United States Court of Appeals

FOR THE DISTRICT OF COLUMBIA CIRCUIT

Argued May 5, 2015 Decided July 31, 2015

No. 14-1206

THE AMERICAN COAL COMPANY,

PETITIONER

v.

FEDERAL MINE SAFETY AND HEALTH REVIEW COMMISSION 

AND DEPARTMENT OF LABOR,

RESPONDENTS

On Petition for Review of a Decision of the 

Federal Mine Safety & Health Review Commission

Jason W. Hardin argued the cause for petitioner. On the 

briefs was Kevin N. Anderson.

Jerald S. Feingold, Attorney, Mine Safety & Health 

Administration, argued the cause for respondent. With him on 

the brief was W. Christian Schumann, Counsel. John T. 

Sullivan, Attorney, entered an appearance.

Before: BROWN, GRIFFITH, and PILLARD, Circuit Judges.

GRIFFITH, Circuit Judge:

The American Coal Company was cited and fined for a 

“fire” on one of its coal stockpiles when safety inspectors 
2

from the Mine Safety and Health Administration observed 

patches of smoldering, smoking coal without visible flames. 

The Federal Mine Safety and Health Act of 1977 allows the 

issuance of safety orders and the imposition of citations and 

fines when a mine operator permits an “accident” to occur in 

its facility, including a “mine fire.” American Coal argues that 

the citation and fine should be vacated because a “fire,” for 

purposes of the Mine Act, exists only when there are visible 

flames. The company also contends that even if a fire could 

exist without visible flames, there was insufficient proof here 

to show a fire of any kind. We disagree on both points and 

deny American Coal’s petition for review. The statutory term 

“fire” is ambiguous, the Secretary of Labor reasonably 

determined that the term does not require the presence of 

flames, and substantial evidence supports the conclusion that 

the smoldering patches on American Coal’s stockpile satisfied 

the Secretary’s interpretation of a “fire.”

I

A

Congress passed the Federal Mine Safety and Health Act 

of 1977 (the Mine Act), Pub. L. No. 95-164, 91 Stat. 1290 

(1977) (codified as amended at 30 U.S.C. § 801 et seq.), “to 

provide more effective means and measures for improving the 

working conditions and practices” in American mines “in 

order to prevent death and serious physical harm” to miners.

30 U.S.C. § 801(c). The Mine Act assigned enforcement and 

other powers to the Secretary of Labor and created within the 

Department of Labor a new agency, the Mine Safety and 

Health Administration (MSHA), to administer its provisions. 

Meredith v. Fed. Mine Safety & Health Review Comm’n, 177 

F.3d 1042, 1054 & n.12 (D.C. Cir. 1999). 
3

Mine inspectors from MSHA perform frequent,

unannounced inspections to ensure that mine operators 

comply with the Mine Act and related safety standards. 30 

U.S.C. § 813(a). An inspector who discovers that a mine 

operator has violated a provision of the Mine Act or any 

related safety standard must issue a citation. Id. § 814(a). The 

Secretary is also required to assess civil penalties for each 

violation. Id. § 820(a).

In addition to citations, the Mine Act authorizes safety 

inspectors to issue “safety orders” to ensure onsite safety “[i]n 

the event of any accident occurring in a coal or other mine.”

Section 103(k), 30 U.S.C. § 813(k) (emphasis added). Safety 

orders allow inspectors to wield broad authority as they deem

necessary. Under the Mine Act, the term “accident” is defined 

to include “a mine explosion, mine ignition, mine fire, or 

mine inundation, or injury to, or death of, any person.”

Section 3(k), id. § 802(k) (emphasis added). In other words, a

safety order under section 103(k) can only issue in the face of 

an active, ongoing accident, of which a mine fire is but one 

example. In this case, the safety inspectors justified the safety 

orders based on their conclusion that the smoldering patches 

they observed on the coal stockpile were a “fire.”

The Mine Act provides a different type of authority to 

inspectors when they discover an “imminent danger.”

“Withdrawal orders” require the mine operator to evacuate the 

area in which the imminent danger exists. Section 107(a), 30 

U.S.C. § 817(a). The Mine Act defines an “imminent danger”

as “any condition or practice in a coal or other mine which 

could reasonably be expected to cause death or serious 

physical harm before such condition or practice can be 

abated.” Id. § 802(j).
4

A mine operator may contest any citation, order, or 

penalty before the Federal Mine Safety and Health Review 

Commission (the Commission), a five-member body also 

established by the Mine Act. The Commission appoints 

administrative law judges (ALJs) to hear and decide the 

dispute in the first instance. Either party to a dispute can 

appeal any decision of an ALJ to the Commission. 

B

American Coal, a subsidiary of Murray Energy, operates a 

coal mine complex in Galatia, Illinois, composed of two 

underground mines: the New Millennium mine and the New 

Future mine. Each mine maintains various surface operations, 

including coal stockpiles where raw coal is stacked once it is 

extracted from the mines. 

On January 19, 2010, two mine inspectors visited the 

Galatia complex and found what they determined were signs 

of “fire” at the New Future stockpile. As the inspectors later 

testified, they observed five spots on the stockpile that emitted 

smoke, radiated heat waves, and were covered in whitish ash 

produced by heated coal. One inspector also testified that he 

smelled an odor like sulfur. Neither inspector, however, 

observed any visible flames, glowing coals, or any other kind 

of illumination. The American Coal safety officer who 

accompanied the inspectors later testified that he did not 

believe the spots were smoldering, and characterized what the 

inspectors called white ash as nothing more than gray rock 

pulled from the mine.

Relying on their observations, the inspectors issued safety 

orders under section 103(k) of the Mine Act for the New 

Future stockpile, giving them broad authority over the 

operation until the “fire . . . presently burning in the coal pile”
5

was brought under control. J.A. 24. The inspectors also issued 

a citation to American Coal for failing to report the accident, 

and the Secretary of Labor later assessed a civil penalty in 

connection with that citation.

American Coal contested the orders, citation, and penalty. 

American Coal and the Secretary agreed that the dispute 

turned exclusively on the meaning of the word “fire” in the 

Mine Act. American Coal argued that the inspectors were not 

authorized to issue safety orders under section 103(k) because 

mere smoldering combustion is not a “fire.” The ALJ agreed 

with American Coal, ruling that the term “fire”

unambiguously required the existence of visible flame. 

Because all agreed that there were no visible flames on the 

New Future stockpile, the ALJ concluded that the safety 

orders were unjustified.

The Secretary appealed his decision to the Commission. 

Before the Commission, the Secretary explained that he 

interpreted “fire” to include both “events marked by flaming 

combustion” and “events marked by smoldering combustion 

that reasonably has the potential to burst into flames.” The 

Secretary insisted that the spots the inspectors had observed 

on the surface of the stockpile satisfied his interpretation of 

“fire” because they were instances of smoldering combustion 

that could have ignited at any time. Thus the question before 

the Commission was whether the term “fire” in the Mine Act

was ambiguous and, if so, whether the Secretary’s 

interpretation of it was reasonable.

The Commission resolved that question in the Secretary’s 

favor. The Commission pointed out that the term “fire” in the 

statute was inextricable from the preceding term “mine,” as 

the only fires at issue under the Mine Act were necessarily 

those associated with mining. The Commission therefore
6

analyzed the Secretary’s interpretation within the overall 

meaning of the statute instead of standing in isolation. The 

Commission concluded that the term “fire” was ambiguous 

and that the Secretary was free to interpret it to include both 

fires involving visible flames and smoldering fires that had 

the reasonable possibility of bursting into flames.

One member of the panel dissented. Though he agreed 

that the statute did not require the presence of visible flames 

to constitute “fire,” he found the Secretary’s definition 

impermissibly vague because it did not provide adequate 

guidance regarding when a given patch of smoldering 

combustion would present a reasonable risk of bursting into 

flame. The dissent feared that the term “reasonably” included 

in the Secretary’s definition was too “open to subjective 

interpretations” and would prove “ultimately useless to 

operators.” J.A. 327. 

On remand, a new ALJ (the previous ALJ having retired), 

applied the Commission’s ruling and upheld the safety order. 

The ALJ concluded that the spots the inspectors had observed 

met the Secretary’s interpretation. American Coal appealed 

this decision, but this time the Commission declined to review

the ALJ’s determination. 

American Coal timely petitioned for review, arguing that 

the term “fire” is not ambiguous, that the Secretary’s 

interpretation of the term is not reasonable, and that there was 

not even sufficient evidence to support the Commission’s 

conclusion that the Secretary’s interpretation was satisfied 

here. We have jurisdiction over a final order of the 

Commission under 30 U.S.C. § 816(a)(1). We review the 

Commission’s legal conclusions de novo. Sec’y of Labor v. 

Twentymile Coal Co., 456 F.3d 151, 156 (D.C. Cir. 2006). We 

review the Commission’s findings of fact for substantial 
7

evidence, meaning that we “determine whether there is such 

relevant evidence as a reasonable mind might accept as 

adequate to support the judge’s conclusion.” Jim Walter Res., 

Inc. v. Sec’y of Labor, 103 F.3d 1020, 1023-24 (D.C. Cir. 

1997). 

II

A

As a threshold matter, American Coal insists that we 

should reverse and remand without considering the merits of 

this dispute because the Commission exceeded its authority 

under the statute. The Mine Act forbids the Commission from 

considering any question that was not first presented to the 

ALJ. 30 U.S.C. § 823(d)(2)(A)(iii), (d)(2)(B). In the hearing 

before the ALJ, the parties stipulated that their dispute turned 

on whether there was a “fire” on the stockpile in the sense 

used in section 3(k) of the Mine Act. In its decision, the 

Commission focused on the larger statutory term “mine fire,”

concluding that “mine” provided indispensable context for 

“fire” and that a “mine fire” could exist even without visible 

flames. Because the Commission considered the meaning of 

the term “mine fire,” as opposed to the meaning of the term 

“fire” standing alone, American Coal believes that the 

Commission improperly considered an argument the parties 

had not briefed.

We find this argument unpersuasive. “[A] reviewing court 

should not confine itself to examining a particular statutory 

provision in isolation. The meaning—or ambiguity—of 

certain words or phrases may only become evident when 

placed in context. It is a ‘fundamental canon of statutory 

construction that the words of a statute must be read in their 

context and with a view to their place in the overall statutory 
8

scheme.’” FDA v. Brown & Williamson Tobacco Corp., 529 

U.S. 120, 132-33 (2000) (internal citation omitted) (quoting 

Davis v. Michigan Dept. of Treasury, 489 U.S. 803, 809 

(1989)). See also Deal v. United States, 508 U.S. 129, 132 

(1993) (observing that it is a “fundamental principle of 

statutory construction (and, indeed, of language itself) that the 

meaning of a word cannot be determined in isolation, but 

must be drawn from the context in which it is used”). In other 

words, the Commission did not consider a different question 

than the meaning of “fire” in section 3(k). It considered the 

question that the parties agreed was at issue and employed 

standard interpretive tools to answer it, including looking to

the statutory context of the disputed term. The Commission 

was well within its authority to do so.

B

The Secretary’s interpretation of the Mine Act must “‘be 

given weight by both the Commission and the courts’” under 

the familiar two-step Chevron standard. Sec’y of Labor v. 

Excel Mining, LLC, 334 F.3d 1, 5-6 (D.C. Cir. 2003) (quoting 

Sec’y of Labor v. Cannelton Indus., Inc., 867 F.2d 1432, 1435 

(D.C. Cir. 1989)). Under the first step of Chevron we consider 

whether Congress has unambiguously addressed the question. 

See Cannelton Indus., 867 F.2d at 1435. If not, we ask 

whether the Secretary’s interpretation is reasonable. Id.

Especially in the context of a remedial health-and-safety act 

like the Mine Act whose “primary purpose . . . [is] to protect 

mining’s most valuable resource—the miner,” Int’l Union, 

United Mine Workers v. Mine Safety & Health Admin., 823 

F.2d 608, 617 (D.C. Cir. 1987) (internal quotation marks 

omitted), we must “‘liberally construe[]’” the Act’s terms, 

meaning that we are all the more “obliged to defer to the 

Secretary’s miner-protective construction of the Mine Act so 
9

long as it is reasonable.” Cannelton Indus., 867 F.2d at 1437 

(internal quotation marks omitted). 

In the statutory scheme of the Mine Act, “the Secretary’s 

litigating position before [the Commission] is as much an 

exercise of delegated lawmaking powers as is the Secretary’s 

promulgation of a . . . health and safety standard,” and so is 

also deserving of deference. Excel Mining, 334 F.3d at 6 

(alterations in original) (quoting RAG Cumberland Res. LP v. 

Fed. Mine Safety & Health Review Comm’n, 272 F.3d 590, 

596 n.9 (D.C. Cir. 2001)); cf. Martin v. Occupational Safety 

& Health Review Comm’n, 499 U.S. 144, 156-57 (1991) 

(explaining that the OSH Act’s analogous allocation of 

responsibilities requires according Chevron deference to the 

Secretary’s litigating positions).

1

We conclude that “fire” as used in the Mine Act is 

ambiguous because there are competing, plausible ways to 

read the term. 

American Coal insists that there was widespread 

agreement at the time the Mine Act was passed in 1977 that a 

fire existed only when there were visible flames. To support 

this proposition, American Coal cites several general-usage 

dictionary definitions and a number of fire insurance cases 

ranging from 1905 to 1969, which arguably identify fire 

exclusively with the presence of flames. See, e.g., W. Woolen 

Mill v. N. Assurance Co. of London, 139 F. 637, 639 (8th Cir. 

1905) (“No definition of fire can be found that does not 

include the idea of visible heat or light, and this is also the 

popular meaning given to the word.”). 
10

The Secretary responds principally in two ways. First, he 

cites a number of cases of similar vintage that explicitly 

distinguish between “smoldering fires” and “flaming fires,” to 

show that contemporary usage employed the term “fire” in 

different ways. See, e.g., Triple A Machine Shop, Inc. v. 

Waterman Steamship Co., 221 F.2d 916, 917 (9th Cir. 1955) 

(“[A] fire so started in the [ship’s hold] would smoulder many 

hours before it burst into flame.”); Ravenscroft v. United 

States, 88 F.2d 418, 419 (2d Cir. 1937) (noting “the danger of 

admitting air to a smoldering fire in cotton”); Petition of 

United States, 105 F. Supp. 353, 359 (S.D.N.Y. 1952) 

(“[Opening the hatch] created a strong circulation of air, 

which fanned the smoldering fire into flame.” (internal 

quotation marks omitted)). Second, the Secretary points to a 

number of technical references focusing on mining and fire 

prevention that distinguish smoldering fire from flaming fire. 

See, e.g., NATIONAL FIRE PROTECTION ASSOCIATION, FIRE 

PROTECTION HANDBOOK 2-18 (Gordon P. McKinnon & Keith 

Tower eds., 14th ed. 1976) (“The observer can be sure there is 

fire where flame can be seen. Flame is rarely separated from 

the burning materials by any appreciable distance. However, 

in certain types of smoldering fires without evidence of flame, 

heat, smoke, and gas can develop.”); DICTIONARY OF MINING,

MINERAL, AND RELATED TERMS 246, 436 (1st ed. 1968)

(defining “fire” as “[f]uel in a state of combustion” and

defining “combustion” as “[t]he action or operation of 

burning” that can be but is not necessarily “accompanied by 

the generation of light and heat”).

We agree with the Secretary. The parties have both 

presented contemporary readings of the term “fire” that 

support their position. For that reason, Chevron step one is 

relatively straightforward here. “Confronting diverse readings 

of the statutory text, we are obliged to defer to the Secretary’s 

miner-protective construction of the Mine Act so long as it is 
11

reasonable.” Cannelton Indus., 867 F.2d at 1437. The parties 

have both provided competing uses of the term in 

contemporary judicial decisions, showing that lawyers and 

judges of the time sometimes understood “fire” to require 

visible flames and sometimes understood that a “fire” could 

exist even when there was only smoldering combustion. And

American Coal cannot successfully distinguish the 

contemporary cases cited by the Secretary that clearly 

differentiate between smoldering fires and flaming fires. True,

each of those cases involved a smoldering fire that was 

succeeded by a flaming fire, and the damage that provoked 

the dispute in each circumstance was caused by the later 

flaming stage. But that merely underscores that in each case 

the court considered the fire to have begun once smoldering 

commenced, even though flames had not yet broken out. This 

alone is reason enough to conclude that “fire” is ambiguous: 

Congress may have meant to include only flaming fires in the 

illustrative list of accidents in the Mine Act, but it may also 

have intended that list to include smoldering fires as well.

We also note that the term “fire” is identified in the statute 

merely as one item in an inclusive list designed to illustrate, 

not comprehensively enumerate, the various forms of 

“accident” that can justify issuing a safety order under section 

103(k). See 30 U.S.C. § 802(k) (stating that an “accident,” for 

purposes of the Mine Act, “includes a mine explosion, mine 

ignition, mine fire, or mine inundation, or injury to, or death 

of, any person” (emphasis added)); see also Burgess v. United 

States, 553 U.S. 124, 131 n.3 (2008) (“[T]he word ‘includes’

is usually a term of enlargement, and not of limitation.”

(internal quotation marks and citation omitted)). In other 

words, Congress enacted the Mine Act to create a 

comprehensive scheme empowering the Secretary and his 

mine inspectors to respond rapidly and flexibly to risks to 

miner safety. And as we have already pointed out, the Mine 
12

Act is a remedial health-and-safety statute, meaning that its 

terms are to be read broadly to offer maximum protection for 

miner safety. It would be senseless, in this context, to read a 

single term in the statute’s inclusive, illustrative list of 

possible accidents in the narrowest possible way, based on a 

cherry-picked selection of contemporary decisional law, so as 

to preclude the Secretary from adopting a reasonable 

construction that increased the safety of miners. On this basis,

we are satisfied that there are competing, plausible 

interpretations of the term “fire,” and so find it ambiguous. 

See Cannelton Indus., 867 F.2d at 1437.

It is true, as American Coal points out, that the generalusage dictionaries from the period when Congress passed the 

Mine Act, define fire only as flaming combustion. But these 

general-usage dictionaries do not change our view that the 

term “fire” is ambiguous in the Act. General-usage 

dictionaries cannot invariably control our consideration of 

statutory language, especially when the “dictionary definition 

of . . . isolated words[] does not account for the governing 

statutory context.” Bloate v. United States, 559 U.S. 196, 205 

n.9 (2010). After all, “‘[t]he plainness or ambiguity of 

statutory language is determined [not only] by reference to the 

language itself, [but as well by] the specific context in which 

that language is used, and the broader context of the statute as 

a whole.’” Yates v. United States, 135 S. Ct. 1074, 1081-82 

(2015) (plurality opinion) (quoting Robinson v. Shell Oil Co.,

519 U.S. 337, 341 (1997) (alterations in Yates)); see also id. 

at 1092 (“[W]e interpret particular words in their context and 

with a view to their place in the overall statutory scheme. And 

sometimes that means . . . that the dictionary definition of a 

disputed term cannot control.” (Kagan, J., dissenting) 

(internal quotation marks and citation omitted)). Though our 

assessment of the ambiguity of statutory text sometimes 

begins and ends with the definitions provided in 
13

contemporary general-usage dictionaries, on other occasions 

it is useful and important to consult more technical sources 

where, as here, the statute focuses on a specific technical 

context. The Mine Act is designed to secure and enhance the 

safety of miners in and around mines. The characteristics of 

fire that matter for the purposes of this statute are those 

relevant in the context of mining and industrial safety. And 

the general-usage dictionaries American Coal cites cannot and 

do not account for these particular characteristics. The 

Secretary, on the other hand, has provided technical 

resources, also from the period when Congress passed the 

Act, that define fire in the specific context of mining and 

industrial safety. For example, the Fire Protection Handbook 

that the Secretary has produced unmistakably supports the 

Secretary’s position by identifying the distinct risks 

associated with “smoldering fires.” NATIONAL FIRE 

PROTECTION ASSOCIATION, FIRE PROTECTION HANDBOOK 4-

34 (George H. Tryon & Gordon P. McKinnon eds., 13th ed. 

1969); see also NATIONAL FIRE PROTECTION ASSOCIATION, 

FIRE PROTECTION HANDBOOK 2-18 (Gordon P. McKinnon & 

Keith Tower eds., 14th ed. 1976) (same). And the Dictionary 

of Mining, Mineral, and Related Terms identifies “the 

generation of light and heat” merely as an “example” of the 

attributes of fire, not as a necessary precondition for fire to 

exist. DICTIONARY OF MINING, MINERAL, AND RELATED 

TERMS 246, 436 (1st ed. 1968); see also DICTIONARY OF 

MINING, MINERAL, AND RELATED TERMS 114 (2d ed. 1997) 

(same). In other words, paying attention to the context of the 

Mine Act, the exchange of contrasting definitions from 

various dictionary sources provides further basis to conclude 

that the term “fire” is ambiguous.

American Coal argues that the structure of the Act as a 

whole unambiguously requires that the term “fire” cover only 

combustion that displays visible flames. Specifically, 
14

American Coal claims that the Secretary’s interpretation is 

clearly foreclosed by the interaction between the two types of 

orders inspectors can issue to deal with mine accidents: safety 

orders under section 103(k) and withdrawal orders under 

section 107(a). American Coal argues that withdrawal orders 

under section 107(a) are designed to deal with conditions that 

pose a future risk of danger, while safety orders under section 

103(k) are designed to deal only with ongoing or completed

accidents, not their prevention. In American Coal’s view, a 

smoldering fire is a pre-accident condition, dangerous only 

because it poses the risk that it will ignite and become a 

flaming fire. Thus, American Coal insists that section 103(k) 

should not permit inspectors to issue safety orders to control 

smoldering fires because 103(k) orders are authorized only to 

confront actively occurring accidents, not to prevent future 

accidents. Instead, inspectors should be authorized to deal 

with smoldering fires only by issuing withdrawal orders under 

section 107(a) because that section offers appropriate 

authority for prophylactic measures. 

We disagree with American Coal’s view of the statute.

For one thing, we cannot agree that smoldering combustion is 

nothing more than a pre-fire state, important only because it 

might burst into flames in the future. Just the opposite. As the 

Secretary has explained, the self-heating properties of coal 

mean that coal stockpiles can begin smoldering and reach 

high temperature points without igniting, generating 

substantial heat and smoke that can imperil miners in the 

vicinity even without bursting into flames. Worse, smoldering 

combustion consumes coal just as surely as does flaming 

combustion. Patches of smoldering combustion can thus eat 

away at the stockpile from within, creating a hidden cavity

that can destabilize the stockpile as a whole or into which a 

miner can fall. A smoldering fire poses active risks and can 
15

constitute an “accident occurring” on a coal stockpile in its 

own right. 30 U.S.C. § 813(k).

Nor do we think American Coal’s account of the structure 

of the Mine Act is correct. Section 103(k) orders are broad, 

flexible tools, authorizing inspectors to confront many 

different circumstances that present immediate risks. For 

example, once safety orders are issued under section 103(k), 

inspectors often modify them to change the requirements 

imposed on mine operators as the accident evolves. See

Performance Coal Co. v. Fed. Mine Safety & Health Review 

Comm’n, 642 F.3d 234, 237 (D.C. Cir. 2011) (“It is 

undisputed that [section] 103(k) orders undergo frequent 

modifications.”). Inspectors sometimes issue section 103(k) 

safety orders first, while trying to deal with an accident, and 

only thereafter issue section 107(a) withdrawal orders to shut 

the mine down completely. See, e.g., Clinchfield Coal Co. v. 

Fed. Mine Safety & Health Review Comm’n, 895 F.2d 773, 

774 (D.C. Cir. 1990). Most obviously, section 103(k) safety 

orders allow inspectors to impose whatever restrictions or 

requirements they judge appropriate to deal with the accident 

in question, while section 107(a) withdrawal orders simply 

close the mine. In short, section 107(a) is an emergency 

blunderbuss, unsubtle and extreme, for circumstances in 

which getting miners out and away is the only appropriate 

response. Section 103(k), which the inspectors used here, is a 

subtler instrument that can be tailored to any situation. 

There is no risk that finding the term “fire” ambiguous 

will destabilize the statute. To the contrary, allowing the 

Secretary to wield section 103(k) orders in a broader range of 

circumstances accords with the statute’s structure by making a

flexible, nuanced tool available to handle accidents while they 

happen but before they become critical.
16

To sum up, the contemporary body of decisional law 

shows competing definitions of the term “fire” in a variety of 

contexts. General-usage and technical dictionary definitions 

from the period when Congress passed the Mine Act offer 

support for both sides of the debate. And finding ambiguity in 

this statutory term does not pose a risk to the structure of the 

statute but rather will conform to that structure by enabling 

the Secretary to use the flexible tool of section 103(k) safety 

orders in an appropriate range of circumstances. Because the 

parties to this dispute have shown that the term “fire” is 

susceptible to multiple plausible interpretations, we find it 

ambiguous and move on to consider whether the Secretary’s 

interpretation warrants deference.

2

Under Chevron step two, we defer to the Secretary’s 

interpretation of an ambiguous term unless it is unreasonable 

or inconsistent with the statute. The Secretary’s interpretation 

contains two elements. To qualify as “fire,” non-flaming 

combustion must qualify as “smoldering” combustion, and it 

must also present a reasonable chance of bursting into flame. 

We find both elements of this interpretation perfectly 

reasonable. 

First, nothing in the statute expressly prohibits the 

Secretary from reading “fire” to cover smoldering 

combustion. And as we explained in our analysis under 

Chevron step one above, there is substantial authority in 

judicial decisions and relevant technical references to support 

the conclusion that smoldering combustion qualifies as a type 

of “fire” whether it displays visible flames or not. It comports

with the goal of protecting miner safety not to ignore an entire 

category of fire simply because it does not show flames.
17

We also conclude that the Secretary was entitled to limit 

his interpretation of “fire” to include only smoldering fires 

that reasonably could ignite at any time. The Secretary has 

explained that the risks posed by a smoldering fire cross a 

critical line that warrants regulation when it reaches the point 

at which it might burst into flame. At that point, the Secretary 

has concluded, a smoldering fire’s danger to miners is 

significant enough to require regulation. That conclusion is 

reasonable. By limiting the scope of his authority to 

smoldering fires that reasonably could burst into flame at any 

time, as opposed to all smoldering combustion, the Secretary 

allows “operators and inspectors [to] focus their attention 

where it will do the most good” and avoids “unduly or 

unnecessarily burden[ing] operators or keep[ing] inspectors 

from attending to other important matters.” Resp. Br. 43. This 

explanation adequately justifies the Secretary’s decision to 

limit the scope of his oversight. 

American Coal raises three challenges to the 

reasonableness of the Secretary’s interpretation. None 

succeed. First, American Coal argues that the interpretation is 

unconstitutionally vague, leaving mine operators unable to 

comply and vulnerable to arbitrary and capricious 

enforcement, which, it submits, is a very ineffective way to 

promote miner safety. The Secretary rejoins that the 

interpretation is adequately specific because it limits its scope 

to smoldering combustion that “reasonably” might ignite. The 

Secretary is confident that “reasonable” mine operators, 

experienced in the industry and well-schooled in the 

characteristics of coal and its propensity to self-heat and 

ignite, will be able to comply.

We agree. There is no doubt that the Secretary has 

provided limited direction. But an interpretation need not be 

prolix to avoid impermissible vagueness. It must merely 
18

provide sufficient guidance so that reasonable regulated 

parties, aware of the goal the regulation seeks to accomplish, 

have “fair warning” of what the regulation requires. Freeman 

United Coal Mining Co. v. Fed. Mine Safety & Health Review 

Comm’n, 108 F.3d 358, 362 (D.C. Cir. 1997). This 

interpretation passes that bar. After all, the opinions that will 

matter in enforcing this standard are those of mine safety 

inspectors and mine operators who see smoldering patches on 

coal stockpiles with great regularity and have extensive

experience in recognizing those patches of smoldering 

combustion that might soon ignite. We are confident that 

reasonable mine operators and reasonable safety inspectors 

will prove able to implement the Secretary’s standard in 

practice.

Second, American Coal argues that the Secretary failed to 

provide a reasonable explanation for his decision to limit his 

interpretation of “fire” to cover only smoldering combustion 

that reasonably has the potential to burst into flames. We 

disagree. Based on his experience, the Secretary concluded 

that once smoldering fires have reached the point at which 

ignition is imminent, they pose risks to the miner significant 

enough to constitute an active accident. As we have already 

explained above, this conclusion was reasonable. American 

Coal seems to suggest that the Secretary could only 

reasonably define “fire” to include all smoldering combustion 

as well as all flaming combustion. But there is no basis for 

that position. After all, an agency need not target every danger 

in order to target any danger. See, e.g., Pers. Watercraft 

Indus. Ass’n v. Dep’t of Commerce, 48 F.3d 540, 544 (D.C. 

Cir. 1995) (“An agency does not have to make progress on 

every front before it can make progress on any front.”

(internal quotation marks omitted)). And agencies may 

marshal their limited resources by pursuing their goals “as 

priorities demand.” Nat’l Cong. of Hispanic Am. Citizens (El 
19

Congreso) v. Marshall, 626 F.2d 882, 888 (D.C. Cir. 1979). 

In light of these principles, the Secretary has provided a 

reasonable explanation for the scope of his interpretation of 

“fire.”

We acknowledge, as American Coal points out, that none 

of the technical treatises the Secretary has cited define fire by 

pointing to the reasonable possibility of ignition. But the 

Secretary has adequately explained his reasoning in limiting 

the scope of “fire” under the statute to cover only smoldering 

combustion that reaches the point at which ignition is an 

immediate risk. The fact that a dictionary or manual does not 

make that distinction in no way invalidates the Secretary’s 

otherwise reasonable explanation for adopting it.

Finally, American Coal argues again that the Secretary’s 

interpretation of the statute is foreclosed by the interaction 

between section 103(k) and section 107(a) of the Mine Act. 

We reject this argument for the reasons we have already 

stated. 

The Secretary’s interpretation of “fire” is reasonable. It 

furthers the statute’s purpose, provides adequate guidance for 

its implementation, and conforms harmoniously to the 

statute’s text and structure. We defer to the Secretary. 

C

Separately, American Coal argues that, even if the 

Secretary’s interpretation of the term “fire” is reasonable, the 

Commission erred in finding that interpretation satisfied here 

because there was insufficient evidence either that the patches 

on the stockpile were instances of smoldering combustion or 

that those patches could reasonably burst into flame at any 

time. Under the deferential standard of review we use to 
20

evaluate the Commission’s factual determinations, we reject

both arguments. See Jim Walter Res., Inc., 103 F.3d at 1023-

24. 

1

Substantial evidence supported the Commission’s 

determination that the safety inspectors observed patches of 

smoldering combustion. One mine safety inspector, Wendell 

Crick, testified that he observed smoking or smoldering areas

and whitish ash, smelled a sulfur-like odor, and observed heat 

waves rising from the smoldering areas. The other inspector

also testified that he saw smoldering patches. American Coal 

sought to counter this evidence with the competing testimony 

of its supervisor, who claimed that what Crick saw was

nothing more than gray rock. We conclude that the 

Commission was justified to rely on the testimony of the mine 

safety inspectors over that of American Coal’s witness.

American Coal attacks Crick’s testimony by insisting that, 

when he discussed visible heat waves rising from the patches 

on the coal stockpile, he was merely speaking generically 

about the phenomena generally associated with smoldering 

coal, not any observations he actually made at the time. But 

when pressed about what he saw rising from the stockpile, 

Crick responded, “You can see the heat waves and . . . a 

whitish coat of ash around the areas that smoke was rising 

from.” J.A. 103. The Commission was entitled to determine 

from this testimony, especially Crick’s reference to “the areas 

that smoke was rising from,” that Crick was in fact reporting 

his observations, not speaking in the abstract. Id. After all, 

when reviewing an agency determination for substantial 

evidence the question is not whether the challenger’s 

construction is plausible but whether the record can support 

the agency’s conclusion. See Fla. Gas Transmission Co. v. 
21

FERC, 604 F.3d 636, 645 (D.C. Cir. 2010). The 

Commission’s determination satisfies that standard.

American Coal also argues that the inspectors’ testimony 

was not reliable because the Secretary did not show that either 

held advanced academic degrees or had completed scientific 

studies relevant to the self-heating properties of coal. There is 

no basis for this challenge. Crick had extensive experience in 

coal mining as a foreman, safety analyst, and surface 

operation instructor. He had been a mine safety inspector for 

three years, and he had extensive volunteer firefighter training 

and experience. We need not determine the minimum 

credentials a mine inspector must have for his judgments to 

provide evidence on which an ALJ can permissibly rely. 

Crick’s credentials are adequate to justify the Commission’s 

reliance on his observations. 

2

We also find that substantial evidence supports the 

Commission’s determination that the smoldering patches 

reasonably had the potential to burst into flame.

In the original hearing, Crick testified that in his judgment 

“if the oxygen or the wind blows or . . . an amount of air hit[]”

the smoldering patches “just right,” they could “burst into 

flame spontaneously at any time.” J.A. 107-08. American 

Coal presented no evidence controverting Crick’s assessment. 

The Commission was entitled to credit Crick’s testimony and 

rely on it to conclude that the smoldering patches satisfied the 

Secretary’s interpretation.

American Coal argues that Crick’s testimony contradicts 

itself. Crick testified that the wind was blowing while he was 

inspecting the New Future stockpile, yet the smoldering 
22

patches had not ignited. Thus his claims about the ignitibility 

of the smoldering patches must be false. But Crick did not say 

that the smoldering patches he observed would necessarily 

ignite whenever the wind blew. The fact that there was wind 

does not mean that the patches were exposed to a sudden 

increase in oxygen level sufficient to trigger their ignition.

American Coal also argues that Crick’s testimony should 

not have been credited because the first ALJ rejected his 

testimony after seeing him testify in person, while the second 

ALJ reversed and credited his testimony on remand based 

only on the transcript of the hearing. Not so. The first ALJ 

concluded only that Crick’s testimony did not warrant “great 

weight,” not that it was incredible. And that determination 

was a natural one given that he had already rejected the 

Secretary’s interpretation of the term “fire.” Crick’s testimony 

regarding the smoldering combustion he observed only makes 

a difference if smoldering combustion can qualify as a “fire.”

Because the ALJ had rejected that construction, it made little 

difference that Crick had testified that “a fire could start up at 

any time.” After the Commission held that the ALJ was 

wrong to reject the Secretary’s interpretation, Crick’s 

testimony was of course far more valuable. Thus on remand

the second ALJ had a blank slate to evaluate the credibility of 

Crick’s testimony. And an ALJ’s credibility determination is 

“entitled to great deference.” Sec’y of Labor v. Keystone Coal 

Mining Corp., 151 F.3d 1096, 1107 (D.C. Cir. 1998). We 

cannot say that the second ALJ erred in any way when she 

relied on Crick’s uncontradicted testimony, backed up by 

Crick’s experience, that the patches on the stockpile that day 

posed the risk of bursting into flame.

We acknowledge that there was little evidence presented 

on whether the smoldering piles might soon burst into flames. 

But “[t]he substantial evidence inquiry turns not on how many 
23

discrete pieces of evidence the Commission relies on, but on 

whether that evidence adequately supports its ultimate 

decision.” Fla. Gas Transmission, 604 F.3d at 645. Crick’s 

testimony was enough to show that the Secretary’s 

interpretation was satisfied. As we have already noted, the 

question we ask when evaluating agency action under the 

substantial evidence standard is not whether the petitioner can 

reasonably read the evidence another way but only whether 

the agency was reasonable to read the evidence the way it did. 

Id. The Commission’s determination on this score satisfies 

that standard.

III

For the foregoing reasons, we deny the petition for 

review.