Subject:  MARTIN v. OSHRC, Syllabus



 
    NOTE: Where it is feasible, a syllabus (headnote) will be released, as
is being done in connection with this case, at the time the opinion is
issued.  The syllabus constitutes no part of the opinion of the Court but
has been prepared by the Reporter of Decisions for the convenience of the
reader.  See United States v. Detroit Lumber Co., 200 U. S. 321, 337.
SUPREME COURT OF THE UNITED STATES


Syllabus



MARTIN, SECRETARY OF LABOR v. OCCUPATIONAL SAFETY AND HEALTH REVIEW
COMMISSION et al.

certiorari to the united states court of appeals for the tenth circuit

No. 89-1541.  Argued November 27, 1990 -- Decided March 20, 1991

The Occupational Safety and Health Act of 1970 assigns distinct regulatory
tasks to two independent administrative actors: petitioner Secretary of
Labor is charged with setting and enforcing workplace health and safety
standards, and respondent Occupational Safety and Health Review Commission
is responsible for carrying out adjudicatory functions.  The Act also
requires a court of appeals reviewing a Commission order to treat as
"conclusive" Commission findings of fact that are "supported by substantial
evidence."  In this case, having found that respondent CF&I Steel
Corporation had equipped some of its employees with loose-fitting
respirators that exposed them to impermissible coke-oven emission levels,
the Secretary issued a citation to CF&I and assessed a monetary penalty
against it for violating a regulation promulgated by the Secretary
requiring an employer to institute a respiratory protection program.  The
Commission vacated the citation, ruling that the facts did not establish a
violation of that regulation, which was the sole asserted basis for
liability, since the regulation expressly requires only that an employer
train employees in the proper use of respirators, whereas another
regulation expressly states the employer's obligation to assure a proper
fit.  The Court of Appeals affirmed, holding that where, as here, the
relevant regulations are ambiguous, a reviewing court must defer to the
Commission's reasonable interpretation rather than the Secretary's
interpretation, since Congress intended to delegate to the Commission the
normal complement of adjudicative powers possessed by traditional
administrative agencies, including the power to "`declare' the law."
Concluding that the Commission's interpretation was a reasonable one, the
court did not assess the reasonableness of the Secretary's competing view.

Held: A reviewing court should defer to the Secretary when the Secretary
and the Commission furnish reasonable but conflicting interpretations of an
ambiguous regulation promulgated by the Secretary under the Act.  Pp.
5-13.

    (a) It must be inferred from the Act's unusual "split enforcement"
structure and from its legislative history that the power to render au
thoritative interpretations of the Secretary's regulations is a necessary
adjunct of the Secretary's rulemaking and enforcement powers.  The
Secretary, as the promulgator of standards, is in a better position than
the Commission to reconstruct the purpose of particular regulations.
Moreover, since the Secretary, as enforcer, comes into contact with a much
greater number of regulatory problems than does the Commission, the
Secretary is more likely to develop the expertise relevant to assessing the
effect of a particular regulatory interpretation.  Furthermore, dividing
the power to make and enforce standards from the power to make law by
interpreting them would make two administrative actors ultimately
responsible for implementing the Act's policy objectives, an outcome
inconsistent with Congress' intent in combining legislative and enforcement
powers in the Secretary.  It must also be concluded that Congress did not
intend to endow the Commission with the normal adjudicative powers
possessed by a traditional, unitary agency.  Such an agency permissibly
uses adjudication to engage in lawmaking and policymaking only because it
also has been delegated the power to make law and policy through rulemaking
and necessarily interprets regulations that it has promulgated.  The more
plausible inference is that the Commission was meant to have the type of
nonpolicymaking adjudicatory powers typically exercised by a court in the
agency-review context, such that the Commission is authorized to review the
Secretary's interpretations only for consistency with the regulatory
language and for reasonableness and possesses no more power than is
necessary to make authoritative findings of fact and to apply the
Secretary's standards to those facts in making a decision.  Although the
Commission was established in response to concerns that combining
rulemaking, enforcement, and adjudicatory power in the Secretary would
leave employers unprotected from prosecutorial bias, such concerns are
dispelled by the vesting of authoritative factfinding and review powers in
a body wholly independent of the administrative enforcer; regulated parties
are protected from biased interpretations when the Commission and
ultimately the court of appeals review the Secretary's interpretation for
reasonableness.  Nor is such an interpretation, when furnished in the
course of an administrative adjudication, a mere "litigating position"
undeserving of judicial deference under this Court's precedents.  Since
such an interpretation is agency action, not a post hoc rationalization of
it, and assumes a form expressly provided for by Congress when embodied in
a citation, the Secretary's litigating position before the Commission is as
much an exercise of delegated lawmaking powers as is the Secretary's
promulgation of health and safety standards.  Pp. 5-12.

    (b) The reviewing court should defer to the Secretary only if the
Secretary's interpretation of an ambiguous regulation is reasonable.  That
interpretation is subject to the same Administrative Procedure Act standard
of substantive review that applies to any other exercise of delegated
lawmaking power.  Moreover, the decision to use a citation as the initial
means for announcing a particular interpretation may bear on the adequacy
of notice to regulated parties, the quality of the Secretary's elaboration
of pertinent policy considerations, and other factors relevant to the
reasonableness of the Secretary's exercise of delegated lawmaking powers.
Since the Court of Appeals did not address the reasonableness of the
Secretary's interpretation, it, rather than this Court, must do so in the
first instance on remand.  Pp. 12-13.

891 F. 2d 1495, reversed and remanded.


    Marshall, J., delivered the opinion for a unanimous Court.
------------------------------------------------------------------------------




Subject: 89-1541 -- OPINION, MARTIN v. OSHRC

 


NOTICE: This opinion is subject to formal revision before publication in
the preliminary print of the United States Reports.  Readers are requested
to notify the Reporter of Decisions, Supreme Court of the United States,
Washington, D. C. 20543, of any typographical or other formal errors, in
order that corrections may be made before the preliminary print goes to
press.
SUPREME COURT OF THE UNITED STATES


No. 89-1541




LYNN MARTIN, SECRETARY OF LABOR, PETI-
TIONER v. OCCUPATIONAL SAFETY and
HEALTH REVIEW COMMISSION et al.


on writ of certiorari to the united states court of appeals for the tenth
circuit

[March 20, 1991]



    Justice Marshall delivered the opinion of the Court.
    In this case, we consider the question to whom should a reviewing court
defer when the Secretary of Labor and the Occupational Safety and Health
Review Commission furnish reasonable but conflicting interpretations of an
ambiguous regulation promulgated by the Secretary under the Occupational
Safety and Health Act of 1970, 84 Stat. 1590, as amended, 29 U. S. C. MDRV
651 et seq.  The Court of Appeals concluded that it should defer to the
Commission's interpretation under such circumstances.  We reverse.

I


A
    The Occupational Safety and Health Act of 1970 (OSH Act or Act)
establishes a comprehensive regulatory scheme designed "to assure so far as
possible . . . safe and healthful working conditions" for "every working
man and woman in the Nation."  29 U. S. C. MDRV 651(b).  See generally
Atlas Roofing Co. v. Occupational Safety and Health Review Comm'n, 430 U.
S. 442, 444-445 (1977).  To achieve this objective, the Act assigns
distinct regulatory tasks to two independent administrative actors: the
Secretary of Labor (Secretary); and the Occupational Safety and Health
Review Commission (Commission), a three-member board appointed by the
President with the advice and consent of the Senate.  29 U. S. C. 15
651(b)(3), 661.
    The Act charges the Secretary with responsibility for setting and
enforcing workplace health and safety standards.  See Cuyahoga Valley R.
Co. v. United Transp. Union, 474 U. S. 3, 6-7 (1985) (per curiam).  The
Secretary establishes these standards through the exercise of rulemaking
powers.  See 29 U. S. C. MDRV 665.  If the Secretary (or the Secretary's
designate) determines upon investigation that an employer is failing to
comply with such a standard, the Secretary is authorized to issue a
citation and to assess the employer a monetary penalty.  15 658-659, 666.
{1}
    The Commission is assigned to "carr[y] out adjudicatory functions"
under the Act.  MDRV 651(b)(3).  If an employer wishes to contest a
citation, the Commission must afford the employer an evidentiary hearing
and "thereafter issue an order, based on findings of fact, affirming,
modifying, or vacating the Secretary's citation or proposed penalty."  MDRV
659(c).  Initial decisions are made by an administrative law judge (ALJ),
whose ruling becomes the order of the Commission unless the Commission
grants discretionary review.  MDRV 661(j).  Both the employer and the
Secretary have the right to seek review of an adverse Commission order in
the court of appeals, which must treat as "conclusive" Commission findings
of fact that are "supported by substantial evidence."  MDRV 660(a)-(b).

B
    This case arises from the Secretary's effort to enforce compliance with
OSH Act standards relating to coke-oven emissions.  Promulgated pursuant to
the Secretary's rulemaking powers, these standards establish maximum
permissible emissions levels and require the use of employee respirators in
certain circumstances.  See 29 CFR MDRV 1910.1029 (1990).  An investigation
by one of the Secretary's compliance officers revealed that respondent CF&I
Steel Corporation (CF&I) had equipped 28 of its employees with respirators
that failed an "atmospheric test" designed to determine whether a
respirator provides a sufficiently tight fit to protect its wearer from
carcinogenic emissions.  As a result of being equipped with these
loose-fitting respirators, some employees were exposed to coke-oven
emissions exceeding the regulatory limit.  Based on these findings, the
compliance officer issued a citation to CF&I and assessed it a $10,000
penalty for violating 29 CFR MDRV 1910.1029(g)(3) (1990), which requires an
employer to "institute a respiratory protection program in accordance with
[29 CFR] MDRV 1910.134."  CF&I contested the citation.
    The ALJ sided with the Secretary, but the full Commission subsequently
granted review and vacated the citation.  See CF&I, 12 OSHC 2067 (1986).
In the Commission's view, the "respiratory protection program" referred to
in MDRV 1910.1029(g)(3) expressly requires only that an employer train
employees in the proper use of respirators;  {2} the obligation to assure
proper fit of an individual employee's respirator, the Commission noted,
was expressly stated in another regulation, namely, MDRV
1910.1029(g)(4)(i). {3}  See 12 OSHC, at 2077-2078.  Reasoning, inter alia,
that the Secretary's interpretation of MDRV 1910.1029(g)(3) would render
MDRV 1910.1029 (g)(4) superfluous, the Commission concluded that the facts
alleged in the citation and found by the ALJ did not establish a violation
of MDRV 1910.1029(g)(3).  See 12 OSHC, at 2078-2079.  Because MDRV
1910.1029(g)(3) was the only asserted basis for liability, the Commission
vacated the citation.  See id., at 2079.
    The Secretary petitioned for review in the Court of Appeals for the
Tenth Circuit, which affirmed the Commission's order.  See Dole v.
Occupational Safety and Health Review Commission, 891 F. 2d 1495 (1989).
The court concluded that the relevant regulations were ambiguous as to the
employer's obligation to assure proper fit of an employee's respirator.
The court thus framed the issue before it as whose reasonable
interpretation of the regulations, the Secretary's or the Commission's,
merited the court's deference.  See id., at 1497.  The court held that the
Commission's interpretation was entitled to deference under such
circumstances, reasoning that Congress had intended to delegate to the
Commission "the normal complement of adjudicative powers possessed by
traditional administrative agencies" and that "[s]uch an adjudicative
function necessarily encompasses the power to `declare' the law."  Id., at
1498.  Although the court determined that it would "certainly [be] possible
to reach an alternate interpretation of the ambiguous regulatory language,"
the court nonetheless concluded that the Commission's interpretation was a
reasonable one.  Id., at 1500.  The court therefore deferred to the
Commission's interpretation without assessing the reasonableness of the
Secretary's competing view.  See ibid.
    The Secretary thereafter petitioned this Court for a writ of
certiorari.  We granted the petition in order to resolve a conflict among
the Circuits on the question whether a reviewing court should defer to the
Secretary or to the Commission when these actors furnish reasonable but
conflicting interpretations of an ambiguous regulation under the OSH Act.
{4}  497 U. S. --- (1990).

II
    It is well established "that an agency's construction of its own
regulations is entitled to substantial deference."  Lyng v. Payne, 476 U.
S. 926, 939 (1986); accord, Udall v. Tall man, 380 U. S. 1, 16-17 (1965).
In situations in which "the meaning of [regulatory] language is not free
from doubt," the reviewing court should give effect to the agency's
interpretation so long as it is "reasonable," Ehlert v. United States, 402
U. S. 99, 105 (1971), that is, so long as the interpretation "sensibly
conforms to the purpose and wording of the regulations," Northern Indiana
Pub. Serv. Co. v. Porter County Chapter of Izaak Walton League of America,
Inc., 423 U. S. 12, 15 (1975).  Because applying an agency's regulation to
complex or changing circumstances calls upon the agency's unique expertise
and policymaking prerogatives, we presume that the power authoritatively to
interpret its own regulations is a component of the agency's delegated
lawmaking powers.  See Ford Motor Credit Co. v. Milhollin, 444 U. S. 555,
566, 568 (1980).  The question before us in this case is to which
administrative actor -- the Secretary or the Commission -- did Congress
delegate this "interpretive" lawmaking power under the OSH Act. {5}
    To put this question in perspective, it is necessary to take account of
the unusual regulatory structure established by the Act.  Under most
regulatory schemes, rulemaking, enforcement, and adjudicative powers are
combined in a single administrative authority.  See, e. g., 15 U. S. C.
MDRV 41 et seq. (Federal Trade Commission); 15 U. S. C. 15 77s-77u
(Securities and Exchange Commission); 47 U. S. C. MDRV 151 et seq. (Federal
Communications Commission).  Under the OSH Act, however, Congress separated
enforcement and rulemaking powers from adjudicative powers, assigning these
respective functions to two independent administrative authorities.  The
purpose of this "split enforcement" structure was to achieve a greater
separation of functions than exists within the traditional "unitary"
agency, which under the Administrative Procedure Act (APA) generally must
divide enforcement and adjudication between separate personnel, see 5 U. S.
C. MDRV 554(d).  See generally Johnson, The SplitEnforcement Model: Some
Conclusions from the OSHA and MSHA Experiences, 39 Admin. L. Rev. 315,
317-319 (1987).
    This is not the first time that we have been called upon to resolve an
OSH Act "jurisdictional" dispute between the Secretary and the Commission.
See Cuyahoga Valley R. Co. v. United Transp. Union, 474 U. S., at 3.  At
issue in Cuyahoga Valley was whether the Commission could conduct an
administrative adjudication notwithstanding the Secretary's motion to
vacate the citation.  We held that the Commission had no such power.  We
noted "that enforcement of the Act is the sole responsibility of the
Secretary," and concluded that "[a] necessary adjunct of that power is the
authority to withdraw a citation and enter into settlement discussions with
the employer."  Id., at 6-7.  The Commission's role as "neutral arbiter,"
we explained, "plainly does not extend to overturning the Secretary's
decision not to issue or to withdraw a citation."  Id., at 7.
    Although the Act does not expressly address the issue, we now infer
from the structure and history of the statute, see id., at 6-7, that the
power to render authoritative interpretations of OSH Act regulations is a
"necessary adjunct" of the Secretary's powers to promulgate and to enforce
national health and safety standards.  The Secretary enjoys readily
identifiable structural advantages over the Commission in rendering
authoritative interpretations of OSH Act regulations.  Because the
Secretary promulgates these standards, the Secretary is in a better
position than is the Commission to reconstruct the purpose of the
regulations in question.  Moreover, by virtue of the Secretary's statutory
role as enforcer, the Secretary comes into contact with a much greater
number of regulatory problems than does the Commission, which encounters
only those regulatory episodes resulting in contested citations.  Cf. Note,
Employee Participation in Occupational Safety and Health Review Commission
Proceedings, 85 Colum. L. Rev. 1317, 1331 and n. 90 (1985) (reporting small
percentage of OSH Act citations contested between 1979 and 1985).
Consequently, the Secretary is more likely to develop the expertise
relevant to assessing the effect of a particular regulatory interpretation.
Because historical familiarity and policymaking expertise account in the
first instance for the presumption that Congress delegates interpretive
lawmaking power to the agency rather than to the reviewing court, see, e.
g., Mullins Coal Co. v. Director, OWCP, 484 U. S. 135, 159 (1987); Ford
Motor Credit Co. v. Milhollin, supra, at 566; INS v. Stanisic, 395 U. S.
62, 72 (1969), we presume here that Congress intended to invest
interpretive power in the administrative actor in the best position to
develop these attributes.
    The legislative history of the OSH Act supports this conclusion.  The
version of the Act originally passed by the House of Representatives vested
adjudicatory power in the Commission and rulemaking power in an independent
standards board, leaving the Secretary with only enforcement power.  116
Cong. Rec. 38716 (1970), reprinted in Legislative History of the
Occupational Safety and Health Act of 1970 (S. 2193, Pub. L. 91-596)
(Committee Print prepared by the Subcommittee on Labor of the Senate
Committee on Labor and Public Welfare), pp. 1094-1096 (1970) (Legislative
History).  The Senate version dispensed with the standards board and
established the division of responsibilities that survives in the enacted
legislation.  The Senate Committee Report explained that combining
legislative and enforcement powers in the Secretary would result in "a
sounder program" because it would make a single administrative actor
responsible both for "formulat[ing] rules . . . and for seeing that they
are workable and effective in their day-to-day application," and would
allow Congress to hold a single administrative actor politically
"accountable for the overall implementation of that program."  S. Rep. No.
91-1282, p. 8 (1970), reprinted in Legislative History 148.  Because
dividing the power to promulgate and enforce OSH Act standards from the
power to make law by interpreting them would make two administrative actors
ultimately responsible for implementing the Act's policy objectives, we
conclude that Congress did not expect the Commission to possess
authoritative interpretive powers.
    For the same reason, we reject the Court of Appeals' inference that
Congress intended "to endow the Commission with the normal complement of
adjudicative powers possessed by traditional administrative agencies."  891
F. 2d, at 1498 (emphasis added).  Within traditional agencies -- that is,
agencies possessing a unitary structure -- adjudication operates as an
appropriate mechanism not only for factfinding, but also for the exercise
of delegated lawmaking powers, including lawmaking by interpretation.  See
NLRB v. Bell Aerospace Co., 416 U. S. 267, 292-294 (1974); SEC v. Chenery
Corp., 332 U. S. 194, 201-203 (1947).  But in these cases, we concluded
that agency adjudication is a generally permissible mode of law- and
policymaking only because the unitary agencies in question also had been
delegated the power to make law and policy through rulemaking.  See Bell
Aerospace, supra, at 292-294; Chenery Corp., supra, at 202-203.  See
generally Shapiro, The Choice of Rulemaking or Adjudication in the
Development of Administrative Policy, 78 Harv. L. Rev. 921 (1965).  Insofar
as Congress did not invest the Commission with the power to make law or
policy by other means, we cannot infer that Congress expected the
Commission to use its adjudicatory power to play a policymaking role.
Moreover, when a traditional, unitary agency uses adjudication to engage in
lawmaking by regulatory interpretation, it necessarily interprets
regulations that it has promulgated.  This, too, cannot be said of the
Commission's power to adjudicate.
    Consequently, we think the more plausible inference is that Congress
intended to delegate to the Commission the type of nonpolicymaking
adjudicatory powers typically exercised by a court in the agency-review
context.  Under this conception of adjudication, the Commission is
authorized to review the Secretary's interpretations only for consistency
with the regulatory language and for reasonableness.  In addition, of
course, Congress expressly charged the Commission with making authoritative
findings of fact and with applying the Secretary's standards to those facts
in making a decision.  See 29 U. S. C. MDRV 660(a) (Commission's factual
findings "shall be conclusive" so long as "supported by substantial
evidence").  The Commission need be viewed as possessing no more power than
this in order to perform its statutory role as "neutral arbiter."  See
Cuyahoga Valley, 474 U. S., at 7.
    CF&I draws a different conclusion from the history and structure of the
Act.  Congress, CF&I notes, established the Commission in response to
concerns that combining rulemaking, enforcement, and adjudicatory power in
the Secretary would leave employers unprotected from regulatory bias.
Construing the Act to separate enforcement and interpretive powers is
consistent with this purpose, CF&I argues, because it protects regulated
employers from biased prosecutorial interpretations of the Secretary's
regulations.  Indeed, interpretations furnished in the course of
administrative penalty actions, according to CF&I, are mere "litigating
positions," undeserving of judicial deference under our precedents.  See,
e. g., Bowen v. Georgetown University Hospital, 488 U. S. 204, 212 (1988).
    Although we find these concerns to be important, we think that they are
overstated.  It is clear that Congress adopted the split-enforcement
structure in the OSH Act in order to achieve a greater separation of
functions than exists in a conventional unitary agency.  See S. Rep. No.
91-1282, supra, at 56, reprinted in Legislative History 195 (individual
views of Sen. Javits) (noting that adjudication by independent panel goes
beyond division of functions under the APA but defending split-enforcement
structure as "more closely [in] accor[d] with traditional notions of due
process").  But the conclusion that the Act should therefore be understood
to separate enforcement powers from authoritative interpretive powers begs
the question just how much Congress intended to depart from the unitary
model.  Sponsors of the Commission purported to be responding to the
traditional objection that an agency head's participation in or supervision
of agency investigations results in biased review of the decisions of the
hearing officer, notwithstanding internal separations within the agency.
See ibid.  See generally 3 K. Davis, Administrative Law Treatise MDRV 18.8,
pp. 369-370 (2nd ed. 1980).  Vesting authoritative factfinding and
ALJ-review powers in the Commission, an administrative body wholly
independent of the administrative enforcer, dispels this concern.
    We harbor no doubt that Congress also intended to protect regulated
parties from biased interpretations of the Secretary's regulations.  But
this objective is achieved when the Commission and ultimately the court of
appeals review the Secretary's interpretation to assure that it is
consistent with the regulatory language and is otherwise reasonable.
Giving the Commission the power to substitute its reasonable
interpretations for the Secretary's might slightly increase regulated
parties' protection from overzealous interpretations.  But it would also
clearly frustrate Congress' intent to make a single administrative actor
"accountable for the overall implementation" of the Act's policy objectives
by combining legislative and enforcement powers in the Secretary.  S. Rep.
No. 91-1282, p. 8, reprinted in Legislative History 148.
    We are likewise unpersuaded by the contention that the Secretary's
regulatory interpretations will necessarily appear in forms undeserving of
judicial deference.  Our decisions indicate that agency "litigating
positions" are not entitled to deference when they are merely appellate
counsel's "post hoc rationalizations" for agency action, advanced for the
first time in the reviewing court.  See Bowen v. Georgetown University
Hospital, supra, at 212; Burlington Truck Lines, Inc. v. United States, 371
U. S. 156, 168 (1962).  Because statutory and regulatory interpretations
furnished in this setting occur after agency proceedings have terminated,
they do not constitute an exercise of the agency's delegated lawmaking
powers.  The Secretary's interpretation of OSH Act regulations in an
administrative adjudication, however, is agency action, not a post hoc
rationalization of it.  Moreover, when embodied in a citation, the
Secretary's interpretation assumes a form expressly provided for by
Congress.  See 29 U. S. C. MDRV 658.  Under these circumstances, the
Secretary's litigating position before the Commission is as much an
exercise of delegated lawmaking powers as is the Secretary's promulgation
of a workplace health and safety standard.
    In addition, the Secretary regularly employs less formal means of
interpreting regulations prior to issuing a citation.  These include the
promulgation of interpretive rules, see, e. g., Marshall v. W and W Steel
Co., 604 F. 2d 1322, 1325-1326 (CA10 1979); cf. Whirlpool Corp. v.
Marshall, 445 U. S. 1, 11 (1980), and the publication of agency enforcement
guidelines, see United States Department of Labor, OSHA Field Operations
Manual (3d ed. 1989).  See generally S. Bokat & H. Thompson, Occupational
Safety and Health Law 658-660 (1988).  Although not entitled to the same
deference as norms that derive from the exercise of the Secretary's
delegated lawmaking powers, these informal interpretations are still
entitled to some weight on judicial review.  See Batterton v. Francis, 432
U. S. 416, 425-426, and n. 9 (1977); Skidmore v. Swift & Co., 323 U. S.
134, 140 (1944); Whirlpool, supra, at 11.  A reviewing court may certainly
consult them to determine whether the Secretary has consistently applied
the interpretation embodied in the citation, a factor bearing on the
reasonableness of the Secretary's position.  See Ehlert v. United States,
402 U. S., at 105.

III
    We emphasize the narrowness of our holding.  We deal in this case only
with the division of powers between the Secretary and the Commission under
the OSH Act.  We conclude from the available indicia of legislative intent
that Congress did not intend to sever the power authoritatively to
interpret OSH Act regulations from the Secretary's power to promulgate and
enforce them.  Subject only to constitutional limits, Congress is free, of
course, to divide these powers as it chooses, and we take no position on
the division of enforcement and interpretive powers within other regulatory
schemes that conform to the split-enforcement structure.  Nor should
anything we say today be understood to bear on whether particular divisions
of enforcement and adjudicative power within a unitary agency comport with
MDRV 554(d) of the APA.
    In addition, although we hold that a reviewing court may not prefer the
reasonable interpretations of the Commission to the reasonable
interpretations of the Secretary, we emphasize that the reviewing court
should defer to the Secretary only if the Secretary's interpretation is
reasonable.  The Secretary's interpretation of an ambiguous regulation is
subject to the same standard of substantive review as any other exercise of
delegated lawmaking power.  See 5 U. S. C. MDRV 706(2)(A); Batterton v.
Francis, supra, at 426.  As we have indicated, the Secretary's
interpretation is not undeserving of deference merely because the Secretary
advances it for the first time in an administrative adjudication.  But as
the Secretary's counsel conceded in oral argument, Tr. of Oral Arg. 18-19,
20-21, the decision to use a citation as the initial means for announcing a
particular interpretation may bear on the adequacy of notice to regulated
parties, see Bell Aerospace, 416 U. S., at 295; Bowen v. Georgetown
University Hospital, 488 U. S., at 220 (Scalia, J., concurring), the
quality of the Secretary's elaboration of pertinent policy considerations,
see Motor Vehicle Mfrs. Assn. of United States, Inc. v. State Farm Mut.
Automobile Ins. Co., 463 U. S. 29, 43 (1983), and other factors relevant to
the reasonableness of the Secretary's exercise of delegated lawmaking
powers.
    CF&I urges us to hold that the Secretary unreasonably interpreted 29
CFR MDRV 1910.1029(g)(3) in this case.  However, because the Court of
Appeals deferred to the Commission's interpretation, it had no occasion to
address the reasonableness of the Secretary's interpretation.  Rather than
consider this issue for the first time ourselves, we leave the issue for
resolution on remand.
    The judgment of the Court of Appeals is reversed, and the case is
remanded for further proceedings consistent with this opinion.
It is so ordered.
 
 
 
 
 
 

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1
    The Secretary has delegated certain statutory responsibilities to the
Assistant Secretary for Occupational Safety and Health, who heads the
Occupational Safety and Health Administration.  See Secretary of Labor's
Order No. 12-71, 36 Fed. Reg. 8754 (1971); Order No. 8-76, 41 Fed. Reg.
25059 (1976); Order No. 9-83, 48 Fed. Reg. 35736 (1983).

2
    "For safe use of any respirator, it is essential that the user be
properly instructed in its selection, use, and maintenance.  Both
supervisors and workers shall be so instructed by competent persons.
Training shall provide the men an opportunity to handle the respirator,
have it fitted properly, test its face-piece-to-face seal, wear it in
normal air for a long familiarity period, and, finally, to wear it in a
test atmosphere."  29 CFR MDRV 1910.134(e)(5) (1990).

3
    This regulation states in pertinent part: "Respirator usage. (i) The
employer shall assure that the respirator issued to the employee exhibits
minimum facepiece leakage and that the respirator is fitted properly."  29
CFR MDRV 1910.1029(g)(4) (1990).  According to the Commission, the
compliance officer who issued the citation "acknowledged that [MDRV
1910.1029(g) (4)(i)] applied," and "that he might have cited the wrong
standard."  CF&I, 12 OSHC 2067, 2078 (1986).

4
    Compare Brock v. Williams Enterprises of Georgia, Inc., 832 F. 2d 567,
569-570 (CA11 1987) (deference to Secretary); United Steelworkers of
America v. Schuylkill Metals Corp., 828 F. 2d 314, 319 (CA5 1987) (same);
and Donovan v. A. Amorello & Sons, Inc., 761 F. 2d 61, 65-66 (CA1 1985)
(same) with Brock v. Cardinal Industries, Inc., 828 F. 2d 373, 376, n. 4
(CA6 1987) (deference to Commission); Brock v. Bechtel Power Corp., 803 F.
2d 999, 1000-1001 (CA9 1986) (same); and Marshall v. Western Electric,
Inc., 565 F. 2d 240, 244 (CA2 1977) (same).

5
    The parties do not challenge the Court of Appeals' conclusion that the
regulations at issue in this case are ambiguous.  We assume that this
conclusion is correct for purposes of our analysis.
