 United States Court of Appeals
         FOR THE DISTRICT OF COLUMBIA CIRCUIT



Argued January 9, 2020                 Decided March 3, 2020

                         No. 19-1089

   BHC NORTHWEST PSYCHIATRIC HOSPITAL, LLC, D/B/A
        BROOKE GLEN BEHAVIORAL HOSPITAL,
                   PETITIONER

                              v.

                   SECRETARY OF LABOR,
                       RESPONDENT


         On Petition for Review of an Order of the
     Occupational Safety & Health Review Commission


     Carla J. Gunnin argued the cause and filed the briefs for
petitioner. Tressi L. Cordaro entered an appearance.

    Anne R. Godoy, Attorney, U.S. Department of Labor,
argued the cause for respondent. With her on the brief were
Edmund C. Baird, Associate Solicitor, Charles F. James,
Counsel, and Jessica Cole, Attorney.

   Before: PILLARD and KATSAS, Circuit Judges, and
SENTELLE, Senior Circuit Judge.

    Opinion for the Court filed by Circuit Judge PILLARD.
                               2
     PILLARD, Circuit Judge: The Occupational Safety and
Health Act’s General Duty Clause, enforced by the U.S.
Secretary of Labor, requires every employer to provide a
workplace “free from recognized hazards that are causing or
are likely to cause death or serious physical harm to [its]
employees.” 29 U.S.C. § 654(a)(1). In this case, the Secretary
cited an inpatient psychiatric facility, Brooke Glen Behavioral
Hospital, for violating the General Duty Clause by
inadequately protecting its employees from the “recognized
hazard[]” of patient aggression toward staff. Brooke Glen now
petitions us for review of the administrative decision affirming
the citation, see BHC Nw. Psychiatric Hosp. LLC, OSHRC
Docket No. 17-0063, 2019 WL 989734 (Jan. 22, 2019) (ALJ),
contending it is not supported by substantial evidence and that
the agency failed to provide adequate notice of the workplace
safety measures the General Duty Clause requires. To the
extent they are preserved, Brooke Glen’s objections fail to
overcome our deference to the agency, so we dismiss in part
and deny in part the petition for review.

                      BACKGROUND

     Brooke Glen, also known as BHC Northwest Psychiatric
Hospital LLC, is a 146-bed facility in Pennsylvania that
employs some 200 staff and treats patients who, due to serious
psychiatric and behavioral issues, often pose a danger to
themselves or others. See id. at *2. Brooke Glen is owned by
Universal Health Services, Inc., and managed by UHS of
Delaware, Inc. The Secretary cited both Brooke Glen and
Arbour-HRI Hospital, a smaller inpatient psychiatric facility in
Massachusetts owned and managed by the same corporate
entities, for violating the General Duty Clause by inadequately
protecting their staff from the risk of patient aggression. Both
UHS facilities contested the citations in separate administrative
proceedings before the same Administrative Law Judge (ALJ).
                                3
The ALJ upheld Brooke Glen’s citation but vacated Arbour-
HRI’s.

     In reviewing the citation of Brooke Glen for violating the
General Duty Clause, the ALJ heard testimony from the
Secretary’s expert, Dr. Jane Lipscomb, and Brooke Glen’s
expert, Monica Cooke, who addressed the effectiveness of
various measures for protecting employees from the
recognized hazard of death or serious physical harm from
patient aggression. See id. at *5. The ALJ qualified both Dr.
Lipscomb and Ms. Cooke as experts, but placed less weight on
Cooke’s testimony because her examination of Brooke Glen’s
workplace violence was limited in time and scope and, in some
respects, unsupported by evidence. See id. at *6-7. The ALJ
took care to note that Brooke Glen was not cited for
inadequately protecting against “the hazard of patient on staff
violence” by “fail[ing] to follow clinical care guidelines” or by
delivering “inappropriate clinical care.” Id. at *11.

     Examining Brooke Glen’s workplace violence program,
the ALJ concluded that the facility failed to update or
implement various written safety policies. For example,
Brooke Glen’s staff training was inadequately implemented:
The facility had a PowerPoint presentation covering workplace
violence, but failed to present evidence of “how or if [the
presentation] was made available to employees.” Id. at *25.
The ALJ found that the facility’s Code 100 system—used to
summon help in psychiatric emergencies—relied on phones
inadequately distributed throughout the facility and walkie-
talkies that staff lacked or that frequently did not work. See id.
at *15-17. Brooke Glen’s written policies required “a post-
incident debriefing of the people involved” in any incident of
patient aggression to better prepare staff to prevent such
violence in the future. Id. at *12. The ALJ found, however,
that staff “debriefings did not consistently occur” and that, even
                                4
when they did, “their scope was often so limited” that they did
not meaningfully contribute to workplace safety. Id. at *12-13.

     Brooke Glen adduced evidence showing that its average
patient aggression rate in 2016 was 4.41 incidents over 1,000
patient days, significantly below both its 2014 average rate
(11.85 incidents) and the total average rate across all UHS
facilities in 2016 (8-10 incidents). The ALJ, however, noted
several flaws in Brooke Glen’s incident reporting process that
impaired the information’s reliability. First, the ALJ found that
staff had no obligation to report “incidents of workplace
violence that did not result in an injury requiring first aid,” and
that staff “could, but were not required to” report incidents in
which a patient injured them. Id. at *19. A related reporting
system that tracked incidents in which patients were restrained
did not capture “the high number of occurrences of patient on
staff violence that did not end in a restraint.” Id. at *13. As for
a third recordkeeping system, MIDAS, the ALJ concluded that
not “all direct care employees” used it, and that information
entered into MIDAS did not “effectively contribute[] to abating
patient on staff violence.” Id. at *14.

     Having concluded that Brooke Glen inadequately
implemented its existing workplace safety program, the ALJ
considered the measures the Secretary recommended Brooke
Glen implement to come into compliance with its obligation to
protect its staff from patient-inflicted harms. The ALJ agreed
that the Secretary’s principal recommendation—having
Brooke Glen complete a self-evaluation and institute a
comprehensive workplace violence prevention and response
program—would effectively address the gaps in the present
system. See id. at *28-29. The ALJ also held that the
Secretary’s more targeted recommendations would materially
reduce the risk of patient-on-staff aggression: ensuring more
consistent reporting of incidents of patient-on-staff aggression
                               5
together with routine debriefing following those incidents to
detect and respond to systemic issues, see id. at *35-37;
increasing staffing to manage the risk of patient aggression, see
id. at *30-33; improving procedures for summoning help
during violent encounters, see id. at *33-35; involving frontline
staff on committees tasked with reviewing workplace safety
policies, see id. at *37-39; and enhancing training regarding
patient-on-staff violence and related policies and procedures,
see id. at *39. In view of the inadequacies in Brooke Glen’s
implementation of its safety program and the clear prospect
that the Secretary’s recommended measures would materially
reduce the hazard of patient-on-staff violence, the ALJ
affirmed the cited General Duty Clause violation. See id.
at *43.

     As mentioned above, the Secretary had also cited another
UHS facility, Arbour-HRI, for violating the General Duty
Clause by inadequately protecting against patient-on-staff
aggression, but on the same day the ALJ upheld Brooke Glen’s
citation, she vacated Arbour-HRI’s. See HRI Hosp., Inc.,
OSHRC Docket No. 17-0303, 2019 WL 989735 (Jan. 22,
2019) (ALJ). Based on a hearing with testimony from the same
experts who had testified about Brooke Glen, the ALJ
concluded that Arbour-HRI had been effectively implementing
its policies, including many of the Secretary’s recommended
safety measures, and that the balance of the recommended
measures would not have meaningfully reduced the hazard of
patient-on-staff violence. See id. at *29-30. For example, the
ALJ concluded that Arbour-HRI’s workplace violence
policies, unlike Brooke Glen’s, were regularly reviewed and
updated with input from frontline staff. See id. at *17-19.
Arbour-HRI’s training program included the same PowerPoint
presentation as Brooke Glen had on file, but, unlike in Brooke
Glen’s case, the ALJ described in detail how Arbour-HRI
effectively used its training materials. See id. at *9. The ALJ’s
                                6
findings also reflect that Arbour-HRI’s staff, unlike Brooke
Glen’s, reported and discussed every incident of patient-on-
staff violence, regardless of severity, see id. at *16, and had
ready means to summon help during violent incidents, see id.
at *27.

     In light of the divergent outcomes, Brooke Glen sought
Occupational Safety and Health Review Commission
(Commission or OSHRC) review of the ALJ’s decision in its
case, but the Commission exercised its discretion to deny
review, rendering the ALJ’s decision the final order of the
Commission. See 29 C.F.R. §§ 2200.90(f), 2200.91(a).
Brooke Glen timely petitioned this court under 29 U.S.C.
§ 660(a).

                          ANALYSIS

      In reviewing an administrative decision affirming a
citation issued under the Occupational Safety and Health Act,
we accept the ALJ’s “findings of fact as ‘conclusive’ if they are
‘supported by substantial evidence on the record considered as
a whole.’” Otis Elevator Co. v. Sec’y of Labor, 762 F.3d 116,
120 (D.C. Cir. 2014) (quoting 29 U.S.C. § 660(a)). The
“application of the law to those facts will be overturned only if
it is arbitrary, capricious, an abuse of discretion, or contrary to
law.” Id. at 120-21. Brooke Glen asserts in its petition for
review that (1) the ALJ’s affirmance of the General Duty
Clause violation is not supported by substantial evidence, and
(2) it lacked adequate notice of the additional workplace safety
measures the hospital needed to implement to avoid liability.
Brooke Glen does not challenge the citation’s penalty of
$12,471.00, having stipulated that the amount would be
appropriate under 29 U.S.C. § 666(j) if the General Duty
Clause violation were affirmed. See BHC Nw., 2019
WL 989734, at *43.
                               7
   I. Substantial Evidence Supports the ALJ’s Decision

     “Substantial-evidence review is highly deferential to the
agency fact-finder, requiring only ‘such relevant evidence as a
reasonable mind might accept as adequate to support a
conclusion.’” Rossello ex rel. Rossello v. Astrue, 529 F.3d
1181, 1185 (D.C. Cir. 2008) (quoting Pierce v. Underwood,
487 U.S. 552, 565 (1988)). Applying that deferential standard,
“the question we must answer is not whether record evidence
supports petitioner’s version of events, but whether it supports”
the ALJ’s conclusion that Brooke Glen violated the General
Duty Clause. AJP Constr., Inc. v. Sec’y of Labor, 357 F.3d 70,
73 (D.C. Cir. 2004) (alterations and internal quotation marks
omitted). Brooke Glen cites evidence that generally supports
its “version of events” but, critically, does not undermine the
ALJ’s conclusion.

     Proving “a violation of the General Duty Clause” requires
the Secretary to

   establish that: (1) an activity or condition in the
   employer’s workplace presented a hazard to an
   employee, (2) either the employer or the industry
   recognized the condition or activity as a hazard, (3) the
   hazard was likely to or actually caused death or serious
   physical harm, and (4) a feasible means to eliminate or
   materially reduce the hazard existed.

SeaWorld of Fla., LLC v. Perez, 748 F.3d 1202, 1207 (D.C.
Cir. 2014) (quoting Fabi Constr. Co. v. Sec’y of Labor, 508
F.3d 1077, 1081 (D.C. Cir. 2007)). Brooke Glen stipulated that
the Secretary established the first two elements, see BHC Nw.,
2019 WL 989734, at *3, and does not here contest the third,
focusing its petition solely on the fourth element—the feasible
means it should have taken to materially reduce the hazard.
                                8
      To prevail on that final element, the Secretary must
“specify the particular steps a cited employer should have taken
to avoid citation” and “demonstrate the feasibility and likely
utility of those measures.” Nat’l Realty & Constr. Co. v.
OSHRC, 489 F.2d 1257, 1268 (D.C. Cir. 1973). Where, as
here, “an employer has existing safety procedures, the burden
is on the Secretary to show that those procedures are
inadequate,” SeaWorld, 748 F.3d at 1215, as measured against
the precautions “a reasonably prudent employer familiar with
the circumstances of the industry” would take, id. at 1207
(quoting Fabi Constr., 508 F.3d at 1081). Rather than dispute
the “feasibility” of the comprehensive workplace violence
program and accompanying safety measures the Secretary
specified, Brooke Glen contests those measures’ “likely
utility,” Nat’l Realty, 489 F.2d at 1268, challenging the ALJ’s
conclusion that the recommended measures would materially
reduce the hazard of patient violence beyond what Brooke
Glen’s existing safety program already achieved. See Pet’r Br.
28-39. Brooke Glen contends that the ALJ should have placed
greater weight on Ms. Cooke’s expert testimony, see id. at
38-39, and that the Secretary’s recommended safety measures
would not materially reduce Brooke Glen’s already low
incidence of patient aggression, see id. at 28-37.

     In particular, Brooke Glen asserts that the ALJ should have
credited its industry expert, Ms. Cooke, over the Secretary’s
expert, Dr. Lipscomb, whom Brooke Glen discounted as “an
academic with no real experience in the industry.” Id. at 38.
Yet we must “accept the ALJ’s credibility determinations
unless they are patently unsupportable,” SeaWorld, 748 F.3d at
1208 (alteration omitted) (quoting AJP Constr., 357 F.3d at
73), including by deferring to “the ALJ’s reasonable
determination regarding not only the relevance but the
reliability of expert testimony,” id. at 1214 (alteration omitted)
(quoting Sec’y of Labor v. Keystone Coal Mining Corp., 151
                               9
F.3d 1096, 1107 (D.C. Cir. 1998)). Under that deferential
standard, Brooke Glen’s challenge fails. The ALJ permissibly
declined to place significant weight on Cooke’s testimony
because, in addition to various temporal, substantive, and
informational limitations on her examination of Brooke Glen’s
safety policies, see BHC Nw., 2019 WL 989734, at *6, her
“expert opinion focused on whether what [Brooke Glen] was
doing was consistent with the industry,” id. at *7. We have
held that “a safety precaution” that “is recognized by safety
experts” need not “find general usage in an industry” or have
“become customary” for “its absence [to] give[] rise to a”
violation of the General Duty Clause. Nat’l Realty, 489 F.2d
at 1266 n.37. Brooke Glen also identifies nothing to contradict
the ALJ’s conclusion that “information Ms. Cooke cites . . . [is]
not adequately borne out by the evidence.” BHC Nw.,
2019 WL 989734, at *6. And, while Brooke Glen asserts that
Dr. Lipscomb relied on an academic study to find fault with
Brooke Glen that it contends was not also brought to bear in
the Arbour-HRI proceeding, the ALJ did consider the study in
both proceedings. Compare id. at *29 & n.69, with HRI Hosp.,
2019 WL 989735, at *8.

     Next, Brooke Glen argues that the Secretary “provided no
evidence of how” the recommended safety measures would
further reduce the already low rate of patient aggression at
Brooke Glen. Pet’r Br. 32. But, for starters, the flaws the ALJ
identified in Brooke Glen’s reporting process diminish the
significance of its recorded rate of patient aggression. Even
accepting the rate on its own terms, a low rate of workplace
accidents cannot alone establish compliance with the General
Duty Clause. Just as “actual occurrence of hazardous conduct
is not, by itself, sufficient evidence of a violation” of the
General Duty Clause, “hazardous conduct need not actually
have occurred,” or have occurred at any particular rate, for an
employer to be liable. Nat’l Realty, 489 F.2d at 1267. The
                               10
General Duty Clause inquires not how an employer’s accident
rate compares with its own history or industry averages, but
whether “a reasonably prudent employer familiar with the
circumstances of the industry would have protected against the
hazard in the manner specified by the Secretary’s citation.”
SeaWorld, 748 F.3d at 1207 (quoting Fabi Constr., 508 F.3d at
1081). The relatively low “overall patient aggression rate” at
Brooke Glen, Pet’r Br. 30, while salutary, does not answer the
key question whether the Secretary’s measures would
appropriately safeguard employees by “materially reduc[ing]
the hazard” of patient-on-staff violence, SeaWorld, 748 F.3d at
1215.

     According to the ALJ, Brooke Glen’s principal
shortcoming was not its rate of patient-on-staff violence, but its
failure to fully “implement the policies it had on paper” to
prevent such violence. BHC Nw., 2019 WL 989734, at *42.
Another reviewing court has similarly held that the fact that an
employer “incorporated the relevant” safety measures “into its
own safety manual does not satisfy its obligation” under the
General Duty Clause unless those measures are actually
“followed and enforced.” Nelson Tree Servs., Inc. v. OSHRC,
60 F.3d 1207, 1211 (6th Cir. 1995). We likewise held in
SeaWorld that an employer’s decision to implement safety
measures only for workers interacting with one killer whale
supported General Duty Clause liability because the employer
failed to institute those measures throughout its facility. See
748 F.3d at 1215. Despite Brooke Glen’s effort to undercut the
ALJ’s findings of inadequate implementation by highlighting
contrary yet highly general testimony from its own risk
manager, see Pet’r Br. 31-32 (quoting J.A. 485-486), the ALJ’s
refusal to credit that testimony is not “patently unsupportable”
based “on the record considered as a whole,” AJP Constr., 357
F.3d at 73 (quoting 29 U.S.C. § 660(a)).
                              11
     In view of the multiple shortcomings in Brooke Glen’s
overall process of preventing and, when it nonetheless occurs,
tracking and addressing patient-on-staff violence, the Secretary
specified a thorough self-evaluation for Brooke Glen “to
determine what action or combination of actions will,” in the
form of a comprehensive workplace violence prevention
program, “eliminate or materially reduce the hazard.” BHC
Nw., 2019 WL 989734, at *29 (quoting Pepperidge Farm, Inc.,
17 BNA OSHC 1993 (No. 89-265, 1997)). Contrary to Brooke
Glen’s assertions, see Pet’r Br. 32-34, the Secretary need not
quantify the extent to which that program and its component
parts “would have materially reduced the likelihood” of
patient-on-staff violence, Nat’l Realty, 489 F.2d at 1267.
Instead, the Secretary satisfied the General Duty Clause’s test
by establishing that a comprehensive workplace safety
program would more effectively and consistently apply
measures designed to reduce patient-on-staff violence than
Brooke Glen’s present system did.

      In sum, substantial evidence supports the ALJ’s
conclusion that Brooke Glen’s incomplete and inconsistently
implemented         safety    protocols    “were     inadequate
to . . . materially reduce the hazard” posed by patient-on-staff
violence.      SeaWorld, 748 F.3d at 1215.          The ALJ’s
determination that a more comprehensively considered and
applied program would materially reduce the hazard was fully
warranted by her legal analysis and evidentiary findings.

   II. The General Duty Clause Provided Fair Notice Here

     Brooke Glen contends that it lacked fair notice that the
General Duty Clause might be applied as it was here—
especially when contrasted with the ALJ’s decision to vacate
the citation in the Arbour-HRI case. “A fundamental principle
in our legal system,” assured here by the Fifth Amendment’s
                               12
Due Process Clause, “is that laws which regulate persons or
entities must give fair notice of conduct that is forbidden or
required.” FCC v. Fox Television Stations, Inc., 567 U.S. 239,
253 (2012). We have “accommodated possible constitutional
problems with fair notice in this context by interpreting
‘recognized hazard’ only to include preventable hazards,”
SeaWorld, 748 F.3d at 1216, and by applying the General Duty
Clause “only when a reasonably prudent employer in the
industry would have known that the proposed method of
abatement was required,” id. (quoting Donovan v. Royal
Logging Co., 645 F.2d 822, 831 (9th Cir. 1981)).

     Contending that the Secretary provided “a fundamental
lack of fair notice . . . regarding what abatement methods would
materially reduce the hazard of patient aggression to staff and
what specific measures must be enacted” to avoid future
citation, Reply Br. 1, Brooke Glen assails the application of the
reasonably-prudent-employer and material-reduction standards
in this case as unconstitutionally vague. But neither a context-
sensitive reasonableness standard nor an unquantified
precautionary threshold is necessarily vague. Cf. Crooks v.
Mabus, 845 F.3d 412, 418 (D.C. Cir. 2016). And even if the
scope of a general standard “may not be clear in every
application,” where its “terms are clear in their application to”
the conduct at issue, the “vagueness challenge must fail.”
Holder v. Humanitarian Law Project, 561 U.S. 1, 21 (2010).

     The Secretary identified specific measures, including an
overarching workplace violence prevention program, needed to
meet the requirements of the General Duty Clause and protect
staff from patient violence at a sizable inpatient psychiatric
hospital like Brooke Glen. The ALJ found that those measures
accord with well-known industry best practices and peer-
reviewed research. See BHC Nw., 2019 WL 989734, at *29.
The need for full and consistent implementation of such
                              13
measures is or should be evident to reasonably prudent
managers of any major psychiatric inpatient hospital—indeed,
as in SeaWorld, the General Duty Clause’s application here
turned in significant part on the employer’s failure to extend
throughout its workplace the very safety “measures it had
[already] applied,” albeit inconsistently. 748 F.3d at 1216. The
ALJ was particularly troubled by the internal disconnect
between Brooke Glen’s written policies and its actual practice,
noting that, had “the record showed that [Brooke Glen] had the
program it described to Ms. Cooke, it would have been more
difficult for the Secretary to meet his burden.” BHC Nw., 2019
WL 989734, at *26 n.62. Brooke Glen can hardly object that
it was blindsided by the utility of measures it had already
embraced, at least on paper.

     The contrast between the ALJ decisions in Arbour-HRI’s
case and this one underscores the point. Brooke Glen contends
that the “diametrically opposite results” in the parallel cases
support its fair-notice claim because an “employer reading the
two decisions to determine its compliance obligations in this
area would be completely mystified.” Pet’r Br. at 45. But the
pair of cases throws into clear relief the nature of Brooke
Glen’s shortfall. Brooke Glen, unlike Arbour-HRI, allowed
whole categories of incidents to go unreported and failed to
review and learn from incidents that had occurred. Compare
HRI Hosp., 2019 WL 989735, at *16, with BHC Nw., 2019
WL 989734, at *12-13, *19. And, unlike Arbour-HRI, Brooke
Glen failed to ensure that staff would have means at hand
throughout the facility to summon help. Compare HRI Hosp.,
2019 WL 989735, at *27, with BHC Nw., 2019 WL 989734, at
*15-17. Likewise, only Brooke Glen failed to involve its
employees in formulating policies to combat patient-on-staff
violence and was unable to show the effectiveness of its
training. Compare HRI Hosp., 2019 WL 989735, at *20, with
BHC Nw., 2019 WL 989734, at *23-25. The non-arbitrariness
                              14
of the ALJ’s decision to affirm Brooke Glen’s citation even as
it vacated Arbour-HRI’s is established by Brooke Glen’s
different factual record—involving similar policies, but
markedly different implementation of them in practice.

     In addition to its as-applied constitutional challenge,
Brooke Glen objects “that rulemaking—rather than the blunt
General Duty Clause—is the only appropriate tool” for the
Secretary “to establish and enforce compliance obligations”
regarding the “nebulous, complicated, and individualized
nature of workplace violence” as it “exists in the behavioral
hospital setting.” Pet’r Br. 46-47. We may not consider this
objection because, absent “extraordinary circumstances,” “[n]o
objection that has not been urged before the Commission shall
be considered by the court.” 29 U.S.C. § 660(a); see also Frank
Lill & Son, Inc. v. Sec’y of Labor, 362 F.3d 840, 844 (D.C. Cir.
2004). Brooke Glen did not raise rulemaking in its petition for
discretionary review and has identified no “extraordinary
circumstances” to excuse that failure. Frank Lill, 362 F.3d at
844 (quoting 29 U.S.C. § 660(a)). By not responding to the
Secretary’s observation that the rulemaking argument was
unpreserved, see Resp’t Br. 47-48, Brooke Glen further
forfeited the point, cf. Perry Capital LLC v. Mnuchin, 864 F.3d
591, 618 (D.C. Cir. 2017). We therefore cannot consider
Brooke Glen’s objection that the Secretary may only police
patient-on-staff violence via notice-and-comment rulemaking,
as opposed to agency adjudication under the General Duty
Clause.

                          *    *   *

     We dismiss the petition for review of the ALJ’s decision
affirming the General Duty Clause citation insofar as the
petition challenges the agency’s authority to guard against
patient-on-staff violence via adjudication rather than
                             15
rulemaking. In all other respects, including as to substantial
evidence and adequate notice, the petition is denied.

                                                  So ordered.
