 United States Court of Appeals
         FOR THE DISTRICT OF COLUMBIA CIRCUIT



Argued September 10, 2015           Decided January 21, 2016

                        No. 12-1072

                    DHL EXPRESS, INC.,
                      PETITIONER

                              v.

           NATIONAL LABOR RELATIONS BOARD,
                     RESPONDENT


                 Consolidated with 12-1143


       On Petition for Review and Cross-Application
                   for Enforcement of an
       Order of the National Labor Relations Board


     David A. Kadela argued the cause and filed the briefs for
petitioner.

    Barbara Sheehy, Attorney, National Labor Relations
Board, argued the cause for respondent. On the brief were
John H. Ferguson, Associate General Counsel, Linda
Dreeben, Deputy Associate General Counsel, Usha Dheenan,
Supervisory Attorney, and Nicole Lancia, Attorney.
                                2
    Anton G. Hajjar and James B. Coppess were on the brief
for movant-intervenor American Postal Workers Union, AFL-
CIO in support of respondent.

    Before: ROGERS, BROWN and GRIFFITH, Circuit Judges.

    Opinion for the Court filed by Circuit Judge BROWN.

     BROWN, Circuit Judge: DHL Express, Inc. (the
Company) petitions for review of the December 22, 2011,
decision and order by the National Labor Relations Board
(NLRB or Board) finding the Company violated Section
8(a)(1) of the National Labor Relations Act (NLRA) by
prohibiting nonworking employees from distributing union
literature in the hallway of its facility. The Board seeks this
court’s enforcement of its order requiring the Company to
cease and desist. We deny the Company’s petition and grant
the Board’s cross-application for enforcement.

                                I.

     This case is governed by Section 7 of the NLRA, 29
U.S.C. § 157, which dictates that “[e]mployees shall have the
right to self-organization, to form, join, or assist labor
organizations . . . and to engage in other concerted activities
for the purpose of collective bargaining or other mutual aid or
protection . . . .” It is a violation of the Act for an employer to
“interfere with, restrain, or coerce employees in the exercise
of the rights guaranteed in section 157 . . . .” Id. §158(a)(1).

                           Background

   DHL Express, Inc. is an express delivery service that
moves mail and freight throughout the United States and in
many foreign countries. DHL’s only U.S. hub is located on
                               3
the grounds of the Cincinnati Airport in Erlanger, Kentucky
(CVG). Jetliners arriving from domestic and international
destinations taxi directly to the sort facility where a
sophisticated system for unloading and reloading freight and
package containers ensures items reach their final
destinations. Over 1,200 workers are employed at the CVG
facility which handles between 560,000 and 630,000
packages each week. Most of this loading and unloading
activity occurs on the first floor and mezzanine level of the
main sort building. The facility operates 24 hours a day with
a part-time morning shift, part-time night shift, and a full-time
day shift. In 2011, fourteen of DHL’s employees were
represented by the International Brotherhood of Teamsters.
The American Postal Workers Union, AFL-CIO (APWU) had
been attempting to organize the Company’s remaining
employees.

     Because the facility is on the grounds of the Cincinnati
airport, DHL must comply with the safety and security
regulations of the U.S. Customs Service, the Federal Aviation
Administration,     and     the    Transportation     Security
Administration. To comply with these security requirements,
ingress and egress to the hallway are controlled, with a
security checkpoint located at the far end. The vast majority
of DHL employees enter and exit through this main hallway
of the administration building. The hallway is used by the
company for a variety of purposes. It contains bulletin boards
and wall-mounted television screens which display upcoming
company events, weather reports, and production statistics.
And there are computer stations employees can use during
non-work time to view benefit and payroll information and to
check personal email.

    The Company has also used the hallway for company-
sponsored events, scheduled and supervised by management.
                             4
DHL organized and hosted a Wellness Fair, Financial Fair,
Education Fair, Autism Speaks fundraiser, and a promotion of
the DHL-sponsored IndyCar, complete with free t-shirts and
hats. These events were scheduled in advance with notice
provided to employees, and they were held at the end of the
overnight shift.       Similarly, the collective bargaining
agreement with the Teamsters provided for union access. Per
that agreement, the Company permitted distribution of union
literature provided the union gave advance notice and allowed
DHL to specify the location and timing of the distribution.
And the ALJ credited testimony that a fitness company was
permitted to offer gym memberships, some employees sold
Super Bowl Raffle tickets in the hallway, and off-duty
employees talked on cell phones and had other social
interactions while transiting the hallway.

    However, certain work-related activities do occur in the
hallway.     Members of DHL’s quality control team
occasionally use the hallway to move damaged or misdirected
packages to the front entrance. And company representatives
frequently conduct tours for new employees and visitors,
which stop in the hallway.

     DHL’s Employee Handbook includes a Solicitation and
Distribution policy which prohibits “interference from
persons who are pursuing a purpose not related to DHL’s
normal business” and forbids any solicitation by non-
employees at any time unless “specifically authorized or
sponsored by DHL.” JA 56. Solicitation between employees
is prohibited during work time or in work areas. See id. DHL
also purports to have an “unwritten” policy which requires
security staff to prevent employees from loitering or
congregating in the hallway, except during company-
sponsored or approved events. DHL admits its employees
have never been officially notified of this security policy.
                               5
     In December 2010 and February 2011, four different
employees handed out union literature in the hallway. In
December when Vida Manuel distributed flyers she was told
by security staff that she could not handbill in the hallway.
Manuel responded that “she had seen the Teamsters in the
hallway doing it before at the tables and she thought she was
able to do it also.” JA 89, 353. Later that month, Manuel and
fellow employees Bob Woodyard and James Hamilton
handed out APWU’s holiday newsletter, standing by the
televisions. They were informed by Jennifer Miller, Captain
of Security, that they could not loiter in the hallway but could
handbill in the cafeteria or break room. When the employees
complained that the Teamsters had been allowed to distribute
literature, Miller reiterated that no employees were permitted
to loiter in the hallway. Miller notified the Human Resources
Manager who repeated the admonition. On February 25,
2011, Manuel, Woodyard, and Charles Teeters stood in the
hallway handing out literature and displaying posters. They
were again told it was against company policy to loiter and
asked to move to the cafeteria, a break room, or an outside
area. Each time the off-duty employees distributed literature
for about 20 minutes. They left — sometimes reluctantly —
when instructed to do so.

                     Procedural History

     The APWU brought two unfair labor practice charges
against DHL, alleging that the Company violated Section
8(a)(1) by prohibiting employees from distributing union
literature during non-work time in a non-work area of its
facility on two occasions in December 2010 and once in
February 2011. The Regional Director issued a Complaint on
the charges on March 25, 2011.
                                6
     On May 16 and 17, 2011, during a hearing before an
Administrative Law Judge, the parties stipulated that, on three
occasions, off-duty DHL employees who were distributing
APWU literature in the hallway were told they could not
loiter there, informed they could distribute the literature
outside or in the cafeteria or breakroom, and were asked to
leave the hallway.

     The General Counsel claimed the hallway is a non-work
area and thus DHL could not prohibit the distribution of union
literature there. DHL countered that the hallway is a work
area and that it had the right under its distribution policy, the
legality of which is not at issue, to prohibit employees from
leafletting there and to limit their leafletting to the facility’s
parking lot, cafeteria, and other non-work areas. The General
Counsel also argued that even if the hallway was a work area,
union distribution could not be prohibited because DHL had
permitted other types of distribution in that area. DHL
contended the other distributions were distinguishable and did
not compromise the Company’s right to enforce its
distribution policy, especially because security-related
considerations justified the prohibition.

     On July 21, 2011, the ALJ found DHL violated Section
8(a)(1) by preventing off-duty employees from distributing
union literature in the hallway — which he described as a
“mixed-use” area of the facility. Specifically, the ALJ found
DHL “compromised the hallway area by permitting non-work
use of it.” JA 26-29. DHL raised several exceptions to the
decision and the Board issued its own decision and order on
December 21, 2011. Two Board members agreed with the
ALJ that the hallway constituted a “mixed-use” area in which
DHL could not prohibit distribution during non-work time.
The third, Member Hayes, concluded the hallway was a work
area but would have found a violation because, in his view,
                               7
the Company’s policy discriminated against the union. The
Board ordered DHL to cease and desist from enforcing its no-
distribution rule and to notify employees that the rule will not
be enforced in the hallway.

    On January 31, 2012, DHL petitioned for review in this
court; the Board filed a cross-application for enforcement.

                              II.

     This court’s “role in reviewing an NLRB decision is
limited.” Wayneview Care Ctr. v. NLRB, 664 F.3d 341, 348
(D.C. Cir. 2011). “[A] decision of the NLRB will be
overturned only if the Board’s factual findings are not
supported by substantial evidence, or the Board acted
arbitrarily or otherwise erred in applying established law to
the facts of the case.” Pirlott v. NLRB, 522 F.3d 423, 432
(D.C. Cir. 2008). Substantial evidence is defined as “such
relevant evidence as a reasonable mind might accept as
adequate to support a conclusion.” Consol. Edison Co. v.
NLRB, 305 U.S. 197, 229 (1938). Judicial review of
the Board’s credibility determinations is especially
deferential: such determinations must be sustained unless they
are “hopelessly incredible or self-contradictory,” Teamsters
Local 171 v. NLRB, 863 F.2d 946, 953 (D.C. Cir. 1988), or
“patently insupportable,” Exxel/Atmos, Inc. v. NLRB, 28 F.3d
1243, 1246 (D.C. Cir. 1994).

     However, deference is not warranted where the Board
“fails to adequately explain its reasoning,” where the Board
leaves “critical gaps” in its reasoning, Point Park Univ. v.
NLRB, 457 F.3d 42, 49-50 (D.C. Cir. 2006), or where the
Board erred in applying law to facts, Perdue Farms, Inc.,
Cookin’ Good Div. v. NLRB, 144 F.3d 830, 834 (D.C. Cir.
1998). But the court may not overturn a Board’s order merely
                              8
because the court “might have reached a different conclusion
had the court considered the issue de novo.” Reno Hilton
Resorts v. NLRB, 196 F.3d 1275, 1282 (D.C. Cir. 1999).

                         A. Jurisdiction

     In its brief, DHL emphatically urges that the Board’s
“mixed-use” presumption is “unreasonable, irrational, and
arbitrary.” But the Board argues this rationality argument was
not presented below and so is not properly before the court.

     We are, of course, precluded from considering any issue
raised by a party for the first time on appeal. See Pirlott v.
NLRB, 522 F.3d 423, 433 (D.C. Cir. 2008) (“It is . . . well
understood that a reviewing court must confine itself to the
grounds upon which the record discloses that the agency’s
action was based.”); see also 29 U.S.C. § 160(e) (“No
objection that has not been urged before the Board . . . shall
be considered by the court, unless the failure or neglect to
urge such objection shall be excused because of extraordinary
circumstances.”).    The question then is whether DHL
challenged the rationality of the “mixed-use” presumption
below in a manner sufficient to put the Board on notice.

     The ALJ’s opinion explicitly characterized the hallway as
a “mixed-use” area. The ALJ therefore applied the Board’s
longstanding “mixed-use” presumption: that an employer
cannot prohibit non-worktime distribution of union literature
in a mixed-use area, absent a showing of special
circumstances. In its exceptions to the ALJ’s findings, DHL
seemed to accept this mixed-use presumption. See, e.g., JA
53-54 (citing, without question, Board precedents holding that
a mixed-use area is “usually properly treated as a non-work
area for purposes of application of these principles”). Indeed,
DHL appeared to be challenging the application of this
                                9
presumption here — not its validity. See, e.g., JA 55 (“The
ALJ’s decision that the hallway is not a work area is flawed
because it fails to recognize the substantial evidence of work-
related activity that regularly occurs in the hallway.”). Only a
single exception and a single sentence in its appeal before the
Board arguably go to the validity of the presumption. See JA
35 (“Respondent excepts to the ALJ’s finding that a mixed-
use area must be treated the same as a non-work area for
purposes of application of a no distribution rule.”); JA 56
(“To conclude as a matter of law, as the ALJ did, that a non-
work area and a mixed-use area are equivalent would be to
abandon the Board’s responsibility to balance employees’
Section 7 rights against an employer’s property and
management rights and to accommodate each with as little
destruction of one as is consistent with the maintenance of the
other.”).

     Our precedent indicates a “vague exception” to an ALJ’s
finding may be sufficient “to preserve an issue for appeal
when petitioner’s ‘brief in support of its exceptions’
adequately put[s] the Board on notice” of the grounds on
which the petitioner is objecting. Parsippany Hotel Mgmt.
Co. v. NLRB, 99 F.3d 413, 417-18 (D.C. Cir. 1996)
(discussing NLRB v. Blake Constr., 663 F.2d 272, 283-84
(D.C. Cir. 1981)).          Alternatively, when a petitioner
“specifically object[s] in its exceptions to the ALJ’s findings,”
then the issue may still be preserved for appeal even though
the petitioner “did not brief and argue the issue to the Board.”
Id. (discussing Davis Supermarkets, Inc. v. NLRB, 2 F.3d
1162 (D.C. Cir. 1993)). Here, we have neither a clear
statement in DHL’s exceptions nor a less-than-clear statement
that is fully explained in the brief. This case is most similar to
Highlands Hospital Corp. v. NLRB, in which we held the
company’s “single reference to the ‘excessive breadth’ of a
remedy with multiple parts [was] insufficient to satisfy
                              10
section 10(e) because it failed to give the Board ‘adequate
notice’ of the argument it [sought] to advance on review.”
508 F.3d 28, 32-33 (D.C. Cir. 2007). We are therefore
precluded from considering any direct challenge to the
Board’s mixed-use presumption.

     But a close reading of the Company’s arguments below
indicates that, while DHL seemed to accept the Board’s
general mixed-use presumption, the Company did challenge
the ALJ’s application of that presumption — claiming the
ALJ’s purported classification of any area not exclusively
devoted to work as “non-work” or “mixed-use” was a novel
misapplication of Board precedent to which the Board
acquiesced. For reasons explained more fully below, we
conclude the ALJ’s decision relating to mixed-use areas also
was controlled by long-settled precedent.

                B. The Balancing of Rights

     The Board and the employers are often not on the same
page. In this case, they might not even be reading from the
same book. For example, the Board, affirming the ALJ,
concludes the hallway is a “mixed use” area in which union
solicitation may not be prohibited. DHL, however, sees the
operative principle quite differently. DHL contends that the
working area of a business includes more than its production,
inventory, and active processing space. Every sizeable
business also requires administrative space where the
business’s payroll, human resources, accounting, security and
other support services are housed. Thus, DHL argues work
necessary to the operation of the business is being performed
in such spaces. And these areas remain as much under the
control of the employer as the active manufacturing or
processing facilities. In this case, the hallway is part of the
administrative portion of the facility, and — being integral to
                              11
the Company’s commitment to maintain a secure facility — is
made available to both outsiders and employees for limited
purposes on a schedule established by management. These
purposes, DHL maintains, must be congruent with the
Company’s need to inform and provide benefits and
assistance to employees and to promote Company objectives.
Thus, APWU’s insistence that off-duty, pro-union employees
may use this space for organizing activity without the
company’s permission and without being relegated to a
particular time and place is viewed by the Company as an
unwarranted disruption of the discipline DHL attempts to
maintain in this administrative space and a violation of the
Company’s property rights.

     DHL correctly identifies Republic Aviation Corp. v.
NLRB, 324 U.S. 793 (1945), as the seminal case articulating
the Board’s responsibility to balance employees’ right to self-
organize against employers’ right to maintain discipline in
their establishments. See id. at 803 n.10 (upholding the
Board’s presumption that it is “not within the province of an
employer to promulgate and enforce a rule prohibiting union
solicitation by an employee outside of working hours,
although     on    company      property”     absent     special
circumstances). The Court in Republic Aviation recognized
neither right was unlimited, a principle that was refined in
NLRB v. Babcock & Wilcox Co.: “Accommodation between
[employee-organizational rights and employer-property
rights] must be obtained with as little destruction of one as is
consistent with the maintenance of the other.” 351 U.S. 105,
112 (1956).

     Still, Congress entrusted the task of balancing between
these conflicting legitimate interests to the Board, not the
judiciary. See Beth Israel Hosp. v. NLRB, 437 U.S. 483, 501
(1978). If the Board’s resolution is rational, consistent with
                              12
the Act, and supported by substantial evidence, it must be
enforced. Id.

     Unfortunately for DHL, there is less to the protection of
employer property rights and managerial prerogatives than the
language of accommodation seems to suggest. The locus of
the accommodation between Section 7 rights and private
property rights “may fall at different points along the
spectrum depending on the nature and strength of the
respective § 7 rights and private property rights asserted in
any given context.” Hudgens v. NLRB, 424 U.S. 507, 522
(1976). In practice, the locus of accommodation shifts on a
sliding scale. When property rights are ascendant, labor
organizers must show their need for access trumps the
employers’ right to exclude. When employee rights are at
their zenith, employers need to make an affirmative showing
that organizational activity cannot be accommodated without
negatively impacting productivity, discipline, security, or
similarly important interests. Employer rights are at their
strongest when dealing with non-employees. Employers can
generally prohibit solicitation and other labor organizing
activities by nonemployee union representatives.             An
employer cannot be compelled to allow nonemployee
organizers onto his property. See Lechmere, Inc. v. NLRB,
502 U.S. 527, 534 (1992). “Nonemployee organizers cannot
claim even a limited right of access to a nonconsenting
employer’s property until ‘[a]fter the requisite need for access
to the employer’s property has been shown.’” Id. (quoting
Centr. Hardware Co. v. NLRB, 407 U.S. 539, 545 (1972)).

     In contrast, the employer’s ability to restrict pro-union
activity by an off-duty employee legally on the premises — in
a non-work area — is quite limited. See ITT Indus. v. NLRB,
251 F.3d 995, 1001 (D.C. Cir. 2001). When organizing
activity is undertaken by employees lawfully on the
                              13
employer’s property, the proper balance is between their right
to organize and an employer’s managerial rights. See, e.g.,
Hudgens, 424 U.S. at 521 n.10 (1976) (“A wholly different
balance was struck when the organizational activity was
carried on by employees already rightfully on the employer’s
property, since the employer’s management interests rather
than his property interests were there involved.”); Babcock,
351 U.S. at 112-13 (“Here the Board failed to make a
distinction between rules of law applicable to employees and
those applicable to nonemployees. The distinction is one of
substance. No restriction may be placed on the employees’
right to discuss self-organization among themselves, unless
the employer can demonstrate that a restriction is necessary to
maintain production or discipline.”). Indeed, the Court has
specifically held that “the Board is entitled to view the
intrusion by employees on the property rights of their
employer as quite limited in this context as long as the
employer’s management interests are adequately protected.”
Eastex, Inc. v. NLRB, 437 U.S. 556, 574 (1978).

     DHL argues that “[d]rawing such a presumption with
respect to mixed-use and incidental-work areas conflicts . . .
with the very distinction that the Supreme Court endorsed in
Republic Aviation — the one between working and non-
working areas.” Pet. Br. 29. However, as Babcock makes
clear, distinctions between employees and non-employees and
between property rights and managerial rights may
dramatically shift the balance. An employer may lawfully
prohibit employees from distributing union literature in work
areas during work time; however, a rule that extends the
prohibition to nonworking areas during nonwork time is
presumptively invalid. See NLRB v. Transcon Lines, 599
F.2d 719, 722 (5th Cir. 1979). The Board still adequately
protects the employer’s management interests by maintaining
the special circumstance exception available to employers for
                                    14
non-work areas. 1 DHL’s argument that the Board was
required to conduct a balancing of its property interests
against its employees’ organizational interests is inapt. See
Hudgens, 424 U.S. at 521 n.10. The company ignores the
differences between employees and strangers and fails to
distinguish property rights from managerial rights. DHL thus
misapprehends the critical point: while the Company may be
able to dictate the terms of access to strangers, contractors,
and other business invitees, “no restriction may be placed on
the employees’ right to discuss self-organization among
themselves, unless the employer can demonstrate that a
restriction is necessary to maintain production or discipline.”
Lechmere, Inc., 502 U.S. at 533.

                             C. Deference

    In an attempt to escape the high level of deference
accorded to agency action, DHL also claims the Board’s
mixed-use presumption is “arbitrary” and “conflicts with
Supreme Court precedent.” As discussed above, these
arguments are likely precluded because DHL failed to
squarely raise them before the Board. But to the extent DHL
1
  For example, in Beth Israel Hospital v. NLRB, the Supreme Court
considered whether two industry-specific presumptions put forth by the
Board were rational. The Board found that rules prohibiting solicitation in
the dining areas of public restaurants were presumptively lawful “because
solicitation has the tendency to upset patrons,” while also holding that
prohibiting solicitation in the cafeteria of a hospital was unlawful “absent
evidence that nonemployee patrons would be upset.” Beth Israel, 437
U.S. at 505-06. The Court approvingly noted that “the Board [had]
concluded that these rules struck the appropriate balance between
organizational and employer rights in the particular industry to which each
is applicable.” Id. at 506. Similarly, in this context, the Board has
concluded that mixed-use areas should not be subject to prohibitions on
distribution unless the employer offers evidence of special circumstances.
This conclusion does not conflict with Republic Aviation or any other
Supreme Court precedent.
                             15
is challenging the “heightened” presumption purportedly
employed by the ALJ — that any area not “exclusively”
devoted to work must be considered a mixed-use area — we
consider and reject that challenge below.

     Because Congress has given the Board such broad
discretion, the Court must “uphold [the] Board rule as long as
it is rational and consistent with the Act, even if we would
have formulated a different rule had we sat on the Board.”
NLRB v. Curtin Matheson Scientific, Inc., 494 U.S. 775, 787
(1990) (citation omitted). The Board has for decades — with
court approval — found areas in which minimal or solely
incidental work is conducted are to be considered “mixed-
use” areas in which a prohibition on distribution during non-
work time has to be justified by special circumstances. See,
e.g., United Parcel Serv., 327 N.L.R.B. 317 (1998), aff’d, 228
F.3d 772 (6th Cir. 2000); Transcon Lines, 235 N.L.R.B. 1163,
1165 (1978), aff’d, 599 F.2d 719 (5th Cir. 1979); Rockingham
Sleepwear, 188 N.L.R.B. 698, 701 (1971). Moreover, the
Board has adequately explained the (rather obvious) reasons
for applying the same presumption to mixed-use areas as to
non-work areas: “[i]t is the main production area of an
employer’s facility where the hazards of littering and
maintaining order are paramount over employee distribution
of literature” such that employee distribution in these mixed-
use areas “does not infringe” on the employer’s interests in
“conducting an orderly nonhazardous workplace.” Found.
Coal West, Inc., 352 N.L.R.B. 147, 150 (2008); cf. Patio
Foods v. NLRB, 415 F.2d 1001, 1003 (5th Cir. 1969) (“[T]he
implicit holding of these cases is that an employer’s
legitimate interest in keeping his employees’ work stations
free of the disruptive influence of handbilling justifies the
prohibition of union literature distribution in work areas
where employees are, in fact, working.”).
                             16
     This presumption necessarily incorporates a balancing of
employer and employee interests, and no court precedent
prevented the Board from reasonably concluding the balance
should be the same for non-work and mixed-use areas. Here,
the ALJ and the Board applied this longstanding presumption
to DHL’s hallway, without modification. Although DHL
fixates on the ALJ’s finding that “the hallway is not
exclusively a work area,” JA 96, neither the ALJ nor the
Board has heightened the standard for employers — a
miniscule amount of nonwork will not now convert a work
area into a “mixed use” area. An examination of the ALJ
opinion, adopted by the Board, shows the ALJ carefully
considered the type, duration, and frequency of work and
nonwork occurring in the hallway prior to concluding that it
should be considered a “mixed-use” area. See JA 96-98.
Although DHL is alarmed by the “exclusivity” language
employed by the ALJ, the record demonstrates that he was
simply responding to the Company’s argument that the
hallway was a work area by stating all the reasons he could
not find it to be exclusively so. See id. This analysis
ultimately amounts to a run-of-the-mill application of the
Board’s traditional mixed-use framework.

     While DHL may not agree with the underlying
presumption, “it is to the Board that Congress entrusted the
task of applying the Act’s general prohibitory language in
light of the infinite combinations of events which might be
charged as violative of its terms.” Beth Israel, 437 U.S. at
500-01. Moreover, the Board’s mixed-use presumption is
quite reasonable: it provides predictability for employers and
employees, it includes a “special circumstances” exception for
employers, and DHL’s only proffered alternative is treating
mixed-use areas, where very little work occurs, as equivalent
to work areas — an outcome that “overcompensate[s] its
                              17
goals and give[s] too little weight to employee organizational
interests.” Id. at 501.

                  D. Substantial Evidence

      Having failed on its broader challenge to the mixed-use
presumption, DHL still contends that the Board’s finding that
the hallway constituted a “mixed-use” area was not supported
by substantial evidence. This court “must uphold the ALJ’s
findings of fact if substantial evidence exists in the record
when viewed as a whole, to support them.” United Parcel
Serv., 228 F.3d at 776; see also Universal Camera Corp., 340
U.S. 474, 477 (1951). “Evidence is considered substantial if
it is adequate, in a reasonable mind, to uphold the decision.”
Roadway Express, Inc. v. NLRB, 831 F.2d 1285, 1289 (6th
Cir. 1987). Here, both the ALJ’s findings and the Board’s
decision were supported by substantial evidence.

     The Board has “long held that merely because a work
function or functions occur in a given space does not render
that space a ‘work area’ within the meaning of the Board’s
rules regarding distribution. Rather, the Board has looked at
the quality and quantity of work, which occurs in the area at
issue, and examine[d] whether the work is more than de
minimus and whether it involves production.” Brockton
Hospital, 333 N.L.R.B 1367, 1375 (2001). To constitute a
work area, “the area must be integral, not merely incidental,
to the employer’s main function.” Meijer, Inc., 344 N.L.R.B.
916, 923 (2005) (emphasis added); see also U.S. Steel Corp.,
223 N.L.R.B. 1246, 1247-48 (1976) (“Respondent’s
contention that all its property is a work area is a contention
that can be asserted by every company, thus effectively
destroying the right of employees to distribute literature.
Some work tasks, whether it be cleaning up, maintenance, or
                                  18
other incidental work, are performed at some time in almost
every area of every company.”).

     Board precedent on this issue is instructive: for example,
in Santa Fe Hotel, the Board identified “the main function of
the Respondent’s hotel-casino [as] to lodge people and permit
them to gamble.” Santa Fe Hotel, 331 N.L.R.B. 723, 723
(2000). Thus, the work activity — “security, maintenance,
and gardening” — asserted by Respondent to occur at the
facility entrance was merely incidental to its main function.
See id. Other cases have followed the same line of analysis.
In Saisa Motor Freight, the Board designated a break room as
a “mixed-use area” because it was an area “where employees
may take breaks and eat” but also “where line haul and city
drivers receive[d] papers from dispatchers and turn[ed] in
documents at the end of a trip.” 333 N.L.R.B. 929 (2001); see
also Transcon Lines, 599 F.2d at 721 (holding the Board’s
mixed-use designation to be supported by substantial
evidence because the drivers’ room was an area where
employees could relax, drink coffee or eat snacks, and
converse freely even though some work was occasionally
conducted there); United Parcel Serv., 228 F.3d at 777
(upholding designation of check-in area as “mixed-use”
because that area “transformed into a congregation point for
the drivers to drink coffee, read magazines and newspapers,
and converse before their morning shift”).

     The Board’s analysis of another hallway in Foundation
Coal is particularly illuminating. 2 As in this case, the hallway
there served as a place for employees to congregate, to view
the bulletin boards, and to use communal goods like the

2
  Only two Board members decided Foundation Coal; the Board therefore
found it unnecessary to rely on that precedent when deciding this case.
DHL Express, Inc., 357 N.L.R.B. No. 145 at 1 n.1 (2011). Regardless, the
logic of Foundation Coal is instructive here.
                              19
company microwave and coffeemaker. See 352 N.L.R.B. at
148 (“There is no dispute that employees use the hallway to
socialize with coworkers before, during, and after work.”).
Some work also took place in the hallway, namely dispatchers
relaying new assignments to employees and human resource
employees discussing safety and other issues with employees.
Id. at 148-49. But the Board identified the employer’s main
function as “the digging, removal, sorting, and distribution of
coal” and noted that “[t]his work is done primarily in the Pit
and loading areas of Respondent’s . . . mine.” Id. at 150.
Because of this, the Board concluded that “[a]t best the
hallway is a mixed use area where both socializing and
nonproduction work, incidental to Respondent’s main
function, the production of coal, take place. Employee
distribution of written materials in the hallway does not
infringe on Respondent’s interests in conducting an orderly
nonhazardous workplace for the mining of coal.” Id.

     So too with DHL’s hallway: there is no question
employees often congregate and socialize in the hallway. The
hallway features televisions, where employees can watch for
weather and company updates, computer stations for checking
benefits information and personal email, and areas for
employees to use their personal cellphones. Moreover, DHL
has allowed the hallway to be used for various fairs, charity
drives, raffles, and the sale of merchandise. The main
function of DHL is the sorting and transfer of packages; this
activity takes place in the sorting facility — not the hallway.
Even though incidental work (like the carrying of packages
and company tours) occasionally occurs in the hallway, the
ALJ and the Board were justified in designating it as a “mixed
use” area.

    None of the cases relied on by DHL undercut this
determination; “[t]he facts in those cases differ substantially
                                20
from the facts at issue here . . . . Those cases dealt with areas
still retaining the characteristics of a work area but where
non-working employees happened to be found . . . .” United
Parcel Serv., 228 F.3d at 777 (discussing the same cases DHL
relies on in its briefing). DHL’s contention that it provides
alternative areas for organizational activities is also irrelevant.
See id. at 778 (“[T]he NLRB has expressly found that a
company may not prohibit the distribution of union literature
in a mixed-use area, even though other non-work areas
existed in the building”); Beth Israel Hosp., 437 U.S. at 505
(“[O]utside of the health-care context, the availability of
alternative means of communication is not, with respect to
employee organizational activity, a necessary inquiry . . . .”).
The Board’s mixed-use determination is therefore supported
by substantial evidence on the record as a whole.

                  E. Special Circumstances

     Even when the Board finds an employer’s prohibition is
invalid, it is still “necessary to examine whether there are
‘special circumstances’ present which rebut the presumption
of invalidity.” U.S. Steel Corp., 223 N.L.R.B. 1246, 1248
(1976). “Special circumstances” in this context means
“problems associated with distribution which go beyond the
normal problems of litter and production efficiency which the
Board took into account in that case when it granted
employers the additional limitation of banning distributions
from work areas.” Id.

     DHL’s facility is located on the grounds of an airport,
and so the company must comply with several sets of federal
safety and security regulations. Its security checkpoint for
employees entering and exiting the building is located at one
end of the hallway. DHL thus asserts that its security and
safety concerns constitute “special circumstances” sufficient
                              21
to support a prohibition on the distribution of union literature
in the hallway.

     DHL need “show only a likelihood of, not actual,
disruption or disturbance.” Brockton Hosp. v. NLRB, 294
F.3d 100, 104 (D.C. Cir. 2002). And at least one court has
previously admonished the Board for failing to give due
consideration to an employer’s safety and security concerns.
In McDonnell Douglas Corp., the Eighth Circuit held that
“when . . . an employer makes a credible showing of special
justifying circumstances, . . . the Board in weighing that
evidence must responsibly and in a meaningful way consider
the importance of the proffered justification.” 472 F.2d 539,
545 (8th Cir. 1973). The employer in that case was “engaged
in highly sophisticated operations in manufacturing aircraft,
missiles, space vehicles, and military airplanes,” and the court
found that the Board gave too little weight to the employer’s
“security problems.” Id. at 545-47.

     The special circumstances question is a closer call here
than whether the hallway is a mixed-use area. But the ALJ
evaluated the specific argument put forward by DHL and
concluded that, “[w]ith respect to security concerns, [a
company director] testified that the employees did not break
any Transportation Security Administration (TSA) policies or
guidelines when distributing union literature in the hallway
area, and [the human resource manager] testified that
employees were not hindered in there [sic] ingress or egress
from the facility.” JA 27. The security concerns at DHL,
while arguably above the norm, do not rise to the level of
those in McDonnell Douglas where the employer was
engaged in classified military work. Moreover, DHL was
unable to point to any instance in which the distribution of
union literature had in fact clogged the hallways, endangered
other employees, or violated any security regulations. At oral
                              22
argument, DHL’s counsel seemed somewhat ambivalent on
this point. The Company could offer no specific evidence of
disruption, instead arguing that its description of the security
challenges should have been sufficient. But the Board has
consistently held that the employer must point to “some
specific evidence of unusual circumstances.” Meijer, 436
F.3d at 545. Also, DHL’s own contention that “[p]ermitting
activities in the hallway that require employees to stop, even
for a moment, [will] impede the progress of the throng of
employees coming down the hallway, causing the hallway to
become congested and creating the potential for a back-up,”
JA 40, is undermined by its allowance of so many other
activities in the hallway — such as the use of cellphones and
computers, socialization of employees, and even solicitation
by a different union — none of which appear to have caused
any safety or security problems.

    Given the absence of evidence that discipline, production,
or security had been adversely affected, the Board’s
determination was supported by substantial evidence on the
record as a whole.

                     F. Burden of Proof

    Finally, DHL contends the Board improperly saddled it
with the burden of proving that one or more on-duty
employees received union literature, when the General
Counsel bears the burden of proof with respect to employees
being off-duty. As the Board held in Stoddard-Quirk, an
unfair labor practice occurs when an employer prevents
employees from distributing union literature in non-work (or
mixed-use) areas during non-work time. See Stoddard-Quirk
Mfg. Co., 138 N.L.R.B. 615 (1962). And it is, of course, the
General Counsel who “carries the burden of proving the
                              23
elements of an unfair labor practice.” NLRB v. Transp. Mgmt.
Corp., 462 U.S. 393, 401 (1983).

     Here, both sides agree the employees distributing the
literature were off-duty. JA 80-81, 101. And no evidence
was adduced that these employees distributed literature to
anyone who was on duty. See id. Board precedent, including
court-approved precedent, does not seem to require the
General Counsel to prove each and every employee who
received the literature was off-duty. See Transcon Lines, 599
F.2d at 722 (“The employer urges that the Board’s proof
failed because it was not shown that at the moment Brown
handed out literature to other drivers . . . he was on non-work
time, and that the precise moment each other driver was
handed a piece of literature . . . he was in non-work status as
well. The employer’s argument is specious with respect to
Brown . . . [and] with respect to drivers who were handed
pieces of literature, the precise nicety of proof hypothesized
by the employer was not required.”).

    Obviously the employer is in a much better position to
demonstrate that on-duty employees received the literature,
and the Board has consistently looked to see whether any such
evidence was adduced. See, e.g., Oak Apparel, Inc., 218
N.L.R.B. 701, 702 n.7 (1975) (“In any event, there is no
evidence that leaflets were distributed to any employees who
were working . . . .”). Moreover, even if some on-duty
employees received the distribution, some off-duty employees
undoubtedly were prevented from receiving this literature
because DHL repeatedly curtailed the distribution. Board
precedent and common sense dictate that the General Counsel
was not required to prove that every single employee who
                                    24
received APWU’s literature was off-duty. 3 Rather, DHL had
the option to demonstrate the contrary and failed to do so.
Under the circumstances, we are satisfied that the General
Counsel proved the unfair labor practice, regardless of
whether some employees who received the distribution were
on the clock.

                                 Conclusion

     Substantial evidence exists on this record to support the
Board’s findings of fact and because we find no errors of law
in the Board’s decision, we deny the petition for review and
grant the Board’s application for enforcement.




3
  While not on precisely this point, the Sixth Circuit’s discussion in United
Parcel Service is instructive: “UPS contends that the NLRB impermissibly
shifted the burden of proof to UPS on this issue, since no UPS supervisor
admitted to seeing the drivers pass around newspapers or other reading
materials. And, several managers testified that they threw away any
reading materials if they happened to see them in the check-in area after
the drivers had left. The ALJ pointed out, though, that there was also no
evidence that UPS ‘posted any warning notices, gave verbal warnings, or
otherwise informed employees that the newspapers and magazines were
being discarded pursuant to the no-distribution rule.’ The ALJ inferred
that the supervisors knew about the sharing of reading materials in the area
since there was evidence that the supervisors routinely mingled with
drivers while such distributions took place. Thus, this is not a matter of
shifting the burden of proof. It is merely a matter of whether the Court
finds the ALJ’s inference to be reasonable.” 228 F.3d at 778 (emphasis
added).
