 United States Court of Appeals
         FOR THE DISTRICT OF COLUMBIA CIRCUIT



Argued October 23, 2014               Decided June 26, 2015

                       No. 13-1315

        PRAIRIE STATE GENERATING COMPANY LLC,
                       PETITIONER

                             v.

   SECRETARY OF LABOR AND FEDERAL MINE SAFETY AND
             HEALTH REVIEW COMMISSION,
                    RESPONDENTS


       On Petition for Review of a Decision of the
    Federal Mine Safety & Health Review Commission


    Ralph Henry Moore, II argued the cause for petitioner.
With him on the briefs was Patrick W. Dennison.

     Edward Waldman, Attorney, Mine Safety & Health
Administration, argued the cause for respondents. With him
on the brief was W. Christian Schumann, Counsel. John T.
Sullivan, Attorney, entered an appearance.

   Before: HENDERSON and PILLARD, Circuit Judges, and
WILLIAMS, Senior Circuit Judge.

    Opinion for the Court filed by Circuit Judge PILLARD.
                                2
     PILLARD, Circuit Judge: Coal powers almost 40% of the
electricity used in the United States. Despite enormous safety
advances in recent decades, underground coal mining remains
one of the handful of the nation’s most dangerous jobs. Cave-
ins, and dusts or gases that pose respiratory or explosion risks,
are leading causes of harm to coal miners.1 Congress enacted
the Federal Mine Safety and Health Amendments Act of 1977
(the Mine Act) to protect America’s miners. The Mine Act
subjects mine operators to substantial safety regulation, under
rules generally applicable to all mines, as well as mine-
specific safety plans suited to the particular geologic
conditions and the operator’s chosen mining system.
Operators must propose mine-specific plans for the approval
of the Secretary of Labor, who acts for those purposes
through a district manager in the Mine Safety and Health
Administration (MSHA). The Mine Act established the
Federal Mine Safety and Health Review Commission, an
independent agency, to review operators’ challenges to
citations and orders the Secretary imposes under the Act.
Petitioner Prairie State Generating Company, LLC (Prairie
State) challenges the Commission’s decision to sustain the
Secretary’s citations against it for operating without approved,
mine-specific plans for roof support and ventilation at Prairie

1
  See, e.g., U.S. Energy Info. Admin., Electric Power Monthly
Table        1.1      (May         2015),       available       at
http://www.eia.gov/electricity/monthly/pdf/epm.pdf; News Release,
U.S. Dep’t of Labor, MSHA, Roof fall accidents remain a leading
cause of coal mining injuries, U.S. Dep’t of Labor (July 2, 2014),
available                                                       at
http://www.msha.gov/MEDIA/PRESS/2014/NR140702.asp;
Mining: Inputs: Occupational Safety & Health Risks, Ctr. for
Disease             Control              &             Prevention,
http://www.cdc.gov/niosh/programs/mining/risks.html (last visited
June 1, 2015).
                               3
State’s underground coal mine at Lively Grove in southern
Illinois. After extensive consultation over the terms of mine-
specific safety plans that would be suitable at Lively Grove,
the MSHA district manager had declined to accept the final
terms that Prairie State proposed. In order to create an
opportunity to challenge the district manager’s plan-suitability
decisions, Prairie State momentarily operated the mine
without approved roof-support and ventilation plans and so
incurred two citations, which it challenges here.

     The principal question before us is which standard the
Commission should use when it reviews the Secretary’s
citation of an operator for failure to follow an approved,
mine-specific plan. The Secretary defends arbitrary-and-
capricious review as appropriately deferential to his
judgments because the Department of Labor is the agency
charged under the Mine Act with expert policymaking
discretion to evaluate and approve mine-specific safety plans.
Prairie State, by contrast, argues for de novo review on the
ground that the Secretary will not have carried his
acknowledged burden to prove the basis for a citation unless
he establishes, without the benefit of deference, the
unsuitability of an operator’s proposed plan. Prairie State
claims two further legal errors: First, that the Commission
erred as a matter of law by not considering evidence that,
Prairie State contends, is relevant notwithstanding that it was
not submitted to the district manager when he decided plan
suitability; and second, that the district manager erroneously
relied on an MSHA Procedure Instruction Letter as a binding,
across-the-board norm in derogation of his duty to make a
case-specific judgment. Finally, Prairie State points out
various ways in which, even if the suitability determinations
were reviewed with deference, it believes the determinations
were contrary to law and unsupported by substantial evidence.
                                4
     We hold that that the Secretary’s judgments regarding the
suitability of mine-specific safety plans are entitled to
deference under the Mine Act, and reject the further claims of
error.

                                I.

     The Mine Act charges two separate agencies with
complementary policymaking and adjudicative functions.2
The Secretary, acting through MSHA, sets regulatory
standards of mine safety, conducts regular mine inspections,
and issues citations and orders in response to violations. 29
U.S.C. § 557a; 30 U.S.C. §§ 813, 814; Thunder Basin Coal
Co. v. Reich, 510 U.S. 200, 202-04 & n.5 (1994). The
Commission, an adjudicatory body established as independent
of the Secretary, reviews challenges to MSHA’s actions. 30
U.S.C. §§ 815(d), 823. The Mine Act’s split-function
approach contrasts with the more typical administrative
structure, in which rulemaking and adjudication are
performed within a single agency. See generally Martin v.
Occupational Safety & Health Review Comm’n, 499 U.S. 144,
151 (1991) (describing the analogous, split-function scheme
under the Occupational Safety and Health Act (OSH Act)); 2
Charles H. Koch, Jr. & Richard Murphy, Administrative Law
& Practice § 5:29 (3d ed.). The extra institutional separation
the Mine Act provides reflects Congress’s concern that the

2
  Pub. L. No. 95-164, 91 Stat. 1290 (1977), codified as amended at
30 U.S.C. § 801 et seq. The Mine Act amended the Federal Coal
Mine Health and Safety Act of 1969 (the Coal Act), Pub. L. No. 91-
173, 83 Stat. 742 (1969), by extending the coverage of the existing
regulatory regime to non-coal mines and strengthening its
protections of miners. See United Mine Workers of Am., Int’l
Union v. Dole, 870 F.2d 662, 666 n.5 (D.C. Cir. 1989); S. Rep. No.
95-181, at 9 (1977), reprinted in 1977 U.S.C.C.A.N. 3401, 3409.
                               5
adjudicatory function be institutionally independent of
potential influence by the agency responsible for
policymaking and enforcement decisions. See S. Rep. No.
95-181, at 47 (1977), reprinted in 1977 U.S.C.C.A.N. 3401,
3447 (“[A]n independent Commission is essential to provide
administrative adjudication which preserves due process and
instills much more confidence in the program.”).

     The Mine Act requires the Secretary, acting through an
MSHA district manager assigned to one of the nation’s twelve
mining districts, to negotiate mine-specific roof-support and
ventilation plans with representatives of the companies that
operate the mines. Congress decided that “individually
tailored plans, with a nucleus of commonly accepted
practices, are the best method of regulating such complex and
potentially multifaceted problems as ventilation, roof control
and the like.” Dole, 870 F.2d at 669 n.10 (quoting S. Rep.
No. 95-181 at 25, 1977 U.S.C.C.A.N. at 3425). As outlined
below, the operators propose plans for the Secretary’s
consideration that they believe are “suitable” to ensure
adequate roof support and ventilation based on each mine’s
unique geology and proposed mining system. 30 U.S.C.
§§ 862(a), 863(o); see Mach Mining, LLC v. Sec’y of Labor,
728 F.3d 643, 649 (7th Cir. 2013). No mine may operate
without an approved plan, and once the Secretary has
approved a plan, its terms are enforceable as if they were duly
promulgated regulations. 30 C.F.R. §§ 75.220(c), 75.370(d);
see Dole, 870 F.2d at 667 & n.7; Zeigler Coal Co. v. Kleppe,
536 F.2d 398, 409 (D.C. Cir. 1976) (interpreting the
predecessor Coal Act).

    The first step in the process of plan approval is for a mine
operator to develop roof-support and ventilation plans it
thinks are suitable, and to submit the plans to the district
manager for his or her consideration. 30 C.F.R. §§ 75.220(a),
                              6
75.370(a); see 30 U.S.C. §§ 862(a), 863(o); Dole, 870 F.2d at
668-69 & n.10. The operator must also provide proposed
plans to the mine workers’ representative prior to submitting
them to the district manager, so that the representative may
make comments for the district manager’s consideration. 30
C.F.R. § 75.370(a)(3), (b). The district manager evaluates the
operator’s proposed plans (and miners’ comments) in
accordance with the Secretary’s policy judgment, and in light
of information about the prospective site and the agency’s
accumulated knowledge and experience. See 30 U.S.C.
§§ 862(a), 863(o); 30 C.F.R. §§ 75.220(a), 75.370(a); S. Rep.
No. 95-181 at 25, 1977 U.S.C.C.A.N. at 3425. If the district
manager deems an operator’s proposed plan insufficient to
ensure miners’ health and safety, he or she denies approval,
explaining relevant concerns to the operator and giving the
operator a chance to address the identified deficiencies. 30
C.F.R. §§ 75.220(b), 75.370(c). The operator and the district
manager then engage in a good-faith negotiation in an effort
to formulate a plan with which they both are satisfied. Id.
§§ 75.220(a), 75.370(a), (c)(2); see Sec’y of Labor v. Carbon
Cnty. Coal Co., 7 FMSHRC 1367, 1371 (1985). The operator
“ha[s] a role to play in developing plan contents, [but] [the
Secretary] always retain[s] final responsibility for deciding
what ha[s] to be included in the plan.” Dole, 870 F.2d at 669
n.10; see 30 U.S.C. §§ 862(a), 863(o) (operators shall only
adopt plans “approved by” the Secretary). In other words,
“‘while the operator proposes a plan and is entitled . . . to
further consultation with the Secretary over revisions, the
Secretary must independently exercise his judgment with
respect to the content of such plans in connection with his
final approval of the plan.’” Dole, 870 F.2d at 669 n.10
(quoting S. Rep. No. 95-181 at 25, 1977 U.S.C.C.A.N. at
3425). If a mine operates without an approved, mine-specific
plan, the Secretary may issue citations, orders to withdraw
                                 7
from the mine, civil fines, and criminal penalties. 30 U.S.C.
§§ 814(a), (d), 815, 820.

     The independent Commission is the administrative
adjudicator under the Mine Act. 30 U.S.C. §§ 815, 823. A
mine operator may appeal a citation issued by the Secretary to
an administrative law judge, who conducts a hearing on
behalf of the Commission in accordance with the
Administrative Procedure Act. Id. §§ 815(d), 823(d)(1). At
the hearing, the Secretary must support its citation by a
preponderance of evidence in the record. See 5 U.S.C.
§§ 554(c)(2), 556(d); Steadman v. SEC, 450 U.S. 91, 102
(1981) (interpreting “substantial evidence” under APA
Section 556 to mean a preponderance of evidence). Based on
the hearing and any related briefing, the ALJ makes findings
of fact and either affirms, modifies, or vacates the Secretary’s
decisions. 30 U.S.C. §§ 815(d), 823(d)(1). A mine operator
may petition the Commission for discretionary review of an
ALJ’s order. Id. § 823(a), (d)(2)(A). The Commission sits in
Washington, D.C., and is comprised of five members, each
appointed by the President with the advice and consent of the
Senate, to a tenure-protected, six-year term. Id. § 823(a), (b).
If the Commission denies review, the ALJ’s decision becomes
final. Id. § 823(d)(1). A person affected by a Commission
decision has a right to review in this court or the court of
appeals for the circuit in which the alleged violation
occurred.3 Id. § 816(a)(1).


3
  By contrast, anyone affected by the promulgation of a generally
applicable rule may directly petition the Courts of Appeals for
review; in those cases, the Mine Act does not call for administrative
review by the Commission (or its ALJs). 30 U.S.C. § 811(d). The
Secretary’s exercise of his general rulemaking authority is subject
to deferential judicial review. Dole, 870 F.2d at 666-67.
                                 8
     An operator may only commence mining under a plan the
Secretary has approved, through a district manager, as
“suitable.” 30 U.S.C. §§ 862(a), 863(o); 30 C.F.R. §§ 75.220,
75.370. Sometimes, as in this case, an operator and district
manager fail to reach agreement on suitable plan terms. The
statute does not explicitly provide for administrative and
judicial review of a district manager’s refusal to accept the
operator’s proposed plan terms as suitable, but the Secretary
and operators have developed a “technical citation” practice
in order to enable review. See Mach Mining, 728 F.3d at 651-
54. An operator that wishes to challenge a district manager’s
suitability decision momentarily commences operations under
its preferred terms, without the requisite approval by the
Secretary, prompting the Secretary to issue a technical
citation that carries a nominal monetary penalty. Id. at 655-
56. The operator then appeals the technical citation to the
Commission and, as appropriate, a federal court of appeals.
The technical citation process is described in the Secretary’s
policy manual. MSHA, Program Policy Manual Vol. V (Dec.
2013, Release V-48), at 5.4

                                II.

     In 2008, Prairie State proposed to construct an
underground coal mine at the Lively Grove site in southern
Illinois. At Lively Grove, Prairie State prepared to use large,
remote-controlled, continuous mining machines that take cuts
into the coal seam, convey the cut coal back to be carted out

4
  A 2006 amendment to the Mine Act codified the technical citation
route to obtaining review in the face of disagreement over mine-
specific accident response plans, 30 U.S.C. § 876(b)(2)(G), but not
with respect to disagreements regarding the suitability of roof-
support and ventilation plans, see Mach Mining, 728 F.3d at 655.
The validity of the technical citation process is not at issue here.
                               9
of the mine, and—once they have tunneled into the seam to a
target depth—withdraw from the coal face so that miners can
use roofbolts or other supports to secure the roof above where
the coal was removed. Prairie State proposed to make 40-foot
deep cuts into the seam, and to create openings 20 feet across
and, at tunnel intersections, 68 feet in diagonal span. For
ventilation, Prairie State proposed to use a “fishtail”
ventilation system, which circulates fresh air into the mine
and splits the air stream, ensuring fresher air to more mine
areas than a single stream that travels further and, it claims,
can carry contaminants within the mine. Prairie State’s
position was that, with the fishtail system, ventilating 9,000 to
12,000 cubic feet per minute of air would suffice, depending
on the number of open crosscuts.

     Area geology around Lively Grove was known to the
Secretary to present risks of roof falls and hazardous methane
emissions. The district manager and his staff reviewed Prairie
State’s submissions in this case, determined that Prairie
State’s proposed plans were inadequate, and communicated
their concerns to Prairie State along with suggested plan
revisions. Over the ensuing year, Prairie State and the district
manager traded written correspondence and engaged in more
than thirty discussions regarding plan terms. They failed to
reach agreement, however, on the issues of maximum
permissible cut depth, tunnel entry width, diagonal span of
tunnel intersections, and the adequacy of the ventilation
system Prairie State proposed in the mine. The district
manager declined to approve, at least at the outset in the
absence of mining history at the site, cuts deeper than 20 feet,
tunnel entries wider than 18 feet, and intersection diagonals
longer than 64 feet. With respect to air quantities, the district
manager called for ventilation of 20,000 to 25,000 cubic feet
per minute—more than twice Prairie State’s proposed
volume. In light of the district manager’s disapproval of
                               10
Prairie State’s proposed terms, Prairie State triggered
technical citations regarding roof-support and ventilation
plans, which it challenged before the Commission.

     The Commission assigned the citation challenges to an
ALJ to conduct a hearing. The ALJ heard testimony on the
merits of Prairie State’s claims. The district manager, along
with the roof-support and ventilation specialists working
under his supervision, testified on the Secretary’s behalf.
Prairie State’s representatives and expert witnesses also
testified. With the benefit of post-hearing briefing, the ALJ
affirmed both citations in a written opinion. The ALJ made
factual findings describing the plan proposal, evaluation,
negotiation, and plan-suitability determinations at Lively
Grove.

     The ALJ sustained the Secretary’s determination that
Prairie State’s proposed plans were unsuitable. Over Prairie
State’s objection, the ALJ held as a matter of law that plan
suitability is appropriately assessed “in terms of the discretion
of the district manager” under a “standard of review [that]
incorporates an element of reasonableness.” 32 FMSHRC
602, 608 (May 2010). The ALJ then rejected Prairie State’s
assertion that the district manager’s discretion was
impermissibly constrained by a Procedure Instruction Letter
that the Secretary had issued outlining procedures for
evaluating operators’ requests for extended cuts. The ALJ
also excluded evidence about plans at other mines that Prairie
State sought to introduce at the hearing on the ground that
Prairie State had not submitted that evidence to the Secretary
during plan negotiations.

     The Commission granted Prairie State’s petition for
discretionary review and affirmed the ALJ on most issues.
The Commission agreed with the ALJ’s determination that the
                              11
citations were subject to arbitrary-and-capricious review by
the Commission and its ALJs because that standard
“appropriately respects the Secretary’s judgment while
allowing review for abuse of discretion, errors of law, and
review of the record under the substantial evidence test.” 35
FMSHRC 1985, 1990, 2013 WL 3947974 (July 2013)
(internal quotation marks omitted). Deference is warranted in
this context, the Commission reasoned, because ALJs and
Commissioners “are not always best-equipped to decide
technical issues regarding ventilation and roof control,” and
“are instead charged with deciding whether the district
manager has made a fair and informed suitability
determination.” Id. at 1989 n.6. One Commissioner
dissented, stating that Commission precedent “ha[d] long held
that the Secretary bears the burden of establishing that the
operator’s plan . . . was unsuitable,” and that the ALJ had
“short-circuited the [review] process by avoiding the
threshold question of unsuitability,” “effectively replac[ing]
the burden of proof with a deferential ‘review’ of the
rationality of the District Manager’s negotiating position.” Id.
at 1998-99 (Young, Comm’r, dissenting).

     The Commission affirmed the ALJ’s rulings regarding
evidentiary exclusions, reliance on the Procedure Instruction
Letter, and the merits of Prairie State’s challenges regarding
cut depth, entry width, and diagonals. The Commission
ordered a limited remand for the ALJ to explain her
conclusion regarding ventilation. On remand, the ALJ
provided further reasoning regarding the ventilation plan
issue, and assessed a $200 penalty for Prairie State’s two
technical citations. Prairie State again appealed to the
Commission, which denied further review. Prairie State then
timely petitioned this court.
                                 12
                                 III.

      We review the legal determinations of the Commission
and its ALJs de novo and factual findings for substantial
evidentiary support. 30 U.S.C. § 816(a)(1); Black Beauty
Coal Co. v. Fed. Mine Safety & Health Review Comm’n, 703
F.3d 553, 558 (D.C. Cir. 2012); Sec’y of Labor v. Keystone
Coal Mining Corp., 151 F.3d 1096, 1099 (D.C. Cir. 1998).
We review evidentiary rulings for abuse of discretion, Mach
Mining, 728 F.3d at 659; cf. Veritas Health Servs., Inc. v.
NLRB, 671 F.3d 1267, 1273 (D.C. Cir. 2012), and accord
“great deference” to the ALJ’s credibility determinations,
Keystone Coal, 151 F.3d at 1107.

                                 A.

    The threshold question in this case concerns the standard
under which the Commission and its ALJs review the
Secretary’s plan-suitability determinations in the context of a
challenge to a technical citation. We may assume, without
deciding, that Chevron governs our consideration of that
question, as Prairie State failed to contest the Secretary’s
assertion that it does.5 Because the Mine Act itself does not
provide a definitive answer, see 30 U.S.C. § 815(d), we

5
  But see Steadman, 450 U.S. at 95 (“Where Congress has not
prescribed the degree of proof which must be adduced by the
proponent of a rule or order to carry its burden of persuasion in an
administrative proceeding, this Court has felt at liberty to prescribe
the standard, for it is the kind of question which has traditionally
been left to the judiciary to resolve.”) (internal quotation marks &
alteration marks omitted); Mach Mining, 728 F.3d at 647
(sustaining without Chevron deference the Commission’s decision
to apply a deferential standard of review to the Secretary’s approval
of mine-specific plan-suitability determinations, citing Steadman).
                              13
consider it under Chevron’s second step, deferring to the
Commission’s reasonable interpretation of the Act, see
Chevron, U.S.A., Inc. v. Natural Res. Def. Council, Inc., 467
U.S. 837, 842-43 (1984).

     The Commission has chosen to review the Secretary’s
plan determinations deferentially, and the Mine Act allows
that choice. It is well established that the Commission and the
courts owe deference to the Secretary’s interpretation of the
Mine Act and generally-applicable regulations promulgated
thereunder. See, e.g., Akzo Nobel Salt, Inc. v. Fed. Mine
Safety & Health Review Comm’n, 212 F.3d 1301, 1303 (D.C.
Cir. 2000); Sec’y of Labor v. Cannelton Indus., Inc., 867 F.2d
1432, 1435 (D.C. Cir. 1989); see generally 2 Koch &
Murphy, Administrative Law & Practice § 5:29. The plans at
issue here are sufficiently analogous to render reasonable the
Commission’s approach.

     The Commission treats mine-specific safety plans as, in
effect, contextually specific, mini regulations, similarly
entitled to deference. The Senate Report supports the
analogy. In discussing the Act’s requirement of mine-specific
plans to govern certain safety issues, the Report stated that
“[s]uch individually tailored plans, with a nucleus of
commonly accepted practices, are the best method of
regulating such complex and potentially multifaceted
problems as ventilation, roof control and the like.” S. Rep.
No. 95-181, at 25, 1977 U.S.C.C.A.N. at 3425. Once the
Secretary approves them, the provisions of a mine-specific
plan are as binding as a generally-applicable, duly-
promulgated rule. Dole, 870 F.2d at 667 & n.7; Zeigler, 536
F.2d at 409. The Commission reasonably deemed the
Secretary’s determinations regarding roof support and
ventilation as worthy of deference, given that they entail case-
by-case judgments in the field based on unique geological
                               14
conditions and mining systems—judgments that the expert,
policymaking agency is charged with and better equipped to
make. See id.; 30 U.S.C. §§ 862(a), 863(o).

     The statutory requirements of negotiation between the
Secretary and an operator in the development of suitable,
mine-specific plans, and the Mine Act’s provision for miners’
input during the plan-approval process, can be thought to play
a role in the development of mine-specific plans akin to that
of notice and comment in formal administrative rulemaking.
Mine operators receive written notice of the reasoning and
bases for the Secretary’s initial plan-suitability determinations
and have multiple opportunities to respond with arguments
and supplemental data. Carbon County, 7 FMSHRC at 1370-
71; 30 C.F.R. §§ 75.220, 75.370. Plan negotiations thus may
reasonably be characterized as serving the same interests as
notice and comment, albeit less formally: notice to affected
parties, opportunities for such parties to develop the record by
submitting factual and legal support, and improvement of the
agency’s decisionmaking. See, e.g., Small Refiner Lead
Phase-Down Task Force v. EPA, 705 F.2d 506, 547 (D.C.
Cir. 1983). Prairie State objects that the Secretary has
effectively imposed rules without the protection of notice and
comment, but the Commission reasonably treated the plan-
negotiation process as giving operators adequate opportunity
to frame the issues, have their views heard, and persuade the
agency to make salutary changes.

     The Supreme Court’s treatment of the split-function
structure created by the OSH Act, which closely parallels the
Mine Act, also supports that analysis. See Martin, 499 U.S. at
152-55. The OSH Act’s “administrative and judicial review
procedures . . . are nearly identical to those in the Mine Act,”
which is “hardly surprising since . . . the Mine Act’s review
process was written to conform to the review process of the
                              15
OSH Act.” Sturm, Ruger & Co. v. Chao, 300 F.3d 867, 872
(D.C. Cir. 2002) (internal quotation marks omitted). In
Martin, the Supreme Court distinguished the split-function
occupational health and safety regime from the typical,
unitary agency that uses adjudication as a policymaking tool,
emphasizing that the independent OSH Review Commission
lacks delegated power to make law and policy. 499 U.S. at
154. The Court stated that “Congress intended to delegate to
the Commission the type of nonpolicymaking adjudicatory
powers typically exercised by a court in the agency-review
context,” and that, “[u]nder this conception of adjudication,
the Commission is authorized to review the Secretary’s
interpretations only for consistency with the regulatory
language and for reasonableness.” Id. at 154-55.

     Just as deference to the Secretary is warranted in the
split-function administrative regime governing occupational
health and safety, the institutional division and allocation of
distinct functions under the Mine Act is fully consistent with
limited, reasonableness review by the Commission of the
Secretary’s plan-suitability determinations.       This court,
following Martin, has recognized that the considered position
of the Secretary in issuing a citation for violation of a
generally-applicable mine safety regulation and defending it
before the Commission is an exercise of delegated lawmaking
power, and so entitled to deference. “The Secretary’s
interpretation before the Commission is ‘agency action, not a
post hoc rationalization of it.’ And, ‘when embodied in a
citation, the Secretary’s interpretation assumes a form
expressly provided for by Congress,’ and is therefore ‘as
much an exercise of delegated lawmaking powers as is the
Secretary’s promulgation of’ a regulation.” Akzo Nobel Salt,
212 F.3d at 1304 (quoting Martin, 499 U.S. at 157).
                             16
    The Seventh Circuit, the only other federal court of
appeals to have decided this issue, held that the process the
Mine Act put in place for developing mine-specific plans is
incompatible with de novo review of such plans by the
Commission:

   [T]he process of approving a ventilation plan
   proposed by the mine operator . . . involves the
   formulation of a standard, not the enforcement of a
   standard. It requires the gathering of information by
   the mine operator and its presentation to the district
   manager, the manager’s examining and assessing that
   material and considering the views of the operator on
   the appropriateness of the plan. At bottom, it entails
   the exercise of the Secretary’s independent judgment
   as to the appropriateness of the plan to ensure the
   health and safety of the miners. There is, in other
   words, a congressional mandate that the Secretary
   exercise independent judgment that the plan
   safeguards those whom it is designed to protect. . . .
   [T]he Secretary’s role of approving the plan is not
   really an enforcement role susceptible to de novo
   review, but rather a role imbued with a legislative or
   policy-making dimension to ensure that the plan is
   reflective of the public interest in mine safety.

Mach Mining, 728 F.3d at 657. In short, the process of
developing mine-specific plans requires the Secretary,
through the district manager, to engage in detail with mine
operators and bring to bear expertise and experience.
Whether the Act thus requires the Commission’s deferential
review, as Mach Mining held, or at least permits it, as we
conclude, deferential review appropriately respects the
Secretary’s policymaking prerogative and ensures that his
determinations are reasonable and adequately supported by
                              17
the evidence. See Motor Vehicle Mfrs. Ass’n of U.S., Inc. v.
Ruckelshaus, 719 F.2d 1159, 1164 (D.C. Cir. 1983).

      We reject Prairie State’s argument that the Mine Act’s
incorporation of APA procedures necessarily puts the onus on
the Secretary to prove to the Commission de novo the
unsuitability of Prairie State’s preferred, mine-specific safety
plans. Prairie State conflates the burden of proof with the
standard of review. The statute requires the Secretary to
prove, by a preponderance of evidence, the bases of citations
it issues. 30 U.S.C. § 815(d); 5 U.S.C. §§ 554(c)(2), 556(d);
see Steadman, 450 U.S. at 102. In this case, the “order” of
which the Secretary is a “proponent,” 5 U.S.C. § 556(d), is the
technical citation, and the basis of that citation is that the
operator mined without an approved, suitable plan, see 30
U.S.C. § 814(a); 30 C.F.R. §§ 75.220(c), 75.370(d). That fact
is not disputed here; the parties stipulated as much in order to
trigger review.

     It does not follow from the Secretary’s burden under the
APA to establish the grounds of a citation that the
Commission must review de novo the Secretary’s underlying
suitability determination. Consistent with the statute, the
Commission has held that the Secretary’s burden is to
persuade the Commission that the district manager did not
abuse his discretion or act arbitrarily and capriciously in
making his suitability determination, for instance by failing to
examine relevant facts and draw reasonable conclusions. See,
e.g., Sec’y of Labor v. Mach Mining, LLC, 34 FMSHRC
1784, 1790 & n.13 (Aug. 2012). As discussed below, the
Commission correctly held the Secretary to that standard in
this case. 35 FMSHRC at 1989-90; see infra Section III-B.
We accept the Commission’s approach as a permissible
reading of the Mine Act.
                              18
     Prairie State relies on our decision in Zeigler for the
proposition that, in reviewing a technical citation for
operating without an approved safety plan, the Commission
must presume the suitability of Prairie State’s preferred plan,
and so require the Secretary to establish its unsuitability.
Zeigler held that mine-specific plan requirements are
enforceable on the same terms as generally-applicable
regulatory standards. 536 F.2d at 409. Prairie State draws
from Zeigler’s observation that a ventilation plan “is not
formulated by the Secretary, but is ‘adopted by the operator,’”
id. at 406, a presumptive legal primacy for the operator’s
plan: It is, in Prairie State’s view, “[i]nherent in the Zeigler
holding is that it is the operator’s proposal that is being
evaluated, not the Secretary’s,” and thus the district manager
may impose no different requirements until the operator’s
plan has been proved to be unsuitable, Petitioner Br. 22. But
that language in Zeigler aimed primarily at quelling operators’
concerns that regulation through mine-specific plans might
lead to “mine inspectors run riot,” using such plans as a
means to evade the process for promulgating general rules on
issues properly subject to general rulemaking by instead
“simply insisting that newly formulated standards be included
in one or another of the plans each operator must adopt.” 536
F.2d at 406. No such end-run around the Mine Act’s general
rulemaking is claimed here. Moreover, Zeigler recognizes, as
do we, both the regulatory character of mine-specific plans,
and the Secretary’s paramount control over and responsibility
for mine-specific plans, which “must also be approved by the
Secretary.” Id.; see also Dole, 870 F.2d at 669 n.10 (although
the operator “ha[s] a role to play in developing plan contents,
[the Secretary] always retain[s] final responsibility for
deciding what ha[s] to be included in the plan”).

   The nub of the parties’ dispute is whether the
Commission reasonably concluded that it owes deference to
                               19
the Secretary’s action in this kind of case, involving a
challenge to a technical citation on the ground that the district
manager unlawfully eschewed Prairie State’s preferred terms.
The question is whether judgments about suitable roof support
and ventilation in a particular underground mine—made by
the specialized, on-the-ground official of the agency that
Congress vested with policymaking authority over mine
safety decisions—are entitled to deference, or whether a
national administrative adjudicator independent of that agency
should exercise its judgment on those issues afresh, without
giving any special weight to the policymaking agency’s
determinations. Given that suitability is a discretionary,
contextual exercise of expert judgment regarding the
safeguards needed to keep miners safe, established principles
of administrative law support the Commission’s deference to
the Secretary here. See, e.g., Martin, 499 U.S. at 154-56.

    We therefore hold that the standard of review applied by
the Commission was at least a permissible one.

                               B.

     Prairie State further contends that, even under deferential
review, the Commission reversibly erred in sustaining the
district manager’s decisions regarding cut depth, entry widths,
diagonals, and ventilation. We disagree.

                               1.

     Prairie State asserts that the Commission’s ALJ
incorrectly refused to consider evidence Prairie State
proffered about plans approved for other mines—information
that it concededly had not submitted or cited to the district
manager during the plan-development process. Prairie State
contends that the ALJ incorrectly “limited the evidence that
the District Manager should have considered to the specific
                              20
mine rather tha[n] what was readily available to him.”
Petitioner Br. 34. It asserts that consideration of practices at
other mines was necessary both to comport with the plan-
approval process and to be fair to operators who seek
approval at new mines of practices already approved
elsewhere.

     We note that, at least ordinarily, the information relevant
to the Secretary’s decision will be that which was before the
agency during the plan-development process. See, e.g., Camp
v. Pitts, 411 U.S. 138, 142 (1973) (the “focal point” in
arbitrary-and-capricious review is “the administrative record
already in existence”); Ass’n of Private Sector Colls. & Univs.
v. Duncan, 681 F.3d 427, 441 (D.C. Cir. 2012) (review is
“limited to assessing the record that was actually before the
agency”); James Madison Ltd. ex rel. Hecht v. Ludwig, 82
F.3d 1085, 1095 (D.C. Cir. 1996). There is no reason to
believe that expecting operators ordinarily to bring probative
information to the attention of the front-line agency decision
maker would encourage them to engage in excessive,
wasteful, and distracting tactics of bombarding the agency
with immaterial information.

     We need not decide, however, whether the ALJ abused
her discretion by declining to consider information that Prairie
State did not cite in the plan-development process, because
Prairie State has failed to explain how admission of such
evidence at the review hearing might have changed the ALJ’s
decision regarding the reasonableness of the Secretary’s plan.
See, e.g., PDK Labs. Inc. v. DEA, 362 F.3d 786, 799 (D.C.
Cir. 2004) (“If the agency’s mistake did not affect the
outcome, if it did not prejudice the petitioner, it would be
senseless to vacate and remand for reconsideration.”). Prairie
State objects that the ALJ refused to consider “plans that were
approved at other mines in District 8,” as well as “studies
                              21
conducted in District 8 concerning the taking of 40-foot
extended cuts.” Petitioner Br. 34. Prairie State does not,
however, establish the comparability and pertinence of those
other mines and studies. We therefore lack a basis on which
to conclude that the proffered evidence might have shown that
the plan-suitability determinations at Lively Grove were
arbitrary or impermissibly inconsistent with determinations at
other mines. Thus, assuming arguendo the ALJ abused her
discretion by concluding that Prairie State could not rely on
materials it failed to reference during plan discussions, we
cannot say that such error harmed Prairie State. See PDK
Labs., 362 F.3d at 799.

                               2.

     Prairie State argues that the Commission erred by failing
to reverse as arbitrary and capricious the Secretary’s cut-depth
determination, which it contends should have authorized
extended, 40-foot cuts immediately upon the opening of the
mine. In particular, Prairie State contends that the district
manager failed to make a mine-specific cut-length
determination, instead unlawfully treating the cut-length
guidance expressed in the Secretary’s internal Procedure
Instruction Letter, No. I08-V-03 (eff. June 6, 2008), as an
across-the-board, binding rule. That Letter defines as an
“extended cut” any instance of continuing to dig into a
working coal face more than twenty feet beyond the last row
of permanent roof supports without stopping to place
additional supports in the newly excavated area. J.A. 293.
The Letter advises against approval of extended cuts until an
operator has first begun mining with standard, 20-foot cuts, so
that a new mine’s roof-support and ventilation needs can be
evaluated under actual operating conditions before extended
cuts are considered. J.A. 293-98; see Nat’l Mining Ass’n v.
Sec’y of Labor, 589 F.3d 1368, 1371-73 (11th Cir. 2009).
                              22
Prairie State argues that, by following the Letter, the district
manager failed to give mine-specific consideration to the
merits of its request immediately to begin mining at Lively
Grove with 40-foot cuts.

     The Commission appropriately concluded, based on the
record, that the district manager fulfilled his obligation to
make a mine-specific determination on maximum permissible
cut length.     The Letter was not an across-the-board,
substantive requirement, but gave guidance for site-specific
consideration of operators’ requests for extended cuts. See
Nat’l Mining Ass’n, 589 F.3d at 1370-72. The district
manager testified that he understood the Letter as counseling
him “to look at developing a 20-foot [cut]” rather than a 40-
foot cut, J.A. 111, and that an operator “couldn’t get 40-foot
cuts without going through [the Letter’s] evaluation process,”
J.A. 112. That directive is consistent with the statutory
requirement that the Secretary’s plan approvals be based on
the conditions prevailing at particular mines. See 30 U.S.C.
§§ 862(a), 863(o). Indeed, the thrust of the Letter is to ensure
that operators and district managers have data from initial
operating experience at a site to inform the decision about cut
length appropriate to the mine. The Commission noted that
the district manager considered evidence that the coal seam at
Lively Grove was gassy and that starting with shorter cuts
would allow better methane and dust control. 35 FMSHRC at
1991-92. It concluded that, in applying the Letter, the district
manager reasonably exercised informed discretion in light of
the information available about mine-specific circumstances
before the mine opened. Id. at 1994-95. We agree that the
record supports that conclusion.6

6
  See, e.g., J.A. 105-06 (hearing testimony from roof support
specialist, on whom the district manager relied, regarding the
                                  23

     Prairie State similarly contends that the Secretary
impermissibly applied a binding, across-the-board norm in
refusing to approve Prairie State’s requested terms governing
entry widths, diagonals, and ventilation.         The district
manager, in Prairie State’s view, engaged in “rote
application” of “District-wide rules,” rather than tailoring the
plan to the specific conditions prevailing at the mine.
Petitioner Br. 41-42. Those contentions are not based on the
Letter as such, as the relevant Letter guidance deals only with
cut depth, but similarly assert that the district manager
derogated from his statutory duty to make mine-specific
suitability determinations.       The record supports the
Commission’s conclusion, however, that the district manager
exercised discretion based on substantial evidence of safety
and health considerations at Lively Grove.7


practice of starting with 20-foot cuts: “[Y]ou’re trying to make me
sound like I’m implementing a rule or some sort of regulation. . . . I
suppose if the mine wanted to address it in another fashion as to
how they would best support that intersection and protect the miner
operator in the making of that first cut, that we would certainly look
at that.”); J.A. 109 (district manager’s testimony that he relied on
the input of his specialists, inter alia, for information and analysis).
Once the district manager observed the mine’s initial, safe
operation with 20-foot cuts, he proceeded to authorize the requested
extended cuts.
7
  See, e.g., J.A. 93 (roof support specialist’s testimony that starting
with 18-foot entry widths was reasonable based on prior
experience, but no suggestion that he interpreted that starting point
as required across the board); J.A. 112 (district manager’s
testimony that approving 18-foot entry width was his standard
practice, but stating that his decisions were “based upon
recommendations from” the specialists advising him, and never
indicating he felt bound by any rule depriving him of discretion).
                                  24
                                  3.

     Finally, Prairie State argues that the Commission erred in
upholding the Secretary’s plan-specific determinations
regarding cut depth, entry width, diagonals, and ventilation on
the ground that they were not supported by substantial
evidence. We disagree. The Commission relied on testimony
of the district manager and his technical team, as well as
correspondence and other documentation concerning safety
and health advantages of the plan terms the district manager
deemed suitable regarding cut depth, entry width, and
diagonals. See 35 FMSHRC at 1990-93; 32 FMSHRC at 604-
10 (ALJ findings and determinations).8 On limited remand,
the ALJ similarly based her findings regarding ventilation on
sufficient evidence in the record, and the Commission denied
further review. 35 FMSHRC 3272, 3274-75 (Oct. 2013).9

     Prairie State’s other arguments that the Secretary’s
determinations were arbitrary and capricious or contrary to
law all lack merit. The Secretary did not ignore, as Prairie
State asserts, certain alleged safety advantages of extended
cuts. Rather, as noted above, the agency determined, in
reasoned fashion and based on substantial evidence, that




8
  See, e.g., J.A. at 111 (district manager’s conclusion that 20-foot
cut depths, 18-foot entry widths, and 64-foot diagonals would be
safer than Prairie State’s proposed corresponding alternatives); J.A.
103 (roof support specialist’s testimony that 20-foot cuts are safer).
9
  See, e.g., J.A. at 84 (ventilation specialist’s testimony that 40-foot
cuts have different impact on ventilation and dust control than 20-
foot cuts).
                                25
extended cuts were not the safer, prudent practice that should
initially be implemented at the mine.10

                           *    *    *

     We deny the petition for review.

                                                      So ordered.




10
   We note that three pages of Prairie State’s opening brief appear
to be taken, virtually verbatim and without adequate attribution,
from Commissioner Young’s dissent. Compare Petitioner Br. 24-
27, with 35 FMSHRC at 2001-02 (Young, Comm’r, dissenting).
This court strongly disapproves of copy-and-paste argument.
Extended quotation without quotation marks or appropriate citation
amounts to misrepresentation to the court, see MODEL RULES OF
PROF’L CONDUCT R. 8.4(c), and disservices the client.
