(Slip Opinion) OCTOBER TERM, 2013 1 

Syllabus 

NOTE: Where it is feasible, a syllabus (headnote) will be released, as is

being done in connection with this case, at the time the opinion is issued.

The syllabus constitutes no part of the opinion of the Court but has been

prepared by the Reporter of Decisions for the convenience of the reader. 

See United States v. Detroit Timber & Lumber Co., 200 U. S. 321, 337. 

SUPREME COURT OF THE UNITED STATES 

Syllabus 

ENVIRONMENTAL PROTECTION AGENCY ET AL. v. 

EME HOMER CITY GENERATION, L. P., ET AL. 

CERTIORARI TO THE UNITED STATES COURT OF APPEALS FOR 

THE DISTRICT OF COLUMBIA CIRCUIT 

No. 12–1182. Argued December 10, 2013—Decided April 29, 2014* 

Congress and the Environmental Protection Agency (EPA or Agency)

have, over the course of several decades, made many efforts to deal 

with the complex challenge of curtailing air pollution emitted in upwind States, but causing harm in other, downwind States. As relevant here, the Clean Air Act (CAA or Act) directs EPA to establish

national ambient air quality standards (NAAQS) for pollutants at

levels that will protect public health. 42 U. S. C. §§7408, 7409. Once 

EPA settles on a NAAQS, the Agency must designate “nonattainment” areas, i.e., locations where the concentration of a regulated pollutant exceeds the NAAQS. §7407(d). Each State must submit a 

State Implementation Plan, or SIP, to EPA within three years of any 

new or revised NAAQS. §7410(a)(1). From the date EPA determines 

that a State SIP is inadequate, the Agency has two years to promulgate a Federal Implementation Plan, or FIP. §7410(c)(1). Among

other components, the CAA mandates SIP compliance with the Good

Neighbor Provision, which requires SIPs to “contain adequate provisions . . . prohibiting . . . any source or other type of emissions activity

within the State from emitting any air pollutant in amounts which 

will . . . contribute significantly to nonattainment in, or interfere with 

maintenance by, any other State with respect to any . . . [NAAQS].”

§7410(a)(2)(D)(i). 

Several times over the past two decades, EPA has attempted to

delineate the Good Neighbor Provision’s scope by identifying when 

—————— 

*Together with No. 12–1183, American Lung Association et al. v. 

EME Homer City Generation, L. P., et al., also on certiorari to the same 

court. 
 

 

 

 

 

 

2 EPA v. EME HOMER CITY GENERATION, L. P. 

Syllabus 

upwind States “contribute significantly” to nonattainment downwind. 

The D. C. Circuit found fault with the Agency’s 2005 attempt, the

Clean Air Interstate Rule, or CAIR, which regulated both nitrogen 

oxide (NOX) and sulfur dioxide (SO2) emissions, the gasses at issue 

here. The D. C. Circuit nevertheless left CAIR temporarily in place, 

while encouraging EPA to act with dispatch in dealing with problems

the court had identified. 

EPA’s response to that decision is the Cross-State Air Pollution

Rule (Transport Rule), which curbs NOX and SO2 emissions in 27 upwind States to achieve downwind attainment of three NAAQS. Under the Transport Rule, an upwind State “contribute[d] significantly”

to downwind nonattainment to the extent its exported pollution both 

(1) produced one percent or more of a NAAQS in at least one downwind State and (2) could be eliminated cost-effectively, as determined

by EPA. Upwind States are obliged to eliminate only emissions 

meeting both of these criteria. Through complex modeling, EPA created an annual emissions “budget” for each regulated State upwind, 

representing the total quantity of pollution an upwind State could 

produce in a given year under the Transport Rule. Having earlier determined each regulated State’s SIP to be inadequate, EPA, contemporaneous with the Transport Rule, promulgated FIPs allocating

each State’s emissions budgets among its in-state pollution sources.

A group of state and local governments (State respondents), joined

by industry and labor groups (Industry respondents), petitioned for

review of the Transport Rule in the D. C. Circuit. The court vacated 

the rule in its entirety, holding that EPA’s actions exceeded the 

Agency’s statutory authority in two respects. Acknowledging that

EPA’s FIP authority is generally triggered when the Agency disapproves a SIP, the court was nevertheless concerned that States would 

be incapable of fulfilling the Good Neighbor Provision without prior 

EPA guidance. The court thus concluded that EPA must give States

a reasonable opportunity to allocate their emission budgets before issuing FIPs. The court also found the Agency’s two-part interpretation of the Good Neighbor Provision unreasonable, concluding that

EPA must disregard costs and consider exclusively each upwind

State’s physically proportionate responsibility for air quality problems downwind. 

Held: 

1. The CAA does not command that States be given a second opportunity to file a SIP after EPA has quantified the State’s interstate

pollution obligations. Pp. 13–18.

(a) The State respondents do not challenge EPA’s disapproval of 

any particular SIP. Instead, they argue that, notwithstanding these

disapprovals, the Agency was still obliged to grant upwind States an 
 

 

 

 

 

 

Cite as: 572 U. S. ____ (2014) 3 

Syllabus 

additional opportunity to promulgate adequate SIPs after EPA had

set the State’s emission budget. This claim does not turn on the validity of the prior SIP disapprovals, but on whether the CAA requires 

EPA do more than disapprove a SIP to trigger the Agency’s authority 

to issue a FIP. Pp. 13–14.

(b) The CAA’s plain text supports the Agency: Disapproval of a 

SIP, without more, triggers EPA’s obligation to issue a FIP. The 

statute sets precise deadlines for the States and EPA. Once EPA issues any new or revised NAAQS, a State “shall” propose a SIP within

three years, 42 U. S. C. §7410(a)(1), and that SIP “shall” include, inter alia, provisions adequate to satisfy the Good Neighbor Provision, 

§7410(a)(2). If the EPA finds a SIP inadequate, the Agency has a

statutory duty to issue a FIP “at any time” within two years. 

§7410(c)(1). However sensible the D. C. Circuit’s exception to this

strict time prescription may be, a reviewing court’s “task is to apply

the text [of the statute], not to improve upon it.” Pavelic & LeFlore v. 

Marvel Entertainment Group, Div. of Cadence Industries Corp., 493 

U. S. 120, 126. Nothing in the Act differentiates the Good Neighbor

Provision from the several other matters a State must address in its 

SIP. Nor does the Act condition the duty to promulgate a FIP on

EPA’s having first quantified an upwind State’s good neighbor obligations. By altering Congress’ SIP and FIP schedule, the D. C. Circuit 

allowed a delay Congress did not order and placed an information 

submission obligation on EPA Congress did not impose. Pp. 14–17. 

(c) The fact that EPA had previously accorded upwind States a 

chance to allocate emission budgets among their in-state sources does 

not show that the Agency acted arbitrarily by refraining to do so 

here. EPA retained discretion to alter its course provided it gave a 

reasonable explanation for doing so. Motor Vehicle Mfrs. Assn. of 

United States, Inc. v. State Farm Mut. Automobile Ins. Co., 463 U. S. 

29, 42. Here, the Agency had been admonished by the D. C. Circuit 

to act with dispatch in amending or replacing CAIR. Endeavoring to 

satisfy that directive, EPA acted speedily, issuing FIPs and the 

Transport Rule contemporaneously. Pp. 17–18.

2. EPA’s cost-effective allocation of emission reductions among upwind States is a permissible, workable, and equitable interpretation

of the Good Neighbor Provision. Pp. 18–31. 

(a) Respondents’ attack on EPA’s interpretation of the Good

Neighbor Provision is not foreclosed by §7607(d)(7)(B), which provides that “[o]nly an objection to a rule . . . raised with reasonable

specificity during the period for public comment . . . may be raised 

during judicial review.” Even assuming that respondents failed to

object to the Transport Rule with “reasonable specificity,” that lapse

is not jurisdictional. Section 7607(d)(7)(B) is a “mandatory,” but not 
 

 

 

 

4 EPA v. EME HOMER CITY GENERATION, L. P. 

Syllabus 

“jurisdictional,” rule, see Arbaugh v. Y & H Corp., 546 U. S. 500, 510, 

which speaks to a party’s procedural obligations, not a court’s authority, see Kontrick v. Ryan, 540 U. S. 443, 455. Because EPA did not 

press this argument unequivocally before the D. C. Circuit, it does

not pose an impassable hindrance to this Court’s review. Pp. 18–19. 

(b) This Court routinely accords dispositive effect to an agency’s 

reasonable interpretation of ambiguous statutory language. The 

Good Neighbor Provision delegates authority to EPA at least as certainly as the CAA provisions involved in Chevron U. S. A. Inc. v. 

Natural Resources Defense Council, Inc., 467 U. S. 837. EPA’s authority to reduce upwind pollution extends only to those “amounts” of

pollution that “contribute significantly to nonattainment” in downwind States. §7410(a)(2)(D)(i). Because a downwind State’s excess 

pollution is often caused by multiple upwind States, however, EPA

must address how to allocate responsibility among multiple contributors. The Good Neighbor Provision does not dictate a method of apportionment. Nothing in the provision, for example, directs the proportional allocation method advanced by the D. C. Circuit, a method

that works neither mathematically nor in practical application. Under Chevron, Congress’ silence effectively delegates authority to EPA

to select from among reasonable options. See United States v. Mead 

Corp., 533 U. S. 218, 229. 

EPA’s chosen allocation method is a “permissible construction of 

the statute.” Chevron, 467 U. S., at 843. The Agency, tasked with

choosing which among equal “amounts” to eliminate, has chosen sensibly to reduce the amount easier, i.e., less costly, to eradicate. The 

Industry respondents argue that the final calculation cannot rely on

costs, but nothing in the Good Neighbor Provision’s text precludes 

that choice. And using costs in the Transport Rule calculus is an efficient and equitable solution to the allocation problem the Good 

Neighbor Provision compels the Agency to address. Efficient because 

EPA can achieve the same levels of attainment, i.e., of emission reductions, the proportional approach aims to achieve, but at a much

lower overall cost. Equitable because, by imposing uniform cost

thresholds on regulated States, EPA’s rule subjects to stricter regulation those States that have done less in the past to control their pollution. Pp. 20–28.

(c) Wholesale invalidation of the Transport Rule is not justified

by either of the D. C. Circuit’s remaining objections: that the

Transport Rule leaves open the possibility that a State might be

compelled to reduce emissions beyond the point at which every affected downwind State is in attainment, so-called “over-control”; and 

that EPA’s use of costs does not foreclose the possibility that an upwind State would be required to reduce its emissions by so much that 
 

 

Cite as: 572 U. S. ____ (2014) 5 

Syllabus 

the State would be placed below the one-percent mark EPA set as the 

initial threshold of “significan[ce].” First, instances of “over-control” 

in particular downwind locations may be incidental to reductions

necessary to ensure attainment elsewhere. As the Good Neighbor 

Provision seeks attainment in every downwind State, however, exceeding attainment in one State cannot rank as “over-control” unless 

unnecessary to achieving attainment in any downwind State. Second, the EPA must have leeway in fulfilling its statutory mandate to

balance the possibilities of over-control and “under-control,” i.e., to 

maximize achievement of attainment downwind. Finally, in a voluminous record, involving thousands of upwind-to-downwind linkages,

respondents point to only a few instances of “unnecessary” emission

reductions, and even those are contested by EPA. Pp. 28–31. 

696 F. 3d 7, reversed and remanded. 

GINSBURG, J., delivered the opinion of the Court, in which ROBERTS, 

C. J., and KENNEDY, BREYER, SOTOMAYOR, and KAGAN, JJ., joined. SCALIA, J., filed a dissenting opinion, in which THOMAS, J., joined. ALITO, J., 

took no part in the consideration or decision of the cases. 
 

 

_________________ 

_________________ 

 

Cite as: 572 U. S. ____ (2014) 1 

Opinion of the Court 

NOTICE: This opinion is subject to formal revision before publication in the

preliminary print of the United States Reports. Readers are requested to

notify the Reporter of Decisions, Supreme Court of the United States, Washington, D. C. 20543, of any typographical or other formal errors, in order

that corrections may be made before the preliminary print goes to press. 

SUPREME COURT OF THE UNITED STATES 

Nos. 12–1182 and 12–1183 

ENVIRONMENTAL PROTECTION AGENCY ET AL., 

PETITIONERS 

12–1182 v. 

EME HOMER CITY GENERATION, L. P., ET AL.; AND 

AMERICAN LUNG ASSOCIATION ET AL., 

PETITIONERS 

12–1183 v. 

EME HOMER CITY GENERATION, L. P., ET AL. 

ON WRITS OF CERTIORARI TO THE UNITED STATES COURT OF 

APPEALS FOR THE DISTRICT OF COLUMBIA CIRCUIT 

[April 29, 2014]

 JUSTICE GINSBURG delivered the opinion of the Court. 

These cases concern the efforts of Congress and the

Environmental Protection Agency (EPA or Agency) to cope 

with a complex problem: air pollution emitted in one 

State, but causing harm in other States. Left unregulated,

the emitting or upwind State reaps the benefits of the 

economic activity causing the pollution without bearing all

the costs. See Revesz, Federalism and Interstate Environmental Externalities, 144 U. Pa. L. Rev. 2341, 2343 

(1996). Conversely, downwind States to which the pollution travels are unable to achieve clean air because of the 

influx of out-of-state pollution they lack authority to control. See S. Rep. No. 101–228, p. 49 (1989). To tackle the 
 

 

 

2 EPA v. EME HOMER CITY GENERATION, L. P. 

Opinion of the Court 

problem, Congress included a Good Neighbor Provision in 

the Clean Air Act (Act or CAA). That provision, in its 

current phrasing, instructs States to prohibit in-state

sources “from emitting any air pollutant in amounts which 

will . . . contribute significantly” to downwind States’ 

“nonattainment . . . , or interfere with maintenance,” of 

any EPA-promulgated national air quality standard. 42 

U. S. C. §7410(a)(2)(D)(i).

Interpreting the Good Neighbor Provision, EPA adopted

the Cross-State Air Pollution Rule (commonly and hereinafter called the Transport Rule). The rule calls for consideration of costs, among other factors, when determining 

the emission reductions an upwind State must make to

improve air quality in polluted downwind areas. The 

Court of Appeals for the D. C. Circuit vacated the rule in

its entirety. It held, 2 to 1, that the Good Neighbor Provision requires EPA to consider only each upwind State’s 

physically proportionate responsibility for each downwind 

State’s air quality problem. That reading is demanded, 

according to the D. C. Circuit, so that no State will be 

required to decrease its emissions by more than its ratable

share of downwind-state pollution. 

In Chevron U. S. A. Inc. v. Natural Resources Defense 

Council, Inc., 467 U. S. 837 (1984), we reversed a D. C.

Circuit decision that failed to accord deference to EPA’s 

reasonable interpretation of an ambiguous Clean Air Act 

provision. Satisfied that the Good Neighbor Provision 

does not command the Court of Appeals’ cost-blind construction, and that EPA reasonably interpreted the provision, we reverse the D. C. Circuit’s judgment. 

I 

A 

Air pollution is transient, heedless of state boundaries.

Pollutants generated by upwind sources are often transported by air currents, sometimes over hundreds of miles, 
 

Cite as: 572 U. S. ____ (2014) 3 

Opinion of the Court 

to downwind States. As the pollution travels out of state, 

upwind States are relieved of the associated costs. Those 

costs are borne instead by the downwind States, whose

ability to achieve and maintain satisfactory air quality is

hampered by the steady stream of infiltrating pollution.

For several reasons, curtailing interstate air pollution

poses a complex challenge for environmental regulators. 

First, identifying the upwind origin of downwind air pollution is no easy endeavor. Most upwind States propel

pollutants to more than one downwind State, many

downwind States receive pollution from multiple upwind 

States, and some States qualify as both upwind and 

downwind. See Brief for Federal Petitioners 6. The overlapping and interwoven linkages between upwind and 

downwind States with which EPA had to contend number 

in the thousands.1 

Further complicating the problem, pollutants do not 

emerge from the smokestacks of an upwind State and 

uniformly migrate downwind. Some pollutants stay within upwind States’ borders, the wind carries others to

downwind States, and some subset of that group drifts to 

States without air quality problems. “The wind bloweth 

where it listeth, and thou hearest the sound thereof, but 

canst not tell whence it cometh, and whither it goeth.”

The Holy Bible, John 3:8 (King James Version). In crafting a solution to the problem of interstate air pollution,

regulators must account for the vagaries of the wind. 

Finally, upwind pollutants that find their way downwind are not left unaltered by the journey. Rather, as the 

gases emitted by upwind polluters are carried downwind,

they are transformed, through various chemical processes, 

into altogether different pollutants. The offending gases 

—————— 

1For the rule challenged here, EPA evaluated 2,479 separate linkages between downwind and upwind States. Brief for Federal Petitioners 6. 
 

 

 

4 EPA v. EME HOMER CITY GENERATION, L. P. 

Opinion of the Court 

at issue in these cases—nitrogen oxide (NOX) and sulfur

dioxide (SO2)—often develop into ozone and fine particulate matter (PM2.5) by the time they reach the atmospheres of downwind States. See 76 Fed. Reg. 48222– 

48223 (2011). See also 69 Fed. Reg. 4575–4576 (2004) 

(describing the components of ozone and PM2.5). Downwind air quality must therefore be measured for ozone and 

PM2.5 concentrations. EPA’s chore is to quantify the

amount of upwind gases (NOX and SO2) that must be

reduced to enable downwind States to keep their levels of 

ozone and PM2.5 in check. 

B 

Over the past 50 years, Congress has addressed interstate air pollution several times and with increasing rigor.

In 1963, Congress directed federal authorities to “encourage cooperative activities by the States and local governments for the prevention and control of air pollution.” 77 

Stat. 393, 42 U. S. C. §1857a (1964 ed.). In 1970, Congress 

made this instruction more concrete, introducing features 

still key to the Act. For the first time, Congress directed 

EPA to establish national ambient air quality standards

(NAAQS) for pollutants at levels that will protect public 

health. See 84 Stat. 1679–1680, as amended, 42 U. S. C. 

§§7408, 7409 (2006 ed.). Once EPA settles on a NAAQS, 

the Act requires the Agency to designate “nonattainment” 

areas, i.e., locations where the concentration of a regulated

pollutant exceeds the NAAQS. §7407(d).

The Act then shifts the burden to States to propose

plans adequate for compliance with the NAAQS. Each 

State must submit a State Implementation Plan, or SIP,

to EPA within three years of any new or revised NAAQS. 

§7410(a)(1). If EPA determines that a State has failed to 

submit an adequate SIP, either in whole or in part, the Act 

requires the Agency to promulgate a Federal Implementation Plan, or FIP, within two years of EPA’s determina­
 

 

Cite as: 572 U. S. ____ (2014) 5 

Opinion of the Court 

tion, “unless the State corrects the deficiency” before a FIP

is issued. §7410(c)(1).2 

The Act lists the matters a SIP must cover. Among SIP

components, the 1970 version of the Act required SIPs to 

include “adequate provisions for intergovernmental cooperation” concerning interstate air pollution. §110(a)(2)(E), 

84 Stat. 1681, 42 U. S. C. §1857c–5(a)(2)(E). This statutory 

requirement, with its text altered over time, has come

to be called the Good Neighbor Provision.

In 1977, Congress amended the Good Neighbor Provision to require more than “cooperation.” It directed States 

to submit SIPs that included provisions “adequate” to 

“prohibi[t] any stationary source within the State from

emitting any air pollutant in amounts which will . . . 

prevent attainment or maintenance [of air quality standards] by any other State.” §108(a)(4), 91 Stat. 693, 42 

U. S. C. §7410(a)(2)(E) (1976 ed., Supp. II). The amended 

provision thus explicitly instructed upwind States to

reduce emissions to account for pollution exported beyond

their borders. As then written, however, the provision

regulated only individual sources that, considered alone,

emitted enough pollution to cause nonattainment in a 

downwind State. Because it is often “impossible to say 

that any single source or group of sources is the one which

actually prevents attainment” downwind, S. Rep. No. 101–

228, p. 21 (1989), the 1977 version of the Good Neighbor 

Provision proved ineffective, see ibid. (noting the provision’s inability to curb the collective “emissions [of] multiple sources”).

Congress most recently amended the Good Neighbor

Provision in 1990. The statute, in its current form, requires SIPs to “contain adequate provisions . . . prohibiting 

—————— 

2FIPs and SIPs were introduced in the 1970 version of the Act; the 

particular deadlines discussed here were added in 1990. See 104 Stat. 

2409, 2422–2423, 42 U. S. C. §§7401(a)(1), 7410(c) (2006 ed.). 
 

 

 

6 EPA v. EME HOMER CITY GENERATION, L. P. 

Opinion of the Court 

. . . any source or other type of emissions activity within

the State from emitting any air pollutant in amounts

which will . . . contribute significantly to nonattainment 

in, or interfere with maintenance by, any other State with 

respect to any . . . [NAAQS].” 42 U. S. C. §7410(a)(2)(D)(i) 

(2006 ed.). The controversy before us centers on EPA’s

most recent attempt to construe this provision. 

C 

Three times over the past two decades, EPA has attempted to delineate the Good Neighbor Provision’s scope

by identifying when upwind States “contribute significantly” 

to nonattainment downwind. In 1998, EPA issued a 

rule known as the “NOX SIP Call.” That regulation limited NOX emissions in 23 upwind States to the extent such

emissions contributed to nonattainment of ozone standards in downwind States. See 63 Fed. Reg. 57356, 57358. 

In Michigan v. EPA, 213 F. 3d 663 (2000), the D. C. Circuit upheld the NOX SIP Call, specifically affirming EPA’s

use of costs to determine when an upwind State’s contribution was “significan[t]” within the meaning of the statute. Id., at 674–679. 

In 2005, EPA issued the Clean Air Interstate Rule, or 

CAIR. 70 Fed. Reg. 25162. CAIR regulated both NOX and 

SO2 emissions, insofar as such emissions contributed to 

downwind nonattainment of two NAAQS, both set in 1997, 

one concerning the permissible annual measure of PM2.5, 

and another capping the average ozone level gauged over

an 8-hour period. See id., at 25171. The D. C. Circuit 

initially vacated CAIR as arbitrary and capricious. See 

North Carolina v. EPA, 531 F. 3d 896, 921 (2008) (per 

curiam). On rehearing, the court decided to leave the rule

in place, while encouraging EPA to act with dispatch in

dealing with problems the court had identified. See North 

Carolina v. EPA, 550 F. 3d 1176, 1178 (2008) (per curiam).

The rule challenged here—the Transport Rule—is EPA’s 
 

 

Cite as: 572 U. S. ____ (2014) 7 

Opinion of the Court 

response to the D. C. Circuit’s North Carolina decision. 

Finalized in August 2011, the Transport Rule curtails NOX 

and SO2 emissions of 27 upwind States to achieve downwind attainment of three different NAAQS: the two 1997 

NAAQS previously addressed by CAIR, and the 2006 

NAAQS for PM2.5 levels measured on a daily basis. See 76 

Fed. Reg. 48208–48209.

Under the Transport Rule, EPA employed a “two-step

approach” to determine when upwind States “contribute[d]

significantly to nonattainment,” id., at 48254, and therefore in “amounts” that had to be eliminated. At step one,

called the “screening” analysis, the Agency excluded as de 

minimis any upwind State that contributed less than one 

percent of the three NAAQS3 to any downwind State 

“receptor,” a location at which EPA measures air quality. 

See id., at 48236–48237.4 If all of an upwind State’s contributions fell below the one-percent threshold, that State

would be considered not to have “contribute[d] significantly” to the nonattainment of any downwind State. Id., 

at 48236. States in that category were screened out and 

exempted from regulation under the rule.

The remaining States were subjected to a second inquiry, which EPA called the “control” analysis. At this 

stage, the Agency sought to generate a cost-effective allocation of emission reductions among those upwind States 

“screened in” at step one.

The control analysis proceeded this way. EPA first 

calculated, for each upwind State, the quantity of emissions the State could eliminate at each of several cost 

—————— 

3With respect to each NAAQS addressed by the rule, the one-percent

threshold corresponded to levels of 0.15 micrograms per cubic meter 

(μg/m3) for annual PM2.5, 0.35 μg/m3 for daily PM2.5, and 0.8 parts per 

billion (ppb) for 8-hour ozone. See 76 Fed. Reg. 48236–48237. 4 If, for example, the NAAQS for ozone were 100 ppb, a contribution of

less than 1 ppb to any downwind location would fall outside EPA’s 

criteria for significance. 
 

 

 

8 EPA v. EME HOMER CITY GENERATION, L. P. 

Opinion of the Court 

thresholds. See id., at 48248–48249. Cost for these purposes is measured as cost per ton of emissions prevented, 

for instance, by installing scrubbers on powerplant smokestacks.5 EPA estimated, for example, the amount each 

upwind State’s NOX emissions would fall if all pollution

sources within each State employed every control measure

available at a cost of $500 per ton or less. See id., at 

48249–48251. The Agency then repeated that analysis at 

ascending cost thresholds. See ibid.6 

Armed with this information, EPA conducted complex

modeling to establish the combined effect the upwind

reductions projected at each cost threshold would have on

air quality in downwind States. See id., at 48249. The 

Agency then identified “significant cost threshold[s],”

points in its model where a “noticeable change occurred in

downwind air quality, such as . . . where large upwind

emission reductions become available because a certain 

type of emissions control strategy becomes cost-effective.” 

Ibid. For example, reductions of NOX sufficient to resolve 

or significantly curb downwind air quality problems could 

be achieved, EPA determined, at a cost threshold of $500 

per ton (applied uniformly to all regulated upwind States).

“Moving beyond the $500 cost threshold,” EPA concluded,

“would result in only minimal additional . . . reductions [in 

emissions].” Id., at 48256.7 

Finally, EPA translated the cost thresholds it had se­

—————— 

5To illustrate, a technology priced at $5,000 and capable of eliminating two tons of pollution would be stated to “cost” $2,500 per ton. 6For SO2, EPA modeled reductions that would be achieved at cost 

levels of $500, $1,600, $2,300, $2,800, $3,300, and $10,000 per ton

eliminated. See id., at 48251–48253. 7For SO2, EPA determined that, for one group of upwind States, all

downwind air quality problems would be resolved at the $500 per ton

threshold. See id., at 48257. For another group of States, however,

this level of controls would not suffice. For those States, EPA found 

that pollution controls costing $2,300 per ton were necessary. See id., 

at 48259. 
Cite as: 572 U. S. ____ (2014) 9 

Opinion of the Court 

lected into amounts of emissions upwind States would be 

required to eliminate. For each regulated upwind State,

EPA created an annual emissions “budget.” These budgets represented the quantity of pollution an upwind State

would produce in a given year if its in-state sources implemented all pollution controls available at the chosen

cost thresholds. See id., at 48249.8 If EPA’s projected

improvements to downwind air quality were to be realized,

an upwind State’s emissions could not exceed the level this

budget allocated to it, subject to certain adjustments not 

relevant here. 

Taken together, the screening and control inquiries 

defined EPA’s understanding of which upwind emissions

were within the Good Neighbor Provision’s ambit. In 

short, under the Transport Rule, an upwind State “contribute[d] significantly” to downwind nonattainment to the 

extent its exported pollution both (1) produced one percent 

or more of a NAAQS in at least one downwind State (step 

one) and (2) could be eliminated cost-effectively, as determined by EPA (step two). See id., at 48254. Upwind

States would be obliged to eliminate all and only emissions meeting both of these criteria.9 

For each State regulated by the Transport Rule, EPA

contemporaneously promulgated a FIP allocating that

State’s emission budget among its in-state sources. See 

id., at 48271, 48284–48287.10 For each of these States, 

—————— 

8 In 2014, for example, pollution sources within Texas would be permitted to emit no more than 243,954 tons of SO2, subject to variations 

specified by EPA. See id., at 48269 (Table VI.F–1). 9Similarly, upwind States EPA independently determined to be “interfer[ing] with [the] maintenance” of NAAQS downwind were required

to eliminate pollution only to the extent their emissions satisfied both

of these criteria. See id., at 48254. 10These FIPs specified the maximum amount of pollution each instate pollution source could emit. Sources below this ceiling could sell 

unused “allocations” to sources that could not reduce emissions to the 

necessary level as cheaply. See id., at 48271–48272. This type of “cap­
 

 

 

10 EPA v. EME HOMER CITY GENERATION, L. P. 

Opinion of the Court 

EPA had determined that the State had failed to submit 

a SIP adequate for compliance with the Good Neighbor 

Provision. These determinations regarding SIPs became 

final after 60 days, see 42 U. S. C. §7607(b)(1)(2006 ed.,

Supp. V), and many went unchallenged.11 EPA views the 

SIP determinations as having triggered its statutory 

obligation to promulgate a FIP within two years, see

§7410(c), a view contested by respondents, see Part II, 

infra. 

D 

A group of state and local governments (State respondents), joined by industry and labor groups (Industry respondents), petitioned for review of the Transport Rule in 

the U. S. Court of Appeals for the D. C. Circuit. Over the 

dissent of Judge Rogers, the Court of Appeals vacated the 

rule in its entirety. See 696 F. 3d 7, 37 (2012). 

EPA’s actions, the appeals court held, exceeded the

Agency’s statutory authority in two respects. By promulgating FIPs before giving States a meaningful opportunity 

to adopt their own implementation plans, EPA had, in the 

court’s view, upset the CAA’s division of responsibility 

between the States and the Federal Government. In the 

main, the Court of Appeals acknowledged, EPA’s FIP 

authority is triggered at the moment the Agency disapproves a SIP. See id., at 30. Thus, when a State proposes 

—————— 

and-trade” system cuts costs while still reducing pollution to target

levels. 11 Three States did challenge EPA’s determinations. See Petition for 

Review in Ohio v. EPA, No. 11–3988 (CA6); Petition for Review in 

Kansas v. EPA, No. 12–1019 (CADC); Notice in Georgia v. EPA, No. 11– 

1427 (CADC). Those challenges were not consolidated with this proceeding, and they remain pending (held in abeyance for these cases) in

the Sixth and D. C. Circuits. See Twelfth Joint Status Report in Ohio 

v. EPA, No. 11–3988 (CA6); Order in Kansas v. EPA, No. 11–1333 

(CADC, May 10, 2013); Order in Georgia v. EPA, No. 11–1427 (CADC, 

May 10, 2013). 
 

Cite as: 572 U. S. ____ (2014) 11 

Opinion of the Court 

a SIP inadequate to achieve a NAAQS, EPA could promulgate a FIP immediately after disapproving that SIP. See 

id., at 32. 

But the Court of Appeals ruled that a different regime 

applies to a State’s failure to meet its obligations under

the Good Neighbor Provision. While a NAAQS was a 

“clear numerical target,” a State’s good neighbor obligation 

remained “nebulous and unknown,” the court observed, 

until EPA calculated the State’s emission budget. Ibid. 

Without these budgets, the Court of Appeals said, upwind

States would be compelled to take a “stab in the dark” at

calculating their own significant contribution to interstate 

air pollution. Id., at 35. The D. C. Circuit read the Act to 

avoid putting States in this position: EPA had an implicit 

statutory duty, the court held, to give upwind States a 

reasonable opportunity to allocate their emission budgets

among in-state sources before the Agency’s authority to

issue FIPs could be triggered. Id., at 37. 

The D. C. Circuit also held that the Agency’s two-part

interpretation of the Good Neighbor Provision ignored

three “red lines . . . cabin[ing the] EPA’s authority.” Id., at 

19. First, the D. C. Circuit interpreted the Good Neighbor 

Provision to require upwind States to reduce emissions in

“a manner proportional to their contributio[n]” to pollution

in downwind States. Id., at 21. The Transport Rule,

however, treated all regulated upwind States alike, regardless of their relative contribution to the overall problem. See id., at 23. It required all upwind States

“screened in” at step one to reduce emissions in accord

with the uniform cost thresholds set during the step two 

control analysis. Imposing these uniform cost thresholds,

the Court of Appeals observed, could force some upwind 

States to reduce emissions by more than their “fair share.” 

Id., at 27. 

According to the Court of Appeals, EPA had also failed

to ensure that the Transport Rule did not mandate up­
 

 

12 EPA v. EME HOMER CITY GENERATION, L. P. 

Opinion of the Court 

wind States to reduce pollution unnecessarily. The Good 

Neighbor Provision, the D. C. Circuit noted, “targets [only]

those emissions from upwind States that ‘contribute significantly to nonattainment’” of a NAAQS in downwind 

States. Id., at 22. Pollution reduction beyond that goal 

was “unnecessary over-control,” outside the purview of the

Agency’s statutory mandate. Ibid. Because the emission 

budgets were calculated by reference to cost alone, the

court concluded that EPA had done nothing to guard 

against, or even measure, the “over-control” potentially

imposed by the Transport Rule. See ibid. 

Finally, by deciding, at the screening analysis, that

upwind contributions below the one-percent threshold 

were insignificant, EPA had established a “floor” on the 

Agency’s authority to act. See id., at 20, and n. 13. Again

pointing to the rule’s reliance on costs, the Court of Appeals held that EPA had failed to ensure that upwind

States were not being forced to reduce emissions below the 

one-percent threshold. See ibid. 

In dissent, Judge Rogers criticized the majority for

deciding two questions that were not, in her view, properly

before the court. See id., at 40–46, 51–58. First, she 

addressed the majority’s insistence that FIPs abide a

State’s opportunity to allocate its emission budget among 

in-state sources. She regarded the respondents’ plea to 

that effect as an untimely attack on EPA’s previous SIP 

disapprovals. See id., at 40–46. Second, in Judge Rogers’ 

assessment, the respondents had failed to raise their 

substantive objections to the Transport Rule with the

specificity necessary to preserve them for review. See id., 

at 51–58. On the merits, Judge Rogers found nothing in

the Act to require, or even suggest, that EPA must quantify a State’s good neighbor obligations before it promulgated a FIP. See id., at 46–51. She also disagreed with

the court’s conclusion that the Transport Rule unreasonably interpreted the Act. See id., at 58–60. 
 

Cite as: 572 U. S. ____ (2014) 13 

Opinion of the Court 

We granted certiorari to decide whether the D. C. Circuit had accurately construed the limits the CAA places on

EPA’s authority. See 570 U. S. ___ (2013). 

II
 

A 

Once EPA has calculated emission budgets, the D. C.

Circuit held, the Agency must give upwind States the 

opportunity to propose SIPs allocating those budgets 

among in-state sources before issuing a FIP. 696 F. 3d, at 

37. As the State respondents put it, a FIP allocating a

State’s emission budget “must issue after EPA has quantified the States’ good-neighbor obligations [in an emission

budget] and given the States a reasonable opportunity to 

meet those obligations in SIPs.” Brief for State Respondents 20. 

Before reaching the merits of this argument, we first

reject EPA’s threshold objection that the claim is untimely.

According to the Agency, this argument—and the D. C.

Circuit’s opinion accepting it—rank as improper collateral 

attacks on EPA’s prior SIP disapprovals. As earlier recounted, see supra, at 9–10, EPA, by the time it issued the

Transport Rule, had determined that each regulated

upwind State had failed to submit a SIP adequate to 

satisfy the Good Neighbor Provision. Many of those determinations, because unchallenged, became final after 60 

days, see 42 U. S. C. §7607(b)(1), and did so before the 

petitions here at issue were filed. EPA argues that the

Court cannot question exercise of the Agency’s FIP authority without subjecting these final SIP disapprovals to 

untimely review.

We disagree. The gravamen of the State respondents’ 

challenge is not that EPA’s disapproval of any particular

SIP was erroneous. Rather, respondents urge that, notwithstanding these disapprovals, the Agency was obliged

to grant an upwind State a second opportunity to promul­
 

 

 

 

 

 

14 EPA v. EME HOMER CITY GENERATION, L. P. 

Opinion of the Court 

gate adequate SIPs once EPA set the State’s emission

budget. This claim does not depend on the validity of the

prior SIP disapprovals. Even assuming the legitimacy of

those disapprovals, the question remains whether EPA 

was required to do more than disapprove a SIP, as the 

State respondents urge, to trigger the Agency’s statutory

authority to issue a FIP.12 

B 

Turning to the merits, we hold that the text of the statute supports EPA’s position. As earlier noted, see supra, 

at 4–5, the CAA sets a series of precise deadlines to which

the States and EPA must adhere. Once EPA issues any 

new or revised NAAQS, a State has three years to adopt a

SIP adequate for compliance with the Act’s requirements.

See 42 U. S. C. §7410(a)(1). Among those requirements is 

the Act’s mandate that SIPs “shall” include provisions

sufficient to satisfy the Good Neighbor Provision. 

§7410(a)(2).

If EPA determines a SIP to be inadequate, the Agency’s

mandate to replace it with a FIP is no less absolute: 

“[EPA] shall promulgate a [FIP] at any time within

2 years after the [Agency] 

“(A) finds that a State has failed to make a required 

submission or finds that the plan or plan revision

submitted by the State does not satisfy the minimum 

[relevant] criteria . . . , or 

—————— 

12The State respondents make a second argument we do not reach.

They urge that EPA could not impose FIPs on several upwind States

whose SIPs had been previously approved by the Agency under CAIR. 

EPA changed those approvals to disapprovals when it issued the

Transport Rule, see 76 Fed. Reg. 48220, and the States assert that the

process by which EPA did so was improper. That argument was not

passed on by the D. C. Circuit, see 696 F. 3d 7, 31, n. 29 (2012), and we

leave it for the Court of Appeals to consider in the first instance on 

remand. 
Cite as: 572 U. S. ____ (2014) 15 

Opinion of the Court 

“(B) disapproves a [SIP] in whole or in part, 

“unless the State corrects the deficiency, and [EPA]

approves the plan or plan revision, before the [Agency] 

promulgates such [FIP].” §7410(c)(1). 

In other words, once EPA has found a SIP inadequate, the

Agency has a statutory duty to issue a FIP “at any time” 

within two years (unless the State first “corrects the deficiency,” which no one contends occurred here). 

The D. C. Circuit, however, found an unwritten exception to this strict time prescription for SIPs aimed at 

implementing the Good Neighbor Provision. Expecting

any one State to develop a “comprehensive solution” to the

“collective problem” of interstate air pollution without first

receiving EPA’s guidance was, in the Court of Appeals’ 

assessment, “set[ting] the States up to fail.” 696 F. 3d, at

36–37. The D. C. Circuit therefore required EPA, after 

promulgating each State’s emission budget, to give the 

State a “reasonable” period of time to propose SIPs implementing its budget. See id., at 37. 

However sensible (or not) the Court of Appeals’ position,13 a reviewing court’s “task is to apply the text [of the 

statute], not to improve upon it.” Pavelic & LeFlore v. 

Marvel Entertainment Group, Div. of Cadence Industries 

Corp., 493 U. S. 120, 126 (1989). Nothing in the Act dif­

—————— 

13On this point, the dissent argues that it is “beyond responsible

debate that the States cannot possibly design FIP-proof SIPs without 

knowing the EPA-prescribed targets at which they must aim.” Post, at 

18. Many of the State respondents thought otherwise, however, when

litigating the matter in Michigan v. EPA, 213 F. 3d 663 (CADC 2000). 

See Final Brief for Petitioning States in No. 98–1497 (CADC), p. 34

(“EPA has the responsibility to establish NAAQS,” but without further

intervention by EPA, “States [have] the duty and right to develop . . . 

SIPs . . . to meet those NAAQS.”). See also id., at 37 (“EPA’s role is to 

determine whether the SIP submitted is ‘adequate’ . . . not to dictate

contents of the submittal in the first instance. . . . [E]ach State has the 

right and the obligation to write a SIP that complies with §[74]10(a)(2), 

including the ‘good neighbor’ provision.”). 
 

 

 

16 EPA v. EME HOMER CITY GENERATION, L. P. 

Opinion of the Court 

ferentiates the Good Neighbor Provision from the several 

other matters a State must address in its SIP. Rather, the 

statute speaks without reservation: Once a NAAQS has 

been issued, a State “shall” propose a SIP within three

years, §7410(a)(1), and that SIP “shall” include, among 

other components, provisions adequate to satisfy the Good

Neighbor Provision, §7410(a)(2). 

Nor does the Act condition the duty to promulgate a FIP

on EPA’s having first quantified an upwind State’s good 

neighbor obligations. As Judge Rogers observed in her 

dissent from the D. C. Circuit’s decision, the Act does not 

require EPA to furnish upwind States with information of 

any kind about their good neighbor obligations before a 

FIP issues. See 696 F. 3d, at 47. Instead, a SIP’s failure 

to satisfy the Good Neighbor Provision, without more,

triggers EPA’s obligation to issue a federal plan within 

two years. §7410(c). After EPA has disapproved a SIP,

the Agency can wait up to two years to issue a FIP, during 

which time the State can “correc[t] the deficiency” on its 

own. Ibid. But EPA is not obliged to wait two years or

postpone its action even a single day: The Act empowers 

the Agency to promulgate a FIP “at any time” within the 

two-year limit. Ibid. Carving out an exception to the Act’s 

precise deadlines, as the D. C. Circuit did, “rewrites a 

decades-old statute whose plain text and structure establish a clear chronology of federal and State responsibilities.” 696 F. 3d, at 47 (Rogers, J., dissenting).

The practical difficulties cited by the Court of Appeals

do not justify departure from the Act’s plain text. See 

Barnhart v. Sigmon Coal Co., 534 U. S. 438, 461–462 

(2002) (We “must presume that a legislature says in a 

statute what it means and means in a statute what it says 

there.” (internal quotation marks omitted)). When Congress elected to make EPA’s input a prerequisite to state 

action under the Act, it did so expressly. States developing vehicle inspection and maintenance programs under 
Cite as: 572 U. S. ____ (2014) 17 

Opinion of the Court 

the CAA, for example, must await EPA guidance before

issuing SIPs. 42 U. S. C. §7511a(c)(3)(B). A State’s obligation to adopt a SIP, moreover, arises only after EPA has 

first set the NAAQS the State must meet. §7410(a)(1).

Had Congress intended similarly to defer States’ discharge

of their obligations under the Good Neighbor Provision, 

Congress, we take it, would have included a similar direction in that section. See Jama v. Immigration and Customs Enforcement, 543 U. S. 335, 341 (2005) (“We do not 

lightly assume that Congress has omitted from its adopted 

text requirements that it nonetheless intends to apply,

and our reluctance is even greater when Congress has 

shown elsewhere in the same statute that it knows how to 

make such a requirement manifest.”).

In short, nothing in the statute places EPA under an 

obligation to provide specific metrics to States before they 

undertake to fulfill their good neighbor obligations. By

altering the schedule Congress provided for SIPs and 

FIPs, the D. C. Circuit stretched out the process. It allowed a delay Congress did not order and placed an information submission obligation on EPA Congress did not 

impose. The D. C. Circuit, we hold, had no warrant thus 

to revise the CAA’s action-ordering prescriptions. 

C 

At oral argument, the State respondents emphasized

EPA’s previous decisions, in the NOX SIP Call and CAIR, 

to quantify the emission reductions required of upwind

States before the window to propose a SIP closed. See Tr. 

of Oral Arg. 37–39, 42–43, 45–46. In their view, by failing

to accord States a similar grace period after issuing States’

emission budgets, EPA acted arbitrarily. See ibid. 

Whatever pattern the Agency followed in its NOX SIP 

call and CAIR proceedings, EPA retained discretion to

alter its course provided it gave a reasonable explanation

for doing so. Motor Vehicle Mfrs. Assn. of United States, 
 

 

 

18 EPA v. EME HOMER CITY GENERATION, L. P. 

Opinion of the Court 

Inc. v. State Farm Mut. Automobile Ins. Co., 463 U. S. 29, 

42 (1983). The Agency presented such an explanation in

the Transport Rule. As noted, see supra, at 6, the D. C. 

Circuit’s North Carolina decision admonished EPA to act 

with dispatch in amending or replacing CAIR, the 

Transport Rule’s predecessor. See 550 F. 3d, at 1178 

(warning EPA that the stay of the court’s decision to vacate CAIR would not persist “indefinite[ly]”). Given North 

Carolina’s stress on expeditious action to cure the infirmities the court identified in CAIR, EPA thought

it “[in]appropriate to establish [the] lengthy transition

period” entailed in allowing States time to propose new or 

amended SIPs implementing the Transport Rule emission 

budgets. See 76 Fed. Reg. 48220 (citing North Carolina, 

550 F. 3d 1176). Endeavoring to satisfy the D. C. Circuit’s

directive, EPA acted speedily, issuing FIPs contemporaneously with the Transport Rule. In light of the firm deadlines imposed by the Act, which we hold the D. C. Circuit

lacked authority to alter, we cannot condemn EPA’s decision as arbitrary or capricious.14 

III
 

A 

The D. C. Circuit also held that the Transport Rule’s

two-step interpretation of the Good Neighbor Provision

conflicts with the Act. Before addressing this holding, we 

take up a jurisdictional objection raised by EPA. 

The CAA directs that “[o]nly an objection to a rule . . . 

—————— 

14 In light of the CAA’s “core principle” of cooperative federalism, the 

dissent believes EPA abused its discretion by failing to give States an

additional opportunity to submit SIPs in satisfaction of the Good 

Neighbor Provision. Post, at 19. But nothing in the statute so restricts 

EPA. To the contrary, as earlier observed, see supra, at 16, the plain

text of the CAA grants EPA plenary authority to issue a FIP “at any

time” within the two-year period that begins the moment EPA determines a SIP to be inadequate. §7410(c)(1) (emphasis added). 
 

 

Cite as: 572 U. S. ____ (2014) 19 

Opinion of the Court 

raised with reasonable specificity during the period for 

public comment . . . may be raised during judicial review.”

42 U. S. C. §7607(d)(7)(B). Respondents failed to state

their objections to the Transport Rule during the comment

period with the “specificity” required for preservation, 

EPA argues. See Brief for Federal Petitioners 34–42. 

This failure at the administrative level, EPA urges, forecloses judicial review. Id., at 34. 

Assuming, without deciding, that respondents did not 

meet the Act’s “reasonable specificity” requirement during

the comment period, we do not regard that lapse as “jurisdictional.” This Court has cautioned against “profligate

use” of the label “jurisdictional.” Sebelius v. Auburn Regional Medical Center, 568 U. S. ___, ___ (2013) (slip op., 

at 6). A rule may be “mandatory,” yet not “jurisdictional,”

we have explained. See Arbaugh v. Y & H Corp., 546 U. S. 

500, 510 (2006). Section 7607(d)(7)(B), we hold, is of that 

character. It does not speak to a court’s authority, but

only to a party’s procedural obligations. See Kontrick v. 

Ryan, 540 U. S. 443, 455 (2004). Had EPA pursued the

“reasonable specificity” argument vigorously before the 

D. C. Circuit, we would be obligated to address the merits

of the argument. See Gonzalez v. Thaler, 565 U. S. ___, 

___ (2012) (slip op., at 10). But EPA did not press the 

argument unequivocally. Before the D. C. Circuit, it indicated only that the “reasonable specificity” prescription

might bar judicial review. Brief for Respondent EPA et al. 

in No. 11–1302 (CADC), p. 30. See also id., at 32. We 

therefore do not count the prescription an impassable

hindrance to our adjudication of the respondents’ attack

on EPA’s interpretation of the Transport Rule. We turn to 

that attack mindful of the importance of the issues respondents raise to the ongoing implementation of the Good 

Neighbor Provision. 
 

 

 

20 EPA v. EME HOMER CITY GENERATION, L. P. 

Opinion of the Court 

B 

We routinely accord dispositive effect to an agency’s 

reasonable interpretation of ambiguous statutory language. Chevron U. S. A. Inc. v. Natural Resources Defense 

Council, Inc., 467 U. S. 837 (1984), is the pathmarking 

decision, and it bears a notable resemblance to the cases 

before us. Chevron concerned EPA’s definition of the term 

“source,” as used in the 1977 Amendments to the CAA. 

Id., at 840, n. 1. Those amendments placed additional 

restrictions on companies’ liberty to add new pollution

“sources” to their factories. See id., at 840. Although

“source” might have been interpreted to refer to an individual smokestack, EPA construed the term to refer to an 

entire plant, thereby “treat[ing] all of the pollutionemitting devices within the [plant] as though they were

encased within a single ‘bubble.’” Ibid. Under the Agency’s

interpretation, a new pollution-emitting device would not 

subject a plant to the additional restrictions if the “alteration [did] not increase the total emissions [produced by]

the plant.” Ibid. 

This Court held EPA’s interpretation of “source” a reasonable construction of an ambiguous statutory term. 

When “Congress has not directly addressed the precise

[interpretative] question at issue,” we cautioned, a reviewing court cannot “simply impose its own construction o[f] 

the statute.” Id., at 843. Rather, the agency is charged 

with filling the “gap left open” by the ambiguity. Id., at 

866. Because “‘a full understanding of the force of the 

statutory policy . . . depend[s] upon more than ordinary 

knowledge’” of the situation, the administering agency’s

construction is to be accorded “controlling weight unless

. . . arbitrary, capricious, or manifestly contrary to the

statute.” Id., at 844 (quoting United States v. Shimer, 367 

U. S. 374, 382 (1961)). Determining that none of those 

terms fit EPA’s interpretation of “source,” the Court deferred to the Agency’s judgment. 
 

Cite as: 572 U. S. ____ (2014) 21 

Opinion of the Court 

We conclude that the Good Neighbor Provision delegates

authority to EPA at least as certainly as the CAA provisions involved in Chevron. The statute requires States to 

eliminate those “amounts” of pollution that “contribute 

significantly to nonattainment” in downwind States. 42 

U. S. C. §7410(a)(2)(D)(i) (emphasis added). Thus, EPA’s 

task15 is to reduce upwind pollution, but only in “amounts”

that push a downwind State’s pollution concentrations

above the relevant NAAQS. As noted earlier, however, the 

nonattainment of downwind States results from the collective and interwoven contributions of multiple upwind 

States. See supra, at 3. The statute therefore calls 

upon the Agency to address a thorny causation problem:

How should EPA allocate among multiple contributing upwind States responsibility for a downwind State’s excess

pollution?

A simplified example illustrates the puzzle EPA faced.

Suppose the Agency sets a NAAQS, with respect to a

particular pollutant, at 100 parts per billion (ppb), and 

that the level of the pollutant in the atmosphere of downwind State A is 130 ppb. Suppose further that EPA has

determined that each of three upwind States—X, Y, and 

Z—contributes the equivalent of 30 ppb of the relevant 

pollutant to State A’s airspace. The Good Neighbor Provision, as just observed, prohibits only upwind emissions 

that contribute significantly to downwind nonattainment. 

EPA’s authority under the provision is therefore limited to

eliminating a total of 30 ppb,16 i.e., the overage caused by 

—————— 

15Though we speak here of “EPA’s task,” the Good Neighbor Provision is initially directed to upwind States. As earlier explained, see 

Part II–B, supra, only after a State has failed to propose a SIP adequate for compliance with the provision is EPA called upon to act. 16Because of the uncertainties inherent in measuring interstate air

pollution, see supra, at 3–4, reductions of exactly 30 ppb likely are 

unattainable. See infra, at 30–31. 
 

 

 

22 EPA v. EME HOMER CITY GENERATION, L. P. 

Opinion of the Court 

the collective contribution of States X, Y, and Z.17 

How is EPA to divide responsibility among the three 

States? Should the Agency allocate reductions proportionally (10 ppb each), on a per capita basis, on the basis of 

the cost of abatement, or by some other metric? See Brief 

for Federal Petitioners 50 (noting EPA’s consideration of 

different approaches). The Good Neighbor Provision does 

not answer that question for EPA. Cf. Chevron, 467 U. S., 

at 860 (“[T]he language of [the CAA] simply does not 

compel any given interpretation of the term ‘source.’”).

Under Chevron, we read Congress’ silence as a delegation 

of authority to EPA to select from among reasonable options. See United States v. Mead Corp., 533 U. S. 218, 229 

(2001).18 

Yet the Court of Appeals believed that the Act speaks

clearly, requiring EPA to allocate responsibility for reducing emissions in “a manner proportional to” each State’s

“contributio[n]” to the problem. 696 F. 3d, at 21. Nothing 

—————— 

17For simplicity’s sake, the hypothetical assumes that EPA has not 

required any emission reductions by the downwind State itself. 18The statutory gap identified also exists in the Good Neighbor Provision’s second instruction. That instruction requires EPA to eliminate 

amounts of upwind pollution that “interfere with maintenance” of a 

NAAQS by a downwind State. §7410(a)(2)(D)(i). This mandate contains no qualifier analogous to “significantly,” and yet it entails a

delegation of administrative authority of the same character as the one

discussed above. Just as EPA is constrained, under the first part of the

Good Neighbor Provision, to eliminate only those amounts that “contribute . . . to nonattainment,” EPA is limited, by the second part of the

provision, to reduce only by “amounts” that “interfere with maintenance,” i.e., by just enough to permit an already-attaining State to

maintain satisfactory air quality. (Emphasis added.) With multiple

upwind States contributing to the maintenance problem, however, EPA 

confronts the same challenge that the “contribute significantly” mandate creates: How should EPA allocate reductions among multiple 

upwind States, many of which contribute in amounts sufficient to 

impede downwind maintenance? Nothing in either clause of the Good 

Neighbor Provision provides the criteria by which EPA is meant to

apportion responsibility. 
 

Cite as: 572 U. S. ____ (2014) 23 

Opinion of the Court 

in the text of the Good Neighbor Provision propels EPA 

down this path. Understandably so, for as EPA notes, the 

D. C. Circuit’s proportionality approach could scarcely be

satisfied in practice. See App. in No. 11–1302 etc. 

(CADC), p. 2312 (“[W]hile it is possible to determine an

emission reduction percentage if there is a single downwind [receptor], most upwind states contribute to multiple

downwind [receptors] (in multiple states) and would have

a different reduction percentage for each one.”). 

To illustrate, consider a variation on the example set out 

above. Imagine that States X and Y now contribute air 

pollution to State A in a ratio of one to five, i.e., State Y 

contributes five times the amount of pollution to State A

than does State X. If State A were the only downwind 

State to which the two upwind States contributed, the

D. C. Circuit’s proportionality requirement would be easy

to meet: EPA could require State Y to reduce its emissions 

by five times the amount demanded of State X.

The realities of interstate air pollution, however, are not

so simple. Most upwind States contribute pollution to 

multiple downwind States in varying amounts. See 76 

Fed. Reg. 48239–48246. See also Brief for Respondent 

Calpine Corp. et al. in Support of Petitioners 48–49 (offering examples). Suppose then that States X and Y also

contribute pollutants to a second downwind State (State

B), this time in a ratio of seven to one. Though State Y 

contributed a relatively larger share of pollution to State 

A, with respect to State B, State X is the greater offender.

Following the proportionality approach with respect to

State B would demand that State X reduce its emissions 

by seven times as much as State Y. Recall, however, that 

State Y, as just hypothesized, had to effect five times as 

large a reduction with respect to State A. The Court of 

Appeals’ proportionality edict with respect to both State A 

and State B appears to work neither mathematically nor 

in practical application. Proportionality as to one down­
 

 

24 EPA v. EME HOMER CITY GENERATION, L. P. 

Opinion of the Court 

wind State will not achieve proportionality as to others. 

Quite the opposite. And where, as is generally true, upwind States contribute pollution to more than two downwind receptors, proportionality becomes all the more 

elusive. 

Neither the D. C. Circuit nor respondents face up to this

problem. The dissent, for its part, strains to give meaning 

to the D. C. Circuit’s proportionality constraint as applied

to a world in which multiple upwind States contribute

emissions to multiple downwind locations. In the dissent’s 

view, upwind States must eliminate emissions by “whatever minimum amount reduces” their share of the overage

in each and every one of the downwind States to which 

they are linked. See post, at 8. In practical terms, this

means each upwind State will be required to reduce emissions by the amount necessary to eliminate that State’s

largest downwind contribution. The dissent’s formulation, 

however, does not account for the combined and cumulative effect of each upwind State’s reductions on attainment in multiple downwind locations. See ibid. (“Under a

proportional-reduction approach, State X would be required

to eliminate emissions of that pollutant by whatever minimum amount reduces both State A’s level by 0.2 unit and 

State B’s by 0.7 unit.” (emphasis added)). The result 

would be costly overregulation unnecessary to, indeed

in conflict with, the Good Neighbor Provision’s goal of 

attainment.19 

—————— 

19To see why, one need only slightly complicate the world envisioned 

by the dissent. Assume the world is made up of only four States—two

upwind (States X and Y), and two downwind (States A and B). Suppose

also, as the dissent allows, see post, at 9, that the reductions State X 

must make to eliminate its share of the amount by which State A is in

nonattainment are more than necessary for State X to eliminate its

share of State B’s nonattainment. As later explained, see infra, at 29– 

30, this kind of “over-control,” we agree with the dissent, is acceptable 

under the statute. Suppose, however, that State Y also contributes to

pollution in both State A and State B such that the reductions it must 
 

 

Cite as: 572 U. S. ____ (2014) 25 

Opinion of the Court 

In response, the dissent asserts that EPA will “simply

be required to make allowance for” the overregulation 

caused by its “proportional-reduction” approach. Post, at 

11. What criterion should EPA employ to determine

which States will have to make those “allowance[s]” and 

by how much? The dissent admits there are “multiple

ways” EPA might answer those questions. Ibid. But 

proportionality cannot be one of those ways, for the

proportional-reduction approach is what led to the overregulation in the first place. And if a nonproportional

approach can play a role in setting the final allocation of 

reduction obligations, then it is hardly apparent why EPA,

free to depart from proportionality at the back end, cannot 

do so at the outset. 

Persuaded that the Good Neighbor Provision does not 

dictate the particular allocation of emissions among contributing States advanced by the D. C. Circuit, we must 

next decide whether the allocation method chosen by EPA 

is a “permissible construction of the statute.” Chevron, 

467 U. S., at 843. As EPA interprets the statute, upwind

emissions rank as “amounts [that] . . . contribute significantly to nonattainment” if they (1) constitute one percent 

—————— 

make to eliminate its proportion of State B’s overage exceed the reductions it must make to bring State A into attainment. In this case, the 

dissent would have State X reduce by just enough to eliminate its share 

of State A’s nonattainment and more than enough to eliminate its 

share of State B’s overage. The converse will be true as to State Y: 

Under the dissent’s approach, State Y would have to reduce by the 

“minimum” necessary to eliminate its proportional share of State B’s 

nonattainment and more than enough to eliminate its proportion of 

State A’s overage. The result is that the total amount by which both

States X and Y are required to reduce will exceed what is necessary for 

attainment in all downwind States involved (i.e., in both State A and 

State B). Over-control thus unnecessary to achieving attainment in all 

involved States is impermissible under the Good Neighbor Provision.

See infra, at 30, n. 23. The problem would worsen were the hypothetical altered to include more than two downwind States and two upwind 

States, the very real circumstances EPA must address. 
 

 

26 EPA v. EME HOMER CITY GENERATION, L. P. 

Opinion of the Court 

or more of a relevant NAAQS in a nonattaining downwind 

State and (2) can be eliminated under the cost threshold 

set by the Agency. See 76 Fed. Reg. 48254. In other 

words, to identify which emissions were to be eliminated, 

EPA considered both the magnitude of upwind States’ 

contributions and the cost associated with eliminating 

them. 

The Industry respondents argue that, however EPA

ultimately divides responsibility among upwind States, 

the final calculation cannot rely on costs. The Good 

Neighbor Provision, respondents and the dissent emphasize, “requires each State to prohibit only those ‘amounts’ 

of air pollution emitted within the State that ‘contribute

significantly’ to another State’s nonattaintment.” Brief for 

Industry Respondents 23 (emphasis added). See also post, 

at 6. The cost of preventing emissions, they urge, is 

wholly unrelated to the actual “amoun[t]” of air pollution

an upwind State contributes. Brief for Industry Respondents 23. Because the Transport Rule considers costs,

respondents argue, “States that contribute identical 

‘amounts’ . . . may be deemed [by EPA] to have [made]

substantially different” contributions. Id., at 30. 

But, as just explained, see supra, at 21–22, the Agency

cannot avoid the task of choosing which among equal 

“amounts” to eliminate. The Agency has chosen, sensibly 

in our view, to reduce the amount easier, i.e., less costly, to

eradicate, and nothing in the text of the Good Neighbor

Provision precludes that choice.

Using costs in the Transport Rule calculus, we agree

with EPA, also makes good sense. Eliminating those 

amounts that can cost-effectively be reduced is an efficient 

and equitable solution to the allocation problem the Good

Neighbor Provision requires the Agency to address. Efficient because EPA can achieve the levels of attainment, 

i.e., of emission reductions, the proportional approach 

aims to achieve, but at a much lower overall cost. Equita­
Cite as: 572 U. S. ____ (2014) 27 

Opinion of the Court 

ble because, by imposing uniform cost thresholds on regulated States, EPA’s rule subjects to stricter regulation

those States that have done relatively less in the past to 

control their pollution. Upwind States that have not yet

implemented pollution controls of the same stringency as

their neighbors will be stopped from free riding on their 

neighbors’ efforts to reduce pollution. They will have to

bring down their emissions by installing devices of the

kind in which neighboring States have already invested. 

Suppose, for example, that the industries of upwind

State A have expended considerable resources installing 

modern pollution-control devices on their plants. Factories in upwind State B, by contrast, continue to run old,

dirty plants. Yet, perhaps because State A is more populous and therefore generates a larger sum of pollution

overall, the two States’ emissions have equal effects on

downwind attainment. If State A and State B are required to eliminate emissions proportionally (i.e., equally), 

sources in State A will be compelled to spend far more per 

ton of reductions because they have already utilized lower 

cost pollution controls. State A’s sources will also have to 

achieve greater reductions than would have been required 

had they not made the cost-effective reductions in the first 

place. State A, in other words, will be tolled for having 

done more to reduce pollution in the past.20 EPA’s costbased allocation avoids these anomalies. 

Obligated to require the elimination of only those

“amounts” of pollutants that contribute to the nonattainment of NAAQS in downwind States, EPA must decide 

how to differentiate among the otherwise like contributions of multiple upwind States. EPA found decisive the 

—————— 

20The dissent’s approach is similarly infirm. It, too, would toll those 

upwind States that have already invested heavily in means to reduce

the pollution their industries cause, while lightening the burden on 

States that have done relatively less to control pollution emanating

from local enterprises. 
 

 

28 EPA v. EME HOMER CITY GENERATION, L. P. 

Opinion of the Court 

difficulty of eliminating each “amount,” i.e., the cost incurred in doing so. Lacking a dispositive statutory instruction to guide it, EPA’s decision, we conclude, is a 

“reasonable” way of filling the “gap left open by Congress.” 

Chevron, 467 U. S., at 866.21 

C 

The D. C. Circuit stated two further objections to EPA’s

cost-based method of defining an upwind State’s contribution. Once a State was screened in at step one of EPA’s 

analysis, its emission budget was calculated solely with 

reference to the uniform cost thresholds the Agency selected 

at step two. The Transport Rule thus left open the 

possibility that a State might be compelled to reduce

emissions beyond the point at which every affected downwind State is in attainment, a phenomenon the Court of 

Appeals termed “over-control.” 696 F. 3d, at 22; see supra, 

at 12. Second, EPA’s focus on costs did not foreclose, as 

the D. C. Circuit accurately observed, the possibility that 

an upwind State would be required to reduce its emissions 

by so much that the State no longer contributed one per­

—————— 

21The dissent, see post, at 12–13, relies heavily on our decision in 

Whitman v. American Trucking Assns., Inc., 531 U. S. 457 (2001). In 

Whitman, we held that the relevant text of the CAA “unambiguously

bars” EPA from considering costs when determining a NAAQS. Id., at 

471. Section 7409(b)(1) commands EPA to set NAAQS at levels “requisite to protect the public health” with “an adequate margin of safety.” 

This mandate, we observed in Whitman, was “absolute,” and precluded 

any other consideration (e.g., cost) in the NAAQS calculation. Id., at 

465 (internal quotation marks omitted). Not so of the Good Neighbor

Provision, which grants EPA discretion to eliminate “amounts [of

pollution that] . . . contribute significantly to nonattainment” downwind. On the particular “amounts” that should qualify for elimination,

the statute is silent. Unlike the provision at issue in Whitman, which 

provides express criteria by which EPA is to set NAAQS, the Good 

Neighbor Provision, as earlier explained, fails to provide any metric by

which EPA can differentiate among the contributions of multiple

upwind States. See supra, at 21–22. 
 

Cite as: 572 U. S. ____ (2014) 29 

Opinion of the Court 

cent or more of a relevant NAAQS to any downwind State.

This would place the State below the mark EPA had set,

during the screening phase, as the initial threshold of 

“significan[ce].” See id., at 20, and n. 13. 

We agree with the Court of Appeals to this extent: EPA

cannot require a State to reduce its output of pollution by

more than is necessary to achieve attainment in every 

downwind State or at odds with the one-percent threshold 

the Agency has set. If EPA requires an upwind State to

reduce emissions by more than the amount necessary to

achieve attainment in every downwind State to which it is 

linked, the Agency will have overstepped its authority, 

under the Good Neighbor Provision, to eliminate those 

“amounts [that] contribute . . . to nonattainment.” Nor 

can EPA demand reductions that would drive an upwind 

State’s contribution to every downwind State to which it is

linked below one percent of the relevant NAAQS. Doing

so would be counter to step one of the Agency’s interpretation of the Good Neighbor Provision. See 76 Fed. Reg. 

48236 (“[S]tates whose contributions are below th[e] 

thresholds do not significantly contribute to nonattainment . . . of the relevant NAAQS.”). 

Neither possibility, however, justifies wholesale invalidation of the Transport Rule. First, instances of “overcontrol” in particular downwind locations, the D. C. Circuit acknowledged, see 696 F. 3d, at 22, may be incidental 

to reductions necessary to ensure attainment elsewhere. 

Because individual upwind States often “contribute significantly” to nonattainment in multiple downwind locations, 

the emissions reduction required to bring one linked

downwind State into attainment may well be large enough 

to push other linked downwind States over the attainment

line.22 As the Good Neighbor Provision seeks attainment 

—————— 

22The following example, based on the record, is offered in Brief for 

Respondent Calpine Corp. et al. in Support of Petitioners 52–54. Ohio, 
 

 

 

 

 

30 EPA v. EME HOMER CITY GENERATION, L. P. 

Opinion of the Court 

in every downwind State, however, exceeding attainment 

in one State cannot rank as “over-control” unless unnecessary to achieving attainment in any downwind State. 

Only reductions unnecessary to downwind attainment 

anywhere fall outside the Agency’s statutory authority.23 

Second, while EPA has a statutory duty to avoid overcontrol, the Agency also has a statutory obligation to avoid 

“under-control,” i.e., to maximize achievement of attainment downwind. For reasons earlier explained, see supra,

at 3–4, a degree of imprecision is inevitable in tackling the 

problem of interstate air pollution. Slight changes in wind

patterns or energy consumption, for example, may vary

downwind air quality in ways EPA might not have anticipated. The Good Neighbor Provision requires EPA to seek 

—————— 

West Virginia, Pennsylvania, and Indiana each contribute in varying

amounts to five different nonattainment areas in three downwind 

States. Id., at 52. Implementation of the Transport Rule, EPA modeling demonstrates, will bring three of these five areas into attainment

by a comfortable margin, and a fourth only barely. See id., at 53, fig. 2. 

The fifth downwind receptor, however, will still fall short of attainment

despite the reductions the rule requires. See ibid. But if EPA were to 

lower the emission reductions required of the upwind States to reduce 

over-attainment in the first three areas, the area barely achieving 

attainment would no longer do so, and the area still in nonattainment

would fall even further behind. Thus, “over-control” of the first three 

downwind receptors is essential to the attainment achieved by the

fourth and to the fifth’s progress toward that goal. 23The dissent suggests that our qualification of the term “overcontrol” is tantamount to an admission that “nothing stands in the way 

of [a] proportional-reduction approach.” Post, at 9. Not so. Permitting

“over-control” as to one State for the purpose of achieving attainment in

another furthers the stated goal of the Good Neighbor Provision, i.e., 

attainment of NAAQS. By contrast, a proportional-reduction scheme is

neither necessary to achieve downwind attainment, nor mandated by

the terms of the statute, as earlier discussed, see supra, at 21–25. 

Permitting “over-control” for the purpose of achieving proportionality 

would thus contravene the clear limits the statute places on EPA’s good

neighbor authority, i.e., to eliminate only those “amounts” of upwind

pollutants essential to achieving attainment downwind. 
Cite as: 572 U. S. ____ (2014) 31 

Opinion of the Court 

downwind attainment of NAAQS notwithstanding the

uncertainties. Hence, some amount of over-control, i.e., 

emission budgets that turn out to be more demanding 

than necessary, would not be surprising. Required to

balance the possibilities of under-control and over-control, 

EPA must have leeway in fulfilling its statutory mandate.

Finally, in a voluminous record, involving thousands of

upwind-to-downwind linkages, respondents point to only a

few instances of “unnecessary” emission reductions, and 

even those are contested by EPA. Compare Brief for

Industry Respondents 19 with Reply Brief for Federal 

Petitioners 21–22. EPA, for its part, offers data, contested 

by respondents, purporting to show that few (if any) upwind States have been required to limit emissions below 

the one-percent threshold of significance. Compare Brief

for Federal Petitioners 37, 54–55, with Brief for Industry 

Respondents 40.

If any upwind State concludes it has been forced to

regulate emissions below the one-percent threshold or

beyond the point necessary to bring all downwind States

into attainment, that State may bring a particularized, asapplied challenge to the Transport Rule, along with any 

other as-applied challenges it may have. Cf. Babbitt v. 

Sweet Home Chapter, Communities for Great Ore., 515 

U. S. 687, 699–700 (1995) (approving agency’s reasonable

interpretation of statute despite possibility of improper 

applications); American Hospital Assn. v. NLRB, 499 U. S. 

606, 619 (1991) (rejecting facial challenge to National 

Labor Relations Board rule despite possible arbitrary 

applications). Satisfied that EPA’s cost-based methodology, on its face, is not “arbitrary, capricious, or manifestly

contrary to the statute,” Chevron, 467 U. S., at 844, we 

uphold the Transport Rule. The possibility that the rule, 

in uncommon particular applications, might exceed EPA’s

statutory authority does not warrant judicial condemnation of the rule in its entirety. 
 

 

 

32 EPA v. EME HOMER CITY GENERATION, L. P. 

Opinion of the Court 

In sum, we hold that the CAA does not command that 

States be given a second opportunity to file a SIP after

EPA has quantified the State’s interstate pollution obligations. We further conclude that the Good Neighbor Provision does not require EPA to disregard costs and consider 

exclusively each upwind State’s physically proportionate 

responsibility for each downwind air quality problem. 

EPA’s cost-effective allocation of emission reductions 

among upwind States, we hold, is a permissible, workable, and equitable interpretation of the Good Neighbor 

Provision. 

* * * 

For the reasons stated, the judgment of the United 

States Court of Appeals for the D. C. Circuit is reversed, 

and the cases are remanded for further proceedings consistent with this opinion. 

It is so ordered.

 JUSTICE ALITO took no part in the consideration or 

decision of these cases. 
_________________ 

_________________ 

 

Cite as: 572 U. S. ____ (2014) 1 

SCALIA, J., dissenting 

SUPREME COURT OF THE UNITED STATES 

Nos. 12–1182 and 12–1183 

ENVIRONMENTAL PROTECTION AGENCY ET AL., 

PETITIONERS 

12–1182 v. 

EME HOMER CITY GENERATION, L. P., ET AL.; AND 

AMERICAN LUNG ASSOCIATION ET AL., 

PETITIONERS 

12–1183 v. 

EME HOMER CITY GENERATION, L. P., ET AL. 

ON WRITS OF CERTIORARI TO THE UNITED STATES COURT OF 

APPEALS FOR THE DISTRICT OF COLUMBIA CIRCUIT 

[April 29, 2014]

 JUSTICE SCALIA, with whom JUSTICE THOMAS joins,

dissenting. 

Too many important decisions of the Federal Government are made nowadays by unelected agency officials

exercising broad lawmaking authority, rather than by the

people’s representatives in Congress. With the statute 

involved in the present cases, however, Congress did it 

right. It specified quite precisely the responsibility of an

upwind State under the Good Neighbor Provision: to 

eliminate those amounts of pollutants that it contributes 

to downwind problem areas. But the Environmental 

Protection Agency was unsatisfied with this system. 

Agency personnel, perhaps correctly, thought it more

efficient to require reductions not in proportion to the 

amounts of pollutants for which each upwind State is

responsible, but on the basis of how cost-effectively each 

can decrease emissions. 
 

 

 

2 EPA v. EME HOMER CITY GENERATION, L. P. 

SCALIA, J., dissenting 

Today, the majority approves that undemocratic revision of the Clean Air Act. The Agency came forward with

a textual justification for its action, relying on a farfetched

meaning of the word “significantly” in the statutory text.

That justification is so feeble that today’s majority does

not even recite it, much less defend it. The majority

reaches its result (“Look Ma, no hands!”) without benefit

of text, claiming to have identified a remarkable “gap” in 

the statute, which it proceeds to fill (contrary to the plain 

logic of the statute) with cost-benefit analysis—and then,

with no pretended textual justification at all, simply extends cost-benefit analysis beyond the scope of the alleged 

gap.

Additionally, the majority relieves EPA of any obligation

to announce novel interpretations of the Good Neighbor 

Provision before the States must submit plans that are 

required to comply with those interpretations. By according the States primacy in deciding how to attain the governing air-quality standards, the Clean Air Act is pregnant with an obligation for the Agency to set those 

standards before the States can be expected to achieve

them. The majority nonetheless approves EPA’s promulgation of federal plans implementing good-neighbor

benchmarks before the States could conceivably have met 

those benchmarks on their own. 

I would affirm the judgment of the D. C. Circuit that

EPA violated the law both in crafting the Transport Rule 

and in implementing it.1 

I. The Transport Rule 

“It is axiomatic that an administrative agency’s power to

promulgate legislative regulations is limited to the authority delegated by Congress.” Bowen v. Georgetown Univ. 

—————— 

1 I agree with the majority’s analysis turning aside EPA’s threshold 

objections to judicial review. See ante, at 13–14, 18–19. 
Cite as: 572 U. S. ____ (2014) 3 

SCALIA, J., dissenting 

Hospital, 488 U. S. 204, 208 (1988). Yet today the majority treats the text of the Clean Air Act not as the source 

and ceiling of EPA’s authority to regulate interstate air 

pollution, but rather as a difficulty to be overcome in 

pursuit of the Agency’s responsibility to “craf[t] a solution

to the problem of interstate air pollution.” Ante, at 3. In 

reality, Congress itself has crafted the solution. The Good 

Neighbor Provision requires each State to eliminate whatever “amounts” of “air pollutant[s]” “contribute significantly 

to nonattainment” or “interfere with maintenance” of 

national ambient air-quality standards (NAAQS) in other

States. 42 U. S. C. §7410(a)(2)(D)(i)(I). The statute addresses solely the environmental consequences of emissions, not the facility of reducing them; and it requires

States to shoulder burdens in proportion to the size of

their contributions, not in proportion to the ease of bearing 

them. EPA’s utterly fanciful “from each according to its 

ability” construction sacrifices democratically adopted text 

to bureaucratically favored policy. It deserves no deference under Chevron U. S. A. Inc. v. Natural Resources 

Defense Council, Inc., 467 U. S. 837 (1984). 

A. Alleged Textual Support: “Significantly” 

In the Government’s argument here, the asserted textual support for the efficient-reduction approach adopted by 

EPA in the Transport Rule is the ambiguity of the word

“significantly” in the statutory requirement that each

State eliminate those “amounts” of pollutants that “contribute significantly to nonattainment” in downwind 

States. §7410(a)(2)(D)(i)(I) (emphasis added). As described in the Government’s briefing: 

“[T]he term ‘significantly’ . . . is ambiguous, and . . . 

EPA may permissibly determine the amount of a

State’s ‘significant’ contribution by reference to the 

amount of emissions reductions achievable through

application of highly cost-effective controls.” Reply 
 

 

4 EPA v. EME HOMER CITY GENERATION, L. P. 

SCALIA, J., dissenting 

Brief for Federal Petitioners 15–16 (emphasis added; 

some internal quotation marks omitted). 

And as the Government stated at oral argument: 

“[I]n terms of the language, ‘contribute significantly,’ 

. . . EPA reasonably construed that term to include a

component of difficulty of achievement [i.e., cost]; that

is, in common parlance, we might say that dunking a

basketball is a more significant achievement for 

somebody who is 5 feet 10 than for somebody who is 6 

feet 10.” Tr. of Oral Arg. 9 (emphasis added). 

But of course the statute does not focus on whether the 

upwind State has “achieved significantly”; it asks whether 

the State has “contributed significantly” to downwind

pollution. The provision addresses the physical effects of

physical causes, and it is only the magnitude of the relationship sufficient to trigger regulation that admits of 

some vagueness. Stated differently, the statute is ambiguous as to how much of a contribution to downwind pollution is “significant,” but it is not at all ambiguous as to

whether factors unrelated to the amounts of pollutants

that make up a contribution affect the analysis. Just as 

“[i]t does not matter whether the word ‘yellow’ is ambiguous when the agency has interpreted it to mean ‘purple,’” 

United States v. Home Concrete & Supply, LLC, 566 U. S. 

___, ___, n. 1 (2012) (SCALIA, J., concurring in part and

concurring in judgment) (slip op., at 2, n. 1), it does not 

matter whether the phrase “amounts which . . . contribute

significantly [to downwind NAAQS nonattainment]” is

ambiguous when EPA has interpreted it to mean 

“amounts which are inexpensive to eliminate.”

It would be extraordinary for Congress, by use of the 

single word “significantly,” to transmogrify a statute that

assigns responsibility on the basis of amounts of pollutants emitted into a statute authorizing EPA to reduce 

interstate pollution in the manner that it believes most 
Cite as: 572 U. S. ____ (2014) 5 

SCALIA, J., dissenting 

efficient. We have repeatedly said that Congress “does not 

alter the fundamental details of a regulatory scheme in

vague terms or ancillary provisions—it does not, one 

might say, hide elephants in mouseholes.” Whitman v. 

American Trucking Assns., Inc., 531 U. S. 457, 468 (2001) 

(citing MCI Telecommunications Corp. v. American Telephone & Telegraph Co., 512 U. S. 218, 231 (1994); FDA v. 

Brown & Williamson Tobacco Corp., 529 U. S. 120, 159– 

160 (2000)).

The statute’s history demonstrates that “significantly” is

not code for “feel free to consider compliance costs.” The 

previous version of the Good Neighbor Provision required 

each State to prohibit emissions that would “prevent attainment or maintenance by any other State of any

[NAAQS].” 91 Stat. 693 (emphasis added). It is evident 

that the current reformulation (targeting “any air pollutant in amounts which will . . . contribute significantly to 

nonattainment in, or interfere with maintenance by, any

other State with respect to any [NAAQS]”) was meant

simply to eliminate any implication that the polluting

State had to be a but-for rather than merely a contributing 

cause of the downwind nonattainment or maintenance 

problem—not to allow cost concerns to creep in through 

the back door. 

In another respect also EPA’s reliance upon the word

“significantly” is plainly mistaken. The Good Neighbor

Provision targets for elimination not only those emissions 

that “contribute significantly to nonattainment [of

NAAQS] in . . . any other State,” but also those that “interfere with maintenance [of NAAQS] by . . . any other 

State.” §7410(a)(2)(D)(i)(I). The wiggle-word “significantly” 

is absent from the latter phrase. EPA does not— 

cannot—provide any textual justification for the conclusion that, when the same amounts of a pollutant travel

downwind from States X and Y to a single area in State A,

the emissions from X but not Y can be said to “interfere 
 

 

6 EPA v. EME HOMER CITY GENERATION, L. P. 

SCALIA, J., dissenting 

with maintenance” of the NAAQS in A just because they 

are cheaper to eliminate. Yet EPA proposes to use the

“from each according to its ability” approach for nonattainment areas and maintenance areas. 

To its credit, the majority does not allude to, much less

try to defend, the Government’s “significantly” argument. 

But there is a serious downside to this. The sky-hook of 

“significantly” was called into service to counter the criterion of upwind-state responsibility plainly provided in the 

statute’s text: amounts of pollutants contributed to downwind problem areas. See Brief for Federal Petitioners 42– 

45. Having forsworn reliance on “significantly” to convert 

responsibility for amounts of pollutants into responsibility 

for easy reduction of pollutants, the majority is impaled

upon the statutory text. 

B. The Alleged “Gap” 

To fill the void created by its abandonment of EPA’s

“significantly” argument, the majority identifies a supposed gap in the text, which EPA must fill: While the text 

says that each upwind State must be responsible for its 

own contribution to downwind pollution, it does not say 

how responsibility is to be divided among multiple States 

when the total of their combined contribution to downwind 

pollution in a particular area exceeds the reduction that

the relevant NAAQS requires. In the example given by

the majority, ante, at 21–22, when each of three upwind 

States contributes 30 units of a pollutant to a downwind

State but the reduction required for that State to comply 

with the NAAQS is only 30 units, how will responsibility 

for that 30 units be apportioned? Wow, that’s a hard 

one—almost the equivalent of asking who is buried in

Grant’s Tomb. If the criterion of responsibility is amounts 

of pollutants, then surely shared responsibility must be 

based upon relative amounts of pollutants—in the majority’s example, 10 units for each State. The statute makes 
 

Cite as: 572 U. S. ____ (2014) 7 

SCALIA, J., dissenting 

no sense otherwise. The Good Neighbor Provision contains a gap only for those who blind themselves to the 

obvious in order to pursue a preferred policy. 

But not only does the majority bring in cost-benefit 

analysis to fill a gap that does not really exist. Having 

filled that “gap,” it then extends the efficiency-based principle to situations beyond the imaginary gap—that is, 

situations where no apportionment is required. Even 

where an upwind State contributes pollutants to only a 

single downwind State, its annual emissions “budget” will

be based not upon the amounts of pollutants it contributes, but upon what “pollution controls [are] available at 

the chosen cost thresholds.” Ante, at 9. EPA’s justification

was its implausible (and only half-applicable) notion that 

“significantly” imports cost concerns into the provision.

The majority, having abandoned that absurdity, is left to

deal with the no-apportionment situation with no defense—not even an imaginary gap—against a crystal-clear 

statutory text. 

C. The Majority’s Criticisms of Proportional Reduction

1. Impossibility 

The majority contends that a proportional-reduction

approach “could scarcely be satisfied in practice” and

“appears to work neither mathematically nor in practical 

application, ante, at 23—in essence, that the approach is

impossible of application. If that were true, I know of no 

legal authority and no democratic principle that would

derive from it the consequence that EPA could rewrite the 

statute, rather than the consequence that the statute

would be inoperative. “There are sometimes statutes 

which no rule or canon of interpretation can make effective or applicable to the situations of fact which they 

purport to govern. In such cases the statute must simply 

fail.” 3 R. Pound, Jurisprudence 493 (1959) (footnote

omitted). In other words, the impossibility argument has 
 

 

 

 

8 EPA v. EME HOMER CITY GENERATION, L. P. 

SCALIA, J., dissenting 

no independent force: It is relevant only if the majority’s

textual interpretation is permissible. But in any event, 

the argument is wrong.

The impossibility theorem rests upon the following 

scenario: “Imagine that States X and Y . . . contribute air 

pollution to State A in a ratio of one to five . . . .” Ante, at 

23. And suppose that “States X and Y also contribute 

pollutants to a second downwind State (State B), this time

in a ratio of seven to one.” Ibid. The majority concludes

that “[t]he Court of Appeals’ proportionality edict with 

respect to both State A and State B appears to work neither mathematically nor in practical application.” Ibid. 

But why not? The majority’s model relies on two faulty

premises—one an oversimplification and the other a misapprehension.

First, the majority’s formulation suggests that EPA 

measures the comparative downwind drift of pollutants in

free-floating proportions between States. In reality, however, EPA assesses quantities (in physical units), not 

proportions. So, the majority’s illustration of a 1-to-5 ratio

describing the relative contributions of States X and Y to

State A’s pollution might mean (for example) that X is

responsible for 0.2 unit of some pollutant above the

NAAQS in A and that Y is responsible for 1 unit. And 

the second example, assuming a 7-to-1 ratio underlying 

State X’s and Y’s contributions to State B’s pollution,

might mean that State X supplies 0.7 unit of the same pollutant above the NAAQS and State Y, 0.1 unit. Under a 

proportional-reduction approach, State X would be required to eliminate emissions of that pollutant by whatever minimum amount reduces both State A’s level by 0.2 

unit and State B’s by 0.7 unit. State Y, in turn, would be 

required to curtail its emissions by whatever minimum 

amount decreases both State A’s measure by 1 unit and

State B’s by 0.1 unit.

But, the majority objects, the reductions that State X 
Cite as: 572 U. S. ____ (2014) 9 

SCALIA, J., dissenting 

must make to help bring State B into compliance may be 

more than those necessary for it to help bring State A into 

compliance, resulting in “over-control” of X with respect to

A. See ante, at 23–25, and n. 19. This objection discloses

the second flaw in the impossibility theorem. Echoing 

EPA, see Brief for Federal Petitioners 47–48, the majority 

believes that the D. C. Circuit’s interpretation of the Good

Neighbor Provision forbids over-control with respect to

even a single downwind receptor. That is the only way in

which the proportional-reduction approach could be 

deemed “to work neither mathematically nor in practical

application” on its face. Ante, at 23. But the premise is 

incorrect. Although some of the D. C. Circuit’s simplified

examples might support that conclusion, its opinion explicitly acknowledged that the complexity of real-world conditions demands the contrary: “To be sure, . . . there may be

some truly unavoidable over-control in some downwind

States that occurs as a byproduct of the necessity of reducing upwind States’ emissions enough to meet the NAAQS 

in other downwind States.” 696 F. 3d 7, 22 (2012). Moreover, the majority itself recognizes that the Good Neighbor

Provision does not categorically prohibit over-control. “As 

the Good Neighbor Provision seeks attainment in every

downwind State, . . . exceeding attainment in one State

cannot rank as ‘over-control’ unless unnecessary to achieving attainment in any downwind State.” Ante, at 29–30. 

The majority apparently fails to appreciate that, having

cleared up that potential point of confusion, nothing 

stands in the way of the proportional-reduction approach.

The majority relies on an EPA document preceding the

Transport Rule to establish the Agency’s supposed belief 

that the proportional-reduction approach “could scarcely

be satisfied in practice.” Ante, at 23. But the document 

says no such thing. Rather, it shows that the Agency

rejected a proportion-based, “air[-]quality-only” methodology not because it was impossible of application, but be­
 

 

 

10 EPA v. EME HOMER CITY GENERATION, L. P. 

SCALIA, J., dissenting 

cause it failed to account for costs. See App. in No. 11– 

1302 etc. (CADC), pp. 2311–2312. The document labels as 

a “technical difficulty” (not an impossibility) the fact that

“most upwind states contribute to multiple downwind 

[receptors] (in multiple states) and would have a different 

reduction percentage for each one.” Id., at 2312. The 

Clean Air Act is full of technical difficulties, and this one 

is overcome by requiring each State to make the greatest

reduction necessary with respect to any downwind area. 

2. Over-Control 

Apparently conceding that the proportional-reduction

approach may not be impossible of application after all, 

the majority alternatively asserts that it would cause 

“costly overregulation unnecessary to, indeed in conflict

with, the Good Neighbor Provision’s goal of attainment.” 

Ante, at 24. This assertion of massive overregulation 

assumes that a vast number of downwind States will be 

the accidental beneficiaries of collateral pollution reductions—that is, nontargeted reductions that occur as a 

consequence of required reductions targeted at neighboring downwind States. (Collateral pollution reduction is 

the opposite of collateral damage, so to speak.) The majority contends that the collateral pollution reductions enjoyed by a downwind State will cause the required upwind 

reductions actually targeting that State to exceed the level 

necessary to assure attainment or maintenance, thus 

producing unnecessary over-control. I have no reason to 

believe that the problem of over-control is as extensive and 

thus “costly” as the majority alleges, and the majority

provides none.

But never mind that. It suffices to say that over-control

is no more likely to occur when the required reductions are 

apportioned among upwind States on the basis of amounts 

of pollutants contributed than when they are apportioned 

on the basis of cost. There is no conceivable reason why 
 

 

Cite as: 572 U. S. ____ (2014) 11 

SCALIA, J., dissenting 

the efficient-reduction States that bear the brunt of the 

majority’s (and EPA’s) approach are less likely to be overcontrolled than the major-pollution-causing States that

would bear the brunt of my (and the statute’s) approach. 

Indeed, EPA never attempted to establish that the

Transport Rule did not produce gross over-control. See 

696 F. 3d, at 27. What causes the problem of over-control

is not the manner of apportioning the required reductions,

but the composite volume of the required reductions in 

each downwind State. If the majority’s approach reduces

over-control (it admittedly does not entirely eliminate it),

that is only because EPA applies its cost-effectiveness

principle not just to determining the proportions of required reductions that each upwind State must bear, but

to determining the volume of those required reductions.

See supra, at 7. 

In any case, the solution to over-control under a proportional-reduction system is not difficult to discern. In 

calculating good-neighbor responsibilities, EPA would 

simply be required to make allowance for what I have 

called collateral pollution reductions. The Agency would

set upwind States’ obligations at levels that, after taking

into account those reductions, suffice to produce attainment in all downwind States. Doubtless, there are multiple ways for the Agency to accomplish that task in accordance with the statute’s amounts-based, proportional

focus.2 The majority itself invokes an unexplained device 

to prevent over-control “in uncommon particular applications” of its scheme. Ante, at 31. Whatever that device is, 

it can serve just as well to prevent over-control under the 

approach I have outlined. 

—————— 

2The majority insists that “proportionality cannot be one of those

ways.” Ante, at 25. But it is easy to imagine precluding unnecessary 

over-control by reducing in a percent-based manner the burdens of each

upwind State linked to a given downwind area, which would retain the 

proportionality produced by my approach. 
 

 

 

12 EPA v. EME HOMER CITY GENERATION, L. P. 

SCALIA, J., dissenting 

I fully acknowledge that the proportional-reduction 

approach will demand some complicated computations

where one upwind State is linked to multiple downwind 

States and vice versa. I am confident, however, that 

EPA’s skilled number-crunchers can adhere to the statute’s quantitative (rather than efficiency) mandate by 

crafting quantitative solutions. Indeed, those calculations 

can be performed at the desk, whereas the “from each 

according to its ability” approach requires the unwieldy

field examination of many pollution-producing sources

with many sorts of equipment. 

D. Plus Ça Change: 

EPA’s Continuing Quest for Cost-Benefit Authority 

The majority agrees with EPA’s assessment that 

“[u]sing costs in the Transport Rule calculus . . . makes

good sense.” Ante, at 26. Its opinion declares that 

“[e]liminating those amounts that can cost-effectively be 

reduced is an efficient and equitable solution to the allocation problem the Good Neighbor Provision requires the 

Agency to address.” Ibid. Efficient, probably. Equitable?

Perhaps so, but perhaps not. See Brief for Industry Respondents 35–36. But the point is that whether efficiency

should have a dominant or subordinate role is not for EPA 

or this Court to determine. 

This is not the first time EPA has sought to convert the

Clean Air Act into a mandate for cost-effective regulation. 

Whitman v. American Trucking Assns., Inc., 531 U. S. 457 

(2001), confronted EPA’s contention that it could consider 

costs in setting NAAQS. The provision at issue there, like 

this one, did not expressly bar cost-based decisionmaking—and unlike this one, it even contained words that 

were arguably ambiguous in the relevant respect. Specifically, §7409(b)(1) instructed EPA to set primary NAAQS

“the attainment and maintenance of which . . . are requisite to protect the public health” with “an adequate margin 
 

Cite as: 572 U. S. ____ (2014) 13 

SCALIA, J., dissenting 

of safety.” One could hardly overstate the capaciousness 

of the word “adequate,” and the phrase “public health” was

at least equally susceptible (indeed, much more susceptible) of permitting cost-benefit analysis as the word “significantly” is here. As the respondents in American Trucking

argued, setting NAAQS without considering costs may 

bring about failing industries and fewer jobs, which in 

turn may produce poorer and less healthy citizens. See 

id., at 466. But we concluded that “in the context of ” the 

entire provision, that interpretation “ma[de] no sense.” 

Ibid. As quoted earlier, we said that Congress “does not 

alter the fundamental details of a regulatory scheme in

vague terms or ancillary provisions—it does not . . . hide 

elephants in mouseholes.” Id., at 468. 

In American Trucking, the Court “refused to find implicit in ambiguous sections of the [Clear Air Act] an 

authorization to consider costs that has elsewhere, and so 

often, been expressly granted,” id., at 467, citing a tradition 

dating back to Union Elec. Co. v. EPA, 427 U. S. 246, 257, 

and n. 5 (1976). There are, indeed, numerous Clean Air 

Act provisions explicitly permitting costs to be taken into 

account. See, e.g., §7404(a)(1); §7521(a)(2); §7545(c)(2); 

§7547(a)(3); §7554(b)(2); §7571(b); §7651c(f)(1)(A). American Trucking thus demanded “a textual commitment of 

authority to the EPA to consider costs,” 531 U. S., at 468—

a hurdle that the Good Neighbor Provision comes nowhere 

close to clearing. Today’s opinion turns its back upon that

case and is incompatible with that opinion.3 

—————— 

3The majority shrugs off American Trucking in a footnote, reasoning

that because it characterized the provision there in question as “absolute,” it has nothing to say about the Good Neighbor Provision, which is 

not absolute. See ante, at 28, n. 21. This is a textbook example of 

begging the question: Since the Good Neighbor Provision is not absolute

(the very point at issue here), American Trucking, which dealt with a 

provision that is absolute, is irrelevant. To the contrary, American 

Trucking is right on point. As described in text, the provision at issue 
 

 

14 EPA v. EME HOMER CITY GENERATION, L. P. 

SCALIA, J., dissenting 

II. Imposition of Federal Implementation Plans 

The D. C. Circuit vacated the Transport Rule for the

additional reason that EPA took the reins in allocating

emissions budgets among pollution-producing sources

through Federal Implementation Plans (FIPs) without

first providing the States a meaningful opportunity to 

perform that task through State Implementation Plans 

(SIPs). The majority rejects that ruling on the ground

that “the Act does not require EPA to furnish upwind

States with information of any kind about their good 

neighbor obligations before a FIP issues.” Ante, at 16. 

“[N]othing in the statute,” the majority says, “places EPA 

under an obligation to provide specific metrics to States

before they undertake to fulfill their good neighbor obligations.” Ante, at 17. This remarkably expansive reasoning

makes a hash of the Clean Air Act, transforming it from a 

program based on cooperative federalism to one of centralized federal control. Nothing in the Good Neighbor Provision suggests such a stark departure from the Act’s fundamental structure. 

A. Implications of State Regulatory Primacy 

Down to its very core, the Clean Air Act sets forth a 

federalism-focused regulatory strategy. The Act begins by

declaring that “air pollution prevention (that is, the reduction or elimination, through any measures, of the amount 

of pollutants produced or created at the source) and air 

pollution control at its source is the primary responsibility 

of States and local governments.” §7401(a)(3) (emphasis

added). State primacy permeates Title I, which addresses

the promulgation and implementation of NAAQS, in particular. Under §7409(a), EPA must promulgate NAAQS 

for each pollutant for which air-quality criteria have been 

—————— 

here is even more categorical (“absolute”) than the provision at issue in
 

American Trucking. 
 

Cite as: 572 U. S. ____ (2014) 15 

SCALIA, J., dissenting 

issued pursuant to §7408. Section 7410(a)(1), in turn,

requires each State, usually within three years of each 

new or revised NAAQS, to submit a SIP providing for its

“implementation, maintenance, and enforcement.” EPA 

may step in to take over that responsibility if, and only if, 

a State discharges it inadequately. Specifically, if the

Agency finds that a State has failed to make a required or

complete submission or disapproves a SIP, it “shall promulgate a [FIP] at any time within 2 years . . . , unless the 

State corrects the deficiency, and [EPA] approves the [SIP]

or [SIP] revision.” §7410(c)(1).

To describe the effect of this statutory scheme in simple 

terms: After EPA sets numerical air-quality benchmarks, 

“Congress plainly left with the States . . . the power to 

determine which sources would be burdened by regulation

and to what extent.” Union Elec. Co., 427 U. S., at 269. 

The States are to present their chosen means of achieving 

EPA’s benchmarks in SIPs, and only if a SIP fails to meet

those goals may the Agency commandeer a State’s authority by promulgating a FIP. “[S]o long as the ultimate

effect of a State’s choice of emission limitations is compliance with the [NAAQS], the State is at liberty to adopt 

whatever mix of emission limitations it deems best suited 

to its particular situation.” Train v. Natural Resources 

Defense Council, Inc., 421 U. S. 60, 79 (1975). EPA, we 

have emphasized, “is relegated by the Act to a secondary 

role in the process of determining and enforcing the specific, source-by-source emission limitations which are 

necessary if the [NAAQS] are to be met.” Ibid. 

The Good Neighbor Provision is one of the requirements 

with which SIPs must comply. §7410(a)(2)(D)(i)(I). The 

statutory structure described above plainly demands that 

EPA afford States a meaningful opportunity to allocate 

reduction responsibilities among the sources within their 

borders. But the majority holds that EPA may in effect 

force the States to guess at what those responsibilities 
 

 

16 EPA v. EME HOMER CITY GENERATION, L. P. 

SCALIA, J., dissenting 

might be by requiring them to submit SIPs before learning 

what the Agency regards as a “significan[t]” contribution—with the consequence of losing their regulatory

primacy if they guess wrong. EPA asserts that the D. C. 

Circuit “was wrong as a factual matter” in reasoning that 

States cannot feasibly implement the Good Neighbor 

Provision without knowing what the Agency considers 

their obligations to be. Brief for Federal Petitioners 29. 

That is literally unbelievable. The only support that EPA 

can muster are the assertions that “States routinely undertake technically complex air quality determinations” 

and that “emissions information from all States is publicly 

available.” Ibid. As respondents rightly state: “All the 

scientific knowledge in the world is useless if the States

are left to guess the way in which EPA might ultimately 

quantify ‘significan[ce].’” Brief for State Respondents 50.

Call it “punish[ing] the States for failing to meet a

standard that EPA had not yet announced and [they] did 

not yet know,” 696 F. 3d, at 28; asking them “to hit the 

target . . . before EPA defines [it],” id., at 32; requiring 

them “to take [a] stab in the dark,” id., at 35; or “set[ting] 

the States up to fail,” id., at 37. Call it “hid[ing] the ball,” 

Brief for State Respondents 20; or a “shell game,” id., at 

54. Call it “pin the tail on the donkey.” Tr. of Oral Arg. 

24. As we have recently explained: 

“It is one thing to expect regulated parties to conform 

their conduct to an agency’s interpretations once the 

agency announces them; it is quite another to require 

regulated parties to divine the agency’s interpretations in advance or else be held liable when the 

agency announces its interpretations for the first

time . . . and demands deference.” Christopher v. 

SmithKline Beecham Corp., 567 U. S. ___, ___ (2012) 

(slip op., at 14). 

That principle applies a fortiori to a regulatory regime 
Cite as: 572 U. S. ____ (2014) 17 

SCALIA, J., dissenting 

that rests on principles of cooperative federalism. 

B. Past EPA Practice 

EPA itself has long acknowledged the proposition that it 

is nonsensical to expect States to comply with the Good

Neighbor Provision absent direction about what constitutes a “significan[t]” contribution to interstate pollution. 

The Agency consistently adopted that position prior to

the Transport Rule. In 1998, when it issued the NOX SIP 

Call under §7410(k)(5), EPA acknowledged that “[w]ithout

determining an acceptable level of NOX reductions, the 

upwind State would not have guidance as to what is an

acceptable submission.” 63 Fed. Reg. 57370. EPA deemed 

it “most efficient—indeed necessary—for the Federal

government to establish the overall emissions levels for 

the various States.” Ibid. Accordingly, the Agency quantified good-neighbor responsibilities and then allowed 

States a year to submit SIPs to implement them. Id., at 

57450–57451. 

Similarly, when EPA issued the Clean Air Interstate

Rule (CAIR) in 2005 under §7410(c), it explicitly “recognize[d] that States would face great difficulties in developing transport SIPs to meet the requirements of today’s

action without th[e] data and policies” provided by the 

Rule, including “judgments from EPA concerning the 

appropriate criteria for determining whether upwind

sources contribute significantly to downwind nonattainment under [§74]10(a)(2)(D).” 70 id., at 25268–25269. 

The Agency thus gave the States 18 months to submit

SIPs implementing their new good-neighbor responsibilities. See id., at 25166–25167, 25176. Although EPA

published FIPs before that window closed, it specified that 

they were meant to serve only as a “Federal backstop” and 

would not become effective unless necessary “a year after

the CAIR SIP submission deadline.” 71 id., at 25330– 

25331 (2006). 
 

 

18 EPA v. EME HOMER CITY GENERATION, L. P. 

SCALIA, J., dissenting 

Even since promulgating the Transport Rule, EPA has

repeatedly reaffirmed that States cannot be expected to

read the Agency’s mind. In other proceedings, EPA has 

time and again stated that although “[s]ome of the elements of the [SIP-submission process] are relatively 

straightforward, . . . others clearly require interpretation

by EPA through rulemaking, or recommendations through

guidance, in order to give specific meaning for a particular

NAAQS.” 76 id., at 58751 (2011). As an example of the

latter, the Agency has remarked that the Good Neighbor 

Provision “contains numerous terms that require substantial rulemaking by EPA in order to determine such basic

points as what constitutes significant contribution,” citing

CAIR. Ibid., n. 6. In fact, EPA repeated those precise 

statements not once, not twice, but 30 times following

promulgation of the Transport Rule.4 

Notwithstanding what parties may have argued in other 

litigation many years ago, it is beyond responsible debate 

that the States cannot possibly design FIP-proof SIPs

without knowing the EPA-prescribed targets at which

they must aim. EPA insists that it enjoys significant

discretion—indeed, that it can consider essentially whatever factors it wishes—to determine what constitutes a 

“significan[t]” contribution to interstate pollution; and it

simultaneously asserts that the States ought to know

what quantities it will choose. The Agency—and the 

—————— 

4 In addition to the citations in text, see 77 Fed. Reg. 50654, and n. 7 

(2012); id., at 47577, and n. 7; id., at 46363, and n. 7; id., at 46356, and 

n. 9; id., at 45323, and n. 7; id., at 43199, and n. 7; id., at 38241, and 

n. 6; id., at 35912, and n. 7; id., at 34909, and n. 7; id., at 34901, and n. 

8; id., at 34310, and n. 7; id., at 34291, and n. 8; id., at 33384, and n. 7; 

id., at 33375, and n. 7; id., at 23184, and n. 7; id., at 22543, and n. 4; 

id., at 22536, and n. 7; id., at 22253, and n. 8; id., at 21915, and n. 7; 

id., at 21706, and n. 6; id., at 16788, and n. 4; id., at 13241, and n. 5; 

id., at 6715, and n. 7; id., at 6047, and n. 4; id., at 3216, and n. 7; 76 id., 

at 77955, and n. 7 (2011); id., at 75852, and n. 7; id., at 70943, and n. 6; 

id., at 62636, and n. 3. 
 

 

 

Cite as: 572 U. S. ____ (2014) 19 

SCALIA, J., dissenting 

majority—cannot have it both ways. 

C. Abuse of Discretion 

The majority attempts to place the blame for hollowing

out the core of the Clean Air Act on “the Act’s plain text.” 

Ante, at 16. The first textual element to which it refers is 

§7410(c)’s requirement that after EPA has disapproved a

SIP, it “shall promulgate a [FIP] at any time within 2 

years.” That is to say, the Agency has discretion whether

to act at once or to defer action until some later point 

during the 2-year period. But it also has discretion to 

work within the prescribed timetable to respect the rightful role of States in the statutory scheme by delaying the

issuance or enforcement of FIPs pending the resubmission

and approval of SIPs—as EPA’s conduct surrounding 

CAIR clearly demonstrates. And all of this assumes that 

the Agency insists on disapproving SIPs before promulgating the applicable good-neighbor standards—though in

fact EPA has discretion to publicize those metrics before 

the window to submit SIPs closes in the first place.

The majority states that the Agency “retained discretion 

to alter its course” from the one pursued in the NOX SIP 

Call and CAIR, ante, at 17, but that misses the point.

The point is that EPA has discretion to arrange things so 

as to preserve the Clean Air Act’s core principle of state

primacy—and that it is an abuse of discretion to refuse to 

do so. See §7607(d)(9)(A); see also 5 U. S. C. §706(2)(A)

(identical text in the Administrative Procedure Act).

Indeed, the proviso in §7410(c)(1) that the Agency’s authority to promulgate a FIP within the 2-year period

terminates if “the State corrects the deficiency, and [EPA] 

approves the [SIP] or [SIP] revision” explicitly contemplates just such an arrangement.5 

—————— 

5 I am unimpressed, by the way, with the explanation that the majority accepts for EPA’s about-face: that the D. C. Circuit admonished it to

“act with dispatch in amending or replacing CAIR.” Ante, at 18 (citing 
 

 

 

20 EPA v. EME HOMER CITY GENERATION, L. P. 

SCALIA, J., dissenting 

The majority’s conception of administrative discretion is 

so sprawling that it would allow EPA to subvert state 

primacy not only with respect to the interstate-pollution

concerns of the Good Neighbor Provision, but with respect 

to the much broader concerns of the NAAQS program 

more generally. States must submit SIPs “within 3 years”

of each new or revised NAAQS “or such shorter period as 

[EPA] may prescribe.” §7410(a)(1) (emphasis added). 

Because there is no principled reason to read that scheduling provision in a less malleable manner than the one at 

issue here, under the majority’s view EPA could demand

that States submit SIPs within a matter of days—or even 

hours—after a NAAQS publication or else face the immediate imposition of FIPs. 

The second element of “plain text” on which the majority 

relies is small beer indeed. The Good Neighbor Provision 

does not expressly state that EPA must publish target 

quantities before the States are required to submit SIPs—

even though the Clean Air Act does so for NAAQS more 

generally and for vehicle inspection and maintenance 

programs, see §7511a(c)(3)(B). From that premise, the 

majority reasons that “[h]ad Congress intended similarly

to defer States’ discharge of their obligations under the

Good Neighbor Provision, Congress . . . would have included 

a similar direction in that section.” Ante, at 17. Perhaps so. But EPA itself read the statute differently when 

it declared in the NOX SIP Call that “[d]etermining the 

overall level of air pollutants allowed to be emitted in a 

State is comparable to determining [NAAQS], which the 

courts have recognized as EPA’s responsibility, and is 

—————— 

North Carolina v. EPA, 550 F. 3d 1176, 1178 (2008) (per curiam)).

Courts of Appeals’ raised eyebrows and wagging fingers are not law,

least so when they urge an agency to take ultra vires action. Nor can 

the encouragement to act illegally qualify as a “good reaso[n]” for an

agency’s alteration of course under FCC v. Fox Television Stations, Inc., 

556 U. S. 502, 515 (2009). 
 

Cite as: 572 U. S. ____ (2014) 21 

SCALIA, J., dissenting 

distinguishable from determining the particular mix of 

controls among individual sources to attain those standards, which the caselaw identifies as a State responsibility.” 63 Fed. Reg. 57369 (emphasis added).

The negative implication suggested by a statute’s failure

to use consistent terminology can be a helpful guide to

determining meaning, especially when all the provisions

in question were enacted at the same time (which is not 

the case here). But because that interpretive canon, like 

others, is just one clue to aid construction, it can be overcome by more powerful indications of meaning elsewhere

in the statute. It is, we have said, “no more than a rule of 

thumb that can tip the scales when a statute could be read

in multiple ways.” Sebelius v. Auburn Regional Medical 

Center, 568 U. S. ___, ___ (2013) (slip op., at 9) (internal

quotation marks and brackets omitted). The Clean Air 

Act simply cannot be read to make EPA the primary regulator in this context. The negative-implication canon is

easily overcome by the statute’s state-respecting structure—not to mention the sheer impossibility of submitting 

a sensible SIP without EPA guidance. Negative implication is the tiniest mousehole in which the majority discovers the elephant of federal control. 

* * * 

Addressing the problem of interstate pollution in the 

manner Congress has prescribed—or in any other manner, 

for that matter—is a complex and difficult enterprise. But 

“[r]egardless of how serious the problem an administrative

agency seeks to address, . . . it may not exercise its authority ‘in a manner that is inconsistent with the administrative structure that Congress enacted into law.’” Brown & 

Williamson, 529 U. S., at 125 (quoting ETSI Pipeline

Project v. Missouri, 484 U. S. 495, 517 (1988)). The majority’s approval of EPA’s approach to the Clean Air Act 

violates this foundational principle of popular government. 

 I dissent.