 United States Court of Appeals
         FOR THE DISTRICT OF COLUMBIA CIRCUIT



Argued February 25, 2019                Decided July 9, 2019

                        No. 18-1150

            TEMPLE UNIVERSITY HOSPITAL, INC.,
                      PETITIONER

                             v.

           NATIONAL LABOR RELATIONS BOARD,
                     RESPONDENT

     TEMPLE ALLIED PROFESSIONALS, PENNSYLVANIA
ASSOCIATION OF STAFF NURSES AND ALLIED PROFESSIONALS,
                     INTERVENOR


                 Consolidated with 18-1164


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


     Shannon D. Farmer argued the cause for petitioner. With
her on the briefs were Meredith Swartz Dante and Katherine J.
Atkinson. Christopher T. Cognato entered an appearance.

    Kellie Isbell, Senior Attorney, National Labor Relations
Board, argued the cause for respondent. With her on the brief
were Peter B. Robb, General Counsel, John W. Kyle, Deputy
                               2
General Counsel, and Julie Brock Broido, Supervisory
Attorney.   David S. Habenstreit, Attorney, entered an
appearance.

    Jonathan Walters argued the cause for intervenor. With
him on the brief was Claiborne S. Newlin.

    Before: HENDERSON and TATEL, Circuit Judges, and
GINSBURG, Senior Circuit Judge.

    Opinion for the Court filed by Senior Circuit Judge
GINSBURG.

     GINSBURG, Senior Circuit Judge: For more than 40 years,
the labor relations of the petitioner, Temple University
Hospital, were conducted under the jurisdiction of the
Pennsylvania Labor Relations Board (PLRB). Since 2006 the
Hospital has been in a collective bargaining relationship with
Temple Allied Professionals, Pennsylvania Association of
Staff Nurses and Allied Professionals (the Union), which
represents a unit of its professional and technical employees.
In 2015 the Union petitioned the National Labor Relations
Board (NLRB) to assert jurisdiction over their relationship.
Over the Hospital’s objections, the NLRB asserted jurisdiction
and certified the Union as the representative of a larger unit of
employees. The Hospital, however, refused to bargain with the
Union in order to contest the NLRB’s jurisdiction and its
certification of the bargaining unit.

     The NLRB rejected the Hospital’s various challenges,
including its argument that the Union was judicially estopped
from bringing a petition before the Board because the Union
had argued in prior proceedings that the NLRB lacked statutory
jurisdiction. Specifically, in denying the Hospital’s request for
review of this question, the NLRB assumed arguendo that the
                                3
doctrine of judicial estoppel applies in NLRB proceedings but,
based upon its understanding of the Supreme Court’s teaching
in New Hampshire v. Maine, 532 U.S. 742 (2001), as applied
to the facts of this case, deemed it inappropriate. We hold that
the NLRB misapplied New Hampshire v. Maine and remand
this case for it to consider whether judicial estoppel is available
in NLRB proceedings and, if so, whether to invoke it.

                         I. Background

    The petitioner is an acute-care hospital located in
Philadelphia, Pennsylvania. In 1910 it was acquired by Temple
University — a private, “State-related university in the higher
education system of the Commonwealth,” Reg’l Dir.’s
Decision and Direction of Election at 3 [hereinafter RD Dec.],
quoting the Temple University-Commonwealth Act, 1965 Pa.
Laws 843, 843 — and became an unincorporated division of
the University. In 1995 the Hospital became a separate
nonprofit corporation, of which the sole shareholder is Temple
University Health System, which was created by the University
to hold its healthcare-related assets. Although the University
and the Hospital are separate corporate entities and separate
employers for the purpose of collective bargaining, there
remain close operational ties between them.

     In 2005 the Union filed a petition with the PLRB seeking
to represent an already-certified bargaining unit of professional
and technical employees at the Hospital (hereinafter technical-
professional unit). In re the Employees of Temple University
Health System, 39 PPER ¶ 49, Case No. PERA-R-05-498-E
(PLRB Apr. 21, 2006). During those proceedings, the
incumbent union, the Professional and Technical Employees
Association, argued the NLRB had jurisdiction over the
Hospital, id., which would preempt the jurisdiction of the state
labor board, see San Diego Building Trades Council v.
                                4
Garmon, 359 U.S. 236, 246 (1959). The Union, of course,
contended the PLRB properly had jurisdiction. The PLRB
concluded it had jurisdiction over the Hospital and held the
previously certified unit was appropriate for collective
bargaining. 39 PPER ¶ 49. The PLRB then conducted an
election; the Union prevailed and has represented the unit ever
since.

     The Union has stipulated that “since 2005, any and all
petitions for representation, requests for certification, petitions
for unit clarification, petitions for amendment [or] clarification
and charges of unfair labor practices have all been filed by [the
Union] with the Pennsylvania Labor Relations Board.” During
that time, the Union filed no fewer than 21 unfair labor practice
charges, including one for which the Union filed its post-
hearing brief as recently as February 2015. See Pennsylvania
Association of Staff Nurses and Allied Professionals v. Temple
University Health System, 48 PPER ¶ 54, Case No. PERA-C-
14-259-E (PLRB Nov. 30, 2016). The Union has further
stipulated that, “in each instance in which a petition or charge
was filed, [the Union] alleged that … Temple University
Hospital … was a public employer within the meaning of
Section 301(1) of PERA,” that is, the orthographically peculiar
Pennsylvania Public Employe Relations Act. As relevant here,
the PERA excludes from the definition of “public employer”
any “employer[] covered or presently subject to coverage under
… the ‘National Labor Relations Act.’” 43 Pa. Stat. Ann.
§ 1101.301(1).

     Nonetheless, in October 2015, when the Union wanted to
add a group of unrepresented employees to the existing
technical-professional unit, it sought the approval of the NLRB
rather than that of the PLRB. The Union had notified the
Hospital of this change, explaining that it anticipated the
Supreme Court’s impending decision in Friedrichs v.
                                 5
California Teachers Ass’n, 136 S. Ct. 1083 (2016), would be
unfavorable to its interests. The Hospital objected; it argued
the NLRB should dismiss the petition on the grounds that (1)
the Union is judicially estopped from invoking the jurisdiction
of the NLRB; (2) the Hospital is a “political subdivision” of
Pennsylvania and therefore is not subject to the jurisdiction of
the NLRB, see 29 U.S.C § 152(2); and (3) due to the close ties
between the Hospital and the University, the NLRB should
exercise its discretion to decline jurisdiction over the Hospital. *
The Hospital further urged the NLRB not to “grant comity” to
the PLRB’s certification of the technical-professional unit, and
instead to determine for itself whether the unit is “appropriate
for the purposes of collective bargaining” under the National
Labor Relations Act (NLRA). See 29 U.S.C. § 159(b).

     An Acting Regional Director of the NLRB conducted a
hearing, after which he rejected all the Hospital’s jurisdictional
challenges and granted comity to the PLRB’s certification of
the bargaining unit; he therefore directed an election among the
petitioned-for employees. The Union won the election and the
Acting Regional Director certified it as the collective-
bargaining representative of the newly expanded technical-
professional unit.

    Upon the Hospital’s request for review of the Acting
Regional Director’s decision, the NLRB agreed to review only
two questions: (1) whether it should exercise its discretion to


*
  Even if an employer comes within the statutory jurisdiction of the
NLRB, the Board may exercise its discretion not to assert
jurisdiction. Amalgamated Ass’n of St., Elec. Ry. & Motor Coach
Emp. of Am., AFL v. NLRB, 238 F.2d 38, 40 (D.C. Cir. 1956) (citing
NLRB v. Denver Bldg. & Const. Trades Council, 341 U.S. 675, 684
(1951)). In 1972 the NLRB had declined to exercise jurisdiction over
the University. Temple University, 194 NLRB 1160, 1161 (1972).
                               6
decline jurisdiction over the Hospital and, if not, then (2)
whether it should extend comity to the PLRB’s certification of
the technical-professional unit; over the dissent of Member
Miscimarra, it denied the request for review as to the other
issues the Hospital had raised, including whether the Union
should be judicially estopped from petitioning the NLRB.
NLRB Order Granting Review in Part and Invitation to File
Briefs at 1. In a footnote explaining its refusal to revisit the
issue of judicial estoppel, the Board said it was “assuming
arguendo that the doctrine of judicial estoppel … applies in
Board proceedings” and then went on to “affirm the Acting
Regional Director’s conclusion” that judicial estoppel was not
appropriate in this case. Id. at 2 n.2. Then, in December 2017,
the Board issued its Decision on Review and Order affirming
the Acting Regional Director’s ruling.

     In order to contest the validity of the certification, the
Hospital refused to bargain with the Union. In response, the
Union filed an unfair labor practice charge with the NLRB,
alleging the Hospital had violated §§ 8(a)(1) and 8(a)(5) of the
NLRA, 29 U.S.C. §§ 158(a)(1) and 158(a)(5). The General
Counsel of the NLRB issued a complaint against the Hospital
and moved for summary judgment, which the NLRB granted
in May 2018. Temple University Hospital, 366 NLRB No. 88
(May 11, 2018). In its Decision and Order, the NLRB did not
address anew the Hospital’s jurisdictional or certification
arguments, stating that “all representation issues raised by the
Respondent were or could have been litigated in the prior
representation proceeding.” Id. The Hospital subsequently
filed a timely petition for review and the NLRB cross-applied
for enforcement of its order.
                               7
                         II. Analysis

     The Hospital raises two issues on appeal: First, whether
the NLRB properly asserted jurisdiction over the Hospital and
second, whether the NLRB properly granted comity to the
PLRB’s certification of the technical-professional unit. We do
not reach the second issue because we conclude the NLRB
erred in arriving at its jurisdictional holding.

     The NLRA exempts “any State or political subdivision
thereof” from the definition of an “employer” within the
jurisdiction of the NLRB. 29 U.S.C § 152(2). In this case, the
Union maintains and the NLRB agrees that the Hospital is not
a “political subdivision” of the Commonwealth of
Pennsylvania, and hence is not exempt from the jurisdiction of
the NLRB. The Hospital contends the Union should have been
judicially estopped from taking that position before the NLRB
because the Union previously “convinc[ed] the PLRB that the
[NLRB] lacked jurisdiction” over the Hospital. That is, the
Union argued to the PLRB during the representation
proceedings in 2005 and 2006 — and implicitly if not explicitly
reiterated in the dozens of cases it has brought before the PLRB
since then — that the NLRB did not have jurisdiction over the
Hospital, and the PLRB agreed; yet, the Union now contends
the NLRB does have jurisdiction.

    The doctrine of judicial estoppel is that “where a party
assumes a certain position in a legal proceeding, and succeeds
in maintaining that position, he may not thereafter, simply
because his interests have changed, assume a contrary position
….” New Hampshire v. Maine, 532 U.S. at 749. The doctrine
“protects the integrity of the judicial process,” Davis v. D.C.,
No. 17-7071, slip op. at 26 (D.C. Cir. June 7, 2019), by
“prohibiting parties from deliberately changing positions
according to the exigencies of the moment,” New Hampshire
                               8
v. Maine, 532 U.S. at 750 (quoting United States v. McCaskey,
9 F.3d 368, 378 (5th Cir. 1993)). The Supreme Court has said
there is no “exhaustive formula for determining the
applicability of judicial estoppel.” Id. at 751. Nevertheless,
the Court has set forth three key factors that “inform the
decision” whether “the balance of equities” favors applying the
doctrine in a particular case: (1) whether the party’s later
position is “clearly inconsistent” with its earlier position; (2)
“whether the party has succeeded in persuading a court to
accept that party’s earlier position, so that judicial acceptance
of an inconsistent position in a later proceeding would create
the perception that either the first or the second court was
misled”; and (3) “whether the party seeking to assert an
inconsistent position would derive an unfair advantage or
impose an unfair detriment on the opposing party if not
estopped.” Id. at 750-51 (cleaned up).

     As a threshold matter, however, one might wonder
whether a doctrine known as “judicial” estoppel has force in
proceedings before the NLRB, which is an administrative
tribunal. Indeed, the Union and the NLRB raise this very
question. Although most circuits have applied judicial estoppel
in cases where the first proceeding was before an agency, see
Spencer v. Annett Holdings, Inc., 757 F.3d 790, 798 (8th Cir.
2014); Mathews v. Denver Newspaper Agency LLP, 649 F.3d
1199, 1210 (10th Cir. 2011); Trustees in Bankr. of N. Am.
Rubber Thread Co. v. United States, 593 F.3d 1346, 1354 (Fed.
Cir. 2010); Valentine-Johnson v. Roche, 386 F.3d 800, 811 (6th
Cir. 2004); Detz v. Greiner Indus., Inc., 346 F.3d 109, 118–19
(3d Cir. 2003); King v. Herbert J. Thomas Mem’l Hosp., 159
F.3d 192, 198 (4th Cir. 1998); Portela-Gonzalez v. Sec’y of the
Navy, 109 F.3d 74, 78 (1st Cir. 1997); Simon v. Safelite Glass
Corp., 128 F.3d 68, 72 (2d Cir. 1997); Rissetto v. Plumbers &
Steamfitters Local 343, 94 F.3d 597, 604 (9th Cir. 1996);
Chaveriat v. Williams Pipe Line Co., 11 F.3d 1420, 1427 (7th
                                9
Cir. 1993), and no circuit has declined to do so, whether a
nonjudicial tribunal may itself invoke judicial estoppel appears
to be an issue of first impression. But cf., e.g., Doe v. Dep’t of
Justice, 123 M.S.P.R. 90, 94–96 (2015) (doctrine applied by
the Merit Systems Protection Board); In re Time Warner Cable,
21 FCC Rcd. 9016, 9020 (2006) (doctrine applied by the
Federal Communications Commission).

     Here, the NLRB held that even “assuming arguendo that
the doctrine of judicial estoppel … applies in Board
proceedings,” the New Hampshire v. Maine factors did not
counsel applying it in this case. NLRB Order Granting Review
in Part and Invitation to File Briefs at 2 n.2. Without
addressing the first factor, the Board adopted the Acting
Regional Director’s conclusion that the second and third
factors were not present, and hence declined to apply the
doctrine. It explained:

         We agree with the Acting Regional Director’s
         findings that processing the petition will not confer an
         unfair advantage on the Petitioner or impose an unfair
         detriment on the Employer; there is no evidence that
         the Petitioner misled the PLRB, and there is an
         inadequate basis to believe the PLRB would have
         reached a different result had the Petitioner taken
         some contrary position before the PLRB.

Id.

     On appeal, “heeding the Supreme Court’s description of
judicial estoppel as ‘an equitable doctrine invoked by a court at
its discretion,’” we review the decision to invoke (or not to
invoke) judicial estoppel for abuse of discretion. Marshall v.
Honeywell Tech. Sys. Inc., 828 F.3d 923, 927 (D.C. Cir. 2016)
(quoting New Hampshire v. Maine, 532 U.S. at 750). At the
                                 10
same time, we must confine our review to the adequacy of the
reasons given by the Board, as “courts may not accept appellate
counsel’s post hoc rationalization for agency action; Chenery
requires that an agency’s discretionary order be upheld, if at
all, on the same basis articulated in the order by the agency
itself.” Erie Brush & Mfg. Corp. v. NLRB, 700 F.3d 17, 23
(D.C. Cir. 2012) (quoting Burlington Truck Lines, Inc. v.
United States, 371 U.S. 156, 168–69 (1962), and citing SEC v.
Chenery, 332 U.S. 194, 196 (1947)); see also DHL Express,
Inc. v. NLRB, 813 F.3d 365, 371 (D.C. Cir. 2016) (“deference
is not warranted where the Board fails to adequately explain its
reasoning”) (cleaned up).

    Notwithstanding the discretionary nature of the NLRB’s
determination whether to invoke judicial estoppel, we must
overturn its decision because, as explained below, the agency
misapplied the teaching of New Hampshire v. Maine. In so
doing, we do not answer the question whether judicial estoppel
applies in NLRB proceedings. The Board merely assumed
arguendo the doctrine applies. Having rejected the Board’s
analysis of the New Hampshire v. Maine factors, we think it
appropriate for the Board to consider in the first instance
whether judicial estoppel is applicable in its proceedings. †


†
 We here clarify a point to guide the agency’s decision on remand:
Subsumed within the Board’s assumption is the argument, advanced
by the Union and by the Acting Regional Director, that the NLRB
“will not bar a party … from invoking rights under the [NLRA] based
on a position the [party] took in a proceeding in which the [NLRB]
was not a party.” Intervenor Br. 12; RD Dec. at 12 (“as the Board
was not a party to the prior proceeding, it is not precluded from
determining jurisdiction”); see also RD Dec. at 8. The relevant
“parties” in the judicial estoppel analysis do not include the forum.
Relatedly, to the extent the NLRB has required identity of the parties
as a prerequisite for judicial estoppel, it appears to have confused
                                11
     Although the NLRB did not expressly say so, we agree
with the Acting Regional Director that the first factor —
whether the Union’s current position is “clearly inconsistent”
with its earlier position — is obviously present here, as the
Board’s counsel on appeal appears to concede. See RD Dec. at
12; Appellee Br. 42. As the Acting Regional Director put it,
“The Hospital is correct that [the Union] argued to the PLRB
that the [NLRB] did not have jurisdiction, that the PLRB
accepted this argument, and that [the Union] currently contends
that the [NLRB] has jurisdiction over the Hospital.” RD Dec.
at 12.

     As for the second factor in New Hampshire v. Maine —
whether the Union “succeeded in persuading” the prior tribunal
— the NLRB was not satisfied because “there is no evidence
that the Petitioner misled the PLRB, and there is an inadequate
basis to believe the PLRB would have reached a different result
had the Petitioner taken some contrary position before the
PLRB.” NLRB Order Granting Review in Part and Invitation
to File Briefs at 2 n.2.         This explanation reflects a
misunderstanding of the second factor. To begin, nothing in
New Hampshire v. Maine suggested the party’s inconsistent
position must be a but-for cause of the first tribunal’s decision.
New Hampshire and Maine had previously litigated the
location of part of the border between them, which had been
“fixed in 1740 by decree of King George II of England” as “the
Middle of the [Piscataqua] River.” 532 U.S. at 746. Because


judicial estoppel with issue preclusion. See, e.g., RD Dec. at 8, 12
(citing In Re Lincoln Ctr. for the Performing Arts, 340 NLRB 1100,
1127 (2003)). Judicial estoppel is “a discrete doctrine” serving a
different purpose than issue preclusion. See New Hampshire v.
Maine, 532 U.S. at 748–49. If one party is taking a position
inconsistent with its position in a prior proceeding, it matters not
whether the adverse party was the same in both proceedings.
                                12
New Hampshire had agreed in the 1970s that the words
“Middle of the River” meant “the middle of the Piscataqua
River’s main channel of navigation,” the Supreme Court
judicially estopped it from asserting in 2001 that “the boundary
runs along the Maine shore.” Id. at 745. Notably, the Court
did not analyze whether or how New Hampshire’s position had
affected its decision in the first proceeding; it was enough that
the Court had adopted the interpretation urged by New
Hampshire. See id. at 752.

      Similarly, there is no independent requirement of evidence
that the party changing its position had actively misled the first
tribunal. In New Hampshire v. Maine the Court said “judicial
acceptance of an inconsistent position in a later proceeding”
may itself be enough to “create the perception that either the
first or the second court was misled.” Id. at 750; see also id. at
755 (“We cannot interpret ‘Middle of the River’ in the 1740
decree to mean two different things along the same boundary
line without undermining the integrity of the judicial process”).
Hence, evidence of deception is not necessary to perfect the
Hospital’s call for judicial estoppel. Of course, that an
inconsistency arose out of “inadvertence or mistake” might be
a valid reason for declining to apply judicial estoppel, see id. at
753, but the NLRB understandably did not rely upon that
possible exception on the facts of this case.

     With regard to the third factor, the Hospital argued it had
incurred an “unfair detriment” as a consequence of the Union
having previously sought the PLRB’s jurisdiction because, had
it been before the NLRB during prior labor disputes, it might
have availed itself of certain legal remedies available under the
NLRA but not under the PERA. The Board adopted the Acting
Regional Director’s conclusion that the unfair detriment
alleged by the Hospital was “not the type of detriment or
advantage about which the Supreme Court was concerned in
                               13
New Hampshire v. Maine.” RD Dec. at 12. Neither the Acting
Regional Director nor the Board gave any explanation of why
the Hospital’s proffer fell short, nor did they specify what
“type” of detriment or advantage would suffice. The NLRB’s
appellate counsel attempts to clarify that there can be no unfair
advantage or detriment because “the Union and Hospital were
on the same side, both arguing that the PLRB had jurisdiction.”
Yet, the same was true in New Hampshire v. Maine; during
their first litigation over their border, New Hampshire and
Maine had agreed upon the meaning of the “Middle of the
River.” See 532 U.S. at 752. We therefore hold the NLRB
failed adequately to explain its determination that there was no
unfair advantage or detriment here. See Radio-Television News
Directors Ass’n v. FCC, 184 F.3d 872, 888 (D.C. Cir. 1999)
(“There is a fine line between agency reasoning that is so
crippled as to be unlawful and action that is potentially lawful
but insufficiently or inappropriately explained. Remand is
generally appropriate when there is at least a serious possibility
that the agency will be able to substantiate its decision given an
opportunity to do so.”) (cleaned up).

     We also reject two other proffered justifications for the
Board’s decision. First, the Union contends that judicial
estoppel applies only to assertions “of fact rather than law or
legal theory.” Intervenor Br. 11 (quoting Lowery v. Stovall, 92
F.3d 219, 224 (4th Cir. 1996)). Second, the Union and the
Board argue that “there is an exception to … judicial estoppel
when it comes to jurisdictional facts or positions.” Intervenor
Br. 11 (quoting Whiting v. Krassner, 391 F.3d 540, 544 (3d Cir.
2004)); see Appellee Br. 40 (citing Hansen v. Harper
Excavating, Inc., 641 F.3d 1216, 1227–28 (10th Cir. 2011)).
Because the Board did not rest its decision on either
proposition, however, we cannot sustain its decision on either
basis. Moreover, we seriously doubt the correctness of the
former, as New Hampshire v. Maine itself concerned New
                               14
Hampshire’s change in position on a legal issue, viz., the proper
interpretation of the words “Middle of the River” in the 1740
decree of King George II. 532 U.S. at 746.

     Having found the NLRB’s analysis of the New Hampshire
v. Maine factors invalid, nothing remains of its reasons for
refusing to apply judicial estoppel. We therefore remand the
case for the Board to determine in the first instance whether
judicial estoppel is available in NLRB proceedings. If the
Board determines that judicial estoppel is available in
appropriate circumstances, then under New Hampshire v.
Maine it will next have to determine — and adequately explain
— whether the Hospital has made a sufficient showing of
unfair advantage or unfair detriment and whether the ultimate
“balance of equities” favors its application on the facts of this
case.

                        III. Conclusion

    For the foregoing reasons, we grant the Hospital’s petition
for review, deny the Board’s cross-application for
enforcement, and remand the case to the Board for proceedings
consistent with this opinion.

                                                   So ordered.
