August 17, 2020
Judicial Review of Mercury and Air Toxics Regulations
Since 1990, the U.S. Environmental Protection Agency’s
the 2000 A&N Finding, holding that the matter was
(EPA’s) efforts to regulate mercury and other hazardous air
nonjusticiable until EPA issued emission standards (UARG
pollutants (HAPs or air toxics) emitted by power plants
v. EPA, No. 01-1074 (D.C. Cir., Jul. 26, 2001)).
have faced numerous legal challenges. The Clean Air Act
(CAA) Amendments of 1990, Pub. L. 101-549, established
The 2005 Delisting and the
a multistep process for EPA to regulate HAP emissions
Clean Air Mercury Rule
from fossil fuel-fired electric utility steam generating units
In 2005, EPA reversed the 2000 A&N Finding (70 Fed.
(i.e., power plants). One of those steps requires EPA to
Reg. 15,994, Mar. 29, 2005). EPA concluded that it had
regulate HAP emissions from power plants if the agency
erred in the 2000 rule by relying solely on environmental
determines that it is “appropriate and necessary” to do so.
factors without considering the potential mercury emissions
reductions achievable under other CAA requirements. EPA
Stakeholders have challenged each of EPA’s “appropriate
determined that in light of these potential reductions,
and necessary” findings and other actions to regulate HAP
regulating power plant emissions under Section 112 was
emissions from power plants. Most recently, litigants are
neither appropriate nor necessary, and it delisted power
challenging EPA’s May 2020 rule that concluded that HAP
plants as a source of HAP emissions.
emission limits for coal- and oil-fired power plants are not
“appropriate and necessary” under the CAA (2020
In place of regulating power plant emissions under Section
Appropriate and Necessary (A&N) Rule, 85 Fed. Reg.
112, EPA issued the Clean Air Mercury Rule (CAMR)
31,286, May 22, 2020). This rulemaking reversed a prior
pursuant to CAA Sections 111(b) for new power plants and
EPA-issued rule that such limits were appropriate and
111(d) for existing power plants (70 Fed. Reg. 28,606, May
necessary, though EPA declined to rescind the emissions
18, 2005). CAMR set mercury performance standards for
limits that were associated with the prior finding. This In
new power plants and created a voluntary mercury cap-and-
Focus reviews the history of litigation challenging EPA’s
trade program for new and existing power plants.
treatment of HAP emissions from power plants under CAA
Section 112 and identifies legal issues that will likely arise
In 2008, the D.C. Circuit vacated the 2005 delisting of
in the current litigation.
power plants as a HAP source because EPA failed to make
the health and environmental findings set forth in CAA
CAA Section 112 Framework
Section 112(c)(9) prior to delisting (New Jersey v. EPA,
CAA Section 112(c) requires EPA to identify and list
517 F.3d 574 (D.C. Cir. 2008)). Further, the court vacated
categories of HAP pollution sources prior to regulating their
CAMR as applied to existing power plants because, as EPA
HAP emissions. Under Section 112(c)(9), EPA may delist a
conceded, if power plants are listed under Section 112(c),
source category only if the EPA Administrator makes
EPA lacked authority to regulate them under Section
specific findings that the health and environmental effects
111(d). The court also vacated and remanded CAMR as
of the sources’ emissions in that category do not exceed
applied to new power plants in part because EPA issued the
certain thresholds.
Section 111(b) new source performance standards based on
the erroneous “vital assumption[]” that EPA would not
Congress explicitly required EPA to assess power plant
regulate new power plants under Section 112.
HAP emissions and consider their regulation. Specifically,
CAA Section 112(n) required EPA to study the “hazards to
The 2012 Mercury and Air Toxics Rule
public health reasonably anticipated to occur” from HAPs
and the 2016 Supplemental Finding
emitted by power plants once the agency had imposed other
After settling a suit seeking enforceable deadlines for EPA
CAA requirements, and to regulate those emissions if the
to regulate HAP emissions from power plants, EPA
agency “finds such regulation is appropriate and necessary
promulgated the Mercury and Air Toxics (MATS) Rule in
after considering the results of the study.”
2012 (77 Fed. Reg. 9304, Feb. 16, 2012). The MATS Rule
reaffirmed the 2000 A&N Finding and, based on additional
The 2000 A&N Finding and Listing
analysis and information, determined that setting HAP
EPA completed the Section 112(n)(1) study in 1998. In
emissions standards for most existing coal- and oil-fired
2000, EPA determined that it was “appropriate and
power plants under Section 112 was “appropriate and
necessary” to regulate HAPs from coal- and oil-fired power
necessary.” As part of the rule, EPA concluded that it was
plants and listed them as a source of hazardous pollution
not “appropriate to consider costs” when making an A&N
(2000 A&N Finding, 65 Fed. Reg. 79,825, Dec. 20, 2000).
finding.
EPA did not issue emission standards as part of the A&N
Finding. In 2001, the U.S. Court of Appeals for the District
The D.C. Circuit upheld the MATS Rule in 2014 (White
of Columbia Circuit (D.C. Circuit) dismissed challenges to
Stallion Energy Ctr. v. EPA, 748 F.3d 1222 (D.C. Cir.
https://crsreports.congress.gov
Judicial Review of Mercury and Air Toxics Regulations
2014)), but the Supreme Court reversed the decision
The public health and environmental organizations, a subset
(Michigan v. EPA, 576 U.S. 743 (2015)), ruling that EPA
of the state and local governments challenging the 2020
must consider cost in Section 112 A&N findings. The Court
A&N Rule, the emissions control technology companies,
declined to vacate the MATS Rule, however, as did the
and the three utility companies have moved to intervene in
D.C. Circuit on remand, leaving the MATS Rule in effect.
Westmoreland’s suit to defend these agency actions.
In response to the Supreme Court’s ruling, EPA finalized a
The court has not set a briefing schedule, and the full set of
supplemental A&N finding in 2016, which concluded that
issues the petitioners will raise is not yet known. Based on
the 2000 A&N finding that regulating power plant
the comments submitted on the proposed 2020 A&N Rule,
emissions is “appropriate and necessary” was still valid
as well as the relevant litigation history, several key issues
after taking into account the MATS Rule’s estimated costs
will likely arise in the case or its aftermath:
(2016 Supplemental Finding, 81 Fed. Reg. 24,420, Apr. 25,
2016). Industry groups challenged the 2016 Supplemental
Whether EPA may reverse an A&N finding without
Finding, but in 2017, the D.C. Circuit paused the litigation
satisfying the Section 112(c)(9) delisting criteria:
while EPA reconsidered it (Murray Energy Corp. v. EPA,
EPA asserts that an A&N finding “is structurally and
No. 16-1127 (D.C. Cir.)).
functionally separate” from the agency’s authority to
delist source categories.
Current Status and Next Steps
Whether the 2020 A&N Rule affects the MATS Rule
The 2020 A&N Rule reversed the 2016 Supplemental
and EPA’s authority to regulate HAP emissions from
Finding. EPA found that its prior analysis was flawed
power plants: Westmoreland will likely argue that
because it gave “equal weight” to direct benefits (HAP
rescinding the prior A&N finding leaves the MATS
emission reductions) and co-benefits (non-HAP emission
Rule without a legal basis, and that the MATS Rule
reductions) of the regulation. Excluding co-benefits from
must therefore be vacated.
the cost-benefit comparison led EPA to conclude that
regulating HAP emissions from power plants is not
Whether EPA’s framework for analyzing benefits
“appropriate and necessary” because monetized costs
and costs is reasonable: Public health and
exceed by a factor of 1,000 the monetized benefits of HAP-
environmental organizations, state and local
specific emissions reduction.
governments, and utility companies will likely challenge
both the agency’s exclusion of co-benefits and how it
The 2020 A&N Rule does not, however, remove coal- and
quantified specific costs and benefits.
oil-fired power plants from the Section 112 list. Consistent
with New Jersey v. EPA, EPA recognized that it could not
Potential effect on related litigation: The court
remove power plants from the Section 112 list by reversing
ordered the parties challenging the 2016 Supplemental
an A&N finding without satisfying the health risk criteria
Finding to submit their proposals for how the case
set forth in CAA Section 112(c)(9). Finding that the
should proceed once it resumes (Chesapeake Climate
estimated cancer risk from exposure to power plant HAPs
Action Network v. EPA, No. 15-1192 (D.C. Cir.)). Those
would fail to meet the health risk criteria, EPA noted that it
proposals will likely address whether the case is moot in
is “extremely unlikely that any EPA Administrator could
light of the reversal of the 2016 Supplemental Finding.
(much less would) lawfully exercise his or her discretion
Environmental groups have also challenged EPA’s HAP
[under CAA Section 112(c)(9)] to ‘de-list’ the coal- and oil-
emissions standards for certain coal waste-fired plants,
fired power plant source category.” As long as power plants
which the agency issued in April 2020 after reevaluating
remain listed as a source category, EPA concluded that the
data from the MATS Rule (Citizens for Pennsylvania’s
MATS Rule emissions limits must remain in effect.
Future v. EPA, No. 20-1207 (D.C. Cir.)). A ruling in the
2020 A&N Rule litigation addressing the legal basis of
Six groups have filed challenges to the 2020 A&N Rule: (1)
the MATS Rule may affect the litigation over the April
Westmoreland Mining Holdings, a coal producer; (2) a
2020 emission standards.
coalition of public health and environmental organizations;
Potential effect on existing power plants: Power
(3) a coalition of 20 states and five local governments; (4) a
plants have already installed controls to comply with the
group of emission control technology suppliers; (5) a state
MATS Rule deadlines. However, the litigation over the
energy utility company; and (6) three utility companies that
2020 A&N Rule could still affect their emission control
generate electricity from low-emissions sources. The D.C.
strategies. Some stakeholders are concerned that if the
Circuit has consolidated the cases, along with a challenge
court vacates the MATS Rule, power plants may shut
by some of the same parties to EPA’s residual risk and
off their existing pollution controls absent federal
technology review (RTR) that accompanied the 2020 A&N
enforcement of their HAP emissions.
Rule (Westmoreland Mining Holdings, LLC v. EPA, No.
20-1160 (D.C. Cir.)). In the RTR, EPA evaluated the risk to
For more information, see CRS In Focus IF11078, EPA
public health remaining after applying the MATS Rule’s
Reconsiders Benefits of Mercury and Air Toxics Limits.
technology-based standards and concluded that no changes
to the MATS Rule were warranted.
Kate R. Bowers, Legislative Attorney
Westmoreland is seeking review of not only the 2020 A&N
Rule but also the 2016 Supplemental Finding, the 2012
Linda Tsang, Legislative Attorney
MATS Rule, and the 2000 A&N Finding and listing rule.
IF11622
https://crsreports.congress.gov
Judicial Review of Mercury and Air Toxics Regulations
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https://crsreports.congress.gov | IF11622 · VERSION 1 · NEW