COMMENTS OF THE ATTORNEYS GENERAL OF NEW YORK, 

CALIFORNIA, MASSACHUSETTS, CONNECTICUT, DELAWARE, MAINE,

MARYLAND, NEW MEXICO, OREGON, RHODE ISLAND, VERMONT, 

WASHINGTON, AND THE DISTRICT OF COLUMBIA ON THE DESIGN OF 

A PROGRAM TO REDUCE CARBON POLLUTION FROM 

EXISTING POWER PLANTS 

Executive Summary

The Environmental Protection Agency is soliciting input from stakeholders in 

developing a proposed rule under section 111(d) of the Clean Air Act (Act) to 

address greenhouse gas emissions from existing power plants: the largest source of 

greenhouse gas emissions in the nation. The Act requires EPA to ensure that 

States achieve emission reductions from existing power plants necessary to protect 

human health and welfare from the harms of carbon pollution. As part of its

outreach effort in advance of proposing a rule in June 2014, EPA has requested the 

view of States on several aspects of regulation under section 111(d), including 

determining the best system of emission reduction and designing criteria by which 

to evaluate the adequacy of state programs. 

The Attorneys General of New York, California, Massachusetts, Connecticut, 

Delaware, Maine, Maryland, New Mexico, Oregon, Rhode Island, Vermont, 

Washington, and the District of Columbia submit these comments in response to 

that request and on related issues concerning EPA’s vital obligation to limit 

greenhouse gas emissions from existing power plants. Although each of the 

undersigned States has already taken significant steps to reduce greenhouse gas

pollution emitted by the power sector, substantial work remains. 

Section I of these comments provides background on the importance of EPA’s 

rulemaking to address carbon pollution from existing power plants. First, we

discuss the serious and well-recognized harms caused by carbon pollution and 

associated with climate change. Against this backdrop, we summarize how EPA 

finally reached the point of regulating greenhouse gas emissions from power plants. 

We then explain the various programs that, in the absence of EPA action until now, 

States have implemented to reduce greenhouse gas emissions from the power 

industry cost-effectively. These approaches include renewable portfolio standards, 

market-based cap-and-trade systems, planned retirements of coal-fired power 

plants, demand management and energy efficiency programs. 

Section II discusses EPA’s legal authority to regulate greenhouse gas 

emissions from existing power plants under section 111(d), including the text and 

legislative history supporting such regulation. Because EPA is regulating 

greenhouse gas emissions from new power plants under section 111(b) and 

greenhouse gases are not regulated as criteria pollutants or as hazardous air 

pollutants, EPA must regulate those emissions from existing power plants under 
section 111(d). The obligation to act is further supported by EPA’s longstanding 

interpretation of the scope of its authority to regulate under section 111(d), which 

was not altered by Congress’s amendment of the statute in 1990. 

Section III concerns the substantive aspects of regulation under section 

111(d), including its cooperative federalism framework and EPA’s role within this 

structure. Although some State Attorneys General have sought to relegate EPA to 

a perfunctory procedural role, EPA’s role is far more central. EPA is first tasked 

with issuing emission guidelines that include minimum substantive emission 

limitations. In doing so, the Act authorizes EPA to determine the degree of emission 

limitation achievable when the best system of emission reduction, as determined by 

EPA to have been adequately demonstrated, is applied. To make this 

determination, EPA must consider a range of systems, including source-based and

system-based1 approaches of emission reduction. Then, EPA prescribes how to 

measure the achievable emission limitation, for example, with a pounds per 

megawatt hour emission rate, or a tons per year mass emission limit. Many 

existing programs that States have employed to begin the urgent task of reducing 

greenhouse gas emissions from the power sector should inform EPA’s determination 

of the reductions achievable.

Finally, in Section IV, we look at the States’ critical responsibilities under 

section 111(d). EPA sets the required degree of emission reduction, but each State 

must actually determine how to regulate its existing sources through its own state

plan. Because section 111(d) puts the States in the driver’s seat to implement and 

enforce the required emission reductions, EPA must give the States options to 

demonstrate compliance with its emission guidelines and tell the States how to 

show that their plans are equivalent to such guidelines. Such alternative 

mechanisms may include trading and other existing state programs, use of multiyear compliance periods, regional cooperation, and phased reductions if, among 

other things, the proposed standards are enforceable and the reductions are

measurable and timely achieved. In short, the statute gives EPA and the States 

sufficient flexibility to achieve meaningful reductions of greenhouse gas emissions

quickly and in a cost-effective way.

1 In its request for input in advance of EPA’s proposed section 111(d) rule, EPA referred to two 

options for addressing carbon pollution from existing power plants, a “source-based approach” and a 

“system-based approach.” CONSIDERATIONS IN THE DESIGN OF A PROGRAM TO REDUCE CARBON 

POLLUTION FROM EXISTING POWER PLANTS (Sept. 23, 2013), available at

http://www2.epa.gov/sites/production/files/2013-09/documents/20130923statequestions.pdf. EPA 

explained that “[a] system-based approach evaluates a broader portfolio of measures including those 

that could be taken beyond the affected sources but still reduce emissions at the source.” Id. at 1-2. 

These comments accordingly use the terms “system-based approach” or a “system-wide approach” to 

mean industry-wide or power sector-wide systems of emission reduction.

2

 
I. The Urgency of Aggressively Addressing the Largest Sources of 

Carbon Pollution

In Massachusetts v. EPA, 549 U.S. 497, 521 (2007), the Supreme Court noted 

that “[t]he harms associated with climate change are serious and well recognized.” 

As the recent draft U.S. Climate Action Report prepared by the Department of State 

succinctly states: “The scientific consensus . . . is that anthropogenic emissions of 

greenhouse gases are causing changes in the climate that include rising average 

national and global temperatures, warming oceans, rising average sea levels, more 

extreme heat waves and storms, extinctions of species, and loss of biodiversity.”

Climate Action Report 2014, U.S. Biennial Report – Highlights at 2.2 The release of 

atmospheric carbon dioxide from human activities is also the primary cause of 

ocean acidification, which causes changes to ecosystems and marine biodiversity,

potentially impacting food security and the economy.3 A recent report confirmed 

that “[t]he ocean continues to acidify at an unprecedented rate in Earth’s history,” 

with a projected increase of 170 percent in ocean acidity by 2100 compared with 

preindustrial levels if carbon dioxide emissions are not reduced.4 Significant 

reductions in greenhouse gas emissions must occur to prevent increases in the 

frequency, magnitude and scale of the adverse impacts of climate change pollution, 

which include:

• more heat-related deaths and illnesses;

• higher smog levels, increasing the rate of asthma, pneumonia and 

bronchitis;

• extreme weather, including storms, floods and droughts;

• loss of water supplies due to increased salinity and saltwater intrusion;

• coastal land loss due to inundation, erosion, submergence and habitat 

loss from a rising sea level;

• increased risk of wildfire;

• loss of snowpack in California’s Sierra Nevada and the Cascade 

mountains in Oregon and Washington;

• ocean acidification;

• threats to ecosystems from the Adirondacks in New York to the Sierra 

Nevada in California;

• disappearance of plant and animal species and a rise of insect-borne 

illnesses, destructive fungi and pests;

• displacement of cold water fish species such as native brook trout in 

New York;

2 Available at http://www.state.gov/e/oes/climate/ccreport2014/index.htm.

3 Ocean Acidification Summary for Policymakers, Third Symposium on the Ocean in a High-CO2 

World, available at http://www.igbp.net/publications/summariesforpolicymakers/summariesforpolicy 

makers/oceanacidificationsummaryforpolicymakers2013.5.30566fc6142425d6c9111f4.html.

4 Id.

3

 
• warmer stream temperatures and reduced stream flow, threatening 

Chinook salmon, coho salmon and steelhead trout species in California, 

Oregon and Washington;

• reduced hydroelectric production from snowmelt-driven shifts in 

stream flow;

• threats to our food production, agriculture and forest productivity;

• threats to our energy, transportation and water resource 

infrastructure; and 

• increased environmental pressures on certain communities in lowlying areas, particularly in Alaskan indigenous communities.

The Supreme Court’s decision not to disturb a federal court of appeals’ ruling 

upholding EPA’s determination that greenhouse gas emissions endanger public 

health and welfare ends the legal debate on climate science, Coalition for 

Responsible Regulation v. EPA, 684 F.3d 102 (D.C. Cir. 2012), cert. denied, 82 

U.S.L.W. 3214 (U.S. Oct. 15, 2013) (No. 12-1272), switching the focus squarely to 

what the federal government and the States can do to address these emissions. 

 

A. The history of federal regulation of power plant greenhouse 

gas emissions

In 2006, after EPA revised its new source performance standards (NSPS) for 

power plants and failed to include standards for greenhouse gas emissions, the 

States of New York, Connecticut, California, Delaware, Maine, New Mexico, 

Oregon, Rhode Island, Vermont, Washington, the Commonwealth of Massachusetts, 

the District of Columbia and the City of New York filed a petition seeking judicial 

review of that failure. New York v. EPA (D.C. Cir. No. 06-1322). The matter was 

ultimately remanded to the agency after the Supreme Court’s decision in 

Massachusetts v. EPA, and in 2010, the parties entered into a settlement agreement 

setting a schedule for EPA to propose and promulgate NSPS for greenhouse gas 

emissions from new and existing power plants. 

Although EPA failed to meet that rulemaking schedule, on June 25, 2013, 

President Obama issued a memorandum to the Administrator of the EPA, in which 

he directed the Administrator to fulfill her statutory duty under sections 111(b) and 

111(d) of the Act “to issue standards, regulations, or guidelines, as appropriate, that 

address carbon pollution from modified, reconstructed, and existing power plants 

and build on State efforts to move toward a cleaner power sector.” The President 

established new dates for the Administrator to issue a new proposal for NSPS for 

greenhouse gas emissions, for the Administrator to propose and finalize emission 

guidelines for existing power plants, and for the States to submit their 

implementation plans pursuant to those guidelines. 

4
EPA proposed NSPS for greenhouse gas 

emissions from new power plants on September 

20, 2013.5 As discussed below, the proposal 

triggered EPA’s obligation to proceed with 

rulemaking under section 111(d), which governs 

regulation of air pollutants for existing sources 

that if new, would be subject to the NSPS. 

EPA’s authority to act under section 111 is 

supported by the Supreme Court’s decision in 

American Electric Power v. Connecticut, 131 S. 

Ct. 2527, 2537 (2011) (AEP), where the Court 

specifically pointed to section 111 in finding that 

the Act “speaks directly” to carbon dioxide 

emissions from power plants and that therefore, 

the Act “and the EPA actions it authorizes” 

displace any federal common law right of action 

to abate carbon dioxide emissions from fossil 

fuel-fired power plants.6

B. State efforts to curb power plant greenhouse gas emissions

Rather than simply wait for federal action, many States moved forward 

independently to implement programs to reduce greenhouse gas emissions from 

fossil fuel-fired power plants. Twenty States and the District of Columbia have set 

greenhouse gas emissions targets, reduced levels of emissions that each State has 

committed to achieve by a specified time.7 States have employed different 

strategies to curb emissions, some of which are highlighted below.

Renewable portfolio standards

Most States now have renewable portfolio standards that require electricity 

providers to obtain a given amount of their electricity from sources such as wind or 

solar energy. These standards create demand for new renewable power generation, 

which can displace generation from existing fossil fuel-fired sources. 

5 EPA had previously proposed an NSPS for greenhouse gas emissions from new power plants on 

April 13, 2012. 77 Fed. Reg. 22,392 (April 13, 2012). After receiving and reviewing more than a 

million public comments on the proposal, EPA decided to issue a new proposal. See

http://www2.epa.gov/sites/production/files/2013-09/documents/20130920proposal.pdf.

6 Because AEP concerned existing power plants, not new ones, the Court’s reference to EPA’s 

authority under the NSPS provisions of the Act to abate carbon dioxide emissions from fossil fuelfired power plants must be to regulation under section 111(d).

7 See http://www.c2es.org/us-states-regions/policy-maps/emissions-targets.

“The unique 

characteristics of carbon 

pollution and the 

interconnected nature of 

the electric power sector 

call for a broad and 

flexible approach to 

designing the program for 

existing power plants.”

EPA Overview Presentation 

of Clean Air Act Section 111

(minute 27:49), available at

http://www2.epa.gov/carbonpollution-standards/what-epadoing#overview.

5

 
Under these programs, state renewable energy targets range from 1.5 

percent (Iowa) to 40 percent (Hawaii), with compliance due over a range of time 

periods. Emission reductions attributable to these standards depend on the level 

and design of the standards and other state-specific factors, like the carbon 

intensity of existing sources and changes in demand. New York’s effort to meet its 

renewable target of 30 percent by 2015 has already eliminated millions of tons of 

carbon dioxide, in addition to other pollutants. The World Resources Institute has 

projected that even States with relatively modest standards of between 8 and 12.5 

percent can achieve reductions in emissions from existing power plants.8

Market-based systems

A number of Northeastern and mid-Atlantic States have joined together to 

reduce greenhouse gas emissions from existing power plants in their States through 

a regional cap-and-trade system known as the Regional Greenhouse Gas Initiative 

(RGGI).9 Pursuant to each RGGI State’s own regulations, regulated power plants

must acquire, either at auction or on a secondary market, one emission allowance 

for each ton of carbon dioxide emitted. RGGI has succeeded in reducing carbon 

dioxide emissions from the power sector by more than 40 percent below 2005 levels, 

with further reductions projected. At the same time, these States have used the 

proceeds from allowance auctions to fund investments in energy efficiency, further 

reducing demand and generating large net economic benefits (hence the coining of 

the term a “cap-and-invest” program). For example, a recent analysis of RGGI’s 

costs and benefits in the participating States found that the program produces a net 

benefit of $1.6 billion in the region (net present value), based on the first three-year 

compliance period.10

8 See Michael Obeiter et al., World Resources Institute, Power Sector Opportunities for Reducing 

Carbon Dioxide Emissions: Ohio 2 (2013), available at

http://www.wri.org/sites/default/files/power_sector_opportunities_for_reducing_carbon_dioxide_emiss

ions_ohio_summary.pdf; Michael Obeiter et al., World Resources Institute, Power Sector 

Opportunities for Reducing Carbon Dioxide Emissions: North Carolina 2 (2013), available at

http://www.wri.org/sites/default/files/power_sector_opportunities_for_reducing_carbon_dioxide_emiss

ions_north_carolina_summary.pdf; Michael Obeiter et al., World Resources Institute, Power Sector 

Opportunities for Reducing Carbon Dioxide Emissions: Michigan 2 (2013), available at

http://www.wri.org/sites/default/files/power_sector_opportunities_for_reducing_carbon_dioxide_emiss

ions_michigan_summary.pdf; Michael Obeiter et al., World Resources Institute, Power Sector 

Opportunities for Reducing Carbon Dioxide Emissions: Pennsylvania 2 (2013), available at

http://www.wri.org/sites/default/files/power_sector_opportunities_for_reducing_carbon_dioxide_e

missions_pennsylvania_summary.pdf.

9 The States that currently participate in RGGI are Connecticut, Delaware, Maine, Maryland, 

Massachusetts, New Hampshire, New York, Rhode Island, and Vermont.

10 See Analysis Group, The Economic Impacts of the Regional Greenhouse Gas Initiative on Ten 

Northeast and Mid-Atlantic States (2011), available at

http://www.analysisgroup.com/uploadedFiles/Publishing/Articles/Economic_Impact_RGGI_Report.pd

f.

6

 
California’s economy-wide cap-and-trade program likewise requires power 

plants to obtain allowances or credits sufficient to match their emissions. The 

program is a key element of the State’s efforts to reduce emissions to 1990 levels by 

2020, as required by the California Global Warming Solutions Act. See CAL.

HEALTH & SAFETY CODE §§ 38550, 38562(a). California projects the combination of 

cap and trade, a renewable portfolio standard, energy efficiency standards for 

consumer and industrial products, and other programs will reduce power sector

emissions by at least 25 percent from 2005 levels by 2025. The state board has set a

declining cap on emissions at a level deemed necessary to achieve the statute’s 

emissions reductions goals, and thus can use the cap as a backstop in the event 

other programs in California’s portfolio fall short of achieving their projected 

reductions.

Demand management

States have achieved significant cost-effective emission reductions and saved 

ratepayers money through efforts to reduce demand for electricity generation. More 

than half of the States require utilities to adopt Energy Efficiency Resource 

Standards, reducing demand by a specified amount each year.11 

Retirement planning and plant refurbishment

Some States have enacted laws to encourage the retirement of old, inefficient 

power plants. Colorado’s Clean Air Clean Jobs Act, HB-1365, required utilities to 

develop plans to reduce carbon dioxide and other emissions from their coal-fired 

power plants. The law encouraged utilities drafting those plans to consider retiring 

those plants and investing in energy efficiency programs, and allowed utilities to 

recover the costs of such changes. The State’s largest utility, Xcel Energy, developed 

a plan to replace coal-fired power plants with natural gas-fired plants. Xcel projects 

its plan will reduce its carbon dioxide emission by 28 percent by 2020 and its 

emissions of other pollutants like sulfur and nitrogen oxides and mercury by more 

than 80 percent each. A similar law in Minnesota led Xcel to replace two existing 

coal-fired power plants and refurbish another, leading to a 21 percent reduction in 

greenhouse gas emissions.

Energy efficiency programs

Other state efforts include energy efficiency standards for consumer products 

and commercial and industrial equipment, residential and commercial building 

codes, and incentives for consumers to adopt more efficient technologies, and 

11 See American Council for an Energy-Efficient Economy, The 2013 State Energy Efficiency 

Scorecard 19-20 (2013), available at http://aceee.org/research-report/e13k.

7

 
investment in energy efficiency projects. Massachusetts’ energy efficiency programs 

have been so successful that the Independent System Operator New England (ISONE), New England’s regional transmission organization which operates the bulk 

electric power generation and transmission system for New England and 

administers wholesale electricity markets, has begun to take the programs into 

account for purposes of its long term load forecasting. For the period 2016 through 

2022, ISO-NE is projecting that, with state energy efficiency investments fully 

included, load growth will remain flat at about 132,000 GWh.12 Such flat load 

growth means that customers reduce energy costs by 1) avoiding the cost of energy 

that would have been used absent energy efficiency; 2) reducing overall energy 

prices since lower demand results in lower prices for everyone; and 3) avoiding 

generation, transmission, and distribution infrastructure costs system-wide. By 

contrast, without including state energy efficiency programs in the projection, load 

growth is forecasted to increase from 144,000 to 152,000 GWh during that same 

period.13 These data show that consumers can dramatically reduce the demand 

curve if state programs offer the right incentives. 

The Massachusetts energy efficiency programs reduced retail sales of 

electricity in the Commonwealth by 2 percent in 2012; that number is expected to 

reach 2.5 percent in 2015, resulting in a cumulative annual carbon dioxide emission 

reduction of three million metric tons in 2015 from electric energy efficiency 

programs implemented from 2005 through 2015.14 Because energy efficiency is less 

expensive than fossil fuel-fired power, the flattening of demand attributable to the 

Massachusetts efficiency programs represents both substantial savings to 

consumers and highly cost-effective reductions in carbon dioxide emissions. 

Oregon’s public purpose charge – 3 percent of the total revenues collected by 

the state’s utilities – provides roughly $60 million per year to support energy 

efficiency, renewable energy, and low-income programs in Oregon. This funding 

supports the Energy Trust of Oregon’s electric programs, including a goal of saving 

over 2,000 GWh of electricity between 2010 and 2014, equivalent to 1 percent of 

electricity sales in 2013 and 2014.

California has likewise focused on energy efficiency as a means to protect its 

consumers and reduce air pollution. For decades, California has enforced an 

expanding network of efficiency standards which help minimize the energy needed 

12 ISO-NE Final 2013 Energy Efficiency Forecast 2016-2022 (Feb. 22, 2013), Slide 37, available at 

http://www.isone.com/committees/comm_wkgrps/othr/enrgy_effncy_frcst/2013frcst/iso_ne_final_ee_forecast_2016_2

022.pdf.

13 Id. 

14 Massachusetts Department of Environmental Protection (November 21, 2013).

8

 
to power appliances and buildings.15 Energy savings are projected at nearly 70,000 

GWh in 2013 alone.16 The California Energy Commission estimates that these 

efficiency standards have generated $74 billion in savings for California consumers 

over the last several decades.17 Energy efficiency is the first resource California 

looks to as it considers its energy needs, and is the first resource considered in 

procurement proceedings under California’s loading order.18 Because California has 

decoupled utility profits from energy sales, its investor-owned utilities have strong 

incentives to pursue these savings.19 Academic analysts have concluded that 

hundreds of thousands of jobs can be created by California’s expanding energy 

efficiency programs.20

States’ innovative programs provide valuable data and experience for EPA to 

consider and upon which it should draw in determining the best system of emission 

reduction from existing power plants.

II. EPA’s Legal Authority to Regulate Greenhouse Gas Emissions from 

Existing Power Plants

EPA historically has interpreted section 111(d) to mandate regulation of 

existing sources’ emissions of pollutants that are not regulated as criteria pollutants

(under sections 108 and 110, 42 U.S.C. §§ 7408, 7410) or as hazardous air pollutants

(under section 112, id. § 7412) once EPA regulates emissions of those pollutants

from new sources under section 111(b). This construction is consistent with the idea 

that section 111(d) provides a “backstop” to regulation of pollutants under the 

national ambient air quality standards (NAAQS) or hazardous air pollutant 

programs. Thus, here power plants emitting greenhouse gases are subject to 

mandatory regulation under section 111(d) because greenhouse gases are not 

regulated as criteria pollutants or as hazardous air pollutants and because EPA has 

15 See generally California Energy Commission, Tracking Progress: Energy Efficiency (2013), 

available at 

http://www.energy.ca.gov/renewables/tracking_progress/documents/energy_efficiency.pdf.

16 Id.

17 See id.

18 See generally California Energy Commission, Implementing California’s Loading Order for 

Electricity Resources (2004), available at http://www.energy.ca.gov/2005publications/CEC-400-2005-

043/CEC-400-2005-043.PDF.

19 See American Council for an Energy-Efficient Economy, State Energy Efficiency Database: 

California (2013), available at http://aceee.org/sector/state-policy/california.

20 David Roland-Holst, Energy Efficiency, Innovation, and Job Creation in California 35 (2008), 

available at 

http://are.berkeley.edu/~dwrh/CERES_Web/Docs/UCB%20Energy%20Innovation%20and%20Job%20

Creation%2010-20-08.pdf.

9

 
moved forward with regulating greenhouse gas emissions from power plants under 

section 111(b). 

Two recent commentators have sought to use a legislative oddity – the 

enactment in 1990 of two differently worded amendments to section 111(d) – to 

argue that EPA is powerless to regulate greenhouse gas emissions from existing 

power plants.21 As explained below, however, Congress’s enactment of these two 

amendments did not change the backstop nature of EPA’s authority to regulate

under section 111(d). Instead, Congress revised section 111(d) to correct a crossreference to section 112 as a result of substantive changes to section 112, not to 

effectuate sweeping change in the coverage of pollutants regulated under section 

111(d). 

A. The language, structure and history of section 111(d) show that 

greenhouse gas emissions from existing power plants are 

subject to regulation under this section.

Under the familiar two-pronged test of Chevron, U.S.A., Inc. v. NRDC, courts 

and agencies “must give effect to the unambiguously expressed intent of Congress.” 

467 U.S. 837, 842 (1984) (Chevron). If the statute is silent or ambiguous with 

respect to the specific issue, the question for the court is whether the agency’s 

answer is based on a permissible construction of the statute. Id. at 842.

At step one of Chevron, “traditional tools of statutory construction,” including 

legislative history and statutory text and structure, are employed to discern 

legislative intent. Id. at 843 n.9. See, e.g., Zuni Public School Dist. No. 89 v. Dep’t 

of Educ., 550 U.S. 81, 89-100 (2007) (considering legislative history and purpose of 

statute first at step one, then again at step two). The text and structure of section 

111(d) and the circumstances surrounding the amendment of section 111(d) make 

clear that power plant greenhouse gas emissions are subject to section 111(d) 

regulation. 

Before its amendment in 1990, section 111(d) authorized regulation of “any 

air pollutant which is not included on a list published under section 7408(a) or 

7412(b)(1)(A) of this title.” See 42 U.S.C. § 7411(d) (West 1977). At that time, 

section 112(b)(1)(A) required EPA to list hazardous air pollutants meriting 

regulation under section 112. See id. § 7412(b)(1)(A). Congress amended the Act 

extensively in 1990 after its approach to regulating hazardous air pollutants 

“proved to be disappointing” due to EPA’s delay in listing those pollutants under 

21 William J. Haun, The Clean Air Act as an Obstacle to the Environmental Protection Agency’s 

Anticipated Attempt to Regulate Greenhouse Gas Emissions from Existing Power Plants, THE 

FEDERALIST SOCIETY (March 2013); Brian H. Potts, The President’s Climate Plan for Power Plants 

Won’t Significantly Lower Emissions, 31 YALE J. REG. ONLINE 1, 9 (Aug. 22, 2013).

10

 
section 112.22 The 1990 amendments overhauled section 112 to identify 188 specific 

hazardous air pollutants and to regulate their emissions. 42 U.S.C. § 7412 (2012). 

To conform the language of section 111(d) to the changes made to section 112, 

Congress also revised section 111(d).

 

However, in an unusual turn of events, different language in the House and 

Senate bills amending section 111(d) was enacted into law without being reconciled 

in conference. In such circumstances, the Statutes at Large, rather than the U.S. 

Code, are controlling.23 The Statutes at Large contain both the House and Senate

amendments to section 111(d). The Senate amendment, set forth at Pub. L. No. 

101-549, § 302(a), 104 Stat. 2399, 2574 (1990), simply substituted the reference to 

the amended section of the Act24 and provides:

Section 111(d)(1) of the Clean Air Act is amended by striking 

‘112(b)(1)(A)’ and inserting in lieu thereof ‘112(b).’

The House amendment, set forth at Pub. L. No. 101-549, § 108(g), 104 Stat. 

2399, 2467 (1990), took a different approach and replaced the simple reference with 

an explanation:

Section 111(d)(1)(A)(i) of the Clean Air Act [42 U.S.C. 7411(d)(1)(A)(i)] 

is amended by striking ‘or 112(b)(1)(A)’ and inserting ‘or emitted from 

a source category which is regulated under section 112.’

Both amendments appear in the House Conference Report, which was enacted by 

both the House and the Senate, H.R. Conf. Rep. 101-952, at 50, 123 (1990), and the 

bill signed by President Bush contained both amendments surrounded by brackets 

with a footnote describing the amendments as “duplicative.” According to the 

codifier, the provisions did nothing more than merely “in different language, change 

the reference to section 112.” The Clean Air Act, as Amended, reprinted in 1 

ENVIRONMENT AND NATURAL RES. POLICY DIV., LIBRARY OF CONGRESS, A LEGISLATIVE 

HISTORY OF THE CLEAN AIR ACT AMENDMENTS OF 1990, at 46 (1998). 

22 See Sierra Club v. EPA, 353 F.3d 976, 979-80 (D.C. Cir. 2004) (describing history of hazardous 

air pollutant provisions between 1970 and 1990).

23 1 U.S.C. § 112 (2012). See United States Nat’l Bank of Oregon v. Indep. Ins. Agents of Am., 508 

U.S. 439, 448 (1993) (“Though the appearance of a provision in the current edition of the United 

States Code is ‘prima facie’ evidence that the provision has the force of law, 1 U.S.C. § 204(a), it is 

the Statutes at Large that provides the ‘legal evidence of laws,’ [1 U.S.C.] § 112, and despite its 

omission from the Code [a provision] remains on the books if the Statutes at Large so dictates”).

24 See 42 U.S.C.A. § 7411(d) (West 1977).

11

 
 Consistent with congressional intent 

and the codifier’s understanding, the revisions

to section 111(d) must be read, as a Chevron

step one matter, as differently worded 

provisions that simply conformed the 

reference in section 111(d) to preclude the 

simultaneous regulation of air pollutants 

under sections 111(d) and 112. Indeed, the 

House and Senate amendments are found

under the headings “Miscellaneous 

Provisions” and “Conforming Amendments,” 

respectively. Pub. L. No. 101-549, §§ 108, 

302(a), 104 Stat. 2399, 2467, 2574 (1990). 

Despite the statutory language and 

structure and the legislative history, two

recent commentators have argued that the 

House amendment precludes EPA regulation 

of greenhouse gas emissions from power 

plants under section 111(d), because 

greenhouse gas emissions would fall under the 

category of any pollutant that happens to be 

emitted from a source category that is being 

regulated under section 112. Nothing in the 

legislative history or structure of section 

111(d) suggests that Congress intended the amendment to effect a sweeping, 

substantive change in the scope of regulation under section 111(d). 

First, “[s]uch a reading would be inconsistent with the general thrust of the 

1990 amendments, which, on balance, reflects Congress’ desire to require EPA to 

regulate more substances, not eliminate EPA’s ability to regulate large categories of 

pollutants like non-[hazardous air pollutants].” 70 Fed. Reg. 15,994, 16,032 (March 

29, 2005). And where the 1990 amendments provided regulatory relief for specific 

categories of sources, they did so explicitly, see, e.g., 42 U.S.C. §§ 7412(e)(1), 

7412(n)(1), and after much discussion.25 As the Supreme Court said in another 

Clean Air Act case, Congress “does not, one might say, hide elephants in 

mouseholes.” Whitman v. Am. Trucking Ass’ns., 531 U.S. 457, 468 (2001). 

25 See, e.g., S. Rep. No. 101-228, at 147 (1989), reprinted in 5 ENVIRONMENT AND NATURAL RES.

POLICY DIV., LIBRARY OF CONGRESS, A LEGISLATIVE HISTORY OF THE CLEAN AIR ACT AMENDMENTS OF 

1990, at 8514-15 (1998) (describing section 112(e) exceptions to general rules for scheduling 

standard-setting for sources under section 112(d)); Senate Debate on S. 1630 (April 3, 1990), 

reprinted in 4 ENVIRONMENT AND NATURAL RES. POLICY DIV., LIBRARY OF CONGRESS, A LEGISLATIVE 

HISTORY OF THE CLEAN AIR ACT AMENDMENTS OF 1990, at 7139-40 (1998) (discussing Senate 

Amendment adding section 112(n) requirement of study of mercury emissions from power plants 

prior to setting standards under section 112).

The bill signed by 

President George H.W. 

Bush contained both 

amendments surrounded 

by brackets with a footnote 

stating: “The amendments . 

. . appear to be duplicative; 

both, in different language, 

change the reference to 

section 112.” 

The Clean Air Act, as 

Amended, reprinted in 1 

ENVIRONMENT AND NATURAL 

RES. POLICY DIV., LIBRARY OF 

CONGRESS, A LEGISLATIVE 

HISTORY OF THE CLEAN AIR ACT 

AMENDMENTS OF 1990, at 46 

(1998). 

12

 
Second, as the former head of EPA’s 

enforcement office recently wrote, such an 

interpretation would make section 111(d) a “dead 

letter” because it is “difficult—perhaps 

impossible—to think of an air pollutant that is (a) 

emitted by stationary sources within the ambit of 

section 111 but (b) not also emitted by some 

sources (stationary or otherwise) that also emit[] 

hazardous air pollutants.” Adam Kushner and 

Judith Coleman, “Lessons from Mercury: Ensuring 

Legal Certainty for New GHG Performance 

Standards from Existing Fossil Fuel Plants,” EE 

News 6 (Oct. 24, 2013) (emphasis original).26 This 

huge gap in regulation would render section 

111(d) ineffective in fulfilling its structural and

historical role as a backstop provision and “impute 

to Congress a purpose to paralyze with one hand 

what it sought to promote with the other.” Clark

v. Uebersee Finanz-Korporation, A.G., 332 U.S. 

480, 488-89 (1947). A “cardinal principal of 

statutory construction” requires courts to reject 

interpretations like this that would render 

statutory provisions superfluous. New York v. 

EPA, 443 F.3d 880, 887 (D.C. Cir. 2006) (quoting 

TRW, Inc. v. Andrews, 534 U.S. 19, 31 (2001)).

B. EPA has reasonably interpreted 

section 111(d) to resolve any ambiguity.

At a minimum, EPA’s interpretation that gives effect to both the Senate and 

House amendments by limiting (not eliminating) its section 111(d) authority when 

it is regulating a source category under section 112 should be upheld because it is a 

permissible construction of the statute. Chevron, 467 U.S. at 843; City of Arlington 

v. FCC, 133 S. Ct. 1863 (2013) (reiterating that Chevron framework applies when 

agency interprets jurisdictional provision of statute it administers). Under EPA’s 

26 Available at http://www.eenews.net/assets/2013/10/24/document_gw_01.pdf. Indeed, the 

commentators do not admit this potential breadth insofar as they suggest that the House 

Amendment precludes regulation of air pollutants emitted by a source category only where the 

source category to be regulated under section 111(d) is also regulated under section 112. Moreover, 

the fortuity that pollutant X shares a source with other more stringently regulated pollutants 

logically should have no bearing on the stringency, or existence of, regulation of pollutant X. See

Desert Citizens Against Pollution v. EPA, 699 F.3d 524, 527-28 (D.C. Cir. 2012) (rejecting argument 

that certain consequences flowed simply because sources listed under one section for their emissions 

of seven particular hazardous air pollutants also emitted other pollutants). 

The Federalist Society’s 

interpretation “would 

make section 111(d) a 

‘dead letter’ because it is 

“difficult—perhaps 

impossible—to think of 

an air pollutant that is 

(a) emitted by stationary 

sources within the ambit 

of section 111 but (b) not 

also emitted by some 

sources (stationary or 

otherwise) that also 

emits hazardous air 

pollutants.”

Adam Kushner and Judith 

Coleman, “Lessons from 

Mercury: Ensuring Legal 

Certainty for New GHG 

Performance Standards 

from Existing Fossil Fuel 

Plants,” (Oct. 24, 2013) at 6.

13

 
interpretation, if EPA is regulating source category X under section 112, section 

111(d) could not be used to regulate any hazardous air pollutant emissions from 

that particular source category. 70 Fed. Reg. at 16,031; see also 73 Fed. Reg. 

44,354, 44,417-18, 44,487, 44,493 (July 30, 2008); 69 Fed. Reg. 4,652, 4,685 (Jan. 30, 

2004).

In Citizens to Save Spencer County v. EPA, 600 F.2d 844, 872 (D.C. Cir. 

1979), the court upheld EPA’s approach of seeking to reconcile seemingly 

inconsistent amendments by giving some effect to both, explaining that:

[where Congress] drew upon two bills originating in different Houses 

and containing provisions that, when combined, were inconsistent in 

respects never reconciled in conference . . . it was the greater wisdom 

for the agency to devise a middle course between inconsistent statutes 

so as to give maximum possible effect to both.

Similarly here, EPA’s interpretation gives effect to each amendment, 

maintaining the focus of the previous version of the Act on specific pollutants, as 

preserved by the Senate amendment, and incorporating the House amendment’s 

reference to specific sources to ensure that section 112 regulated source categories 

will not be subject to duplicative regulation of hazardous air pollutants under both 

section 112 and section 111(d). As a Chevron step two matter, EPA’s interpretation 

giving effect to both amendments is a reasonable one. Chevron, 467 U.S. at 843;

Smiley v. Citibank, N.A., 517 U.S. 735, 744-745 (1996).27

Thus, because greenhouse gases are not regulated as hazardous air 

pollutants or criteria pollutants, and because EPA has moved forward with 

regulation of power plant greenhouse gas emissions under section 111(b), power 

plant greenhouse gas emissions must be regulated under section 111(d).

III. The Cooperative Federalism Framework of Section 111(d)

Section 111(d) establishes a framework that gives EPA and the States 

distinct but complementary roles to regulate air pollutants from existing sources 

that, if new, would be subject to NSPS. Section 111(d) requires EPA to prescribe 

regulations that establish a section 110-like procedure under which each State shall 

submit to EPA a plan establishing, implementing and enforcing standards of 

performance for such sources. “Standard of performance” is defined as a standard 

for emissions of air pollutants that reflects the degree of emission limitation 

27 See also Am. Water Works Ass’n v. EPA, 40 F.3d 1266, 1271 (D.C. Cir. 1994) (quoting Chem. 

Mfrs. Ass’n v. NRDC, 470 U.S. 116, 126 (1985); Desert Citizens Against Pollution, 699 F.3d at 527-28 

(agreeing with EPA’s interpretation that section 112(c)(6)’s cross-reference to sections 112(d)(2) and 

(d)(4) only meant that seven pollutants specified in section 112(c)(6) were subject to standards 

required in latter sections, not that all hazardous air pollutants emitted by sources that also emitted 

seven pollutants were subject to these standards).

14

 
achievable through the application of the best system of emission reduction that, 

considering the cost of achieving the reduction and any nonair quality health and 

environmental impact and energy requirements, EPA determines has been 

adequately demonstrated. 42 U.S.C. § 7411(a)(1). 

As discussed below, the definition of “standard of performance” calls for EPA 

to determine the adequately demonstrated best system of emission reduction and 

the corresponding achievable degree of emission limitation.28 Once EPA sets the 

floor in its emission guidelines, each State must submit a plan establishing 

standards of performance for existing sources and implementing and enforcing such 

standards. 42 U.S.C. § 7411(d)(1). 

Thus, like the section 110 state implementation plan (SIP) framework and 

procedure, section 111(d) directs EPA to work hand-in-hand with the States to 

ensure that each State – through its plan – achieves the reductions that EPA has 

determined are achievable through the application of the best system of emission 

reduction that has been adequately demonstrated. This cooperative federalism 

allows EPA to establish the minimum reductions required, while giving the States 

flexibility to determine how to achieve those reductions (or more). 

A. Section 111(d) requires EPA to establish emission guidelines, 

including substantive limitations, for existing sources.

Under section 111(d), EPA issues emission guidelines and, “in compliance 

with those guidelines and subject to federal oversight, the States then issue 

performance standards for stationary sources within their jurisdiction.” AEP, 131 

S. Ct. at 2537 (citing 42 U.S.C. § 7411(d)). The statutory framework thus requires 

EPA to “establish guidelines as to what the best system for each such category of 

existing sources is” and the States to apply those guidelines. H.R. Rep. No. 95-294, 

at 195, as reprinted in 1977 U.S.C.C.A.N. 1077, 1274. 

To fulfill its statutory responsibilities, EPA must establish substantive 

emission limitations for existing sources. Pursuant to section 111(a), EPA must 

determine the emission reduction achievable through application of the best system 

of emission reduction it determines is adequately demonstrated, considering costs

and other factors. 42 U.S.C. § 7411(a). Based on this determination, EPA uses its 

expertise to establish standards for new and modified sources under section 111(b) 

and emission guidelines for the States to follow under section 111(d). For EPA to 

evaluate the adequacy of state plans under section 111(d)(2), as the statute requires 

it to do, EPA must first establish a benchmark. That way it can, if necessary, step 

28 “Emission limitation” is defined in section 302 to mean requirements which limit the quantity, 

rate or concentration of emissions of air pollutants on a continuous basis, including any requirement 

relating to the operation or maintenance of a source to assure continuous emission reduction, and 

any design, equipment, work practice or operational standard promulgated under this chapter. 42 

U.S.C. § 7602.

15

 
in where a State either submits an unsatisfactory plan or fails to enforce provisions 

of an approved plan. 42 U.S.C. § 7411(d)(2).

 

Another group of State Attorneys General has pointed to the language in 

section 111(d) that requires EPA to establish a procedure similar to that under 

section 110 for submission of state plans as limiting the agency’s role to a 

perfunctory one.29 EPA correctly dismissed that interpretation at the beginning of 

the section 111(d) program. That interpretation cannot be squared with the 

statute’s directive that EPA evaluate the content of state plans under section 111(d) 

and “prescribe a plan for a State in cases where the State fails to submit a 

satisfactory plan.” 42 U.S.C. § 7411(d)(2). And if the States alone could determine 

the standards to be applied, it would not have been necessary for Congress to 

expressly require EPA to allow the States to consider the “remaining useful life of a 

source” when applying those standards. Indeed, the very language upon which 

these commentators rely, requiring EPA to establish a “procedure similar to that 

provided by section 7410,” does not support their interpretation because EPA uses 

its scientific expertise to establish substantive standards under section 110 

(national ambient air quality standards), which the States then develop plans to 

implement. Thus, section 111(d) plainly 

requires EPA to establish minimum 

emission limitations to guide the States in 

devising their plans and to provide an 

objective measure against which EPA may 

judge the equivalency of the performance 

standard(s) included in each state plan.

EPA’s longstanding interpretation of 

its authority further affirms that it is, at a 

minimum, allowed to establish substantive 

guidelines. See Chevron, 467 U.S. at 842

(agency’s interpretation will be upheld if 

based on permissible statutory construction).

In its rulemaking proposal to establish 

general procedures under section 111(d), 

EPA explained that it would publish 

guideline documents setting minimum 

emission limitations that reflect the best 

available demonstrated systems of emission 

control. 39 Fed. Reg. 36,102 (Oct. 7, 1974).

EPA reiterated in the preamble to its 

final rule that the agency has the statutory 

29 Perspective of 18 States on Greenhouse Gas Emission Performance Standards for Existing 

Sources under § 111(d) of the Clean Air Act, submitted to EPA under cover letter dated September 

11, 2013 by the State of Nebraska Office of the Attorney General (“Nebraska”). 

EPA’s regulations call for 

guideline documents to include:

• a description of adequately 

demonstrated systems of 

emission reduction, 

• the degree of emission 

reduction achievable with 

each system,

• the costs and environmental 

effects of each system,

• an emission guideline 

reflecting the application of 

the best system of emission 

reduction adequately 

demonstrated for existing 

sources, and 

• the time within which 

compliance with equivalent 

emission standards can be 

achieved.

40 C.F.R. § 60.22(b). 

16

 
authority to set minimum emission guidelines for state emission standards included 

in state plans. 40 Fed. Reg. 53,340, 53,342 (Nov. 17, 1975). Responding to industry 

comments questioning EPA’s authority to prescribe more than procedural 

requirements for state plan adoption and submittal, EPA correctly reasoned that its 

interpretation was necessary to implement section 111(d) effectively. If EPA had no 

authority to set minimum substantive guidelines, the States would be able to set 

“extremely lenient standards” for air pollutants subject to regulation only under 

Section 111(d) – which would leave “a gaping loophole in a statutory scheme 

otherwise designed to force meaningful action.” Id. at 53,343. 

Thus, if the Administrator determines that a designated pollutant may cause 

or contribute to endangerment of public health or welfare, emission standards shall 

be no less stringent than EPA’s emission guidelines.30 40 CFR § 60.24(a)(d). EPA 

has followed this approach in each of the emission guidelines it has promulgated

pursuant to section 111(d), repeatedly establishing minimum emission limitations 

in its final emission guidelines for each State to include in its respective plan.31 A 

contrary interpretation would undermine the intent of section 111(d) to provide a 

backstop for emissions of harmful unregulated air pollutants from existing sources 

and also effectively would nullify section 111(d)’s provisions concerning EPA’s role 

in determining the best system of emission reduction and in approving state 

plans.32

30 EPA’s guidelines to the States are not enforceable against a source, but may be used to judge the 

adequacy of state plans. 40 Fed. Reg. at 53,343.

31 See, e.g., 40 C.F.R. § 60.31d (establishing emission guideline for sulfuric acid production units at 

0.25 grams sulfuric acid mist per kilogram of sulfuric acid produced); 40 C.F.R. § 60.33b 

(establishing emission guidelines for pollutants emitted by municipal waste combustors); 40 C.F.R. § 

60.33e (establishing specified emission limits for pollutants emitted by hospital, medical, infectious 

waste incinerators); 40 C.F.R. § 1515 (establishing specified emission limits for pollutants emitted by 

small municipal waste combustion units); 40 C.F.R. § 60.2515 (establishing specified emission limits 

for pollutants emitted by commercial and industrial solid waste incineration units); 40 C.F.R. § 

60.2983 (establishing specified emission limits for pollutants emitted by other solid waste 

incineration units); 40 C.F.R. § 60.5015 (establishing specified emission limits for pollutants emitted 

by sewage sludge incineration units).

32 Cf. Big Rivers Elec. Corp. v. EPA, 523 F.2d 16, 22 (6th Cir. 1975) (EPA acted within its authority 

in rejecting alternate control strategies in lieu of emission limitations that Kentucky sought to 

include in its state implementation plan and explaining that under section 110’s “dual scheme, the 

freedom of the States to choose the manner of achieving this goal [of reducing air pollution] was 

made subject to the absolute requirement that every state plan include emission limitations as an 

ingredient”).

17

 
B. EPA must evaluate the full range of available systems in 

determining the achievable emission reductions from existing 

power plants.

EPA must require emission reductions at a level that is achievable when 

applying the best system of emission reduction that EPA determines is adequately 

demonstrated, considering the cost of achieving the reduction and any nonair

quality health and environmental impact and energy requirements. 42 U.S.C. § 

7411(a); AEP, 121 S. Ct. at 2549. Because section 111(d) applies only to existing 

sources, Congress recognized from the outset a need for flexibility in determining 

appropriate control measures. See ‘‘Clean Air Act Amendments of 1977,’’ Committee 

on Interstate and Foreign Commerce, H.R. Rep. No. 95–294 at 195, reprinted in 4 ‘‘A 

Legislative History of the Clean Air Act Amendments of 1977,’’ Congressional 

Research Service, 2662. Therefore, to achieve the greatest level of reductions from 

existing power plants cost effectively, EPA must evaluate diverse types of systems 

when considering the best demonstrated system of emission reduction, in keeping 

with the highly interconnected nature of the existing sources at issue here. 

1. EPA must consider system-based approaches as well as sourcebased approaches to determine the best system of emission 

reduction adequately demonstrated and the corresponding 

emission limitation.

EPA must consider existing systems of emissions reductions in determining

the “best system of emission reduction” for greenhouse gases emitted by power 

plants. Because the statute does not separately define “system,” the assumption is 

that “the ordinary meaning of that language accurately expresses the legislative 

purpose.” Engine Mfrs. Ass’n v. S. Coast Air Quality Mgmt. Dist., 541 U.S. 246, 252-

53 (2004) (quotations and citations omitted). At the time that Congress created the 

NSPS program in 1970, system was defined as “a complex unity formed of many 

often diverse parts subject to a common plan or serving a common purpose.” 

Webster’s Third New International Dictionary of the English Language Unabridged 

2322 (1968). This broad definition includes not just source-specific systems or 

approaches to reducing emissions, but also system-wide approaches that have been 

adequately demonstrated. Source-specific changes that reduce carbon emissions 

include plant efficiency improvements, heat rate improvements, switching to or cofiring with lower carbon fuels, combined heat and power programs, and carbon 

capture and sequestration. System-wide approaches would include those programs 

that shift generation from less efficient to more efficient plants and to renewable 

energy and programs that reduce the need for generation and could drive or 

otherwise implicate the source-specific approaches noted above. Such systems 

would include emissions from all power plants or from multiple power plants within 

a regional, state or regulatory system to which each power plant must adhere. 

18
Because existing power plants are components of a complex and 

interconnected electricity grid, or network, EPA must consider system-wide 

programs that reduce carbon emissions from this sector. Approaches for reducing 

emissions from existing power plants will be most effective if they reflect the fact 

that power plants operate not in isolation, but as parts of large, dynamic gridconnected systems. 

For example, ISO-NE, New England’s regional transmission organization, 

includes 300 generating plants and 8,000 miles of transmission lines. ISO-NE

serves 6.5 million households and businesses, and its 400 market participants 

complete wholesale electricity transactions valued annually at ten billion dollars.33 

The interconnected nature of the electricity system is taken into account for 

purposes of system management; for example, decisions concerning plant 

retirements and dispatch are made on the basis of system-wide considerations. See, 

e.g., ISO-NE Non-Price Retirement Determination Letters and Resource 

Responses.34

EPA has previously recognized the interconnected relationship between 

regional multi-state power pool dispatch decisions and resulting emissions impacts 

in the participating States. In EPA’s SIP call for nitrogen oxides (NOx SIP call), 

EPA approved a redistribution of the NOx SIP call budgets for Connecticut, 

Massachusetts and Rhode Island based on a Memorandum of Understanding

33 See ISO-NE history, available at http://www.iso-ne.com/aboutiso/co_profile/history/index.html.

34 Available at http://www.isone.com/genrtion_resrcs/reports/non_prc_retremnt_lttrs/2011/salem_retirement_election.pdf.

http://www.isorto.org/site/c.jhKQIZPBImE/b.2604471/k.B14E/Map.htm

19

 
(MOU) entered into by the three States and EPA. 64 Fed. Reg. 49,987, 49,989 

(Sept. 15, 1999). EPA noted that the States belonged to the same power pool and 

that, because “dispatch is determined on the power pool level rather than the State 

level, dispatch itself may result in redistribution of generation and resulting 

emissions among the States in the power pool.” Id. Therefore, EPA concluded “a 

redistribution, based on the MOU, of budgets within that power pool is appropriate 

if the same overall budget results.” Id. 

“[S]tandards adopted for existing sources under section 111(d) of the Act are 

to be based on available means of emission control (not necessarily technological).” 

H.R. Rep. No. 95-294, at 11, as reprinted in 1977 U.S.C.C.A.N. 1077, 1088. Thus, in 

analyzing the best system to reduce greenhouse gas emissions from power plants 

that is adequately demonstrated, EPA must consider electric power system-based 

approaches and existing state and regional programs, including those described 

above, that have successfully reduced carbon dioxide emissions from the power 

sector as a whole. See Essex Chem. Corp. v. Ruckelshaus, 486 F.2d 427, 433-34

(D.C. Cir. 1973) (explaining that “[it] is the system which must be adequately 

demonstrated and the standard which must be achievable”). Such reductions, 

which have resulted in part from system-based approaches that provide incentives 

for sources to increase efficiency and find reductions elsewhere in the power sector, 

must be considered by EPA in determining the best system of emission reduction. 

In addition to recognizing the true nature of electricity generation and supply, such 

an approach offers the greatest potential for achieving significant greenhouse gas 

reductions from existing power plants.

2. EPA may determine that the emission limitation is best 

measured by mass and best achieved in phases.

EPA’s emission guideline must reflect the application of the best system of 

emission reduction as determined by EPA. See 40 C.F.R. § 60.22(b). In establishing 

the emission guideline, EPA may determine that the best metric is a mass-based 

limit and that existing power plants may achieve increasingly stringent limitations 

in phases. 

Although EPA has typically defined an emission limitation by an emission 

rate, for example, pounds per megawatt hour (lbs/MWh), EPA is not constrained to 

do so. The Act defines “emission limitation” as a limit on “the quantity, rate or 

concentration of emissions of air pollutants on a continuous basis.” 42 U.S.C. § 

7602(k). Thus, EPA may find that the best metric for the achievable emission 

limitation is a mass-based limit or cap on the quantity of emissions, for example, 

tons/year, as long as the source is continuously subject to the emission limitation or 

standard. See 42 U.S.C. § 7602(k) (defining “emission limitation”). In Sierra Club 

v. EPA, 551 F.3d 1019, 1027 (D.C. Cir. 2008), the court rejected EPA’s attempt to 

exempt major sources from normal emission standards under section 112 during 

startups, shutdowns and malfunctions and explained that “[w]hen sections 112 and 

20
302(k) are read together, . . . Congress has required that there must be continuous 

section 112-compliant standards.” Thus, when sections 111(d) and 302(k) are read 

together, the source must be continuously subject to section 111(d)-compliant 

standards.35 

To ensure that sources are subject to continuous emission limitations, section 

111(d) standards, whether in emission rate or mass-based form, must be reliable 

and enforceable. See Kennecott Copper Corp. v. Train, 526 F.2d 1149, 1155 (9th Cir. 

1975) (finding that intermittent control systems are not reliable or enforceable and 

therefore violate statute’s requirement that NAAQS be met by continuous emission 

limitations to maximum extent possible). Thus, although EPA may broadly define a 

“system” for purposes of determining what level of emission reductions are 

achievable, state plans must ensure that emission limits can be enforced against 

covered facilities, as is done through the RGGI program for example.

EPA also may determine that the best demonstrated system of emission 

reduction can achieve specified limitations in phases. For example, certain 

renewable energy programs may require investment and time to realize lower 

emissions, or certain retirement planning and clean energy incentives may mean 

that greater emission reductions will be achieved later in time. In such 

circumstances, a phased approach may best reflect the achievable emission 

limitations. See 42 U.S.C. § 7411(d)(1). EPA has discretion under section 111(d) to 

so determine and to allow States to give affected sources more time to meet more 

stringent reduction requirements, based on when the reductions may be achieved, 

provided that the critical goal of achieving significant emission reductions from this 

industry sector expeditiously is maintained. Id.; see 70 Fed. Reg. at 28,620.

IV. Evaluating Equivalency of State Programs Under Section 111(d)

Once EPA sets the floor in its emission guidelines, each State must submit a 

plan establishing standards of performance for existing sources and implementing 

and enforcing such standards. 42 U.S.C. § 7411(d)(1). As under section 110, it is up 

to the States to make the choices.36 So long as the States demonstrate that the 

steps and strategies proposed in their plans meet EPA’s guidelines, the States 

35 In this way, the definition of “standard of performance” in section 302, which means “a 

requirement of continuous emission reduction,” is also satisfied. 42 U.S.C. § 7602(l).

36 In the section 110 context, which provides insight because of section 111(d)’s reference thereto, 

courts have rejected attempts by EPA to dictate to the States the choices they employ in their SIPs. 

See Train v. NRDC, 421 U.S. 60, 79 (1975) (explaining that although EPA is “plainly charged” with 

setting NAAQS, EPA has “no authority to question the wisdom of a State’s choices of emission 

limitations if they are part of a plan which satisfies the standards of § 110(a)(2)”); Union Electric Co. 

v. EPA, 427 U.S. 246, 268-69 (1976) (rejecting claims of technological or economic infeasibility as 

basis for EPA to deny SIP, because “Congress plainly left with the States ... the power to determine 

which sources would be burdened by regulation and to what extent” and that Congress considered 

risks associated with technology forcing and “decided that the dangers posed by uncontrolled air 

pollution made them worth taking”).

21

 
retain the authority to determine how to achieve the overall emission limitations. 

See, e.g., Virginia v. EPA, 108 F.3d 1397, 1410 (D.C. Cir. 1997) (finding that EPA 

has no authority under section 110, as amended in 1990, to force a State to adopt 

particular control measures). At the same time, EPA must ensure that state plans 

achieve real, quantifiable and enforceable reductions.

Because the States must demonstrate that their plans comport with EPA’s 

guidelines, EPA should provide sufficient guidance regarding the minimum 

requirements and how the States can show that their strategies will achieve the 

necessary reductions. Equivalency determinations should be guided by the general 

principles discussed above: that Congress gave EPA the authority to require the 

States to achieve specified reductions, that Congress gave the States the authority 

to set performance standards for existing sources, and that Congress recognized the 

need for flexibility, including the appropriateness of considering remaining useful 

life and other factors for particular sources.

A. The States must be given flexibility in their plans provided 

that their proposed programs are enforceable.

Given the daunting challenge of addressing climate change, EPA should fully 

embrace the flexibility built into the statutory design by accepting a variety of state 

programs under section 111(d) so long as those programs achieve the emission 

limitation EPA sets and are enforceable.37 As discussed above, many States have 

already implemented a variety of programs that have achieved significant 

reductions of carbon dioxide emissions from the power sector. These programs 

include 1) both interstate and intrastate market-based programs that cap carbon 

dioxide emissions at reduced levels, 2) retirement and refurbishment planning as 

well as renewable portfolio standards that encourage a shift away from more 

carbon-intensive electricity production, and 3) demand side management and 

energy efficiency programs that reduce the amount of electricity needed and thereby 

cause a decrease in carbon dioxide pollution. Because these types of programs have 

succeeded in reducing carbon pollution from the power sector, the States should be 

permitted to rely on these programs in their plans, subject to EPA review, to 

demonstrate equivalency consistent with section 111(d)’s requirements.

37 The National Association of Regulatory Utility Commissioners (NARUC), whose members’ 

fundamental role is to assure that utilities provide reliable electricity at a fair cost, recently 

recognized the need to address greenhouse gas emissions with flexibility and from a regional 

perspective, resolving that, among other things, “ the guidelines should provide sufficiently flexible 

compliance pathways or mechanisms that recognize State and regional variations to achieve the 

most cost-effective emissions reductions in each State;...” Resolution on Increased Flexibility with 

Regard to the EPA’s Regulation of Greenhouse Gas Emissions from Existing Power Plants, available 

at

http://www.naruc.org/Resolutions/Resolution%20on%20Increased%20Flexibility%20with%20Regard

%20to%20the%20EPAs%20Regulation%20of%20Greenhouse%20Gas%20Emissions%20from%20Exis

ting%20Power%20Plants.pdf.

22

 
Similarly, if EPA elects to issue a rate-based emission guideline, EPA should 

provide guidance to the States, for the purpose of demonstrating equivalency of 

state programs. For example, if EPA issues a pounds-per-megawatt hour carbon 

dioxide limit on power plant emissions, it should provide guidance on how to 

translate that rate-based emission guideline into a mass-based standard, for 

example, tons of carbon dioxide emitted annually from power plants, individually 

and/or combined in a state or regional system (see below).

EPA should also provide adequate guidelines on appropriate implementation 

and enforcement mechanisms, such as monitoring and reporting requirements.

These guidelines are necessary to ensure that each State meets its obligations and 

that no “double counting” occurs. One option EPA could consider that would allow 

for flexibility yet ensure enforceability would be to allow the States to utilize a 

multi-year compliance period. Under this approach, each source is required to 

demonstrate full compliance on a multi-year, instead of an annual, basis.

B. States should be allowed to use trading programs to meet their 

section 111(d) obligations. 

Cap-and-trade programs are well-suited to address greenhouse gas emissions 

from existing power plants in light of the ability of such programs to ensure source 

compliance with emission limitations and the difference in “hot spot” effects caused 

by greenhouse gas emissions and criteria pollutants. If a cap-and-trade program 

sets the cap appropriately below current emissions and mandates that all emissions 

from sources in the category are covered by sufficient allowances, such a program 

should qualify as a system that requires continuous emission reduction. See 42 

U.S.C. §§ 7411(a); 7602(l).38 As discussed below and in the next section, EPA 

should therefore allow the States to use intrastate and interstate cap-and-trade 

programs in meeting their section 111(d) obligations. 

EPA has previously allowed the States to implement trading programs to 

satisfy their section 111(d) obligations. For example, in its municipal waste 

combustor rule, EPA allowed the States to establish a program to enable municipal 

waste combustor plants to engage in trading of nitrogen oxides emission credits, so 

long as EPA approved the trading program before implementation. 60 Fed. Reg. 

65,387, 65,402 (Dec. 19, 1995); 40 CFR § 60.33b. 

38 EPA may consider scenarios in which emissions reductions attributable to renewables 

generation and increased end use energy efficiency would be credited on the basis of carbon dioxide 

emissions avoided, and such credits used by covered facilities to achieve compliance with the 

emission guidelines. See, e.g., Natural Resources Defense Council, Closing the Power Plant Carbon 

Pollution Loophole: Smart Ways the Clean Air Act Can Clean Up America’s Biggest Climate 

Polluters (March 2013). In considering these scenarios, EPA should evaluate and articulate any 

methodology to be used to determine credit eligibility sufficient to satisfy section 111(d)’s existing 

source emission limitation requirement.

23

 
Similarly, in the Clean Air Mercury Rule (CAMR), EPA authorized the States 

to participate in a cap-and-trade program to meet their section 111(d) obligations. 

70 Fed. Reg. at 28,616-17. Although that rule was vacated by the D.C. Circuit on 

other grounds,39 there are several aspects of that rulemaking that could inform 

EPA’s thinking here, especially given that greenhouse gas emissions do not pose the 

type of “hot spot” concerns as pollutants such as mercury. 

First, in determining that a cap-and-trade program could be considered the 

best system of emission reduction, EPA concluded that it was the best system “in 

the relevant timeframe.” 70 Fed. Reg. at 28,617. That is instructive here where in 

light of the potential options for existing power plants, supply side energy efficiency, 

fuel switching, and co-firing with cleaner fuels, shifting dispatch to lower emitting 

facilities, and demand side energy efficiency are some of the emission reduction 

strategies available “in the relevant timeframe.”

Second, EPA allowed each State to choose whether to fulfill its section 111(d) 

obligations by participating in a cap-and-trade program or selecting some other 

means to stay within its statewide emissions budget. A similar approach could 

work here for greenhouse gas emissions. Third, EPA required new units to be 

subject to the cap-and-trade program and to hold sufficient allowances to cover their 

emissions. See 70 Fed. Reg. at 28,632. EPA let each State choose an allocation 

method and choose whether to set aside allowances to account for new units. See id.

at 28,632; 69 Fed. Reg. at 12,406-409. Similarly, the States should have the option 

of including all power plants, including those that may come on-line after a state 

plan is approved, within a trading plan for greenhouse gas emissions. A state plan 

could specify its allocation method and specify how new units will be 

accommodated. 

A source category cap-and-trade program, whether standing alone or as an

element of a larger state cap-and-trade program, will drive reductions both at and 

outside the source category because cap-and-trade is designed to provide an 

economic incentive for sources to increase efficiency and deploy other means of 

reducing emissions and for end users to innovate, as well. All reductions 

attributable to such a market-based approach should be considered for purposes of 

EPA’s best system of emissions reduction determination. Nevertheless, while capand-trade drives reductions outside the source, it is not necessary to quantify and 

account for those reductions for compliance purposes. For all the reasons discussed 

39 The D.C. Circuit vacated the section 112 delisting rule that EPA relied upon to promulgate 

CAMR under section 111(d). New Jersey v. EPA, 517 F.3d 574 (D.C. Cir. 2008). References to the 

CAMR in this paper do not reflect any support or endorsement of EPA’s attempt through CAMR to 

regulate hazardous air pollutants under section 111 rather than section 112. As discussed above, a 

cap-and-trade program involving greenhouse gas emissions does not raise the type of local air 

pollution concerns that were present with respect to CAMR.

24

 
above, EPA should allow the States to use a cap-and-trade system under section 

111(d).

C. The States should be allowed to work together to meet their 

obligations.

The States should be allowed to cooperate with each other to achieve the 

overall reductions and to demonstrate regional compliance, consistent with the Act’s 

general encouragement of cooperative activities by the States and local government 

for the prevention and control of air pollution. 42 U.S.C. § 7402. Moreover, as a 

matter of state sovereignty, the States should be given the choice of working in 

coordination with their sister States to meet their section 111(d) obligations, so long 

as each individual state plan is enforceable against covered facilities and ensures 

against both States claiming “credit” for the same emission reductions. 

Regional efforts can reduce emissions at least as effectively as individual 

state efforts, and more cost-efficiently. Regional efforts may be especially 

appropriate because, as discussed above, existing power plants are components of a 

complex and interconnected electricity grid, or network, that supplies the nation’s 

energy. Allowing regional cooperation among States that share an electricity grid 

would also decrease the likelihood of emissions leakage by maintaining an even 

playing field among those sources within the same regional transmission 

organization. 

EPA in the section 110 context has already recognized that redistribution of 

NOx emissions among three States within a power pool is appropriate if the overall 

budget remains the same. 64 Fed. Reg. at 49,989.40 The same rationale applies 

here to allow the States to cooperate together to achieve overall regional reductions

under section 111(d), provided that those reductions are enforceable.

D. EPA should evaluate allowing the States to implement their 

state plan reduction requirements in phases.

EPA should evaluate allowing the States to implement their state plan 

reduction requirements in phases and require sources to meet specified emission 

reductions by certain target dates, according to when the reductions are achievable. 

A phased approach would allow the States to account for planned retirements, or 

the remaining useful life of sources, and call for more modest reductions sooner and 

greater reductions later when an old, less efficient source will be replaced, or at 

least have its electricity production replaced, by a cleaner more efficient source or 

demand reduction measures. See 42 U.S.C. § 7411(d)(1); H.R. Rep. No. 95-294, at 

195, as reprinted in 1977 U.S.C.C.A.N. 1077, 1274 (explaining that EPA’s 

“guidelines must take into account the remaining useful life of existing sources”). 

40 See discussion infra pp. 19-20.

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However, any phasing must be scrutinized to account for the critical need to reduce 

greenhouse gas emissions from power plants as expeditiously as possible.

V. Conclusion

Section 111(d) gives EPA and the States the necessary authority to make 

meaningful reductions of harmful greenhouse gas emissions from existing power 

plants. Existing state programs adequately demonstrate that significant emission 

reductions from the power sector are achievable. EPA accordingly should apply the 

best system of emission reduction as reflected by these state programs and require 

the States to achieve the corresponding emission limitation as expeditiously as 

possible. By working together, as mandated by section 111(d), EPA and the States 

can reduce carbon pollution as necessary to protect human health and welfare.

Respectfully submitted, Dated: December 16, 2013

___________________________________

Eric T. Schneiderman

Attorney General of New York

Kamala D. Harris

Attorney General of California

Gary King

Attorney General of New Mexico

Martha Coakley

Attorney General of Massachusetts

Ellen F. Rosenblum

Attorney General of Oregon

George C. Jepsen

Attorney General of Connecticut

Peter F. Kilmartin

Attorney General of Rhode Island

26
Joseph R. Biden, III

Attorney General of Delaware

William Sorrell

Attorney General of Vermont

Janet T. Mills

Attorney General of Maine

Bob Ferguson

Attorney General of Washington

Douglas F. Gansler

Attorney General of Maryland

Irvin B. Nathan

Attorney General District of Columbia

27