authority, custom, or general consent, as a
model or example; criterion; test.’” Id. (quoting Webster’s
Second New International Dictionary 2455 (1945)). The
Court then stated that “[t]he criteria referred to in § 209(a)
relate to the emission characteristics of a vehicle or engine.”
Id. at 253. A vehicle meets the criteria relating to emission
characteristics in one of three ways: by not emitting “more
than a certain amount of a given pollutant”; by being
“equipped with a certain type of pollution-control device”; or
by having “some other design feature related to the control of
emissions.” Id. Accordingly, even a requirement “that
certain purchasers may buy only vehicles with particular
emission characteristics” constitutes an “attempt to enforce”
a “standard.” Id. at 255. In light of this definition, § 209(a)
precludes state or local governments from imposing any
restriction that has the purpose of enforcing emission
characteristics for pre-sale, motor vehicles.

    After a new motor vehicle is sold “to an ultimate
purchaser,” 42 U.S.C. § 7550(3), the express preemption
clause no longer applies. Instead, the CAA preserves state
and local governments’ authority over post-sale motor
vehicles. Section 209(d) of the CAA provides: “Nothing in
this part shall preclude or deny to any State or political
subdivision thereof the right otherwise to control, regulate, or
restrict the use, operation, or movement of registered or
licensed motor vehicles.” 42 U.S.C. § 7543(d). A vehicle is
registered or licensed after sale to a consumer, so the saving
28                IN RE VOLKSWAGEN LITIGATION

clause applies to post-sale vehicles.14 The CAA does not
define “operation,” so taking South Coast’s lead, we look to
the dictionary, which defines it as “the quality or state of
being functional or operative” or the “method or manner of
functioning.” Operation, Webster’s Third New International
Dictionary 1518 (2002). Removing or making inoperable a
vehicle’s emission control system (i.e., tampering) affects the
vehicle’s “quality” and “method” of functioning (i.e.,
operation). Therefore, the plain language of § 209(d)
preserves state and local governments’ authority to prohibit
tampering with emission control systems in post-sale
vehicles.

     Despite the saving clause, the EPA retains some authority
over post-sale vehicles. The CAA requires manufacturers of
new motor vehicles to warrant the emission control system of
the vehicle for the “useful life” of the vehicle, with the useful
life being 10 years or 100,000 miles. 42 U.S.C. §§ 7521(d),
7541(a)(1). Manufacturers must test post-sale vehicles for
compliance with EPA emission standards by performing “in-
use verification testing” on vehicles obtained from consumers
at prescribed mileage intervals. See § 7541(b); 40 C.F.R.
§ 86.1845–04. If, pursuant to an EPA mandatory reporting
regulation, a manufacturer reports that a “specific emission-
related defect exists in twenty-five or more vehicles or
engines of the same model year,” 40 C.F.R. § 85.1903(a)(2),
then the EPA can require the manufacturer to conduct a recall
and remedy the defect, all at the manufacturer’s expense,
42 U.S.C. § 7541(c), (d). The EPA also has the authority to
require manufacturers to make post-sale “[c]hanges to the


     14
        See, e.g., Nev. Rev. Stat. § 482.423 (2019) (indicating that the
“certificate of registration and license plates for the vehicle” will be issued
only after “the sale of a new vehicle”).
                 IN RE VOLKSWAGEN LITIGATION                          29

configuration of vehicles covered by a Certificate of
Conformity,” including changes to vehicle software. See
40 C.F.R. § 86.1842–01(b). Failure to comply with any EPA
post-sale regulation can result in civil enforcement actions
and other penalties. 42 U.S.C. § 7524.

    Last, the CAA prohibits tampering with air pollution
control devices in all motor vehicles, both pre-sale and post-
sale. See § 7522(a)(3)(A), (B).15 These sections make it a
violation of the CAA “for any person to remove or render
inoperative” an air pollution control device both before and
after “sale and delivery to the ultimate purchaser,” or to
install a defeat device on any motor vehicle at any time. Id.
In the event of a tampering violation, the CAA provides for


   15
        42 U.S.C. § 7522(a)(3) provides that it shall be unlawful:

          (A) for any person to remove or render inoperative any
          device or element of design installed on or in a motor
          vehicle or motor vehicle engine in compliance with
          regulations under this subchapter prior to its sale and
          delivery to the ultimate purchaser, or for any person
          knowingly to remove or render inoperative any such
          device or element of design after such sale and delivery
          to the ultimate purchaser; or

          (B) for any person to manufacture or sell, or offer to
          sell, or install, any part or component intended for use
          with, or as part of, any motor vehicle or motor vehicle
          engine, where a principal effect of the part or
          component is to bypass, defeat, or render inoperative
          any device or element of design installed on or in a
          motor vehicle or motor vehicle engine in compliance
          with regulations under this subchapter, and where the
          person knows or should know that such part or
          component is being offered for sale or installed for such
          use or put to such use.
30                  IN RE VOLKSWAGEN LITIGATION

the imposition of a civil penalty not to exceed $25,000 per
vehicle, with additional limitations on penalties for related
offenses committed by specified persons. § 7524(a).16 The
EPA can give effect to the CAA’s penalty provision through
a civil or administrative action. § 7524(b), (c). When
imposing a civil penalty through an administrative action, the
EPA must “take into account” a range of factors, including
“the gravity of the violation, the economic benefit or savings
(if any) resulting from the violation, the size of the violator’s
business, the violator’s history of compliance with this
subchapter, action taken to remedy the violation, the effect of
the penalty on the violator’s ability to continue in business,




     16
          42 U.S.C. § 7524(a) provides:

            Any person who violates sections 7522(a)(1),
            7522(a)(4), or 7522(a)(5) of this title or any
            manufacturer or dealer who violates section
            7522(a)(3)(A) of this title shall be subject to a civil
            penalty of not more than $25,000. Any person other
            than a manufacturer or dealer who violates section
            7522(a)(3)(A) of this title or any person who violates
            section 7522(a)(3)(B) of this title shall be subject to a
            civil penalty of not more than $2,500. Any such
            violation with respect to paragraph (1), (3)(A), or (4) of
            section 7522(a) of this title shall constitute a separate
            offense with respect to each motor vehicle or motor
            vehicle engine. Any such violation with respect to
            section 7522(a)(3)(B) of this title shall constitute a
            separate offense with respect to each part or
            component.       Any person who violates section
            7522(a)(2) of this title shall be subject to a civil penalty
            of not more than $25,000 per day of violation.
                IN RE VOLKSWAGEN LITIGATION                           31

and such other           matters     as    justice    may      require.”
§ 7524(c)(2).17

                                   IV

    We now consider the application of the preemption
doctrine to the Counties’ anti-tampering rules. We first ask
whether the CAA’s express preemption provision preempts
the Counties’ anti-tampering rules. To the extent the CAA’s
express preemption provision does not apply, we ask whether
the Counties’ rules conflict with the CAA, and therefore are
impliedly preempted. See Williamson, 562 U.S. 329–30.

                                   A

    Volkswagen argues that § 209(a), the CAA’s express
preemption provision, preempts the Counties’ imposition of
anti-tampering rules on pre-sale vehicles. We agree. Section
209(a) precludes a local government from enforcing “any
standard relating to the control of emissions from new motor
vehicles.” 42 U.S.C. § 7543(a). The Counties seek to
enforce rules prohibiting persons from making changes to a
motor vehicle’s emission control system. See Rules of Envtl.
Prot. Comm’n of Hillsborough Cty., Rule 1-8.05(1); Utah
Admin. Code R. 307-201-4. The EPC additionally seeks to
enforce a rule prohibiting the installation of any device
designed “to defeat or render inoperable any component of a
motor vehicle’s emission control system.” Rules of Envtl.
Prot. Comm’n of Hillsborough Cty., Rule 1-8.05(6). Because
these requirements relate to the emission control system of a


    17
      When the EPA initiates a civil action, the district court must “take
into account” the same range of factors when assessing a penalty.
42 U.S.C. § 7524(b).
32            IN RE VOLKSWAGEN LITIGATION

vehicle, they constitute standards for purposes of § 209(a).
Therefore, § 209(a) preempts the Counties’ enforcement of
these rules with respect to new motor vehicles. See 42 U.S.C.
§ 7543(a).

    The Counties argue that their anti-tampering rules are not
“emission standards” for purposes of § 209(a) because they
do not attempt to enforce the limitations on emissions of
pollutants from new motor vehicles that are set forth in § 202
of the CAA, 42 U.S.C. § 7521 (emission standards for new
motor vehicles). In the same vein, the Counties argue that the
anti-tampering rules are not “standard[s] relating to the
control of emissions” because they merely prohibit tampering
with emission control systems. According to the Counties,
these anti-tampering rules do not relate to the control of
emissions because “[a] vehicle does not have to exceed
emission standards for a tampering violation to occur; a
violation occurs whenever there is ‘the act of removing or
rendering inoperative any emission control device or element
of design.’” These arguments fail, because South Coast
defined “standard” as denoting not only “numerical emission
levels with which vehicles or engines must comply, e.g.,
42 U.S.C. § 7521(a)(3)(B)(ii),” but also “emission-control
technology with which they must be equipped, e.g.,
§ 7521(a)(6).” South Coast, 541 U.S. at 253. Because the
Counties’ rules attempt to enforce the integrity of “the
emission-control technology with which” the pre-sale
vehicles must be equipped, id., they attempt to enforce a
“standard,” and are therefore preempted by § 209(a).

                              B

   We turn to Volkswagen’s argument that § 209(a) also
expressly preempts the Counties’ anti-tampering rules as
              IN RE VOLKSWAGEN LITIGATION                   33

applied to post-sale vehicles. It clearly does not. By its
terms, § 209(a) preempts state and local regulations “relating
to the control of emissions from new motor vehicles.”
42 U.S.C. § 7543(a) (emphasis added). The provision does
not apply to post-sale vehicles.

     Nevertheless, Volkswagen argues that the preemptive
effect of § 209(a) does not end as soon as the “equitable or
legal title” to a vehicle has “been transferred to an ultimate
purchaser.” § 7550(3). According to Volkswagen, a long line
of federal authority recognizes that § 209(a) would be a dead
letter if a state or local government could impose a different
emission standard the moment after title is transferred to a
purchaser. In the leading case of Allway Taxi, Inc. v. City of
New York, a district court upheld a local ordinance requiring
licensed taxicabs to use a certain type of gasoline and to be
equipped with an emission control device, but stated that a
state or locality is not necessarily “free to impose its own
emission control standards the moment after a new car is
bought and registered” because that “would be an obvious
circumvention of the Clean Air Act and would defeat the
congressional purpose of preventing obstruction to interstate
commerce.” 340 F. Supp. 1120, 1124 (S.D.N.Y. 1972).
Volkswagen further notes that the EPA cited Allway Taxi
with approval in the preamble to a regulation, stating that the
“EPA expects that the principles articulated in Allway Taxi
will be applied by the courts.” Control of Air Pollution,
59 Fed. Reg. 31306, 31330 (June 17, 1994).

    Volkswagen’s reliance on Allway Taxi is misplaced. The
Counties’ anti-tampering rules do not require Volkswagen to
comply with a local emission standard that is different from
the federal standard, nor do they impose a standard that
would effectively require car manufacturers to alter their
34              IN RE VOLKSWAGEN LITIGATION

manufacture of new vehicles before sale. Rather, the anti-
tampering rules prohibit post-sale tampering with federally
mandated emission control systems. In this context, the
Counties can regulate Volkswagen’s post-sale tampering with
vehicles’ emission control systems to make them less
effective just as it can penalize the local garage mechanic
who disconnects vehicles’ emission control devices to
improve performance or gas mileage. Such an exertion of
authority is not expressly preempted by § 209(a).

                                   V

    Because we reject Volkswagen’s argument that § 209 of
the CAA expressly preempts the Counties’ anti-tampering
rules as applied to post-sale vehicles, we turn to the more
difficult question raised by the parties: whether the CAA
impliedly preempts the Counties’ anti-tampering rules as
applied to post-sale vehicles.

    Volkswagen’s theory of implied preemption is based only
on the doctrine of obstacle preemption.18 Specifically,
Volkswagen claims that the Counties’ anti-tampering rules
stand “as an obstacle to the accomplishment and execution of
the full purposes and objectives” of Title II, Part A of the
CAA, and therefore they are impliedly preempted. Oneok,
575 U.S. at 377 (quoting ARC Am. Corp., 490 U.S. at
100–01).

     18
      Volkswagen does not argue that Congress intended to occupy the
field of emission regulations, nor could it, given that Congress
contemplated that state and local governments would play a role in
implementing the motor vehicle controls mandated by the CAA. See
42 U.S.C. § 7416. Nor does Volkswagen argue that it is impossible to
comply with both state and federal regulations, given that § 7522(a)(3)(A)
and the Counties’ anti-tampering rules prohibit the same conduct.
              IN RE VOLKSWAGEN LITIGATION                    35

    In considering Volkswagen’s obstacle preemption
arguments, we begin with the text and structure of the CAA.
See Garcia, 140 S. Ct. at 804. As directed by the Supreme
Court, we consider the impact of Congress’s inclusion of a
saving clause, see Williamson, 562 U.S. at 335; Whiting, 563
U.S. at 600–01, in light of the presumption “that ‘the historic
police powers of the States’ are not superseded ‘unless that
was the clear and manifest purpose of Congress,’” Arizona,
567 U.S. at 400 (citation omitted).

    The CAA’s preemption clause (§ 209(a)) and saving
clause (§ 209(d)) allocate authority between the federal
government and state governments as follows: Section
209(a) gives the EPA exclusive authority to establish
standards for new vehicles, 42 U.S.C. § 7543(a), while
§ 209(d) preserves the authority of state and local
governments over post-sale vehicles, 42 U.S.C. § 7543(d).
The plain language of § 209(d), providing that nothing in
Title II “shall preclude or deny to any State or political
subdivision thereof the right otherwise to control, regulate, or
restrict the use, operation, or movement of registered or
licensed motor vehicles,” appears to give states substantial
authority to enforce standards related to post-sale vehicles,
including sanctioning tampering with emission control
systems. Id.; see also Whiting, 563 U.S. at 611 (holding that
Congress’s express reservation of state authority to impose
certain civil sanctions means what it says). The language of
§ 209(d) also indicates that Congress foresaw “the likelihood
of a continued meaningful role” for state enforcement.
Williamson, 562 U.S. at 335. Indeed, the vast majority of
states have laws prohibiting tampering with air pollution
36              IN RE VOLKSWAGEN LITIGATION

control systems in motor vehicles.19 We may presume that
Congress was aware of these laws and did not intend to
displace them, given that many of these state laws existed
during the period in which Congress amended the CAA
without making any changes to the preservation of state
authority.20 See, e.g., Wis. Admin. Code NR § 154.17(2)
(1972); Mont. Admin. R. 17.8.325 (effective Dec. 31, 1972);

     19
        See Ala. Admin. Code r. 335-3-9.06; Alaska Admin. Code tit. 18,
§ 52.015; Ariz. Rev. Stat. Ann. § 28-1522; Ark. Admin. Code 014.01.5-7;
Cal. Code Regs. tit. 16, § 3362.1; Colo. Rev. Stat. § 42-4-314; Conn. Gen.
Stat. Ann. § 14-164c; Del. Code Ann. tit. 21, § 6701; D.C. Mun. Regs.
tit. 18, § 750; Fla. Stat. Ann. § 316.2935; Ga. Code Ann. § 40-8-130;
Haw. Code R. § 11-60.1-34; Idaho Code Ann. § 49-229; Ill. Admin. Code
tit. 35, § 240.103; 326 Ind. Admin. Code 13-2.1-3; Iowa Code Ann.
§ 321.78; La. Admin. Code tit. 55,§ 817; Md. Code Ann. Transp. § 22-
402.1; 310 Mass. Code Regs. 60.02; Mich. Comp. Laws Ann.
§§ 324.6504, 324.6535; Minn. R. 7023.0120; Mo. Code Regs. Ann. tit. 10,
§ 10-5.381; Mont. Admin. R. 17.8.325; 129 Neb. Admin. Code Ch. 36,
§ 001; Nev. Admin. Code § 445B.575; N.H. Code Admin. R. Env-A
1102.01; N.J. Admin. Code § 7:27–15.7; N.Y. Comp. Codes R. & Regs.
tit. 6, § 218-6.2; 19a N.C. Admin. Code 3D.0542; N.D. Admin. Code
33.1-15-08-02; Ohio Admin. Code 3745-80-02; Okla. Stat. Ann. tit. 47,
§ 12-423; Or. Rev. Stat. Ann. § 815.305; 75 Pa. Stat. and Cons. Stat. Ann.
§ 4531; 280-30 R.I. Code R. § 1.13.2; S.C. Code Ann. § 16-21-90; Tenn.
Comp. R. & Regs. 1200-03-36-.03; 30 Tex. Admin. Code § 114.20; Utah
Admin. Code r. R307-201-4; 16-5 Vt. Code R. § 702; 9 Va. Admin. Code
§ 5-40-5670; Wash. Admin. Code § 173-421-100; W. Va. Code Ann.
§ 22-5-15; Wis. Admin. Code NR § 485.06; 20.0002-13 Wyo. Code R.
§ 2.
     20
       Congress amended the CAA three times since enacting the saving
clause in 1967, see Clean Air Amendments of 1970, Pub. L. No. 91-604,
84 Stat. 1676 (1970); Clean Air Act Amendments of 1977, Pub. L. No.
95-95, 91 Stat. 685 (1977); Clean Air Act, Amendments, Pub. L. No. 101-
549, 104 Stat. 2399 (1990), but the language of the saving clause has
never changed, see Air Quality Act of 1967, Pub. L. No. 90-148, § 208(c),
81 Stat. 485, 501 (1967), renumbered at 84 Stat. at 1694, and codified at
42 U.S.C. § 7543(d).
                IN RE VOLKSWAGEN LITIGATION                           37

see also Goodyear Atomic Corp. v. Miller, 486 U.S. 174,
184–85 (1988) (“[Courts] generally presume that Congress is
knowledgeable about existing law pertinent to the legislation
it enacts.”).21    Congress’s “certain awareness of the
prevalence of state” law, coupled with its “silence on the
issue,” “is powerful evidence that Congress did not intend” to
preempt local anti-tampering laws. Wyeth, 555 U.S. at 575;
see also Bonito Boats, Inc. v. Thunder Craft Boats, Inc.,
489 U.S. 141, 166–67 (1989) (“The case for federal pre-
emption is particularly weak where Congress has indicated its
awareness of the operation of state law in a field of federal
interest, and has nonetheless decided to ‘stand by both
concepts and to tolerate whatever tension there is between
them.’” (alteration adopted and citation omitted); Head v.
N.M. Bd. of Exam’rs in Optometry, 374 U.S. 424, 432 (1963)
(holding that a state law did not stand “as an obstacle to the
full effectiveness of the federal statute” because the federal
government “apparently viewed state regulation of
advertising as complementing its regulatory function, rather
than in any way conflicting with it”). Accordingly, the
CAA’s text and structure, particularly in light of the
presumption that Congress does not impliedly preempt states’
historic police powers, weigh against a conclusion that


    21
        To the extent we give weight to the EPA’s interpretation of the
CAA in this context, it is clear that the EPA did not read the CAA as
preempting the states’ enforcement efforts.          See Approval and
Promulgation of Air Quality State Implementation Plans (SIP), 63 Fed.
Reg. 6651-01, 6652 (Feb. 10, 1998) (“Even though there is a federal [anti-
tampering] law which provides for EPA enforcement, many states [have
enacted anti-tampering laws] and use them successfully as enforcement
tools for resolutions of consumer complaints involving tampered vehicles,
deterrence of tampering, deterrence of selling tampered vehicles, and
enforcement of tampering violations.”). We note, once again, that the
EPA declined to provide its opinion on this issue. See supra at 8 n.4.
38            IN RE VOLKSWAGEN LITIGATION

Congress intended to preempt the Counties’ anti-tampering
rules.

    Nor are there other factors weighing in favor of obstacle
preemption. The regulation of air pollution from post-sale
vehicles does not involve a “uniquely federal” area of
enforcement, Whiting, 563 U.S. at 604, because the basic
division of responsibility in Title II of the CAA reflects the
cooperative federalism principles that have long informed this
nation’s air pollution control laws, see supra Part III.A. And
even if the regulation of post-sale vehicles were an important
area of federal concern, the EPA’s ability to enforce the
federal anti-tampering law, 42 U.S.C. § 7522(a)(3)(A), is not
impeded by the Counties’ parallel rules, and so there is no
basis to infer a congressional intent to preempt them. See
Whiting, 563 U.S. at 605 (holding that a state law regulating
unauthorized alien employment did not interfere with federal
immigration law where the federal program “operates
unimpeded by the state law”). We also see no indication that
Congress struck a balance in the enforcement of post-sale
emission standards that would be upset by state anti-
tampering rules. Unlike Arizona and Geier, where Congress
“deliberately sought” a particular policy goal at the expense
of others, Geier, 529 U.S. at 879; see also Arizona, 567 U.S.
at 405, the text and structure of the CAA expresses a general
policy to prohibit tampering by “any person” at any time.
§ 7522(a)(3)(A).         Faced with such a generalized
congressional objective, and the fact that Congress does not
occupy the field of post-sale emission regulations, see supra
at 34 n.18, we cannot infer that Congress made a “deliberate
choice” to preclude state regulations that overlap with federal
law. Arizona, 567 U.S. at 405.
                 IN RE VOLKSWAGEN LITIGATION                            39

    Accordingly, we conclude that Congress intended to
allow states to enforce anti-tampering rules related to post-
sale vehicles, and that such rules are not impliedly preempted.

                                    VI

    Despite the strong indications that Congress did not
intend to preempt state efforts to prevent tampering in post-
sale vehicles, Volkswagen argues that interpreting the CAA
as allowing such state enforcement efforts would defeat the
“purposes and objectives of Congress.” Oneok, 575 U.S. at
377 (citation omitted). Therefore, Volkswagen asserts, the
Counties’ anti-tampering rules are preempted under ordinary
preemption principles. Volkswagen relies on two distinct
aspects of Title II to support its argument: (1) the provisions
requiring manufacturers to ensure that post-sale vehicles
comply with certain emission requirements on a model-wide
basis, and (2) the provisions authorizing the EPA to impose
civil penalties on persons who tamper with vehicles. We
consider each of these arguments in turn.

                                    A

    Volkswagen first argues that Congress intended to give
the EPA exclusive oversight over post-sale compliance with
emission standards on a model-wide basis, and the Counties’
anti-tampering rules pose an obstacle to this goal.22

    22
       Volkswagen claims that the legislative history of the CAA supports
this theory because it indicates that Congress wanted to avoid a patchwork
of varying emission standards for vehicles nationwide, further supporting
its argument that the Counties’ anti-tampering rules are preempted. Even
if we consider this legislative history, however, it is inapplicable here.
The Counties’ rules (just like every other state anti-tampering rule) do not
impose unique emission standards; rather, they permit local governments
40               IN RE VOLKSWAGEN LITIGATION

Volkswagen’s argument proceeds in three steps. First,
Volkswagen points to the sections of the CAA imposing post-
sale obligations on manufacturers and tasking the EPA with
ensuring compliance with those obligations. For instance, the
CAA requires manufacturers to ensure that their vehicles’
emission control system remains functional for at least
10 years or 100,000 miles, see 42 U.S.C. §§ 7521(a)(1), (d),
7541(a)(1), (b), and to conduct a recall if certain model-wide
defects are detected, see § 7541(c), (d). Second, Volkswagen
acknowledges that the CAA’s saving clause preserves some
state enforcement authority over post-sale vehicles. Finally,
Volkswagen argues that the only way to harmonize the saving
clause with the EPA’s post-sale enforcement responsibilities
is to conclude that Congress intended the EPA to regulate
post-sale emission standards on a model-wide basis at the
manufacturer level without any interference from the states,
and that Congress also intended the states to enforce the same
standards only on an individual-vehicle basis at the end-user
level. In other words, Volkswagen claims that Congress
intended to prevent state and local governments from
enforcing their anti-tampering rules against manufacturers
that engage in post-sale tampering on a model-wide basis.
The district court concluded that such a division of authority
between the federal and state governments would be sensible
because the EPA was in a better position to regulate
tampering when such conduct “involves thousands of


to prohibit and penalize tampering with approved emission control
systems, which is exactly what the federal anti-tampering law prohibits.
The existence of identical federal and local laws would not, as the district
court put it, “create nightmares for the manufacturers.” Therefore,
Volkswagen’s concern about a patchwork of varying anti-tampering rules
is unwarranted. And as the Supreme Court has instructed, a mere overlap
in federal and state laws does not, without more, raise the inference that
Congress intended to preempt the state laws. Garcia, 140 S. Ct. at 806.
              IN RE VOLKSWAGEN LITIGATION                   41

vehicles, and the changes are made through software updates
instituted on a nationwide basis.”

    We disagree. Whether such a division of labor is
reasonable from a policy perspective (or is merely a reading
of the CAA tailored to fit Volkswagen’s unique
circumstances), this theory of partial preemption is not
“grounded in the text and structure” of the CAA. Garcia,
140 S. Ct. at 804 (citation and internal quotation marks
omitted). Nothing in the CAA raises the inference that
Congress intended to place manufacturers beyond the reach
of state and local governments. Volkswagen itself concedes
that the CAA does not afford “a wide-ranging grant of
immunity [from state enforcement actions] based on the
identity of the actor (auto manufacturers).” As the district
court put it, if “a manufacturer were to tamper with a single
in-use vehicle during vehicle maintenance, the Clean Air Act
would not bar a state or local government from bringing a
tampering claim against the manufacturer if the tampering
occurred within its borders.” Nor does anything in the text or
structure of the CAA raise the inference that Congress
intended to shield a person from state enforcement actions if
that person tampered with a large number of vehicles or
engaged in systematic rather than sporadic tampering. The
CAA prohibits “any person” from tampering with an
emission control device, manufacturers and dealers and local
mechanics alike. 42 U.S.C. § 7522(a)(3)(A). And contrary
to Volkswagen’s assertion, the CAA does not classify
tampering by reference to its scope. See id. Indeed, the CAA
is entirely silent on this issue, probably because Congress did
not contemplate that a manufacturer would systematically
tamper with emission control devices on post-sale vehicles in
order to ensure the devices were effectively (and illegally)
disabled. Thus, there is little textual evidence from which we
42            IN RE VOLKSWAGEN LITIGATION

can infer that Congress made “a deliberate choice” to shield
such a manufacturer from state enforcement actions. Arizona,
567 U.S. at 405.

    In short, we cannot discern a congressional intent, let
alone a “clear and manifest purpose of Congress,” to give the
EPA exclusive authority over large-scale, post-sale tampering
by manufacturers, while giving state and local governments
concurrent authority only when the tampering is conducted on
a more casual, individual basis. Id. at 400. Because we see
no indication that Congress intended to preempt state and
local authority to enforce anti-tampering rules on a model-
wide basis, we reject Volkswagen’s argument that
interpreting § 209(d) according to its terms would cause the
CAA to “destroy itself.” Geier, 529 U.S. at 872 (citation
omitted).

                              B

    Volkswagen next argues that the CAA’s penalty
provision, 42 U.S.C. § 7524, shows that Congress struck a
balance of interests with respect to the imposition of
penalties, and this balance would be disturbed if states could
impose their own penalties for tampering with post-sale
vehicles. By including a penalty provision in Title II of the
CAA, so the argument goes, Congress intended the EPA to
have the exclusive authority to determine the appropriate
penalty for every tampering violation. Therefore, the
potential for any state penalties (large or small) “would
seriously undermine the congressional calibration of force.”

   To support its claim that the CAA gives the EPA
exclusive authority over the imposition of penalties,
Volkswagen first relies on a line of cases interpreting the
              IN RE VOLKSWAGEN LITIGATION                  43

National Labor Relations Act as preventing states from
imposing any remedies for activities potentially covered by
the Act. See San Diego Bldg. Trades Council, Millmen’s
Union, Local 2020 v. Garmon, 359 U.S. 236 (1959);
Amalgamated Ass’n of Street, Elec. Ry. & Motor Coach
Emps. of Am. v. Lockridge, 403 U.S. 274 (1971); Wis. Dep’t
of Indus., Labor & Human Relations v. Gould Inc., 475 U.S.
282 (1986). Volkswagen’s reliance is misplaced, because
those cases involved a “special preemption rule” applicable
to “state laws regulating matters that the National Relations
Act ‘protects, prohibits, or arguably protects.’” Garcia,
140 S. Ct. at 807 (quoting Gould, 475 U.S. at 286). Garmon
and its progeny are based on “a presumption of federal pre-
emption,” Brown v. Hotel & Rest. Emps. & Bartenders Int’l
Union Local 54, 468 U.S. 491, 502 (1984), “designed to
prevent ‘conflict in its broadest sense’ with the ‘complex and
interrelated federal scheme of law, remedy, and
administration’” of the National Labor Relations Act, Gould,
475 U.S. at 286 (quoting Garmon, 359 U.S. at 243). The
Supreme Court has declined to extend this rule to other
contexts. See Garcia, 140 S. Ct. at 807 (rejecting the
argument that such a rule is “operative or appropriate” in a
context not involving the National Labor Relations Act). And
it is clearly not applicable here, where the federal law makes
“the States and the Federal Government partners in the
struggle against air pollution,” Gen. Motors Corp., 496 U.S.
at 532, and where we assume that Congress did not intend to
displace the historic police powers of the states.

    Volkswagen also offers textual arguments to support its
claim. First, Volkswagen points to the list of factors the EPA
“shall take into account” before assessing a civil
administrative penalty. 42 U.S.C. § 7524(c)(2). According
to Volkswagen, those factors evince “the clear and manifest
44            IN RE VOLKSWAGEN LITIGATION

purpose of Congress” to vest in the EPA the exclusive
authority to penalize post-sale tampering, Arizona, 567 U.S.
at 400, because those factors indicate that the EPA has
discretion to determine the appropriate punishment.
Volkswagen also suggests that “it would be virtually
impossible for the EPA to strike its preferred balance in
quantifying a penalty” if states were allowed to enforce their
own anti-tampering laws independently, because the EPA
would have no control over the total amount of penalties
actually imposed. Second, Volkswagen points to the CAA’s
penalty ceiling, which places a cap on federal penalties for
tampering, as evidence that Congress intended to preclude
states from enforcing their own anti-tampering rules, or at
least the penalty components of those rules. See § 7524(a)
(limiting the penalties for tampering to no more than $25,000
per vehicle, with additional limitations for related offenses
committed by specified persons).             If states could
independently impose penalties, Volkswagen argues, the
penalty cap would be meaningless.

    These arguments fail. An exclusive federal regime (such
as the regime created by the National Labor Relations Act, as
explained in Garmon and its progeny) may preclude the
imposition of state penalties. But the mere fact that a federal
statute permits the imposition of federal penalties, without
more, does not raise the inference that Congress created an
exclusive federal regime. Because the CAA is, and always
has been, a cooperative-federalism partnership, see supra Part
III.A., there is no basis for Volkswagen’s argument that
Congress’s authorization of federal penalties, along with
guidance on how those penalties should be imposed,
expressly or impliedly forecloses state and local governments
from enforcing their own rules or imposing sanctions of their
choosing. To the contrary, the statutory provisions guiding
                IN RE VOLKSWAGEN LITIGATION                          45

the EPA in developing an appropriate penalty, including the
non-exhaustive list of assessment factors and the penalty cap,
are directed only at the EPA; there is no suggestion that
Congress wanted to exclude state and local anti-tampering
remedies. While this gives the EPA the authority to control
only the amount of the federal penalty, we see nothing
inherently problematic about the EPA’s inability to control
the total liability that may be imposed for a tampering
violation. The potential for overlapping state and federal
penalties has never, without more, raised the inference that
Congress intended to preempt state law. See Garcia, 140 S.
Ct. at 806; California v. Zook, 336 U.S. 725, 737 (1949).23

    In fact, the text and structure of the CAA provides greater
support to the Counties. “Given that Congress specifically
preserved” the states’ authority to engage in post-sale
enforcement, see § 7543(d), “it stands to reason that Congress
did not intend to prevent the States from using appropriate
tools to exercise that authority.” Whiting, 563 U.S.
at 600–01. Indeed, a determination that the CAA did not
preserve state enforcement of anti-tampering rules as applied
to post-sale vehicles would be inconsistent with the
congressional framework. For example, if the CAA’s penalty
provision preempted state and local governments from
imposing any penalty for post-sale tampering, then the EPA


     23
        Volkswagen appears to argue that because Congress listed certain
factors that the EPA “shall take into account” when determining the
appropriate federal penalty, but did not require the EPA to consider the
possibility that states might enforce their own anti-tampering rules, we
must infer that Congress intended to give the EPA exclusive authority to
penalize tampering. In other words, Volkswagen wants us to presume that
Congress intends to displace state enforcement authority unless it
expressly preserves it. This argument turns the presumption that Congress
intends to preserve historic police powers on its head, and we reject it.
46              IN RE VOLKSWAGEN LITIGATION

would be the sole enforcement authority for every incident of
tampering with air pollution control equipment, including
illegal alterations by the local garage mechanic or do-it-
yourself efforts to disable a catalytic converter.24 But nothing
in the CAA suggests that Congress intended the EPA to take
over such local law enforcement issues, to the exclusion of
state and local governments, which would have the effect of
preempting anti-tampering rules in nearly every state. See
supra at 35–36 & n.19. The Supreme Court has warned
against “setting aside great numbers of state statutes to satisfy
a congressional purpose which would be only the product of
[judicial] imagination.” Zook, 336 U.S. at 732–33. Given the
prevalence of state anti-tampering rules, we are especially
mindful of the Court’s warning.

    In sum, the CAA’s cooperative federalism scheme, its
express preservation of state and local police powers post
sale, and the complete absence of a congressional intent to
vest in the EPA the exclusive authority to regulate every
incident of post-sale tampering, raises the strong inference
that Congress did not intend to deprive the EPA “of effective
aid from local officers experienced in the kind of enforcement
necessary to combat” the evil of tampering with emission
control systems. Id. at 737. Therefore, Volkswagen’s
penalty-provision arguments are not sufficient to pass over
the “high threshold” which “must be met if a state law is to be

     24
        As the district court correctly explained, in 1990, Congress
expanded the scope of its anti-tampering provision to include individuals,
as well as manufacturers, dealers, service operators, and local mechanics.
Compare Clean Air Act, Amendments, Pub. L. No. 101-549 § 228(b),
104 Stat. 2399 (1990), with Clean Air Act Amendments of 1977, Pub. L.
95-95 § 219(a), 91 Stat. 685 (1977). Notably, there is nothing in the 1990
amendments that would indicate a congressional intent to make the EPA
the sole enforcer of tampering.
                  IN RE VOLKSWAGEN LITIGATION              47

preempted for conflicting with the purposes of a federal Act.”
Whiting, 563 U.S. at 607 (citation omitted).

                                   ***

    We affirm the district court’s dismissal of the Counties’
complaints to the extent they sought to apply anti-tampering
rules to new motor vehicles. However, we reverse the district
court’s dismissal of the Counties’ complaints regarding post-
sale tampering. We are mindful that our conclusion may
result in staggering liability for Volkswagen. But this result
is due to conduct that could not have been anticipated by
Congress: Volkswagen’s intentional tampering with post-sale
vehicles to increase air pollution. We assume that this
conduct will be as rare as it is unprecedented. In any event,
we may not strain our application of the Supreme Court’s
preemption doctrine, or our interpretation of statutory
language, to avoid this outcome. “Ordinarily, state causes of
action are not pre-empted solely because they impose liability
over and above that authorized by federal law, and no clear
purpose of Congress indicates that we should decide
otherwise in this case.” ARC Am. Corp., 490 U.S. at 105
(citation omitted).

   AFFIRMED IN PART; REVERSED IN PART.25




   25
        Each party shall bear its own costs.
