PRECEDENTIAL

          UNITED STATES COURT OF APPEALS
               FOR THE THIRD CIRCUIT
                    _____________

                       No. 16-1058
                      _____________

               HELEN MINING COMPANY,
                             Petitioner

                             v.

 *JAMES E. ELLIOTT, SR.; DIRECTOR OFFICE OF
 WORKERS’ COMPENSATION PROGRAMS UNITED
      STATES DEPARTMENT OF LABOR,
                           Respondents
               _______________

          On Petition for Review of an Order of the
                   Benefits Review Board
                   (BRB-1:15-0067 BLA)
                     _______________

                          Argued:
                     September 9, 2016

Before: JORDAN, VANASKIE, and KRAUSE, Circuit
Judges.


     
         Amended per Clerk’s Order of April 29, 2016.
                   (Filed: June 14, 2017)
                     _______________

Christopher Pierson, Esq. (Argued)
Burns White
48 26th Street
Burns White Center
Pittsburgh, PA 15212
       Attorney for Petitioner Helen Mining Co.

Robert J. Bilonick, Esq.
Heath M. Long, Esq. (Argued)
Pawlowski Bilonick & Long
603 North Julian Street
P.O. Box 658
Ebensburg, PA 15931
      Attorney for Claimant-Respondent James E. Elliott, Sr.

Sean Bajkowski, Esq. (Argued)
Rae Ellen James, Esq.
Kathleen H. Kim, Esq.
United States Department of Labor
Office of the Solicitor
Room N-2117
200 Constitution Avenue, N.W.
Washington, DC 20210
       Attorney for Federal Respondent Director, Office of
       Workers’ Compensation Programs
                       _______________

                OPINION OF THE COURT
                    _______________




                             2
KRAUSE, Circuit Judge.

       The Black Lung Benefits Act (BLBA) confers on coal
workers generally the right to claim workers’ compensation
benefits for disabilities arising out of coal dust exposure. 30
U.S.C. §§ 901–45. Typically, the burden of proof rests on the
miner to establish each element necessary for entitlement to
benefits. For miners who meet particular criteria, however,
the BLBA provides that certain elements will be presumed,
subject to rebuttal by the party opposing benefits, i.e., by the
coal mine operator-employer, if identifiable, or, alternatively,
by the Secretary of Labor. 30 U.S.C. § 921(c). At issue in
this case is whether a 2013 regulation, specifying the standard
a coal mine operator must meet to rebut the presumed
element of disability causation, is ultra vires to the BLBA.
See 20 C.F.R. § 718.305(d)(1) (2013). For the reasons set
forth below, we agree with the Benefits Review Board’s
conclusion that operators are subject to the regulation’s
rebuttal standard because the regulation permissibly fills a
statutory gap in the legislation. We also agree that the record
adequately supports the ALJ’s conclusion that the operator
did not meet that rebuttal standard in this case. Accordingly,
we will affirm the award of benefits and deny the operator’s
petition for review.

I.     Background

        Coal mine operator Helen Mining Company seeks
review of an award of black lung benefits to Claimant-
Respondent James E. Elliott, Sr. Before turning to the facts
of this particular case, we briefly review the historical
development of the relevant benefits scheme to give context
to the challenges raised by Helen Mining in this appeal.




                               3
       A.     Statutory and Regulatory Context

        In 1969, Congress passed Title IV of the Federal Coal
Mine Health and Safety Act, also known as the BLBA, to
provide benefits to coal miners whose exposure to coal dust
has resulted in the crippling pulmonary condition of
pneumoconiosis, commonly known as “black lung.” Pub. L.
No. 91-173, § 401, 83 Stat. 742, 792 (1969) (codified as
amended at 30 U.S.C. § 901); see also Mullins Coal Co. of
Va. v. Dir., OWCP, 

, 138 (1987).1 To prove
entitlement to benefits, a miner must establish four elements:
(1) disease, i.e., he has pneumoconiosis; (2) disease causation,
i.e., the pneumoconiosis arose out of dust exposure from his
coal mine employment; (3) disability, i.e., he has a totally
disabling respiratory or pulmonary impairment that prevents
him from performing coal mining or comparable work; and
(4) disability causation, i.e., pneumoconiosis is a
“substantially contributing cause” of his disability. 20 C.F.R.
§§ 718.204(C)(1), 725.202(d)(2) (citing 20 C.F.R.
§§ 718.201–718.204); see also Dir., OWCP v. Mangifest, 

, 1320 (3d Cir. 1987). BLBA benefits were initially
administered by the Social Security Administration, pursuant
to regulations promulgated by the then-Secretary of Health,
Education, and Welfare, and were paid from federal funds.
30 U.S.C. §§ 921–24; Pauley v. BethEnergy Mines, Inc., 

, 683–84 (1991). Today, such claims for BLBA


       1
         The statutory scheme underlying entitlements to
black lung benefits, as we have previously noted, “could
hardly be more complicated,” Helen Mining Co. v. Dir.,
OWCP (Burnsworth), 

, 1271–73 (3d Cir. 1991)
(en banc), and we do not aspire here to a full exegesis,
focusing instead on the provisions relevant to this case.




                               4
benefits are administered by the Director of the Office of
Workers’ Compensation Programs, pursuant to regulations
promulgated by the Secretary of Labor. 30 U.S.C. §§ 902(c),
932; 

.

        Congress has amended the BLBA in numerous
respects over the years, but three have particular relevance to
this appeal. First, in an effort to relax the burden on miners to
prove entitlement to benefits, the Black Lung Benefits Act of
1972 added a provision establishing that any miner who can
prove he worked fifteen years or more in an underground coal
mine and can establish the third element—that he is
disabled—is entitled to “a rebuttable presumption that [he] is
totally disabled due to pneumoconiosis” and is therefore
entitled to black lung benefits. Pub. L. No. 92-303, § 4(c), 86
Stat. 150, 154 (codified at 30 U.S.C. § 921(c)(4)) (hereinafter
“the § 921(c)(4) presumption”); 

.2 In
essence, if a miner could prove qualifying employment and
disability, then the other elements, including disability
causation, would be presumed to be met as well, shifting the
burden to the party opposing benefits—at that point in time,
the Secretary—to rebut the presumption by means specified
in § 921(c)(4). As to the element of disability causation, for
example, § 921(c)(4) specified that the Secretary may rebut
by “establishing that … [the miner’s] respiratory or

       2
         This rebuttable presumption specifically benefits
miners whose pneumoconiosis is not sufficiently pervasive to
manifest itself in a chest X-ray. See 30 U.S.C. § 921(c)(4).
For miners who can prove the disease by chest X-ray, the
presumption of entitlement to benefits is irrebuttable. 30
U.S.C. § 921(c)(3).




                               5
pulmonary impairment did not arise out of, or in connection
with, employment in a coal mine.” 30 U.S.C. § 921(c)(4)(B);
see also 

–86.3

        Second, the BLBA from its inception had anticipated a
gradual transition to the processing of claims by approved
state workers’ compensation programs or, in the absence of
an approved program, by the Secretary himself, with mine
operators bearing financial responsibility for the payment of
benefits. See Federal Coal Mine Health and Safety Act of
1969, § 422, 83 Stat. 741, 796–97 (codified as amended at 30
U.S.C. § 932). But the 1972 Act set the date for that
transition as January 1, 1974, providing that all claims filed
on or after that date would be paid not from federal funds, but
by the private coal mine operator that employed the miner,
see Black Lung Benefits Act of 1972, § 5(1), (2), 86 Stat.
150, 155 (codified as amended at 30 U.S.C. § 932), and a
subsequent amendment ensured that if a responsible operator
could not be identified, benefits would be paid by a fund,
administered by the Secretary, into which mine operators
would contribute.4 Thus, from that point forward,



      3
         The statute provides, in the alternative, that the
Secretary may rebut the presumption by disproving the
disease element, specifically by “establishing that … [the
miner claiming the presumption] does not, or did not, have
pneumoconiosis.” 30 U.S.C. § 921(c)(4)(A). This is the only
other rebuttal method prescribed for the Secretary, and it is
not relevant to this appeal.
      4
        The Black Lung Disability Trust Fund was created by
the Black Lung Benefits Revenue Act of 1977. See Pub. L.




                              6
the party opposing benefits would be not only the Secretary,
but either the Secretary or the mine operator, depending on
which was the payor.

        Finally, in another amendment passed in 1977,
Congress expanded the definition of pneumoconiosis beyond
the class of clinical diseases recognized as pneumoconiosis
(so-called “clinical pneumoconiosis”) to include “any chronic
dust disease of the lung … arising out of coal mine
employment” (now referred to as “legal pneumoconiosis”).
Black Lung Benefits Reform Act of 1977, Pub. L. No. 95-
239, sec. 2(a), § 402(b), 92 Stat. 95, 95 (codified at 30 U.S.C.
§ 902(b)); see 20 C.F.R. § 718.201(a). The upshot of this
amendment, when considered together with § 921(c)(4), was
that the disease and disease causation elements overlapped, so
if the Secretary could not rebut the presumption by proving
that the miner did not have a disease “arising out of coal mine
employment” (elements one and two), 30 U.S.C. § 902(b);
see supra note 3, then he could only rebut disability causation
by showing that the miner’s impairment did not result from
that disease (element four). See 30 U.S.C. § 902(b).

       Soon after these amendments took effect, however,
“the number of black lung benefit claims soared,” B & G
Constr. Co. v. Dir., OWCP, 

, 242 (3d Cir. 2011),
leading Congress to reverse course and amend the § 921(c)(4)
presumption so that it would no longer apply to claims filed
on or after January 1, 1982, see Black Lung Benefits Revenue
Act of 1981, Pub. L. No. 97, § 202(b)(1), 95 Stat. 1635, 1643.
For the next several decades, miners applying for benefits


No. 95-227, §§ 2–3, 95 Stat. 11, 11–15 (1978) (codified as
amended at 26 U.S.C. § 4121; 30 U.S.C. § 934).




                               7
under the Act could not claim the benefit of the § 921(c)(4)
presumption.

        With the Patient Protection and Affordable Care Act,
however, Congress changed its mind once more and revived
the § 921(c)(4) presumption for all claims filed after January
1, 2005 that were still pending on or after March 23, 2010.
Pub. L. No. 111-148, § 1556(a), (c), 124 Stat. 119, 260
(2010). For the reasons explained, the party opposing
benefits at this point in time could be either the Secretary or
the mine operator. However, when Congress reinstated
§ 921(c)(4), it did not alter the original language of that
provision. Thus, while the presumption would apply to any
qualifying miner as against any opposing party, the statute
still specified only how “the Secretary”—originally, the only
opposing party—could rebut the presumed elements, and
made no explicit provision for rebuttal by operators.

       The following year, the Department of Labor
promulgated a regulation to fill that gap and to expound on
the rebuttal standard. 20 C.F.R. § 718.305 (2013) (hereinafter
“the Regulation”); see also Regulations Implementing the
Byrd Amendments to the Black Lung Benefits Act:
Determining Coal Miners’ and Survivors’ Entitlement to
Benefits, 78 Fed. Reg. 59,102, 59,106–07 (Sept. 25, 2013).5
The Regulation thus prescribes the means of rebuttal for any

       5
          Although Elliott applied for benefits in 2012 and the
Regulation was not promulgated until the following year, the
Regulation “applies to all claims filed after January 1, 2005,
and pending on or after March 23, 2010.” 20 C.F.R.
§ 718.305(a) (2013). Thus, Helen Mining does not challenge
its applicability to Elliott on this ground.




                              8
“party opposing entitlement” to benefits, encompassing both
the Secretary and mine operators. 20 C.F.R. § 718.305(d)(1)
(2013). And to rebut the presumed element of disability
causation, the Regulation specifies that, short of disproving
the presence of disease,6 such opposing party must
“[e]stablish[] that no part of the miner’s respiratory or
pulmonary total disability was caused by pneumoconiosis.”
20 C.F.R. § 718.305(d)(1)(ii) (2013). Put another way, the
opposing party must “rule out” any connection between
pneumoconiosis and a miner’s disability. See Kline v. Dir.,
OWCP, 

, 1179 (3d Cir. 1989) (describing a
regulation with similar “no part” language as imposing a “rule
out” standard). The validity of the Regulation and, in
particular, its imposition of the rule out standard on mine
operators, is the central issue on appeal.

       B.     Factual and Procedural History

       Elliott worked in a coal mine for over twenty-three
years, until 1993. During that time, he developed a chronic
cough, and about three or four years after his retirement, he
developed more acute breathing problems characterized by
shortness of breath and chest pain. Elliott timely filed a claim
for benefits under the BLBA in September 2012, alleging that
he suffered from respiratory difficulties due to his coal mine
employment. The Director of the United States Department
of Labor, Office of Workers’ Compensation Programs, issued

       6
         Consistent with the alternate means of rebuttal
provided by the statute, see supra note 3, the Regulation also
provides that a party opposing the award of benefits may
rebut the presumption by disproving the presence of the
disease in its legal or clinical form.          20 C.F.R. §
718.305(d)(1)(i) (2013).




                               9
a proposed Decision and Order awarding benefits on June 4,
2013.    Petitioner Helen Mining conceded it was the
responsible employer, but it challenged Elliott’s entitlement
to benefits and requested a formal hearing before an
Administrative Law Judge (ALJ).

       At an April 2014 hearing before an ALJ, the parties
stipulated that Elliott suffered from a totally disabling
respiratory impairment.       Because Helen Mining thus
conceded disability and because Elliott demonstrated a term
of employment greater than fifteen years,7 the ALJ
determined that § 921(c)(4) applied and that the other
elements, including disability causation, would be presumed.
Elliott thus was presumed totally disabled due to
pneumoconiosis, and the ALJ shifted the burden to Helen


      7
          The § 921(c)(4) presumption applies only if the
miner’s fifteen years of work were performed underground.
See 30 U.S.C. § 921(c)(4). However, employment “in
conditions substantially similar to those in underground
mines” will qualify if the miner can demonstrate that he was
“regularly exposed to coal-mine dust while working there.”
20 C.F.R. § 718.305(b)(1)(i), (b)(2).        Elliott worked
underground for only ten years, but the ALJ credited his
testimony regarding the “dusty conditions of his aboveground
mining positions” and thus determined that he had shown
enough total years of qualifying work to invoke the
presumption. Helen Mining challenged this finding on its
appeal to the Benefits Review Board, but the Board rejected
it, and Helen Mining has waived the issue on appeal by
failing to raise it in its opening brief to this Court. See
Laborers’ Int’l Union of N. Am., AFL-CIO v. Foster Wheeler
Corp., 

, 398 (3d Cir. 1994).




                             10
Mining to rebut the other elements as permitted by the
Regulation.

       As part of its effort to rebut the presumption, Helen
Mining offered the opinions of Doctors Gregory Fino and
Samuel Spagnolo, both of whom attributed Elliott’s
respiratory impairment to a diagnosis of adult-onset asthma
unrelated to coal dust exposure. The ALJ did not find their
testimony persuasive and concluded that Helen Mining had
failed to rule out coal dust-induced pneumoconiosis as a
cause of Elliott’s disability and thus had failed to rebut the
presumption. 20 C.F.R. § 718.305(d)(1).8 He therefore
awarded benefits to Elliott.

       On appeal to the Benefits Review Board (the “BRB,”
or “the Board”), Helen Mining argued that the ALJ should not
have required it to meet the rule out standard prescribed by
the Regulation because the Regulation, which imposes that
rebuttal burden on both operators and the Secretary, should be
deemed ultra vires to the statute, which imposes it on the
Secretary alone.       The BRB rejected this argument,
specifically holding that the Regulation is valid and that the
ALJ was correct to apply it here because the Regulation

      8
         Elliott also argued before the ALJ that he could
establish disability causation even without the benefit of
§ 921(c)(4)’s presumption, and, to that end, he proffered
testimony and reports of experts who had diagnosed him with
qualifying diseases that they opined were caused, at least in
part, from coal mine dust exposure. The ALJ did not find
those experts persuasive either but concluded their opinions
were inconsequential because the presumption did apply and
Helen Mining did not satisfy the rule out standard to rebut it.




                              11
“fill[s] the statutory gap created by the omission of a specific
reference to responsible operators, clarif[ies] ambiguous
phraseology, and effectuate[s] the purposes of the Act, i.e., to
compensate miners with fifteen or more years of coal mine
employment who are disabled by pneumoconiosis.” JA 10a.
The Board proceeded to hold that the ALJ correctly applied
that standard and that, having reasonably rejected the
opinions of Helen Mining’s medical experts, the ALJ
properly concluded Helen Mining had failed to rebut the
presumption. The Board therefore affirmed the ALJ’s
decision, and Helen Mining petitioned this Court for review.9

II.    Jurisdiction and Standard of Review

      The BRB had jurisdiction to review the ALJ’s decision
pursuant to 33 U.S.C. § 921(b)(3), as incorporated by 30
U.S.C. § 932(a). This Court has jurisdiction over this appeal
because Elliott’s exposure to coal mine dust occurred in

       9
         Although the ALJ based his ruling on the Regulation,
20 C.F.R. § 718.305(d), which imposes the rule out standard
on the party seeking to rebut disability causation, he also at
several points described the presumption as establishing that
pneumoconiosis was a “substantially contributing cause” of
Elliott’s disability. JA 29a–30a, 32a, 34a–35a. That
language may have been imprecise, but it is clear that the ALJ
in fact applied the rule out standard by requiring Helen
Mining to provide medical evidence completely
“disassociating” Elliott’s disability from any coal dust-related
disease and concluding Helen Mining had not met its burden
under the Regulation. JA 34a. The Board affirmed that
determination, and the application of the Regulation’s rule out
standard to operators is therefore squarely before us on
appeal.




                              12
Pennsylvania, and 33 U.S.C. § 921(c), as incorporated by 30
U.S.C. § 932(a), allows an aggrieved party to seek review of a
BRB decision in the U.S. Court of Appeals for the Circuit in
which the injury occurred.

        We review the Board’s decision only to determine
“whether an error of law has been committed and whether the
Board has adhered to its scope of review.” Hill v. Dir.,
OWCP, 

, 268 (3d Cir. 2009) (quoting
Kowalchick v. Dir., OWCP, 

, 619 (3d Cir.
1990)). “We exercise plenary review over the ALJ’s legal
conclusions that were adopted by the Board.” 

Board is bound by the ALJ’s findings of
fact if they are supported by substantial evidence,” but if a
petitioner challenges a finding of fact, “we must
independently review the record and decide whether the
ALJ’s findings are rational, consistent with applicable law
and supported by substantial evidence on the record
considered as a whole.” 

is “such
relevant evidence as a reasonable mind might accept as
adequate to support a conclusion.” 

        Helen Mining raises on appeal the same two issues it
raised before the Board. That is, first, it challenges the
validity of the Regulation to the extent it imposes on
operators (and not merely on the Secretary) the burden to
rebut disability causation using the rule out standard, and
second, it contends that even if the Regulation applies, it
satisfied the rule out standard through expert medical
evidence that the ALJ erroneously rejected. As explained
below, we find each of these arguments unavailing.




                             13
      A.     Validity of Regulation

        We first consider Helen Mining’s challenge to the
Regulation’s imposition of the rule out standard on operators.
In addressing the validity of a regulation promulgated through
notice-and-comment procedures, we apply the familiar two-
step analysis of Chevron U.S.A., Inc. v. Natural Resources
Defense Council, Inc., 

(1984). If Congress has
directly and clearly spoken to the precise question at issue,
our Chevron analysis is complete at Step One, and Congress’s
unambiguously expressed intent controls. 

–43. If, however, we determine that Congress has not
addressed “the precise question at issue,” whether by being
“silent or ambiguous with respect to the specific issue” or by
leaving “a gap for the agency to fill,” then we must proceed to
the second step and determine whether the agency’s
construction of the statute is reasonable. 

–44.10


      10
          As a threshold matter, Chevron deference is only
appropriate “when it appears that Congress delegated
authority to the agency generally to make rules carrying the
force of law, and that the agency interpretation claiming
deference was promulgated in the exercise of that authority.”
United States v. Mead Corp., 

, 226–27 (2001).
The Secretary of Labor is authorized to promulgate rules and
regulations necessary for the administration and enforcement
of the BLBA, 30 U.S.C. § 936(a), and the parties do not
challenge the exercise of that authority to promulgate the
Regulation through notice-and-comment rulemaking here.
       Even greater deference is due when Congress has left
not merely an implicit gap for the agency to fill but has made
an “express delegation of authority to the agency to elucidate




                              14
              1.     Chevron Step One

       Helen Mining urges that the validity of the Regulation
be resolved at Step One because, in its view, the requirement
that operators rule out any connection between disease and
disability is contrary to the intent of Congress as clearly and
unambiguous expressed in § 921(c)(4). In a nutshell, Helen
Mining’s argument is that: (a) by providing miners with a
presumption described as “rebuttable,” Congress confirmed
that any opposing party—whether the Secretary or an
operator—has the opportunity to rebut disability causation;
(b) Congress expressly constrained the Secretary to rebut
disability causation by “establishing that … [the miner’s
disease] did not arise out of, or in connection with,
employment in a coal mine,” 30 U.S.C. § 921(c)(4), and was
silent as to the rebuttal standard for operators; ergo (c)
Congress clearly and unambiguously intended to allow


a specific provision of the statute by regulation,” which then
must be given “controlling weight unless [it is] arbitrary,
capricious, or manifestly contrary to the statute.” 

–44. Arguably, that is the case here, for in
addition to delegating general rulemaking, Congress directed
the Secretary to, “by regulation[,] prescribe standards for
determining … whether a miner is totally disabled due to
pneumoconiosis,” 30 U.S.C. § 921(b), and the standard for an
operator to rebut a presumption that a miner is totally
disabled due to pneumoconiosis could be viewed as falling in
this category. We do not reach this question, however, both
because it was not addressed by the parties, and because we
conclude that even applying the lesser deference afforded by
the traditional two-step Chevron inquiry, the Regulation still
stands.




                              15
operators to rebut disability causation without having to
“establish[] that … [the disease] did not arise out of, or in
connection with, employment in a coal mine,” 

this syllogism, Helen Mining reasons, the Regulation’s
rule out standard—interpreting § 921(c)(4) to require any
party opposing benefits to “[e]stablish[] that no part of the
miner’s respiratory or pulmonary total disability was caused
by pneumoconiosis,” 20 C.F.R. § 718.305(d)(1)(ii)—is ultra
vires to the extent it purports to apply to operators.

       The flaw in Helen Mining’s logic is apparent in its
premise: The fact that Congress spoke explicitly to the
rebuttal standard for the Secretary and was silent as to
operators is the very reason we must conclude that Congress
did not unambiguously reject or accept that rebuttal standard
for operators. “[S]uch silence, after all, normally creates
ambiguity. It does not resolve it.” Barnhart v. Walton, 

, 218 (2002). And our inquiry is only resolved at
Chevron Step One if “Congress has directly spoken to the
precise question at issue.” 

–43.
Where, as here, Congress has not done so, and is instead
“silent or ambiguous with respect to the specific issue,”
leaving “a gap for the agency to fill,” controlling precedent
directs that the agency is indeed empowered to fill that void.

is a textbook example of an agency filling
such a void, and its validity therefore must be addressed at
Chevron Step Two.

      This conclusion is reinforced when we consider
§ 921(c)(4) “in context,” interpreting the statute to create “a
symmetrical and coherent regulatory scheme.” FDA v.
Brown & Williamson Tobacco Corp., 

, 132–33
(2000). The BLBA elsewhere provides that black lung




                              16
benefits are only available to miners who are disabled “due
to” pneumoconiosis, 30 U.S.C. § 901(a)—language we
previously recognized may invoke a broad range of meanings
and thus does not clearly and unambiguously identify the
standard for proving disability causation. Bonessa v. U.S.
Steel Corp., 

, 728–29, 733 (3d Cir. 1989). At
the time we examined the statute in Bonessa, the standard for
a living miner to affirmatively prove disability causation had
not yet been defined by regulation, so we imported the
“substantially contributing cause” standard that had been
articulated by the agency for survivors seeking death benefits,

733–34, and the agency subsequently
incorporated that very standard into a new regulation directed
at living miners who cannot claim the benefit of the
presumption, 20 C.F.R. § 718.204(c); see Regulations
Implementing the Federal Coal Mine Health and Safety Act
of 1969, as Amended, 65 Fed. Reg. 79.920, 79,948 (Dec. 20,
2000). Just as Congress’s silence in § 901(a) created a void
for the agency to set the causal standard for miners proving
entitlement, 

, 733, so too did
Congress’s silence in § 921(c)(4) create a void for the agency
to set the causal standard for operators seeking to rebut the
presumption of entitlement. In neither case do we read that
silence as an affirmative rejection or acceptance of a
particular standard at Chevron Step One.11

      11
         For that reason, Helen Mining fares no better in
arguing that § 921(c)(4) reflects Congress’s unambiguous
adoption of a modified “substantially contributing cause”
standard than it does in arguing that § 921(c)(4) reflects
Congress’s unambiguous rejection of the rule out standard.
No doubt, construing the statute as a whole in the absence of
the Regulation, Helen Mining’s construction might have more




                              17
        Helen Mining, however, contends that we are bound to
do just that and to hold that Congress unambiguously rejected
a rule out standard for miners in light of Usery v. Turner
Elkhorn Mining Co., 

(1976). Usery considered a
challenge by a group of operators to the § 921(c)(4)
presumption soon after it was created by the Black Lung
Benefits Act of 1972. See 

11–12, 37. The operators
argued that they should be permitted to oppose benefits
without being subject to the statutory rebuttal standard
imposed on the Secretary, and the Court agreed, reasoning
that it was “clear as a matter of statutory construction that the
[§ 921(c)(4)] limitation on rebuttal evidence is inapplicable to
operators. By the language of [§ 921(c)(4)], the limitation
applies only to ‘the Secretary’ and not to an operator seeking
to avoid liability ….” 

(citing H.R. Rep. No. 92-
1048, at 8 (1972) (Conf. Rep.); S. Rep. No. 92-780, at 8


traction, for there would be internal consistency in adopting
as the standard by which operators must rebut disability
causation when it is presumed, i.e., that pneumoconiosis was
not a “substantially contributing cause” of the miner’s
disability, the inverse of the standard by which minors must
establish disability causation in the absence of such a
presumption, i.e., that pneumoconiosis was a “substantially
contributing cause” of their disability. See 20 C.F.R.
§ 718.204(c)(1). But the Regulation adopts a different
standard, see 20 C.F.R. § 718.305(d)(1)(ii), and at Chevron
Step One, we look to whether the “administrative
construction[] [is] contrary to clear congressional intent,”

n.9, not whether the statute could
reasonably be construed another way “in the absence of an
administrative interpretation” 

                               18
(1972) (Conf. Rep.); S. Rep. No. 92-743, at 12 (1972)).12 The
Court went on to note, however, that it was not addressing
whether a regulation could permissibly fill that gap in the law,
and while it acknowledged that the Secretary had
promulgated an implementing regulation that appeared to
apply to claims payable by operators, it declined to consider
the validity of that regulation because it had not been raised
by the parties. 

In short, by establishing that the
statute is silent as to operators and leaving open the

       12
          We also note that this holding from Usery has little
bearing on the statute as it operates today, given the statutory
amendments that have been passed since the time of that
decision. At the time Usery was decided, only disabilities
caused by clinical pneumoconiosis were compensable under
the Act, and therefore the statutory rebuttal methods were
truly limiting in that they did not allow a party to rebut the
causal element by proving that a miner was not entitled to
benefits because he was disabled by some other coal dust-
induced lung disease that was not clinical pneumoconiosis.
See 

–35. Now, however, the statute has
been amended to cover benefits for disabilities arising from
any “chronic dust disease of the lung and its sequelae …
arising out of coal mine employment,” known as “legal
pneumoconiosis.” Black Lung Benefits Reform Act of 1977,
Pub. L. No. 95-239, § 2(a), 92 Stat. 95, 95 (codified at 30
U.S.C. § 902(b)); 20 C.F.R. § 718.201(a)(2). Because all
totally disabling lung diseases caused by coal dust exposure
are now covered under the Act, the operators’ concerns
expressed in Usery that they would be prohibited from
presenting relevant evidence to rebut the link between
pneumoconiosis and disability no longer pertain. See W. Va.
CWP Fund v. Bender, 

, 139 (4th Cir. 2015).




                              19
possibility that this silence could be filled by regulation,
Usery, if anything, confirms that this question may not be
resolved at Chevron Step One.13

       Having concluded that § 924(c) is “silent or
ambiguous” as to the rebuttal standard for operators and that
Congress has not “directly spoken to the precise question at
issue,” 

–43, we must proceed to
consider the Regulation at Step Two of the Chevron analysis.

              2.     Chevron Step Two

        At Step Two, we consider whether the agency’s
regulation that fills a statutory gap is “based on a permissible
construction of the statute.” 

. We
must still at this stage consider the plain language of the
statute, along with its origin and purpose, in reviewing the
reasonableness of the regulation, see Zheng v. Gonzales, 

, 119 (3d Cir. 2005), but if the regulation reflects a
reasonable statutory interpretation, we will defer to that


       13
          Helen Mining also highlights Judge Niemeyer’s
reliance on Usery in his concurrence in Mingo Logan Coal
Co. v. Owens to argue that the plain language of the statute
permitted an operator to rebut using a “substantially
contributing cause” standard. 

, 560–61 (4th Cir.
2013) (Niemeyer, J., concurring).        That concurrence,
however, was published about two months before the
Regulation went into effect, and the Fourth Circuit
subsequently considered and affirmed the validity of the
Regulation, noting that Judge Niemeyer’s concurrence in
Owens “did not consider the language of any regulation.”

n.12.




                              20
construction, even if we may have interpreted the statute
otherwise, 

n.11.

       Here, Helen Mining devoted the bulk of its briefing
and argument to Chevron Step One, only weakly contesting
the reasonableness of the Regulation.14 And for three good
reasons.

        First, the Regulation furthers Congress’s goals in
enacting § 924(c). The sequence of legislative amendments
here—the enactment of § 924(c) specifying the presumption
and the means of rebuttal for “the Secretary” at a time when
the Secretary was the only payor, the repeal of § 924(c), and
its eventual revival at a point in time when operators were the
primary payors—itself suggests that Congress may well have
intended § 924(c) to reach any party opposing benefits and
that its failure to further amend the statute upon reinstatement

       14
          At some points Helen Mining appears to concede
Step Two. See Oral Argument at 14:38 (No. 16-1058),
available at http://www.ca3.uscourts.gov/oral-argument-
recordings (responding to question whether Helen Mining
disputes the reasonableness of the regulation at Chevron Step
Two by stating, “Not based on the case law that’s out there.
No.”). However, at other points it appears to argue that a
more reasonable interpretation of § 921(c)(4) would require
operators to meet the “substantially contributing cause”
standard required for miners not entitled to the presumption.
Pet’r’s Br. 28–29 (citing 20 C.F.R. § 718.204(c)(1)).
Reasonable as it may be however, see supra note 11, Helen
Mining’s interpretation does not render the agency’s different
interpretation an unreasonable one. See 

n.11.




                              21
to include operators “reflects nothing more than a drafting
error” that “needs common sense revision.” G.L. v. Ligonier
Valley Sch. Dist. Auth., 

, 625 (3d Cir. 2015).
That is to say, the Regulation can be viewed not merely as a
reasonable construction of an ambiguous statute, but as the
proper construction of the statute as Congress intended it.
That conclusion is reinforced when we consider that Congress
imposed § 924(c)(4)’s presumption because Congress had
become “[d]issatisfied with the increasing backlog of
unadjudicated claims and the relatively high rate of claim
denials” under the original Act, 

, and
it sought to give preference to those miners most at risk for
disease because of their long-term coal dust exposure, see S.
Rep. No. 92-743, at 11 (1972). Placing a heightened burden
on the party seeking to overcome the presumption—whether
that party is the Secretary or the operator—reinforces that
preference and expedites the processing of these claims.

       Second, we have long approved of the rule out
standard as a reasonable burden of proof for operators seeking
to disprove disability causation and to avoid paying black
lung benefits. In Carozza v. U.S. Steel Corp., 

(3d
Cir. 1984), for example, we addressed a similar regulation
that required operators to rule out a connection between
disability and pneumoconiosis in order to overcome an
interim presumption.15 Recognizing that pneumoconiosis

      15
          Although this case predated Chevron, we employed
an analysis that closely tracked the test eventually adopted by
the Supreme Court in that case. See 

;

–43. The interim presumption that
was at issue was established by a now-superseded
Department of Labor regulation under the Black Lung




                              22
may contribute to a miner’s disability by aggravating other
non-work-related conditions, we held that the Secretary’s
decision to require a party opposing benefits to rule out even
such a slight connection between pneumoconiosis and
disability was in accord with workers’ compensation
principles, “consistent with the remedial purposes of
Congress[,] and well within the rulemaking authority
conferred on the Secretary.” 

& n.1; see also 

–79.

       Third, it is particularly appropriate for us to defer to
the agency’s interpretation of this statute because it forms the
basis for a complex regulatory scheme.            While some
distinguished jurists have recently raised thought-provoking
questions about the proper bounds of Chevron and judicial
deference, see, e.g., Egan v. Delaware River Port Auth., 

, 278–83 (3d Cir. 2017) (Jordan, J., concurring in the
judgment); Gutierrez-Brizuela v. Lynch, 

,
1151–55 (10th Cir. 2016) (Gorsuch, J., concurring), there
remains general consensus that such deference is appropriate
where the agency oversees a “complex and highly technical”


Benefits Reform Act of 1977 and established that any miner
who worked for at least ten years and could demonstrate one
of a list of medical criterion was presumed to be disabled due
to pneumoconiosis. See 

(citing 20
C.F.R. § 727.203(a) (1983)); 

–89.
Like the Regulation here, the Department of Labor regulation
also provided that the party opposing benefits could rebut the
presumption by establishing that “the total disability or death
of the miner did not arise in whole or in part out of coal mine
employment.” 20 C.F.R. § 727.203(b)(3) (1983) (emphasis
added); see also 

–89.




                              23
regulatory program, Thomas Jefferson Univ. v. Shalala, 

, 512 (1994), or has particular substantive expertise
and specialized experience, see FERC v. Elec. Power Supply
Ass’n, 

, 782–84 (2016); 

–
82 (Jordan, J., concurring).16 Here, as the Supreme Court
observed, the BLBA created a “highly technical regulatory
program,” and “[t]he identification and classification of
medical eligibility criteria” for that program “necessarily
require significant expertise and entail the exercise of
judgment grounded in policy concerns.” 

. In promulgating the Regulation, the agency applied that
experience and judgment to weigh the competing standards
and to adopt the rule out standard. See Regulations
Implementing the Byrd Amendments to the Black Lung
Benefits Act: Determining Coal Miners’ and Survivors’
Entitlement to Benefits, 78 Fed. Reg. 59,102, 59,106–07
(Sept. 25, 2013). While Helen Mining’s “substantially
contributing cause” standard may also be reasonable, “the

      16
          See, e.g., ECM BioFilms, Inc. v. FTC, 

(6th Cir. 2017); Baylor Cty. Hosp. Dist. v. Price, 

, 264 (5th Cir. 2017); Defenders of Wildlife v. Zinke, 

, 1089 (D.C. Cir. 2017); Compassion Over Killing
v. FDA, 

, 856 (9th Cir. 2017); In re Vehicle
Carrier Servs. Antitrust Litig., 

, 86 n.17 (3d Cir.
2017); Buffalo Transp., Inc. v. United States, 

,
385 (2d Cir. 2016); Zero Zone, Inc. v. U.S. Dep’t of Energy,

, 668 (7th Cir. 2016); Doe v. Cape Elizabeth
Sch. Dist., 

, 77 n.7 (1st Cir. 2016); WildEarth
Guardians v. U.S. Fish & Wildlife Serv., 

, 683
(10th Cir. 2015); 

; Draper v. Colvin,

, 560 (8th Cir. 2015); Davis v. Producers Agric.
Ins. Co., 

, 1286 (11th Cir. 2014).




                             24
Secretary’s interpretation need not be the best or most natural
one … to warrant deference,” 

, and
we cannot say that the heavier burden that the Regulation
places on operators is unreasonable.

       For all of these reasons, we hold that the Regulation is
a permissible exercise of the Secretary’s rulemaking power
and join the other Courts of Appeals that consistently have
reached that conclusion. See 

; Big
Branch Res., Inc. v. Ogle, 

, 1071 n.5 (6th Cir.
2013); cf. Antelope Coal Co./Rio Tinto Energy Am. v.
Goodin, 

, 1347 (10th Cir. 2014) (declining to
address the operator’s ultra vires argument).

       B.     Application of the Regulation to this Case

       Assuming the validity of the Regulation, Helen Mining
also argues that it produced evidence sufficient to rebut the
§ 921(c)(4) presumption even under the rule out standard, and
that the ALJ only concluded it did not because he improperly
rejected Helen Mining’s medical expert testimony. In
reviewing an ALJ’s interpretation of expert medical evidence,
we bear in mind that “[t]he Board is bound by an ALJ’s
findings of fact if they are supported by substantial evidence,”
and therefore we must review the record to “decide whether
the ALJ’s findings are supported by substantial evidence,”
defined as “such relevant evidence as a reasonable mind
might accept as adequate to support a conclusion.”

–20. “Physicians’ reasoning,
consideration of records, and credentials are relevant to an
ALJ's determination” whether to reject medical expert
opinions, and an ALJ may properly reject such opinions if
they are “inadequately explained, insufficiently reasoned, or




                              25
contrary to clinical evidence.” Balsavage v. Dir., OWCP, 

, 396–97 (3d Cir. 2002).

       The error ascribed by Helen Mining is twofold: first,
that the ALJ discredited its experts based on a
misunderstanding of the Preamble to a relevant regulation
and, second, that the ALJ mischaracterized a portion of one
expert’s testimony. We address each argument in turn.

       First, Helen Mining argues that the ALJ incorrectly
deemed its experts’ testimony to conflict with the Preamble to
the 2001 revision to 20 C.F.R. § 718.201 (hereinafter “the
Preamble”). See Regulations Implementing the Federal Coal
Mine Health and Safety Act of 1969, as Amended, 65 Fed.
Reg. 79,920, 79,939 (Dec. 20, 2000). The testimony at issue
is that of Dr. Fino—opining that Elliott was disabled by
asthma and that dust exposure from coal mine employment
could not be the source of that impairment because asthma
cannot be caused by coal dust inhalation—and that of Dr.
Spagnolo—opining that Elliott had asthma that impaired his
lung function but could not be due to coal dust exposure
because prior coal dust exposure would “probably not”
aggravate asthma once a worker left the mine. The ALJ
determined that these opinions were entitled to little weight,
in part because they contradicted the Department’s findings
on the connection between asthma and coal dust exposure as
reflected in the Preamble. The relevant section of the
Preamble reads:

      The term “chronic obstructive pulmonary
      disease” (COPD) includes three disease
      processes characterized by airway dysfunction:
      chronic bronchitis, emphysema and asthma.




                             26
      Airflow limitation and shortness of breath are
      features of COPD, and lung function testing is
      used to establish its presence. Clinical studies,
      pathological findings, and scientific evidence
      regarding the cellular mechanisms of lung
      injury link, in a substantial way, coal mine dust
      exposure to pulmonary impairment and chronic
      obstructive lung disease.

65 Fed. Reg. at 79,920, 79,939.

       This Preamble reflects the agency’s assessment of
medical and scientific evidence upon which it relied in
drafting the 2001 revision to the regulatory definition of
pneumoconiosis. 

79,939. Because an “ALJ
should reject as insufficiently reasoned any medical opinion
that reaches a conclusion contrary to objective clinical
evidence without explanation,” Kertesz v. Crescent Hills Coal
Co., 

, 163 (3d Cir. 1986), an ALJ may
reasonably rely on the agency’s findings expressed in the
Preamble in determining how much weight to assign to an
expert’s opinion, see Helen Mining Co. v. Dir., OWCP
(Obush), 

, 257 (3d Cir. 2011).

       Here, the ALJ observed that the agency had already
recognized a proven link between coal dust exposure and
pulmonary impairments like asthma, and he reasonably
interpreted the opinions of Drs. Fino and Spagnolo as being
contrary to that position. Although at times the Preamble
references broad categories of respiratory diseases, it
specifically cites at least one example of a study that
demonstrates the link between coal dust exposure and asthma.
See 65 Fed. Reg. at 79,943. Tellingly, the Preamble also




                             27
explicitly identifies Dr. Fino as an expert known to disagree
with the conclusions expressed in the Preamble and explains
that the agency does not credit his opinion because it is not
“in accord with the prevailing view of the medical community
or the substantial weight of the medical and scientific
literature.” 65 Fed. Reg. at 79,939. Neither of Helen
Mining’s experts cited a scientific study or treatise to
challenge the agency’s assessment or to support their
conclusions that coal dust inhalation would not cause asthma
or aggravate it after leaving work in the mines. We therefore
conclude, as the BRB did, that the ALJ’s findings in this
respect were supported by substantial evidence. See 

–57.

       Second, Helen Mining argues that the ALJ
mischaracterized Dr. Fino’s testimony as internally
inconsistent and improperly discounted it on that basis. Our
own review of the record assures us that the ALJ’s
discounting of this testimony on the basis of its internal
discrepancies is also supported by substantial evidence. Dr.
Fino acknowledged that Elliott reported the onset of his
cough while working in the mines, and he conceded that the
cough may have then been associated with coal dust; at the
same time, however, Dr. Fino attributed Elliott’s cough to
asthma that he “believe[d]” began after Elliott left the mines.
JA 77a. We agree with the ALJ that Dr. Fino did not
adequately explain those inconsistencies.

       Helen Mining now attempts to supply such an
explanation by distinguishing Elliott’s prior cough due to coal
dust exposure from his current symptoms, which Helen
Mining describes as shortness of breath due to asthma. But
that cannot be reconciled with Dr. Fino’s testimony—which




                              28
refers to both the coughing “[t]hat began while [Elliott] was
working in the mines” and “the cough that he’s having now”
and states that “it’s all due to asthma.” JA 77a:6-14, 78a:2-4.
Rather, the record, in view of Dr. Fino’s failure to
disassociate that cough from coal dust exposure, supports the
ALJ’s discounting of Dr. Fino’s persuasiveness. See Mancia
v. Dir., OWCP, 

, 593 (3d Cir. 1997).

       In sum, the ALJ did not err in rejecting the medical
expert testimony of Helen Mining’s experts, and absent that
testimony, the record does not otherwise provide a basis to
rebut the presumption of Elliott’s entitlement to benefits.
Accordingly, we agree with the BRB that the ALJ’s
conclusion that Helen Mining failed to overcome the
§ 921(c)(4) presumption was supported by substantial
evidence. See 

; Lango v. Dir.,
OWCP, 

, 576–78 (3d Cir. 1997).

IV.   Conclusion

        Because we conclude that the Regulation’s imposition
of a rule out standard on operators is not ultra vires to the
BLBA, and because we conclude the ALJ did not err in
rejecting the only evidence Helen Mining proffered to rebut
the § 921(c)(4) presumption in this case, we will deny the
petition for review.




                              29