Green Mountain Chrysler Plymouth Dodge Jeep v. Crombie

OPINION and ORDER

TABLE OF CONTENTS

Page

INTRODUCTION...............................................................300

BACKGROUND................................................................303

I. Clean Air Act.................................. 303

II. Environmental Policy and Conservation Act...................................305

III. Massachusetts v. EPA......................................................307

EVIDENTIARY ISSUES............... 310

I. Daubert Challenges ........................................................310

A. James Hansen, Ph.D....................................................312

1. Hansen’s Qualifications..............................................312

2. Hansen’s Testimony................................................313

3. Reliability of Hansen’s Testimony ....................................316

4. Relevance of Hansen’s Testimony.....................................320

B. Admissibility of Testimony of Dr. Barrett N. Rock .........................320

1. Dr. Rock’s Qualifications ............................................320

2. Dr. Rock’s Testimony...............................................321

3. Reliability of Dr. Rock’s Testimony............. 322

4. Relevance of Dr. Rock’s Testimony...................................325

C. Admissibility of Testimony of K.G. Duleep.................................325

1. Duleep’s Qualifications..............................................325

2. Duleep’s Testimony.................................................327

a. Methodology...................................................327

b. Validation of Results With Lumped Parameter Model...............328

c. Duleep’s Cost Analysis..........................................329

3. Evaluating the Reliability of Duleep’s Testimony.......................329

4. Relevance of Duleep’s Testimony.....................................333

II. Discovery Violation ..........................................................333

FINDINGS AND CONCLUSIONS ...............................................336

I. The State Regulations......................................................336

A. Implementation of California’s AB 1493 ...................................336

*300 B. Adoption of Vermont’s GHG Emissions Standards..........................338

C. The Global Warming Connection.........................................339

D. The GHG Regulation Provisions .........................................341

II. Preemption................................................................343

A. The Preemption Doctrines Do Not Apply .................................343

B. Express Preemption....................................................350

1. De Facto Fuel Economy Standard....................................351

2. “Related to” Fuel Economy Standard.................................353

C. Field Preemption......................................................354

D. Conflict Preemption....................................................355

1. Frustration of Congressional Intent to Maintain Nationwide Fuel Economy Standards ..............................................356

2. Technological Feasibility and Economic Practicability, Including Restricting Consumer Choice, Reducing Employment and Decreasing Traffic Safety....................................................357

a. History of Technology-forcing Regulations.........................358

b. Austin’s Testimony .............................................359

c. Manufacturers’ Testimony.......................................360

d. Duleep’s Testimony.............................................364

e. Conclusions....................................................365

(1) Austin’s baseline assumptions and methodology.................365

(2) Alternative fuels ............................................369

(a) Diesel..................................................370

(b) Ethanol ................................................373

(c) Hydrogen...............................................376

(d) Plug-in hybrids..........................................376

(3) Other technologies...........................................377

(a) GDI/turbo..............................................378

(b) Camless valve actuation ..................................379

(c) Rolling resistance improvements...........................379

(d) Reductions in aerodynamic drag...........................380

(e) Continuously variable transmission (“CVT”).................380

(f) Electronic power steering.................................381

(g) A/C credits .............................................381

(h) Credit trading...........................................381

(i) Efforts to promote technology generally....................382

(4) Consumer choice............................................384

(5) Product withdrawal and job loss...............................386

(6) Safety.....................................................389

III. Foreign Policy Preemption..................................................392

A. National Foreign Policy on GHG Emissions ...............................392

B. Zschernig Preemption..................................................395

C. Garamendi Preemption.................................................395

CONCLUSION.................................................................397

ORDER........................................................................399

Introduction

In these consolidated cases, Plaintiffs, a collection of new motor vehicle dealers, automobile manufacturers and associations of automobile manufacturers, seek declaratory and injunctive relief from regulations adopted by Vermont in the fall of 2005 that establish greenhouse gas (“GHG”) emissions standards for new automobiles. The *301 Plaintiffs in Docket No. 2:05-cv-302 1 brought six claims for declaratory and in-junctive relief: express and implied preemption under the Energy Policy and Conservation Act of 1975, 49 U.S.C. §§ 32901-32919 (“EPCA”) (Count I); preemption under the Clean Air Act as amended, 42 U.S.C. §§ 7401-7671q (“CAA”) (Count II); violation of the CAA (Count III); foreign policy preemption (Count IV); violation of the dormant Commerce Clause (Count V); and violation of the Sherman Act (Count VI). The Plaintiff 2 in Docket No. 2:05-cv-304 alleged preemption under EPCA (Count I) and under the CAA (Count II). 3 On May 3, 2006, five non-profit environmental advocacy groups 4 were permitted to intervene as defendants in the cases, and on July 27, 2006 the State of New York was also permitted to intervene as a defendant.

Prior to trial, Defendants twice sought to stay these cases, pending resolution of the related case filed in California, Central Valley Chrysler-Jeep, Inc. v. Witherspoon, No. 1:04-cv-06663-REC-LJO (E.D. Cal. filed Dec. 7, 2004), and the Supreme Court’s review of Massachusetts v. EPA 415 F.3d 50 (D.C.Cir.2005), rev’d — U.S. -, 127 S.Ct. 1438, 167 L.Ed.2d 248 (2007). The requests were denied, on May 3, 2006, and February 15, 2007.

Defendants also sought to obtain dismissal of these cases for lack of ripeness via motions to dismiss for lack of subject matter jurisdiction (Doc. 48) and judgment on the pleadings (Doc. 162), because their regulation had not received a waiver from EPA, a necessary antecedent to enforcement. The Court concluded that the cases were constitutionally and prudentially ripe, given that the Vermont regulation had been formally enacted, those affected by the regulation had to begin now to comply with it, the constitutional challenges were currently as concrete and fit for decision as they would be in the future, and Plaintiffs’ demonstration of hardship tipped the balance in favor of exercising jurisdiction on prudential grounds. Mem. Op. & Order 17-19 (Doc. 165).

Defendants moved for judgment on the pleadings on all counts of both complaints, and the ’304 plaintiff moved for partial summary judgment on the ground that the regulations are preempted by EPCA. Although Defendants initially agreed with the ’304 plaintiff that the case was appropriate for summary adjudication (although differing on the appropriate outcome), at oral argument they took the position, shared by the ’302 plaintiffs, that significant material facts remained in dispute. Accordingly, the Court deferred ruling on the motions and allowed the case to proceed to trial. The ’302 plaintiffs dismissed their Counts III, V and VI, and the consolidated cases proceeded to trial on the re *302 maining claims. The trial was conducted over sixteen days in April and May, 2007. This opinion constitutes the Court’s findings of fact and conclusions of law pursuant to Rule 52(a) of the Federal Rules of Civil Procedure.

Presented as a challenge to the validity of a state statute on preemption grounds, this case involves the degree of interplay and overlap between two federal statutes, the Clean Air Act, 42 U.S.C. §§ 7401-7671q, and the Energy Policy and Conservation Act, 49 U.S.C. §§ 32901-32919. Section 202 of the CAA requires the Environmental Protection Agency (“EPA”) to establish standards for the control of any air pollutant emitted from new motor vehicles or new motor vehicle engines which in its judgment causes or contributes to air pollution that may endanger public health or welfare. 42 U.S.C. § 7521(a)(1). Section 209(a) preempts a state from adopting its own motor vehicle emission control standards, while Section 209(b) requires EPA to waive preemption for a California-adopted standard that meets certain conditions. 42 U.S.C. § 7543(a), (b). Other states may adopt a California standard for which a waiver has been granted, as long as the states adopt the standard at least two years before the commencement of the model year. 42 U.S.C. § 7507.

In 2004, California adopted' a comprehensive set of GHG emissions regulations for new motor vehicles, including standards applicable to large-volume motor vehicle manufacturers beginning in model year 2009. California applied to EPA for a waiver of federal preemption under the CAA in 2005; its application remains pending. Also in 2005, Vermont adopted California’s GHG regulations. 5

Section 502 of EPCA directs the Department of Transportation (“DOT”) to set fuel economy standards for new passenger vehicles and light trucks. 49 U.S.C. § 32902. Section 509 of EPCA preempts any state laws or regulations related to fuel economy standards. 49 U.S.C. § 32919(a). Because there is a relationship between decreasing carbon dioxide emission from the tailpipe of a motor vehicle and increasing its fuel economy, Plaintiffs challenged Vermont’s regulations as preempted by EPCA, among other contentions.

Recently, in Massachusetts v. EPA, — U.S. — , 127 S.Ct. 1438, 167 L.Ed.2d 248 (2007), the United States Supreme Court confirmed that EPA has the authority to regulate GHG emissions from new motor vehicles under Section 202(a)(1) of the CAA. It commented: “that DOT sets mileage standards in no way licenses EPA to shirk its environmental responsibilities .... The two obligations may overlap, but there is no reason to think the two agencies cannot both administer their obligations and yet avoid inconsistency.” 127 S.Ct. at 1462.

Given that automobile manufacturers require lead time in order to make design changes to them vehicles to attempt to comply with the regulations, and given that it has taken years to process waiver applications (although EPA has consistently granted California’s applications for a waiver of preemption), the Court and the parties have proceeded with this case on the assumption that EPA will grant California’s waiver application. If it does not, of course, Vermont’s regulation is preempted by the CAA’s section 209(a).

In this decision the Court addresses first the statutory background of the case, *303 and includes a summary of the decision in Massachusetts v. EPA, — U.S. -, 127 5.Ct. 1438, 167 L.Ed.2d 248 (2007). The Court turns next to the question whether the opinions and testimony of Defendants’ witnesses Duleep, Rock and Hansen must be excluded from consideration either as a sanction for discovery violations or as precluded by Daubert v. Merrell Dow Pharmaceuticals, Inc., 509 U.S. 579, 113 S.Ct. 2786, 125 L.Ed.2d 469 (1993). Then, in the first section of the Findings and Conclusions, the Court outlines the context of the GHG regulation in California and Vermont, along with the concerns about global warming that led to the regulation’s development, and details the GHG regulation itself. Next the Court discusses express and implied preemption, concluding first that this is not rightly a case about federal preemption, but about potential conflict between two federal statutes. Second, the Court concludes that EPCA does not expressly preempt Vermont’s GHG regulations, nor are Vermont’s GHG regulations precluded under principles of field or conflict preemption. Finally, the Court deals with the remaining legal challenge to the regulation, concluding that the regulation does not impermissibly intrude upon the foreign affairs prerogatives of the President and Congress of the United States.

Background

I. Clean Air Act

EPA is the federal agency entrusted with overseeing the regulation of pollution, including air pollution from mobile sources. In 1965, Congress enacted the Motor Vehicle Air Pollution Control Act, to be added to the CAA as Title II, to control emissions from new motor vehicles. Pub.L. No. 89-272, 79 Stat. 992 (1965); see Motor Vehicle Mfrs. Ass’n of the United States, Inc. v. N.Y. State Dep’t of Envtl. Conservation, 17 F.3d 521, 524-25 (2d Cir.1994) (“MVMA III”); Motor & Equip. Mfrs. Ass’n, Inc. v. EPA 627 F.2d 1095, 1101 (D.C.Cir.1979) (‘MEMA I ”). The original enactment did not contain a preemption provision. The House Committee acknowledged States’ basic rights and responsibilities for control of air pollution, 6 although it alluded to its conviction that federal standards were preferable to regulation by individual states. H.R.Rep. No. 89-899, (1965), reprinted in 1965 U.S.C.C.A.N. 3608, 3612; see also H.R.Rep. No. 90-728 (1967), reprinted in 1967 U.S.C.C.A.N.1938, 1955-56 (discussing legislative history of Pub.L. No. 89-272); accord MEMA I, 627 F.2d at 1108 & n. 24.

With the enactment of the Air Quality Act of 1967, Pub.L. No. 90-148, 81 Stat. 485 (1967), Congress amended Title II, redesignated as the National Emission Standards Act, to address the question of the extent to which the newly promulgated federal standards should supersede state and local laws on motor vehicle emissions. The new provision preempted states’ power to set standards for emissions from new *304 motor vehicles and engines, but provided that more stringent standards could be set for California if it had shown that it required such standards to meet compelling and extraordinary conditions, and the standards were consistent with the federal emission standards. Id., 81 Stat. at 501. 7 The provision represented a compromise “between the states, which wanted to preserve their traditional role in regulating motor vehicles, and the manufacturers, which wanted to avoid the economic disruption latent in having to meet fifty-one separate sets of emissions control requirements.” MEMA I, 627 F.2d at 1109.

In 1970 Congress amended the CAA to require a ninety percent reduction in tailpipe emissions from light-duty vehicles 8 of carbon monoxide and hydrocarbons within five years and of nitrogen oxides within six years. Clean Air Amendments of 1970, Pub.L. No. 91-604, 84 Stat. 1676 (1970). Section 202(a)(2) of the amended statute required EPA to take technical and economic factors into consideration when prescribing a regulation’s effective date, providing that any regulation could only take effect “after such period as the Administrator finds necessary to permit the development and application of the requisite technology, giving appropriate consideration to the cost of compliance.” Id. sec. 6(a), § 202(a)(2), 84 Stat. at 1690 (codified as amended at 42 U.S.C. § 7521(a)(2)).

Although the deadlines were extended, by the early 1980s the required reductions had been achieved, largely by the development and introduction of the catalytic converter. See Holly Doremus, “Constitutive Law and Environmental Policy,” 22 Stanford Envtl. L.J. 295, 345-46 (2003); Whitman v. Am. Trucking Ass’ns, 531 U.S. 457, 492, 121 S.Ct. 903, 149 L.Ed.2d 1 (2001) (Breyer, J., concurring) (catalytic converter technology helped achieve substantial reduction in emissions without predicted economic catastrophe).

The 1977 Amendments to the CAA, “lengthy, detailed, technical, complex, and comprehensive,” Chevron U.S.A., Inc. v. Natural Resources Defense Council, Inc., 467 U.S. 837, 848, 104 S.Ct. 2778, 81 L.Ed.2d 694 (1984), included the waiver provision that currently appears at § 7543(b). Clean Air Act Amendments of 1977, Pub.L. No. 95-95, sec. 207, § 209(b). With the 1977 Amendments Congress also permitted other states to adopt California’s standards, if that state’s standards “are identical to the California standards for which a waiver had been granted,” and both states adopt the standards at least two years before the commencement of the model year to be regulated. Id. sec. 177 (codified at 42 U.S.C. § 7507); see MVMA III, 17 F.3d at 525.

Amid growing concern over the threat of global warming, acid rain, and “holes” in the atmospheric ozone layer, and following a decade of stalemated debate in Washington over air pollution control, Congress enacted the Clean Air Act Amendments of 1990, Pub.L. No. 101-549, 104 Stat. 2399 (1990). See James Miskiewicz & John S. Rudd, Civil & Criminal Enforcement of the Clean Air Act After the 1990 Amendments, 9 Pace Envtl. L.Rev. 281, 286

*305 (1992). Title II of its eleven titles imposed new controls on motor vehicles. See Secs. 201-35, 104 Stat. at 2471-2531. Stringent “Tier I” emissions requirements for non-methane hydrocarbons, carbon monoxide, oxides of nitrogen and particulate matter were to be phased in during model years 1994 to 1996. See Sec. 203, § 202, 104 Stat. at 2474-75. More stringent “Tier II” standards would be imposed by EPA for model year 2004 and thereafter unless it determined that such standards were not necessary, technically feasible, or cost-effective. See id., 104 Stat. at 2476-78. 9 The 1990 CAA amendments aimed to clean up gasoline and diesel fuel by setting requirements for reduced fuel volatility, fuel reformulation, oxygenated fuels and desul-furization of diesel fuels, as well as the complete phase-out of lead in gasoline by the end of 1995. See Secs. 216-17, 219-20, § 211, 104 Stat. at 2489-2501. The act also created a clean-fuels vehicle program. See Sec. 229(a), §§ 241-250, 104 Stat. at 2511-29.

Currently, Section 202 of the CAA authorizes the EPA Administrator to establish “standards applicable to the emission of any air pollutant from any class or classes of new motor vehicles or new motor vehicle engines, which in his judgment cause, or contribute to air pollution which may reasonably be anticipated to endanger public health or welfare.” 42 U.S.C. § 7521(a)(1). Any such regulation, which currently applies to emissions of hydrocarbons, carbon monoxide, oxides of nitrogen and particulate matter, may take effect only after any necessary period “to permit the development and application of the requisite technology, giving appropriate eonsideration to the cost of compliance.” Id. § 7521(a)(2).

Section 209(a) of the CAA prohibits any state or political subdivision from adopting or attempting to enforce “any standard relating to the control of emissions from new motor vehicles or new motor vehicle engines.” 42 U.S.C. § 7543(a). Section 209(b) requires EPA to waive federal preemption for California, if California has determined that its state standards “will be, in the aggregate, at least as protective of public health and welfare as applicable Federal standards,” unless EPA finds that California’s determination is arbitrary and capricious, the state doesn’t need the standards to meet compelling and extraordinary conditions, or the standards are not consistent with § 7521(a). Id. § 7543(b). Section 177 allows a state to adopt and enforce standards identical to California standards for which a waiver has been granted, as long as the standards are adopted at least two years before the commencement of the model year to which they apply. Id. § 7507.

II. Environmental Policy and Conservation Act

In 1975, in response to the energy crisis of the 1970’s, Congress enacted the Energy Policy and Conservation Act. Pub.L. 94-163, 89 Stat. 871 (1975); see General Motors Corp. v. Nat’l Highway Traffic Safety Admin., 898 F.2d 165, 167 (D.C.Cir.1990). The Act’s purposes included “providing] for improved energy efficiency of motor vehicles.” Pub.L. No. 94-163, § 2, 89 Stat. 87, 874 (1975) (codified at 42 U.S.C. § 6201). EPCA’s Title III amended the Motor Vehicle Information and Cost Savings Act by adding a new Title V, *306 devoted to improving automotive efficiency by establishing average fuel economy standards. See Sec. 301, §§ 501-12, 89 Stat. at 901-16.

Title V set mandatory average fuel economy performance standards for passenger automobiles, beginning in model year 1978 at eighteen miles per gallon (mpg) and increasing to 27.5 mpg by model year 1985. This had the effect of requiring manufacturers to improve the fuel economy of their fleets by fifty percent by model year 1980, and by one hundred percent by model year 1985. General Motors, 898 F.2d at 167. Although Congress set the standard for passenger automobiles at 27.5 mpg by 1985, EPCA authorizes the Secretary of Transportation to set standards at the maximum feasible level for light duty highway vehicles for each model year, and for passenger automobiles after model year 1985. See S.Rep. No. 94-516, at 119, 153-54 (1975) (Conf.Rep.), reprinted in 1975 U.S.C.C.A.N.1956, 1959-60, 1994-95. The Secretary of Transportation has delegated his EPCA authority to the National Highway Traffic Safety Administration (“NHTSA”). 49 C.F.R. § 1.50(f).

The statute thus provided for fleet-wide average fuel economy standards that would apply to all passenger automobiles or light-duty trucks sold by a manufacturer in a given year, known as “corporate average fuel economy,” or “CAFE” standards. Pub.L. No. 94-163, Sec. 301, § 502, 89 Stat. at 902. Manufacturers that fail to comply may be assessed civil penalties. Id. § 508.

In determining maximum feasible average fuel economy, NHTSA was directed to consider: “(1) technological feasibility; (2) economic practicability; (3) the effect of other Federal motor vehicle standards on fuel economy; and (4) the need of the Nation to conserve energy.” Id. § 502; see also S.Rep. No. 94-516 at 154, 1975 U.S.C.C.A.N. at 1995. It did not prescribe the formula for determining CAFE standards but “gave [NHTSA] broad guidelines within which to exercise its discretion.” Competitive Enter. Inst. v. NHTSA, 901 F.2d 107, 121 (D.C.Cir.1990) (“CEI I”). NHTSA exercised its authority to decrease CAFE standards from the Congressional benchmark of 27.5 mpg for passenger automobiles for model year 1986, 1987, 1988 and 1989. See id. at 124; Pub. Citizen v. NHTSA, 848 F.2d 256, 260 (D.C.Cir.1988).

As enacted, EPCA included a preemption clause, § 509(a), which provided that “[w]henever an average fuel economy standard established under this part is in effect, no State or political subdivision of a State shall have authority to adopt or enforce any law or regulation relating to fuel economy standards or average fuel economy standards applicable to automobiles covered by such Federal standard.”

In 1994 Congress recodified certain laws related to transportation, including the fuel economy laws, into Title 49 of the United States Code. Revision of Title 49, United States Code Annotated, “Transportation,” Pub.L. No. 103-272, 108 Stat. 745 (1994). Both House and Senate reports accompanying the bill stated that the purpose of the bill was to “revise, codify, and enact [the laws] without substantive change ... and to make other technical improvements in the Code.” S.Rep. No. 103-265, at 1 (1994); H.R.Rep. No. 103-180, at 1, reprinted in 1994 U.S.C.C.A.N. 818, 818. The Senate Report described standard changes that were made uniformly throughout the revised subtitles of Title 49, including:

“United States Government” is substituted for “United States” (when used in referring to the Government), “Federal Government,” and other terms identifying the Government the first time the *307 reference appears in a section. Thereafter, in the same section, “Government” is used unless the context requires the complete term to be used to avoid confusion with other governments.

S.Rep. No. 103-265, at 4. The report stated: “this bill makes no substantive change in the law.” Id. at 5.

The current section setting forth the factors that the Secretary of Transportation must take into consideration when determining maximum feasible average fuel economy has not changed substantively from the 1975 enactment. Section 32902(f) now reads: “When deciding maximum feasible average fuel economy under this section, the Secretary of Transportation shall consider technological feasibility, economic practicability, the effect of other motor vehicle standards of the Government on fuel economy, and the need of the United States to conserve energy.” 49 U.S.C. § 32902(f). NHTSA has interpreted economic practicability to include consideration of consumer choice, economic hardship for the automobile industry, and vehicle safety. See, e.g., CEI I, 901 F.2d at 120, n. 11; Center for Auto Safety v. NHTSA, 793 F.2d 1322, 1340 (D.C.Cir.1986) (“CAS F).

EPCA’s current preemption provision also is essentially unchanged from its original enactment: “[w]hen an average fuel economy standard prescribed by this chapter is in effect, a State or a political subdivision of a State may not adopt or enforce a law or regulation related to fuel economy standards or average fuel economy standards for automobiles covered by an average fuel economy standard under this chapter.” 49 U.S.C. § 32919(a).

Currently, the average fuel economy standard for passenger automobiles remains at 27.5 mpg, the standard enacted in 1975 and in place since model year 1985. See 49 U.S.C. § 32902(b).

In 2006 NHTSA reformed the structure of the CAFE program for light trucks and has permitted manufacturers to comply with either the reformed or the unreformed standards during a transition period of model years 2008 through 2010. See Final Rule, Average Fuel Economy Standards for Light Trucks Model Years 2008-2011, 71 Fed.Reg. 17566 (Apr. 6, 2006). Under reformed CAFE, a manufacturer’s required fuel economy level for a particular light truck is a function of the truck’s “footprint” (calculated by multiplying the vehicle’s wheelbase by its average track width), the target fuel economy for that footprint value, and the actual production figures for the vehicle. Id. at 17568. The unreformed CAFE standards for light trucks are 22.5 mpg for model year 2008, 23.1 mpg for model year 2009, and 23.5 mpg for model year 2010. Id. NHTSA projects industry-wide fuel economy levels under reformed CAFE at 22.7 mpg for model year 2008, 23.4 mpg for model year 2009, and 23.7 mpg for model year 2010. Id. at 17624. There is no CAFE standard for light trucks currently in place for any model year past 2010.

III. Massachusetts v. EPA

Based on respected scientific opinion that rising global temperature is related to a significant increase in the concentration of carbon dioxide in the atmosphere, a group of private organizations petitioned EPA to begin regulating carbon dioxide and other GHG emissions from new motor vehicles under § 202 of the Clean Air Act. The petitioners contended that GHG emissions, because of their heat-trapping ability, have significantly accelerated climate change, and that the United Nations Intergovernmental Panel on Climate Change (“IPCC”) had warned that “carbon dioxide remains the most important contributor to [man-made] forcing of climate change.” *308 Massachusetts v. EPA, 127 S.Ct. at 1449 (quoting 1995 IPCC report). EPA denied the petition, giving two grounds for its decision: 1) it lacked authority under the Clean Air Act to regulate greenhouse gases; and 2) even if it had authority, it would not be appropriate to issue such regulations at this time. EPA Notice of Denial of Petition for Rulemaking, 68 Fed.Reg. 52,922, 52,925 (Sept. 8, 2003).

The petitioners, joined by several states and local governments, challenged this determination in the United States Court of Appeals for the District of Columbia Circuit. Several states and trade associations joined EPA in opposing the appeal. Although the three judges on the panel wrote separate opinions, two judges agreed “that the EPA Administrator properly exercised his discretion under § 202(a)(1) in denying the petition for rule-making.” Massachusetts v. EPA 415 F.3d 50, 58 (D.C.Cir.2005), rev’d — U.S. -, 127 S.Ct. 1438, 167 L.Ed.2d 248 (2007).

Judge Randolph’s opinion announcing the judgment of the Court assumed that the petitioners had Article III standing to challenge the denial of the rulemaking petition, and assumed that EPA had statutory authority to regulate greenhouse gases from new motor vehicles. Id. at 55-56. Given the considerable discretion enjoyed by the EPA Administrator, the multitude of policy considerations that entered into the Administrator’s decision not to regulate, and precedent that counseled “uphold[ing] agency conclusions based on policy judgments” concerning “issues on the frontiers of scientific knowledge,” Envtl. Def. Fund v. EPA 598 F.2d 62, 82 (D.C.Cir.1978), the decision not to regulate was a proper exercise of discretion, according to the opinion. Massachusetts v. EPA 415 F.3d at 58.

Judge Sentelle wrote separately because he concluded that the petitioners had not demonstrated the element of injury necessary to establish standing under Article III. Id. at 59 (Sentelle, J., dissenting in part and concurring in judgment). He concurred in the judgment, however, as the outcome closest to the one he would have preferred.

Judge Tatel dissented, concluding that at least one petitioner, the Commonwealth of Massachusetts, had standing. He examined the language of CAA section 202(a)(1), which authorizes EPA to prescribe standards for the emission of any air pollutant from new motor vehicles that in the Administrator’s judgment cause or contribute to air pollution which may reasonably be anticipated to endanger public health or welfare. 42 U.S.C. § 7521(a)(1). Although EPA had concluded that carbon dioxide and other greenhouse gases are not air pollutants, Judge Tatel noted that Congress had defined “air pollutant” very broadly to include “any air pollution agent or combination of such agents, including any physical, chemical, biological, radioactive ... substance or matter which is emitted into or otherwise enters the ambient air.” 42 U.S.C. § 7602(g). In his view, EPA had disregarded the plain language of the statute without justification. Massachusetts v. EPA 415 F.3d at 67-73 (Tatel, J., dissenting).

One justification offered by EPA had been its contention that the only practical way to regulate carbon dioxide emissions from motor vehicles is to require increased fuel economy, and that such regulation would overlap with DOT’S authority to set average fuel economy standards under EPCA. Judge Tatel dismissed the argument: “[gjiven that the two regulatory regimes — one targeted at fuel conservation and the other at pollution prevention — are overlapping, not incompatible, there is no reason to assume that Congress exempted C02 from the meaning of ‘air pollutant’ *309 within the CAA.” Id. at 72. He pointed out that Congress accepted regulatory overlap in this area, as evidenced by EPCA’s recognition of the relevance of other motor vehicle standards of the Government in setting fuel economy standards, and by the 1977 CAA Amendments’ emphasis on EPA’s comprehensive authority over air pollutants, even those already regulated by another agency. Id. at 73.

Judge Tatel also rejected EPA’s second reason for declining to act: that the agency gave appropriate reasons for its decision and acted within its discretion.

The Supreme Court granted certiorari to address whether EPA has the authority to regulate GHG emissions from new motor vehicles under § 202(a)(1), and whether EPA may decline to issue such emission standards based on policy considerations. The Court held as a preliminary matter that the petitioners had standing to challenge the EPA’s denial of their rulemaking petition. Massachusetts v. EPA 127 S.Ct. at 1458.

In connection with its ruling on standing, the Supreme Court noted that “EPA does not dispute the existence of a causal connection between man-made greenhouse gas emissions and global warming,” but “does not believe that any realistic probability exists that the relief petitioners seek would mitigate global climate change and remedy their injuries.” Id. at 1457. The Court disagreed: “[jludged by any standard, U.S. motor-vehicle emissions make a meaningful contribution to greenhouse gas concentrations and hence, according to petitioners, to global warming.” Id. at 1457-58. Moreover, the Court noted the legitimacy of small and incremental regulatory steps: “[ajgencies, like legislatures, do not generally resolve massive problems in one fell regulatory swoop. They instead whittle away at them over time, refining their preferred approach as circumstances change and as they develop a more nuanced understanding of how best to proceed.” Id. at 1457.

On the issue of EPA’s authority to regulate, the Supreme Court held that it had “little trouble concluding” that it did, given the CAA’s “sweeping” definition of air pollutant. Id. at 1459-60. The Court rejected outright the argument that EPA is not permitted to regulate carbon dioxide emissions from motor vehicles because it would have to tighten mileage standards, which is the province of the Department of Transportation under EPCA.

But that DOT sets mileage standards in no way licenses EPA to shirk its environmental responsibilities. EPA has been charged with protecting the public’s ‘health’ and ‘welfare,’ a statutory obligation wholly independent of DOT’S mandate to promote energy efficiency. The two obligations may overlap, but there is no reason to think the two agencies cannot both administer their obligations and yet avoid inconsistency.