 United States Court of Appeals
        FOR THE DISTRICT OF COLUMBIA CIRCUIT



Argued November 15, 2016         Decided January 24, 2017

                       No. 15-1204

    800 RIVER ROAD OPERATING COMPANY, LLC, D/B/A
           WOODCREST HEALTH CARE CENTER,
                     PETITIONER

                            v.

          NATIONAL LABOR RELATIONS BOARD,
                    RESPONDENT

     1199 SEIU UNITED HEALTHCARE WORKERS EAST,
                     INTERVENOR


                Consolidated with 15-1281


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


    Brian J. Gershengorn argued the cause for Petitioner.
With him on the briefs were Harold P. Coxson and Seth D.
Kaufman.

    Marni von Wilpert, Attorney, National Labor Relations
Board, argued the cause for Respondent. With her on the
                             2
brief were Kira Dellinger Vol, Supervisory Attorney, Richard
Griffin, Jr., General Counsel, John H. Ferguson, Associate
General Counsel, and Linda Dreeben, Deputy Associate
General Counsel.

    Katherine H. Hansen argued the cause for Intervenor in
support of Respondent. With her on the brief was William S.
Massey.

    Before: ROGERS, BROWN, and MILLETT, Circuit Judges.

    Opinion for the Court filed by BROWN, Circuit Judge.

    BROWN, Circuit Judge: On March 9, 2012, a unit of
employees at 800 River Road Operating Company d/b/a
Woodcrest Healthcare Center (“Woodcrest”) elected 1199
SEIU United Healthcare Workers East Union (“the Union”)
as its exclusive collective-bargaining representative.
Woodcrest filed objections to the election with the National
Labor Relations Board (“the NLRB” or “the Board”). It now
challenges certain conduct that occurred during the ensuing
representation hearing.

     Woodcrest asserts three reasons to conclude the Hearing
Officer abused his discretion in the underlying proceeding,
and it also argues the Board abused its discretion when it
affirmed the Hearing Officer’s recommendations to overrule
Woodcrest’s objections. It now asks this Court to set aside
the Board’s order requiring it to bargain with the Union, see
800 River Road Operating Co., 362 N.L.R.B. No. 114 (2015),
and to remand for a new election. The Board and the Union
as Intervenor seek enforcement of the Board’s order.

    We deny Woodcrest’s petition and grant the Board’s
cross-application for enforcement.
                               3
                               I.

     Woodcrest argues the Hearing Officer abused his
discretion in three respects. Because Woodcrest seeks to set
aside the Board’s affirmation of the Hearing Officer’s
recommendations, assessing these challenges requires detailed
consideration of the underlying facts and procedural history.

                               A.

     On January 23, 2012, the Union filed a petition to
represent a unit of employees at Woodcrest, a skilled nursing
facility in Milford, New Jersey. The election took place on
March 9, 2012, resulting in a 122–81 vote in favor of
representation. Two additional ballots were challenged.

     Woodcrest filed twelve timely objections to the conduct
of the election, see 29 C.F.R. § 102.69(a), alleging various
forms of unlawful conduct had occurred prior to the election.
See 29 U.S.C. § 158(a)(1) (making it unlawful “for an
employer . . . to interfere with, restrain, or coerce employees”
during a representation election).           Pursuant to Board
regulations, Woodcrest attached a “written offer of proof” to
its objections that “identif[ied] each witness [it] would call to
testify concerning the issue and summarizing each witness’s
testimony.” 29 C.F.R. § 102.66(c); id. § 102.69(a). Only the
Regional Director reviewed the content of this offer of proof.
See id. § 102.69(a) (“The party filing the objections shall
serve a copy of the objections, including the short statement
of reasons therefor, but not the written offer of proof, on each
of the other parties to the case . . . .” (emphasis added)); id.
(“The regional director will transmit a copy of the objections
to each of the other parties to the proceeding, but shall not
transmit the offer of proof.” (emphasis added)).
                                 4
     Based on this offer of proof, the Regional Director
determined Objections One and Two should proceed to a
hearing before an NLRB Hearing Officer; the remaining ten
objections were dismissed. See id. § 102.69(c)(1)(ii) (noting
the Regional Director will set objections for hearings if he
“determines that the evidence described in the accompanying
offer of proof could be grounds for setting aside the election if
introduced at a hearing . . . .” (emphasis added)). Both of the
surviving objections pertained to behavior of certain
Woodcrest supervisors during the “critical period”—i.e., the
period of time between the petition for representation and the
election. Objection One alleged three Woodcrest supervisors
(Janet Lewis, Bonita Thornton, and Jane Cordero) “created a
coercive atmosphere and/or interfered with employee free
choice by soliciting Union authorization cards and/or creating
the impression that they had solicited or were soliciting [such]
cards.” Pet’r Br. 8. Objection Two claimed three Woodcrest
supervisors (Israel Vergel de Dios, Cordero, and Thornton)
“created a coercive atmosphere and/or interfered with
employee free choice by promoting the Union and/or creating
the impression that they favored the Union, conveying to
voters that they should support the Union.” Pet’r Br. 9. See
Harborside Healthcare, Inc., 343 N.L.R.B. 906, 909 (2004)
(setting forth the NLRB’s two-prong test for assessing
coercive supervisory conduct during an election).

     The hearing took place over the course of three days—
Thursday May 10, Friday May 11, and Monday May 14. On
the morning of the first day, Woodcrest called four witnesses.
First, it solicited testimony from Loesha Chase, who had
previously worked as a companion to two of Woodcrest’s
residents through a third-party company. 1         Woodcrest

1
 Chase stopped working for Woodcrest in 2004, but she still visited
Woodcrest regularly in her capacity as a companion to its residents.
                              5
believed Chase “possessed knowledge of its supervisors’
coercive and objectionable conduct and other information
related to the union organizing campaign.” Pet’r Br. 10.
Instead, Chase said she had no knowledge of what occurred at
Union meetings, no knowledge regarding the solicitation of
Union cards, and no knowledge about which supervisors (if
any) were involved in the organizing drive.           Second,
Woodcrest called Vergel de Dios, one of the supervisors it
believed had committed objectionable conduct by
“surreptitiously threatening employees with consequences if
they did not support the Union or sign an authorization card.”
Pet’r Br. 10.       He denied engaging in this conduct.
Additionally, Vergel de Dios denied exerting influence over
how his employees would testify if subpoenaed about his pre-
election conduct. Instead, he explained he knew his staff
would testify “truthfully”—i.e., that he never had “an
influence with them to vote yes.” J.A. 197–98. Throughout
his testimony, Woodcrest also repeatedly sought permission
to treat Vergel de Dios as a hostile witness, permission the
Hearing Officer did not grant.

     Third, Woodcrest called Lewis, another supervisor whom
it believed had committed objectionable conduct by soliciting
Union cards and influencing employees to join the Union.
Lewis said she had not encouraged employees to research the
Union and had no knowledge of objectionable conduct
committed by Thornton. She also denied being approached
by employees as a source of Union authorization cards and
asked Woodcrest’s attorney, “What’s a [U]nion card?” J.A.
225.

    Lastly, Woodcrest called Lorri Senk, the administrator
responsible for operational and human resources functions.
Senk testified Susan Langdon—an evening supervisor of
Woodcrest’s registered nurses—had told her about Jane
                                6
Cordero’s involvement in organizing the Union. Langdon
informed Senk that Langdon had overheard Cordero speaking
to an unnamed licensed practical nurse about “getting
employees to attend [a] [U]nion meeting.” J.A. 229–30.
Langdon believed Cordero withheld information about Union
representatives making home visits and phone calls to
Woodcrest employees. Additionally, Senk testified Maria
Sanchez, a Woodcrest employee, “had stated on several
occasions” that various supervisors—including Cordero and
Lewis—were involved in the Union organizing campaign.
J.A. 239. Finally, Senk stated she found a list of “[U]nion
insiders” slipped under her door that included Dave Repoli—
Woodcrest’s former administrator, Clarice Gogia—
Woodcrest’s former Director of Nursing, and Jane Cordero.
J.A. 234.

     On the morning of the hearing’s second day, Woodcrest
presented three additional witnesses.          First, it called
Cordero—the supervisor about whom Senk had testified.
Cordero denied participating in any untoward Union
authorization card distributions. She also denied engaging in
any conversations about getting employees to attend Union
meetings, which contradicted Senk’s testimony. Second,
Woodcrest called Clarice Gogia—one of the employees
included on the list of “Union insiders” Senk said she had
received. Gogia testified her last day of employment at
Woodcrest was June 15, 2011—six months before the Union
filed its petition for representation. 2 She denied having any
knowledge of any supervisors engaging in objectionable
conduct.       Finally, Woodcrest called Katherine Frost,
Woodcrest’s former Director of Admissions and Marketing.
Frost ceased working at Woodcrest in July 2011—

2
  In his report, the Hearing Officer stated Gogia ceased employment
in June, 2012.
                              7
approximately six months before the filing of the
representation petition—and testified she entered Woodcrest
only once per month during the three-month critical period.
Nevertheless, Woodcrest believed she was “actively involved
in assisting the Union’s organizing efforts.” Pet’r Br. 10.
Like the others, she denied giving such assistance, instead
testifying she made no observations about a Union drive
during her visits, and she “wouldn’t know any [U]nion
contacts.” J.A. 291; see also J.A. 293 (noting she learned of
the election only after it occurred). She also stated she knew
of no objectionable supervisory conduct.

    At this point, a midday recess was taken. During the
recess, the parties discussed three separate groups of
witnesses, each of which is crucial to this case.

     First, Woodcrest met ex parte to request the Hearing
Officer issue subpoenas to six of Vergel de Dios’s
approximately twenty-four subordinates regarding his pre-
election conduct. See 29 C.F.R. § 102.66(f) (permitting ex
parte requests). NLRB regulations mandate issuance of such
subpoenas, id., but, instead, the Hearing Officer invited the
Union’s attorney to participate in both an off-the-record and
an on-the-record conversation about the potential witnesses.

    Woodcrest explained its need for the subpoenas based on
the allegedly conflicting testimony of Vergel de Dios and
Senk. Whereas Vergel de Dios had testified he did not tell his
subordinates what to say if asked about his pre-election
conduct, Senk testified Vergel de Dios had stated at a meeting
of department heads “he didn’t have anything to worry about
because he had spoken with his people and he knew what they
would say, and they would have his back.” J.A. 301.
Woodcrest interpreted Senk’s testimony as demonstrating
                              8
Vergel de Dios had sought to influence any future testimony
given by his employees.

     Woodcrest had not previously interviewed any of the six
witnesses because they had all exercised their Johnnie’s
Poultry rights not to speak to Woodcrest before the hearing.
See 146 N.L.R.B. 770, 775 (1964) (holding that, when
interrogating an employee before a hearing, an employer
“must communicate to the employee the purpose of the
questioning, assure him that no reprisal will take place, and
obtain his participation on a voluntary basis . . . ”).
Nevertheless, Woodcrest argued it had a “reasonable belief”
the six employees would have “factually based firsthand
knowledge” of Vergel de Dios’s pre-election conduct because
they were “members of his department.” J.A. 304. Their
testimony would help Woodcrest establish Vergel de Dios’s
lack of candor regarding whether he attempted to exert
influence over his subordinates’ potential testimony. Further,
Woodcrest stated that, based on Vergel de Dios’s purportedly
dishonest testimony, “[a] conclusion could be drawn about
how that group of employees even voted.” J.A. 301.

    Next, the parties discussed subpoenas that had already
been issued to eight Woodcrest employees. Woodcrest
contended these individuals “were actively engaged in the
[Union] campaign [and were] the most likely people to know
whether the supervisors engaged in pro-union conduct.” J.A.
309. All eight employees also had exercised their Johnnie’s
Poultry rights, meaning Woodcrest could not attest to the
content of their testimony. Despite this fact, Woodcrest
represented it would ask “specific, direct questions as to what
knowledge they have, if any, as to were supervisors engaging
in pro-union conduct [sic].” J.A. 308. Throughout the
discussion, the Hearing Officer seemed to presume the
                              9
witnesses definitively had no firsthand knowledge, as
exemplified by the following exchanges:

       HEARING OFFICER: Okay. My inclination
       is that there is nothing that [the subpoenaed
       witness] is going to tell us that is going to—
       there’s no direct knowledge of, there’s no facts
       that she has that—

       MR. MENDELSON: Well, how would any of
       us know it. She hasn’t been vetted.

       HEARING         OFFICER      POMIANOWSKI:
       Right. . . .

J.A. 309. And again:

       HEARING OFFICER: What I’m saying is . . .
       [the witness] does not have any factually
       based, direct knowledge about the objections,
       themselves.

       MR. MENDELSON: I can’t agree with that
       statement.

J.A. 320.

    Lastly, the parties discussed five witnesses with whom
Woodcrest had previously spoken. Consequently, Woodcrest
could affirmatively assert these individuals possessed
knowledge of, among other things, supervisory solicitation of
Union cards and support of the Union.

     After the recess concluded, Woodcrest put three more
witnesses on the stand. First, Cartney Ezyk testified. During
the recess, Woodcrest represented to the Hearing Officer that
                              10
Ezyk would testify he was told employees who wanted Union
authorization cards should speak to Lewis, and Ezyk’s
testimony backed up this representation. Second, Woodcrest
called Remi Sajimi, a licensed practical nurse at Woodcrest.
Sajimi had also exercised Johnnie’s Poultry rights, but, during
the recess, Woodcrest represented to the Hearing Officer
Sajimi would testify “Jane Cordero told her . . . that [she]
would make sure certain employees made it to a [U]nion
meeting.” J.A. 308. On the stand, Sajimi denied this.
Finally, Woodcrest called Thornton—the last of the
supervisors whom it believed had engaged in objectionable
conduct. She, like the others, denied any wrongdoing. 3

     At the conclusion of the afternoon testimony, the Hearing
Officer denied the requests for the six subpoenas of Vergel de
Dios’s subordinates. He explained the subpoenas were
“exploratory” and emphasized Woodcrest’s inability to make
an offer of proof that the witnesses had “specific knowledge,
firsthand knowledge, factually based on the objections.” J.A.
344–45. For the same reasons, he also explained he would
not permit the eight, already-subpoenaed witnesses to testify.
However, he stated the five “vetted” witnesses with direct
knowledge could testify on Monday.

     When Monday morning arrived, however, Woodcrest
refused to continue participating in the Hearing. After
informing the Hearing Officer his Friday-afternoon rulings
had “irrevocably and hopelessly compromised [its] ability to
make [its case],” J.A. 363, it voluntarily left the proceedings.




3
  Woodcrest had planned on calling a fourth witness—Ms.
Beziole—but the Hearing Officer would not hear her testimony.
                                 11
                                 B.

     On June 4, 2012, the Hearing Officer recommended
overruling both of Woodcrest’s election objections. The
report faulted Woodcrest for not presenting witnesses with
“first-hand factual knowledge” of the objections, despite its
“prior representation to the Regional Director.” J.A. 23. It
also noted Woodcrest’s refusal to continue participating in the
Hearing. The Hearing Officer concluded Woodcrest was
“using the hearing to investigate” conduct rather than present
a case. J.A. 24. The report did not mention either the denial
of the six requested subpoenas or the refusal to hear the
testimony from the eight subpoenaed witnesses.

     On January 9, 2013, the Board affirmed the Hearing
Officer’s report, concluding that, under the circumstances,
“the hearing officer acted reasonably to halt the employer’s
manifest fishing expedition.” J.A. 70. Though the Board
acknowledged the Hearing Officer committed error by not
issuing the six subpoenas, the error was not prejudicial. See
J.A. 70 (noting “it is reasonable to conclude that even had the
hearing officer issued the requested subpoenas, he would have
refused to permit the witnesses to testify or, if presented with
a petition, would have revoked those subpoenas”). The Board
certified the Union as the exclusive collective-bargaining
representative for the relevant Woodcrest employees on
November 26, 2014. 4

    The National Labor Relations Act (“the Act”) does not
permit this Court to directly review the Board’s certification
decision.   See 29 U.S.C. § 159(d); see also Boire v.

4
  The Board issued its first certification decision on July 10, 2013,
see 800 River Road Operating Co., 359 N.L.R.B. No. 129 (2013),
but that order was set aside after the Supreme Court’s decision in
NLRB v. Noel Canning, 134 S. Ct. 2550 (2014).
                              12
Greyhound Corp., 376 U.S. 473, 476–80 (1964). To obtain
review, an employer must refuse, as Woodcrest did here, to
bargain with the Union. Consequently, on February 7, 2013,
the Union filed unfair labor practice claims under 29 U.S.C.
§ 158(a)(1) and (5). The NLRB’s General Counsel (“GC”)
issued a complaint against Woodcrest on February 19, 2013,
and the Board granted summary judgment in favor of the GC
on June 15, 2015. See 800 River Road Operating Co., 362
N.L.R.B. No. 114 (2015). The unfair labor practice order
gives this Court jurisdiction under 29 U.S.C. § 160(e) and (f).

     Woodcrest now asks this Court to set aside the Board’s
June 15 order and to remand with instructions for a new
election rather than a new hearing. It alleges the Hearing
Officer abused his discretion and caused prejudicial error
when he failed to (1) issue the requested subpoenas for six of
Vergel de Dios’s employees; (2) permit eight subpoenaed
witnesses to testify at the Hearing; and (3) grant Woodcrest’s
request to treat Vergel de Dios as a hostile witness.
Woodcrest also contends the Board abused its discretion when
it “inexplicably affirmed [the Hearing Officer] with little
analysis” and overruled Woodcrest’s objections. Pet’r Br. 21,
30. The Board seeks enforcement of its June 15 order, which
compels Woodcrest to provide the Union with certain
requested information, as well as to bargain with the Union.
The Union intervened in support of the Board.

                              II.

                              A.

     This Court has noted that, “[o]n questions regarding
representation, we accord the Board an especially wide degree
of discretion.” Randell Warehouse of Ariz., Inc. v. NLRB, 252
F.3d 445, 447–48 (D.C. Cir. 2001). We “will overturn a
Board decision to certify an election in only the rarest of
                              13
circumstances.” N. of Market Senior Servs., Inc. v. NLRB,
204 F.3d 1163, 1167 (D.C. Cir. 2000); see also id. (“A party
seeking to overturn an election bears a heavy burden of
showing that the election is invalid.” (emphasis added));
Randell Warehouse, 252 F.3d at 448 (“[T]he scope of our
review of the Board’s decisions in cases involving
certification is extremely limited.”).

     Notwithstanding this extraordinary deference, the
Board’s discretion “has limits.” Int’l Transp. Serv. Inc. v.
NLRB, 449 F.3d 160, 163 (D.C. Cir. 2006). The Court is “not
merely the Board’s enforcement arm,” Randell Warehouse,
252 F.3d at 448, and will not simply “rubberstamp” Board
decisions. Int’l Transp. Serv., 449 F.3d at 163. Instead, we
have the “responsibility to examine carefully both the Board’s
findings and its reasoning . . . .” Randell Warehouse, 252
F.3d at 448. Additionally, this Court sets aside Board orders
that have “no reasonable basis in law, either because the
proper legal standard was not applied or because the Board
applied the correct standard but failed to give the plain
language of the standard its ordinary meaning.” NLRB v.
McClatchy Newspapers, Inc., 964 F.2d 1153, 1156 (D.C. Cir.
1992).

                              B.

     We will “affirm the Board’s order to bargain unless the
Board abused its discretion in overruling [an employer’s]
objections,” Randell Warehouse, 252 F.3d at 448, and the
abuse of discretion was prejudicial, see Ozark Auto. Distribs.,
Inc. v. NLRB, 779 F.3d 576, 582 (D.C. Cir. 2015) (noting the
harmless-error rule exists “[i]n administrative law, as in
federal civil and criminal litigation”). An error is harmless
unless it “affected the outcome of the [underlying]
proceedings.” United States v. Coumaris, 399 F.3d 343, 347
                               14
(D.C. Cir. 2005); see also Salem Hosp. Corp. v. NLRB, 808
F.3d 59, 68 (D.C. Cir. 2015) (noting no prejudice occurs
where “excluded evidence would not compel or persuade to a
contrary result”). Whether an error is prejudicial “depends on
a number of factors, including the closeness of the case, the
centrality of the issue in question, and the effectiveness of any
steps taken to mitigate the effects of the error.” Huthnance v.
District of Columbia, 722 F.3d 371, 381 (D.C. Cir. 2013).

                              III.

    Woodcrest faults the Hearing Officer for failing to
provide a full and fair hearing of its objections.

                               A.

     First, Woodcrest claims the denial of its request to
subpoena six of Vergel de Dios’s subordinates destroyed a
“central” aspect of its case because the employees “would
have” provided testimony concerning Vergel de Dios’s
“objectionable and coercive conduct.” Pet’r Br. 23. Since
NLRB regulations mandate the issuance of such subpoenas,
29 C.F.R. § 102.66(f), the denial undisputedly constituted
error—a fact the NLRB recognized when it adopted the
Hearing Officer’s recommendations.       Thus, to prevail,
Woodcrest need only demonstrate the error was not harmless.
See Salem Hosp., 808 F.3d at 68 (noting no prejudice occurs
where “excluded evidence would not compel or persuade to a
contrary result”).

     Unfortunately for Woodcrest, it cannot make this
showing here. The company’s failure to meet this burden has
less to do with the Hearing Officer’s rulings than its lawyer’s
litigation choices.
                              15
     Most notably, Woodcrest walked out of the hearing on
Monday morning. This voluntary choice means we cannot
separate the harm Woodcrest suffered (if any) as a result of
the Hearing Officer’s denial from the prejudice caused by
Woodcrest’s decision to truncate the hearing. For instance,
according to Woodcrest, the subpoena denials prevented six
of Vergel de Dios’s employees from providing testimony
establishing Vergel de Dios’s improper influence over his
subordinates. Yet, Woodcrest’s choice not to present its five
remaining witnesses also prevented the Hearing Officer from
hearing from an employee who allegedly would have testified
Vergel de Dios told him to “vote what your heart tells you, as
well as vote what is best for you.” J.A. 316–17. If this
witness testified consistently, he would have directly undercut
Vergel de Dios’s denial. See J.A. 206–07. Perhaps
Woodcrest was prejudiced by the Hearing Officer’s decision
to deny the subpoenas. See Ozark, 779 F.3d at 585 (noting
the Court’s willingness to “assum[e] that the documents, if
disclosed, would have supported the company’s claim” when
assessing the prejudicial effect of a hearing officer’s decision
to quash subpoenas). But perhaps Woodcrest’s own decision
to short-circuit the hearing and forgo the evidence it might
have provided had a greater impact. Woodcrest cannot
simply create (or contribute to the creation of) prejudice and
then plead reversible error. It must demonstrate the NLRB’s
error was dispositive. See Salem Hosp., 808 F.3d at 68.

     Additionally, Woodcrest has not actually shown the
denials “excluded critical evidence.” Pet’r Br. 21. In its
brief, Woodcrest claims the six employees were “central” to
its case because they “would have testified as to Vergel de
Dios’ objectionable and coercive conduct.” Pet’r Br. 23
(emphasis added). Woodcrest also argues the centrality of the
testimony would have prevented the Hearing Officer from
revoking the subpoenas once given.          See 29 C.F.R.
                              16
§ 102.66(f) (permitting revocations “if, in [the hearing
officer’s] opinion, the evidence whose production is required
does not relate to any matter under investigation or in
question in the proceedings”). But Woodcrest does not back
up these claims with any concrete evidence. When arguing
before the Hearing Officer and this Court, all Woodcrest
offered to support its “reasonable belief” that these witnesses
had relevant knowledge was the fact that they were “members
of [Vergel de Dios’s] department.” See, e.g., J.A. 304; Oral
Arg. Tr. 10–11. It could not specify why these six, as
compared to the other approximately eighteen employees
supervised by Vergel de Dios, had relevant knowledge. Oral
Arg. Tr. 42–43. And, when pressed at oral argument to
justify the need for the testimony, Woodcrest’s counsel
admitted it did not “know[] at the end of the day” what they
would say. Oral Arg. Tr. 10.

     By contrast, it appears Woodcrest voluntarily chose not
to call witnesses whom it had expressly identified as having
knowledge about Vergel de Dios’s behavior.                When
Woodcrest first filed its objections, it submitted to the
Regional Director a list of witnesses it planned to call, along
with a description of what they would say in their testimony.
See 29 C.F.R. § 102.69(a). According to Board case law, this
offer of proof needed to “specifically identify[] witnesses who
would provide direct rather than hearsay testimony to support
its objections, specifying which witnesses would address
which objections.” Transcare N.Y., Inc., 355 N.L.R.B. 326,
326 (2010); see also City Wide Insulation of Madison, Inc.,
338 N.L.R.B. 793, 795 (2003) (noting the objecting party
must send this evidence to the Regional Office). This offer of
proof served as the basis for the Regional Director’s decision
to set the two objections for a hearing. See 29 C.F.R.
§ 102.69(c)(1)(ii) (noting the Regional Director will set
objections for hearings if he “determines that the evidence
                               17
described in the accompanying offer of proof could be
grounds for setting aside the election if introduced at a
hearing . . . .” (emphasis added)). In his report recommending
Woodcrest’s first two objections proceed to a hearing, the
Regional Director explicitly stated Woodcrest’s offer of proof
“provided the names of several supervisory and bargaining
unit employees whom it contends will testify that
Environmental Director Israel Vergel de Dios . . . actively
supported the Union.” J.A. 6. In support, Woodcrest
“assert[ed] that the witnesses will testify that Vergel de Dios
expressed his opinion to unit employees that they were
underpaid and unappreciated and, thus, needed the protection
of the Union.” Ibid. Yet, at oral argument, Woodcrest’s
counsel stated neither the six subpoenaed employees nor the
five employees it refused to call on Monday were on the list
submitted to the Regional Director. Oral Arg. Recording
49:20; Oral Arg. Tr. 49. Assuming Woodcrest provided
truthful submissions to the Regional Director, it cannot now
demonstrate to this Court that the Hearing Officer’s refusal to
issue the subpoenas served as the source of prejudice, as
compared to Woodcrest’s own decision not to call the
employees it asserted had already provided it with direct
knowledge of Vergel de Dios’s coercive conduct.

     All told, Woodcrest’s voluntary decision to leave the
Hearing, its failure to demonstrate the centrality of the
witnesses to its case, and the potential for the Hearing Officer
to exercise permissible discretion to revoke the subpoenas
means Woodcrest cannot prove the denial of the six
subpoenas “irreparably prejudiced” its case. Pet’r Br. 38. It
thus has not demonstrated reversible error occurred.

    In addition to its prejudice arguments, Woodcrest points
to our decision in ManorCare, LLC v. NLRB, 823 F.3d 81, 87
(D.C. Cir. 2016), and urges us to find, as we did there, that the
                              18
Board abused its discretion because its analysis was too
“cursor[y]” or “truncated.” But that decision has no bearing
on the instant case. In ManorCare, the employer presented
direct testimony from multiple employees that two other
employees had threatened to “punch[] people in the face,”
“beat[] people up,” and “slash [people’s] tires,” among other
things. Id. at 83–84. This testimony was also corroborated by
“several other managers and supervisors.” Id. at 84. The
Hearing Officer found these threats disturbed the laboratory
conditions necessary for a fair and free election, id., but the
Board reversed, finding the threatening statements were
jocular in nature, id. at 85. In doing so, the Board disregarded
its own precedent, which laid out six factors for assessing a
threat’s seriousness and its likelihood of causing voter
intimidation. Id. at 85–87. Instead, “the Board cursorily
acknowledged its own precedent and then dismissed the effect
of the threatening statements.” Id. at 87. Within that context,
we found the Board’s discussion “too brief to demonstrate
how the facts of [that] case align[ed] with the Board’s
precedent.” Id.

     Here, by contrast, we contextualize the Board’s
discussion within a hearing where ten witnesses provided
virtually no testimony of objectionable conduct, a fact which
the Hearing Officer discussed at length in his report. See J.A.
25–30 (summarizing each of the ten witness’s testimony and
highlighting how each failed to corroborate Woodcrest’s
representations); see also J.A. 70 (Board adoption of Hearing
Officer’s recommendations) (referencing this same lack of
corroboration to support its conclusion that Woodcrest was
not prejudiced by the denial of the subpoenas). Further, we
place it within a hearing where the employer chose to
voluntarily walk out rather than proffer any additional
evidence to strengthen its case—another fact acknowledged
by the Hearing Officer. See J.A. 23. Within this framework,
                                19
we cannot find the NLRB abused its discretion when it
affirmed the Hearing Officer’s recommendations, concluded
Woodcrest was engaging in a “fishing expedition,” J.A. 70,
and dismissed the error as harmless. See Huthnance, 722
F.3d at 381 (noting courts consider “the closeness of the case”
when assessing the prejudicial effect of an error).

                                B.

     Woodcrest next contends the Hearing Officer abused his
discretion when he refused to permit eight, already-
subpoenaed witnesses to testify. Woodcrest argues the
Hearing Officer imposed a “novel requirement” by insisting
Woodcrest confine its case only to witnesses it had previously
“vetted.” Pet’r Br. 47. According to Woodcrest, this
imposition is especially inappropriate in the context of such
investigation hearings, which provide no pre-hearing
discovery mechanisms and which afford subpoenaed
witnesses the right not to speak to the employer beforehand.
Johnnie’s Poultry Co., 146 N.L.R.B. at 775. Since all eight
witnesses had exercised these rights, Woodcrest asserts the
“vetting” requirement placed it in an impossible position. 5

    As a general matter, Woodcrest identifies a valid
potential concern. The Hearing Officer did repeatedly inform
Woodcrest he wanted to hear from witnesses with “firsthand”
or “direct” knowledge. See, e.g., J.A. 304, 309, 320. Under
NLRB regulations, the employer has the burden of
demonstrating objectionable conduct.              Harborside
Healthcare, 343 N.L.R.B. at 910 (noting the objecting party

5
  Just how impossible is difficult to assess. Woodcrest represented
to the Board that it interviewed “between 100 and 150 employees”
over four days. J.A. 76. But the record does not reveal how many
of these employees spoke at length to Woodcrest, as opposed to
summarily exercising their Johnnie’s Poultry rights.
                             20
has the burden “to establish, not just that objectionable acts
occurred, but also that they interfered with the employees’
exercise of free choice to such an extent that they materially
affected the results of the election”); Amalgamated Clothing
Workers of Am. v. NLRB, 424 F.2d 818, 827 (D.C. Cir. 1970)
(noting a party “must produce specific evidence” of
inappropriate conduct). And, it must meet this burden,
notwithstanding the lack of discovery mechanisms, the
existence of Johnnie’s Poultry rights, and the bar against
using a representation hearing as a “fishing expedition.”
Cauthorne Trucking, 256 N.L.R.B. 720, 720 (1981).
Furthermore, particularly in cases like the instant one—where
the supervisors cause the allegedly objectionable conduct—
the employer may find it difficult to find either a supervisor
eager to confess or an employee willing to implicate a
supervisor. In that case, limiting witnesses solely to those
with “direct knowledge” may constitute an abuse of discretion
that hamstrings the employer, leaving no feasible means for it
to meet the evidentiary burden.

     But that is not the case here. After two days of
testimony, and in the absence of any proffer outlining the
anticipated testimony’s relevance, the Hearing Officer did not
abuse his discretion by refusing to hear eight additional
witnesses.

     Given the specific and direct testimony prefigured by
Woodcrest’s submissions to the Regional Director, the initial
focus on general witnesses is puzzling. Despite its offer of
proof, nine out of Woodcrest’s ten witnesses provided no
direct testimony of objectionable conduct and, in fact,
provided testimony that directly contradicted Woodcrest’s
                              21
representations. 6 Though the Hearing Officer never saw the
offer of proof, he knew of its existence and what it must
contain. See J.A. 23 (noting, in his report, Woodcrest did not
provide “any testimony of first-hand factual knowledge of
facts surrounding the alleged objectionable conduct[,] . . .
notwithstanding counsel’s prior representation to the Regional
Director that it would present direct factual testimony from
witnesses to demonstrate that Petitioner engaged in the
alleged objectionable conduct”). After two days, it was
reasonable for the Hearing Officer to conclude he needed a
more substantial proffer to justify allowing the parade of
witnesses to continue.

     Furthermore, though the Hearing Officer used words like
“direct” and “firsthand,” J.A. 309, 320, the record read as a
whole reveals the Hearing Officer’s willingness to allow
witnesses to testify, so long as Woodcrest could provide any
basis—even circumstantial evidence—for that testimony. Or,
to put it another way, we read the Hearing Officer not as
asking Woodcrest to tell him what the witnesses would say,
but to tell him how it knew what the witnesses likely would
say.

     The Hearing Officer’s differing treatment of two of
Woodcrest’s potential witnesses—Remi Sajimi and Ms.
Beziole—illustrates this point. Sajimi had exercised her
Johnnie’s Poultry rights, and Woodcrest accordingly could
not vet her. Woodcrest represented to the Hearing Officer
that an employee with “direct knowledge” had told Woodcrest
she had “overheard . . . Cordero telling Remi that [Cordero]
would make sure certain employees attended a [U]nion
meeting.” J.A. 307. Despite this extremely attenuated,
6
 The tenth witness provided hearsay testimony about Langdon—a
Woodcrest supervisor—and Sanchez—a Woodcrest employee;
Woodcrest did not follow up by calling either party to testify.
                             22
hearsay evidence, the Hearing Officer stated Sajimi had
“direct knowledge,” J.A. 308, and she was permitted to
testify. In contrast, the Hearing Officer did not permit the
testimony of Ms. Beziole. Unlike Sajimi, Woodcrest believed
Ms. Beziole had relevant knowledge only because she was a
“[U]nion supporter.” J.A. 309. Woodcrest used this same
“Union supporter” assertion to justify its need for the eight
subpoenas. The Hearing Officer refused to hear from all nine
witnesses on the same grounds: Woodcrest could not make
any proffer to back up its representations about what the
employees would say once called. The decision to deny the
eight subpoenas also came after Remi Sajimi testified, where
she contradicted Woodcrest’s representation and instead
corroborated Cordero’s version of events.

     Under these circumstances, we cannot say the Hearing
Officer abused his discretion by requiring Woodcrest to
provide even the most basic proffer in support of its request
for additional witnesses after two full days of testimony.
Moreover, even had we found the Hearing Officer abused his
discretion, Woodcrest’s voluntary decision to walk out of the
hearing again prevents it from demonstrating reversible error.
See supra Part III.A. Thus, under either the abuse-of-
discretion or reversible-error prongs of the analysis,
Woodcrest’s argument fails.

                             C.

    Finally, we easily dismiss Woodcrest’s contention that
the Hearing Officer abused his discretion by refusing to allow
Woodcrest to treat Vergel de Dios as a hostile witness.
NLRB regulations expressly state “rules of evidence
prevailing in courts . . . shall not be controlling” in
proceedings challenging election results.          29 C.F.R.
§ 102.66(a). Consequently, we cannot say the Hearing
                             23
Officer abused his discretion by opting not to apply a
nonbinding rule, especially since the Hearing Officer did
permit Woodcrest to ask leading questions and to continue
lines of questioning to which the Union objected. See, e.g.,
J.A. 184–85 (allowing leading questions); J.A. 185
(overruling objection because the Hearing Officer “want[ed]
to see where this is going”); J.A. 196 (overruling relevance
objection because he “still want[ed] to hear it”); J.A. 206–07
(noting he “wanted to hear the answer” to the leading question
“did you . . . ever have the discussion about words to the
effect of voting what your heart tells you” or “vote what is
best for you”); J.A. 208–09. As a result, we also cannot say
the Board abused its discretion when it affirmed the Hearing
Officer’s recommendations, particularly given the “especially
wide degree of discretion” this Court affords the Board “[o]n
questions regarding representation.” Randell Warehouse, 252
F.3d at 447–48.

                             IV.

    Because we hold the Board did not abuse its discretion,
we deny Woodcrest’s request to set aside the Board’s June 15
order and to remand with direction for a new election. We
grant the NLRB’s cross-application for enforcement of the
same order.

                                                  So ordered.
