United States Postal Service v. American Postal Workers Union

United States Court of Appeals
FOR THE DISTRICT OF COLUMBIA CIRCUIT

Argued November 17, 2008 Decided January 23, 2009

No. 08-5056

UNITED STATES POSTAL SERVICE,
APPELLEE

v.

AMERICAN POSTAL WORKERS UNION,
APPELLANT

Appeal from the United States District Court
for the District of Columbia
(No. 06cv00793)

Darryl J. Anderson argued the cause and filed the briefs for
appellant.
Fred E. Haynes, Assistant U.S. Attorney, argued the cause
for appellee. With him on the brief were Jeffrey A. Taylor, U.S.
Attorney, R. Craig Lawrence, Assistant U.S. Attorney, and
Teresa A. Gonsalves, Appellate Counsel, U.S. Postal Service.
Before: SENTELLE, Chief Judge, and GRIFFITH, Circuit
Judge, and EDWARDS, Senior Circuit Judge.
Opinion for the Court filed by Senior Circuit Judge
EDWARDS.
 2

EDWARDS, Senior Circuit Judge: This case involves an
action brought in District Court by the United States Postal
Service (“USPS” or “Postal Service”), under the Postal
Reorganization Act, 39 U.S.C. § 1208(b), to vacate an
arbitrator’s award granting a grievance filed by the American
Postal Workers Union (“APWU” or “the union”). The union’s
grievance was filed under a collective bargaining agreement
(“CBA”) between USPS and APWU, and it challenged the
dismissal of an employee, Lorraine Daliessio, who had been
employed by USPS. The Postal Service argued to the arbitrator
that, because Daliessio was a probationary employee when
separated from employment, she could be terminated without
cause and without access to the grievance and arbitration
procedures available to nonprobationary employees under the
parties’ CBA.
The parties agreed that the arbitrator had the authority to
decide whether the grievance was arbitrable under the CBA.
The arbitrator ruled that Daliessio’s grievance was arbitrable,
because the grievant was not separated during her probationary
period. The arbitrator reached this conclusion in part because
the Postal Service had failed to give proper notice as required by
the USPS Employee and Labor Relations Manual (“ELM”)
when it purported to separate Daliessio. Finding no just cause,
the arbitrator ordered Daliessio reinstated with seniority and
back pay.
The District Court vacated the award. U.S. Postal Serv. v.
Am. Postal Workers Union AFL-CIO, 536 F. Supp. 2d 12
(D.D.C. 2008). The District Court agreed with USPS that,
because controlling arbitral precedent “expressly disallows
probationary employees access to grievance procedures for
challenges to a separation based on non-compliance with [the]
ELM,” id. at 17, the arbitrator’s award “exceeded the authority
granted by the [parties’] National Agreement.” Id. On appeal,
APWU argues that the District Court erred in failing to adhere
 3

to the commands of United Steelworkers of America v.
Enterprise Wheel & Car Corp., 363 U.S. 593 (1960), and its
progeny, governing judicial review of arbitration awards. The
Enterprise Wheel line of cases, which controls the disposition of
this case, emanates from section 301 of the Labor-Management
Relations Act of 1947, 29 U.S.C. § 185(a) (“LMRA”).
Section 1208(b) of the Postal Reorganization Act, 39
U.S.C. § 1208(b), gives federal district courts jurisdiction
over suits for violations of contracts between the United
States Postal Service and unions representing postal
employees. Section 1208(b ) is virtually identical to section
301(a) of the [LMRA], which provides that “[s]uits for
violation of contracts between an employer and a labor
organization representing employees . . . may be brought in
any district court of the United States having jurisdiction of
the parties.” [Id.] We have previously applied cases
interpreting section 301(a) in determining the scope of
section 1208(b).
U.S. Postal Serv. v. Nat’l Rural Letter Carriers’ Ass’n, 959 F.2d
283, 286 (D.C. Cir. 1992) (second alteration in original).
Under Enterprise Wheel, a court may not vacate an
arbitrator’s award if it “draws its essence” from the parties’
collective bargaining agreement. 363 U.S. at 597. It does not
matter whether the arbitrator’s decision on the merits appears to
be misguided. “When an arbitrator resolves disputes regarding
the application of a contract, and no dishonesty is alleged, the
arbitrator’s ‘improvident, even silly, factfinding’ does not
provide a basis for a reviewing court to refuse to enforce the
award.” Major League Baseball Players Ass’n v. Garvey, 532
U.S. 504, 509 (2001) (quoting United Paperworkers Int’l Union,
AFL-CIO v. Misco, Inc., 484 U.S. 29, 39 (1987)). In other
words, the Supreme Court has made it abundantly clear that “a
federal court may not overrule an arbitrator’s decision simply
because the court believes its own interpretation of the contract
 4

would be the better one.” W.R. Grace & Co. v. Local Union
759, Int’l Union of the United Rubber, Cork, Linoleum & Plastic
Workers of Am., 461 U.S. 757, 764 (1983). Because the
arbitrator’s award in this case drew its essence from the parties’
CBA, the award cannot be overturned by a federal court.
Accordingly, we reverse the judgment of the District Court and
remand the case for judgment to be entered in favor of APWU.
I. BACKGROUND
A. The National Agreement
The APWU and USPS are parties to a collective bargaining
agreement covering employees at postal facilities throughout the
United States. The instant dispute is governed by the CBA that
was in effect between 1994 and 1998. See Collective
Bargaining Agreement Between American Postal Workers
Union, AFL-CIO and United States Postal Service, Nov. 21,
1994 – Nov. 20, 1998 (the “National Agreement”), reprinted in
Joint Appendix (“J.A.”) 30.
Article 15 of the National Agreement sets forth the parties’
grievance-arbitration procedure. A grievance under the CBA is
defined as a complaint by an employee or the union that
involves the interpretation, application of, or compliance with
the provisions of the contract. National Agreement, Art. 15.1,
J.A. 43. In the event that a grievance is not resolved under the
contractual grievance procedure, the matter may be submitted to
a neutral arbitrator jointly chosen by the parties. Id. at Art. 15.2,
J.A. 43-46. Cases involving interpretive issues of general
application under the National Agreement are arbitrated at the
national level, and the resulting awards establish controlling
precedent on the meaning of the National Agreement. Id. at Art.
15.5, J.A. 47-49. “Area Level Arbitration” cases, as
distinguished from “National Panel” cases, are final and binding
only on the parties to the individual case. Id.
 5

The ELM also contains provisions relating to the terms and
conditions of employment of employees covered by the CBA.
However, unlike the CBA, the ELM is not a product of
collective bargaining between APWU and USPS. The Postal
Service may add to and amend the terms of the ELM, but the
union must be notified of any changes and it may challenge
them on the ground that they conflict with the terms of the
National Agreement or are otherwise unfair, unreasonable, or
inequitable. Id. at Art. 19, J.A. 74. In addition, the parties have
agreed that the provisions of the ELM “shall be continued in
effect” unless changed in accordance with procedures set forth
in Article 19. Id.
The ELM establishes, inter alia, detailed procedures
covering the separation of probationary employees. Under the
terms of the ELM, an appointing official must “notify[] the
employee in writing why she or he is being terminated and the
effective date of the action,” along with “the appointing
official’s conclusions as to the inadequacies of performance or
conduct.” ELM 365.326, reprinted in J.A. 173. The ELM
requires that the notice of termination be given to the employee
before the end of the probationary period. Id. at 365.327, J.A.
174.
Under the CBA, new employees are considered
probationary for the first 90 days of employment. Pursuant to
Article 12 of the National Agreement, USPS may separate
employees during their probationary period without just cause.
The CBA provides:
The probationary period for a new employee shall be ninety
(90) calendar days. The Employer shall have the right to
separate from its employ any probationary employee at any
time during the probationary period and these probationary
employees shall not be permitted access to the grievance
procedure in relation thereto.
 6

National Agreement, Art. 12.1.A, J.A. 31.
For a time, USPS and APWU officials disagreed over
whether an employee who was separated during his or her
probationary period could challenge the employer’s action under
the CBA grievance and arbitration procedures. The union
contended that separations must comply with ELM procedures
and that claims of noncompliance could be brought to
arbitration. The Postal Service disagreed, contending that
Article 12.1.A made it clear that probationary employees who
were separated had no access to the CBA grievance and
arbitration procedures. In 2000, in a USPS action seeking to
vacate an arbitrator’s award, the Fourth Circuit agreed with the
Postal Service that the CBA barred all arbitral challenges to the
separation of probationary employees. See U.S. Postal Serv. v.
Am. Postal Workers Union, AFL-CIO, 204 F.3d 523 (4th Cir.
2000).
The matter finally came to a head in 2001, when National
Arbitrator Shyam Das presided over an arbitration proceeding
that concerned the meaning of Article 12.1.A. In particular,
Arbitrator Das was asked to decide what claims, if any, a
probationary employee could pursue under the parties’ CBA
grievance and arbitration procedures to challenge a separation
action taken within the employee’s probationary period. See In
re Postal Serv., Am. Postal Workers Union and Nat’l Ass’n of
Letter Carriers, Case No. Q98C-4Q-C 99251456 (Nat’l Award,
Sept. 10, 2001) (Das, Arb.) (“Das Award”), reprinted in J.A. 69.
Arbitrator Das concluded that probationary employees may not
challenge separations on the grounds of alleged noncompliance
with ELM procedures. However, the Das Award also made
clear that the union may arbitrate the question of whether an
employee’s separation occurred during the probationary period.
On this second point, Arbitrator Das noted that “Article 12.1.A
has no application if the separation action does not occur during
the probationary period.” Id. at J.A. 92.
 7

Arbitrator Das also noted that Article 12 does not define
what constitutes a separation under the CBA. To fill this
definitional void, he looked to the ELM and ruled that
[the] definition [of “separation”] is provided . . . in Section
365.11 of the ELM which states: “Separations are
personnel actions that result in employees’ being removed
from the rolls of the Postal Service.”
Id. at J.A. 88.
The parties agree that the Das Award provides the
controlling arbitral precedent regarding the meaning of Article
12.1.A, and that the Das decision is binding on the parties to this
dispute.
B. Facts and Proceedings Below
The facts as reported in the arbitrator’s award, the District
Court’s decision, and the record on appeal are straightforward
and largely undisputed. Lorraine Daliessio was hired on
November 22, 1997, as a part-time flexible mark-up clerk in the
Computer Forwarding unit at the Philadelphia Pennsylvania Post
Office. Decl. Of Vivian T. Barnett, reprinted in J.A. 258 at ¶¶ 1,
4. Daliessio’s 90-day probationary period was scheduled to end
on February 19, 1998. Id. at ¶ 4. On December 30, 1997, at her
30-day evaluation, Daliessio’s supervisor, Vivian Barnett,
informed her that she had been rated “unacceptable” in two key
performance areas: work quality and work quantity. Id. at ¶ 5.
On January 30, 1998, Daliessio’s supervisor gave her an
unsatisfactory rating and checked the box on an evaluation form
indicating that she would not recommend Daliessio for retention
or rehire. Daliessio declined to sign the form. Her supervisor
told her to clean out her locker, turn in her I.D., and go home.
Daliessio did so, and did not return to work. Id. at J.A. 259 ¶¶
7-8.
 8

On February 4, 1998, Supervisor Barnett sent a letter to the
Manager of Labor Relations asking that action be taken to
remove Daliessio from the employment rolls effective January
30, 1998. Id. at J.A. 260 ¶ 9. On February 20, 1998, one day
after Daliessio’s probationary period ended, the Manager of
Labor Relations sent a letter to Daliessio stating: “This will
confirm your separation from the Postal Service [as] a result of
lack of proficiency.” Notice of Separation, Feb. 20, 1998,
reprinted in J.A. 164-65. The union filed a grievance to
challenge the separation. The grievance was denied by the
Postal Service and appealed to arbitration by the union. Appeal
to Arbitration, Sept. 14, 1998, reprinted in J.A. 156.
Arbitrator Loeb heard the grievance in late 2005 and issued
a decision on January 28, 2006. In re Postal Serv. and Am.
Postal Workers Union, No. C94C-4C-D 98076813 (Reg’l
Award, Jan. 28, 2006) (Loeb, Arb.) (“Loeb Award”), reprinted
in J.A. 52. The parties agreed that, under the Das Award,
Arbitrator Loeb could properly decide whether the grievant was
separated during her probationary period. The parties also
agreed that if Loeb determined that the grievant was not
separated within her probationary period, her grievance on the
merits was arbitrable. After explaining the controlling
principles in the Das Award and then making findings regarding
Daliessio’s dismissal, Arbitrator Loeb concluded that
Daliessio’s claim was arbitrable because she was not separated
until after her probationary period. Loeb found that the
grievant’s purported “separation” consisted of USPS sending her
home and telling her not to come back to work. However, in
Arbitrator Loeb’s view, “[n]either the recommendation nor the
order not to return to work terminated the Grievant. The
supervisor, her manager and the Manager of Labor Relations all
recognized that was the case by their actions.” Id. at J.A. 66.
 9

After concluding that the grievant was not separated during
her probationary period, Arbitrator Loeb went on to discuss the
ELM. He observed, inter alia, that because the ELM
declare[s] that separation must take place during the
employee’s probationary period and [sets] the conditions by
which it must terminate the employee, the Employer cannot
prohibit the Grievant from accessing the grievance
procedure on the basis of Article 12 to allege that she was
not terminated during her probation.
Id. at J.A. 67. In the end, Arbitrator Loeb concluded: “The
plain fact of the matter is that the Employer failed to terminate
the Grievant, as that term is understood in Article 12[,] within
her probationary period.” Id. at J.A. 68. Finding no just cause
for dismissal, the arbitrator ordered Daliessio reinstated with
seniority and back pay.
The District Court granted summary judgment to USPS and
vacated the Loeb Award. See U.S. Postal Serv., 536 F. Supp. 2d
12. Characterizing the issue in the case as “whether APWU’s
grievance challenging Daliessio’s ‘termination’ was arbitrable,”
id. at 16, the District court held that the arbitrator’s decision
“exceeded the authority granted by the National Agreement.”
Id. at 17.
Because the Das Award . . . expressly disallows
probationary employees access to grievance procedures for
challenges to a separation based on non-compliance with
ELM Section 365.32, Loeb’s reliance on those procedures
to determine that Daliessio was not terminated within the
probationary period is misplaced. In fact, it runs directly
counter to Article 12.1.A as interpreted by the Das Award.
Id. at 17-18. Holding that “[t]his flawed analysis constitutes . . .
manifest disregard of the National Agreement,” the District
Court vacated the arbitration award. Id. at 18.
 10

II. ANALYSIS
A. Standard of Review
“Our review of a district court’s decision on a summary
judgment motion is de novo. We will affirm the district court’s
grant of summary judgment to [the Postal Service] only if
[USPS] has demonstrated in view of all the facts – and the
reasonable inferences drawn therefrom in the light most
favorable to [the union], the non-moving party – that ‘there is no
genuine issue as to any material fact and that the moving party
is entitled to judgment as a matter of law.’ FED. R. CIV. P.
56(c).” Teamsters Local Union No. 61 v. United Parcel Serv.,
272 F.3d 600, 603 (D.C. Cir. 2001) (citation omitted).
“Unless the parties clearly and unmistakably provide
otherwise,” “the question of arbitrability – whether a
collective-bargaining agreement creates a duty for the parties to
arbitrate the particular grievance – is undeniably an issue for
judicial determination.” AT&T Techs., Inc. v. Comm’ns
Workers of Am., 475 U.S. 643, 649 (1986). It is undisputed in
this case that the parties agreed to present the question of
arbitrability to the arbitrator. Therefore, judicial review of the
arbitrator’s award here is strictly limited pursuant to the
Supreme Court’s decision in Enterprise Wheel and its progeny.
We are only called upon to determine whether the
arbitrator’s award “draws its essence from the collective
bargaining agreement.” Enterprise Wheel, 363 U.S. at 597. An
arbitrator may not, of course, “dispense his own brand of
industrial justice.” Id. However, “as long as the arbitrator is
even arguably construing or applying the contract and acting
within the scope of his authority, that a court is convinced he
committed serious error does not suffice to overturn his
decision.” Misco, 484 U.S. at 38; see also Garvey, 532 U.S. at
509 (“Courts are not authorized to review the arbitrator’s
decision on the merits despite allegations that the decision rests
 11

on factual errors or misinterprets the parties’ agreement.”)
(citation omitted). So long as the arbitrator’s award draws its
essence from the parties’ agreement, the arbitrator has the right
to be wrong and a court may not second-guess his decision.
B. The Arbitrator’s Award in This Case
There is some force to the Postal Service’s argument that,
on the merits, Arbitrator Loeb’s Award is questionable. It is
undisputed that the Das decision establishes the controlling law
under the parties’ CBA concerning the meaning of Article
12.1.A. As noted above, Arbitrator Das ruled that “Article
12.1.A denies a probationary employee access to the grievance
procedure to challenge his or her separation on the grounds of
alleged noncompliance with the procedures in Section 365.32 of
the ELM.” Das Award, J.A. 93. The Postal Service contends
that Arbitrator Loeb was faithless to this principle when he cited
the ELM in determining that Daliessio was improperly
separated.
Although the Postal Service may have an arguable ground
to disagree with the arbitrator’s decision, this is no basis for a
court order vacating the Loeb Award. The question before this
court is not whether the arbitrator’s decision is wrong on the
merits, but whether his decision draws its essence from the
parties’ CBA. We hold that it does.
Arbitrator Loeb was asked to construe Article 12.1.A of the
National Agreement. In so doing, he was plainly aware that he
was bound by the Das Award. The Loeb Award discusses the
Das decision in some detail, focusing in particular on Das’s
holdings regarding when a probationary employee may
permissibly challenge her separation. After reviewing the CBA
and the relevant arbitral precedent, Arbitrator Loeb first held
that:
In view of those authorities, the undersigned must conclude
that the Union has a right to challenge the Grievant’s
 12

termination through the grievance procedure. . . .
Regardless of how the Union chooses to characterize the
nature of the grievance or how badly it feels that the Service
transgressed the requirements in Section 365.327 of the
ELM, the issue before the Arbitrator is not the process the
Service employed when it terminated the Grievant, but
whether she was discharged during her probationary period.
The answer is that she was not.
Loeb Award, J.A. 66.
Loeb then recited findings of fact in support of his
conclusion that the grievant had not been terminated during her
probationary period:
The record is clear that the Grievant was advised on
January 30, 1998 that her work was unsatisfactory and that
her supervisor would not recommend her retention. She
memorialized those comments on the Form 1750 by
checking the box indicating that she would not recommend
the Grievant be retained by the Service. The Grievant
claimed that she never saw that section of the evaluation
form, but in view of her subsequent EEO statement her
claim is not credible. The Grievant’s credibility, however,
is not an issue in this case. What matters is what the Postal
Service did which is sent her home and told her not to come
back to work. Neither the recommendation nor the order
not to return to work terminated the Grievant. The
supervisor, her manager and the Manager of Labor
Relations all recognized that was the case by their actions.
The supervisor and the manager by requesting that Labor
Relations separate the Grievant and Labor Relations by
sending a letter to that effect to the Grievant. The letter,
which was dated February 20, 1998, was sent by certified
mail to the Grievant’s address of record. She effectively
evaded receipt of the letter by refusing to claim it. Thanks
to her tactics it was not until late March that the Postal
 13

Service finally constructively delivered the letter to the
Grievant’s address of record. By then it was too late.
Id. at 66-67. These findings are plainly adequate to support
Loeb’s judgment. It is significant that Loeb’s critical findings
of fact do not rest on the employer’s compliance or
noncompliance with the ELM. Rather, Loeb simply looked at
the record and decided that, as he viewed the facts, the employee
was not effectively terminated until after her probationary
period.
After discussing the applicable contract provision, making
it clear that he understood and meant to rely on the principles set
forth in the Das Award, and reciting his critical findings of fact
in support of his judgment, Arbitrator Loeb then went on to
discuss the ELM. It is at this point that the opinion engenders
great confusion. The Loeb Award states that,
[h]ad the Service not drafted Sections 365.323 and .326 of
the ELM, it would not have mattered when the Employer
sent the letter out or when the Grievant received it as
Article 12, Section 1.A. only states that if the Service
intends to terminate a probationary employee it must do so
during his probationary period. The ELM radically altered
that scheme . . . provid[ing] the manner in which separation
must occur.
Id. at 67. This portion of the Loeb Award, at least if read in
isolation, seems to be at odds with Das’s ruling that a “challenge
to the validity of the procedures followed in effecting a
separation is barred by the broad prohibitory language of Article
12.1.A.” Das Award, J.A. 92.
What is most noteworthy, however, is that, when Loeb’s
opinion is read as a whole, it is clear that Arbitrator Loeb
obviously understood that he was bound by Arbitrator Das’s
decision. It is also clear that Loeb did not mean to say that a
probationary employee may gain access to the grievance
 14

procedure to challenge his or her separation solely on the
grounds of alleged noncompliance with ELM procedures.
Rather, he parroted the command from the Das Award: “A
dispute as to whether or not the Postal Service’s action
separating the employee occurred during his or her probationary
period is arbitrable because that is a precondition to the
applicability of Article 12.1.A.” Loeb Award, J.A. 66 (quoting
Das Award, J.A. 93).
Loeb did not hold that the employer must adhere to ELM
procedures; rather, he seems to suggest nothing more than that
the factors listed in the ELM are among those that might be
relevant in deciding whether an employee has been separated
within her probationary period. And, as noted above, before he
discussed the ELM, Loeb listed the facts that he found to be
controlling and none of these facts had to do with any alleged
breach of the ELM by USPS.
It is hardly surprising that Loeb looked to the ELM for
affirmation, because Das also looked to the ELM in deciding the
meaning of “separation” under Article 12. Das said:
The Unions also are correct in pointing out that Article
12 does not define what constitutes a separation. That
definition is provided, however, in Section 365.11 of the
ELM which states:
Separations are personnel actions that result in
employees’ being removed from the rolls of the Postal
Service.
Das Award, J.A. 88. Furthermore, the Das decision does not say
that an arbitrator cannot look to the ELM for guidance. Rather,
what Das says is that probationary employees may not pursue an
action in arbitration based solely on a claim that the employer
failed to follow the “procedures” under the ELM. Das Award,
J.A. 90. Loeb never assumed that the issue in this case was
whether the Postal Service failed to follow ELM procedures.
 15

Rather, Loeb clearly stated that the issue before him was
whether the grievant was terminated during her probationary
period:
Regardless of how the Union chooses to characterize the
nature of the grievance or how badly it feels that the Service
transgressed the requirements in Section 365.327 of the
ELM, the issue before the Arbitrator is not the process the
Service employed when it terminated the Grievant, but
whether she was discharged during her probationary period.
Loeb Award, J.A. 66. Nothing in the Das Award barred Loeb
from addressing the issue of whether the grievant was
discharged during her probationary period; and nothing in Das’s
decision barred Loeb from looking to the ELM to gain some
guidance on how to determine whether an employee was in fact
terminated during her probationary period.
In the end, the most that can be said is that the Loeb Award
is somewhat confusing in its gratuitous observations about the
ELM and arguably dubious in its judgment on the merits. But
there can be no doubt whatsoever that the Loeb Award draws its
essence from the parties’ agreement and the Das Award. It does
not matter whether we agree with Loeb’s reasoning or judgment,
so long as we find that his award rested on his construction of
the CBA. See Madison Hotel v. Hotel & Rest. Employees, Local
25, AFL-CIO, 144 F.3d 855, 859 (D.C. Cir. 1998) (en banc)
(“[I]t is enough to sustain the award that the arbitrator,
permissibly drawing on the sources just mentioned as well as on
the explicit provisions of the contract itself, purported to be
interpreting the contract in rendering his final decision.”)
(internal quotation omitted).
As noted above, under Enterprise Wheel and its progeny,
the arbitrator has a right to be wrong in his interpretation of the
parties’ CBA. The parties bargained for Arbitrator Loeb to be
the reader of their CBA. In other words, “the parties have
 16

necessarily bargained for the arbitrator’s interpretation of the
[arbitral] law and are bound by it.” Am. Postal Workers Union
v. U.S. Postal Serv., 789 F.2d 1, 6 (D.C. Cir. 1986). Arbitrator
Loeb did not “render[ ] a judgment based on external legal
sources, wholly without regard to the terms of the parties’
contract.” Id. at 8. Nor is he accused of any misconduct. Am.
Postal Workers Union, AFL-CIO v. U.S. Postal Serv., 52 F.3d
359, 362 (D.C. Cir. 1995) (stating that an arbitrator influenced
by bribery or fraud could be viewed as “dispensing his own
brand of industrial justice”). Rather, he looked to and relied on
the proper sources of his authority, so it cannot be said that he
“dispense[d] his own brand of industrial justice.” Enterprise
Wheel, 363 U.S. at 597. USPS and the APWU authorized
Arbitrator Loeb “to give meaning to the language of the
agreement.” Misco, 484 U.S. at 38. Were this court to vacate
the arbitrator’s award, we would simply be substituting our own
interpretation of Article 12.1.A and the Das decision for
Arbitrator Loeb’s. We have no authority to do this.
C. The Decision of the Fourth Circuit Has No Preclusive
Effect in This Case
Finally, USPS contends that, because the decision by the
Fourth Circuit in United States Postal Serv. v. American Postal
Workers Union, AFL-CIO, 204 F.3d 523, conclusively
determined the same issues the Loeb Award purported to
address in a proceeding involving the same parties, collateral
estoppel precludes enforcement of the Loeb Award. USPS Br.
at 34. We disagree.
“Under collateral estoppel, once a court has decided an
issue of fact or law necessary to its judgment, that decision may
preclude relitigation of the issue in a suit on a different cause of
action involving a party to the first case.” Novak v. World Bank,
703 F.2d 1305, 1309 (D.C. Cir. 1983) (quoting Allen v.
McCurry, 449 U.S. 90, 94 (1980)). However, “[c]ollateral
estoppel is generally inappropriate when the issue is one of law
 17

and there has been a change in the legal context after the first
decision.” Pharm. Care Mgmt. Ass’n v. District of Columbia,
522 F.3d 443, 447 (D.C. Cir. 2008); see also Montana v. United
States, 440 U.S. 147, 161 (1979) (observing that collateral
estoppel has no application when there has been change in the
legal context). The legal context has changed in this case,
because the contractual principle applied by the Fourth Circuit
is not the same as the principle subsequently announced by Das
and applied by Loeb.
The Fourth Circuit said that the parties’ agreement
“precludes an arbitrator from determining whether a
probationary employee was actually separated in the first
place. . . . In other words, so long as the matter involves
probationary employees and the question of separation, no
grievance may be brought.” U.S. Postal Serv., 204 F.3d at 528.
Arbitrator Das completely rejected this construction of the
contract when he held that:
A dispute as to whether or not the Postal Service’s action
separating the employee occurred during his or her
probationary period is arbitrable because that is a
precondition to the applicability of Article 12.1.A.
Das Award, J.A. 93. Arbitrator Loeb followed Das, as he was
authorized to do.
In short, the Fourth Circuit decision is not in the least bit
binding in this case. The parties bargained for Das’s
interpretation of the contract, not the Fourth Circuit’s contrary
construction, and Loeb followed Das. See Am. Postal Workers
Union, 789 F.2d at 6-7 (“Since the arbitrator is the ‘contract
reader,’ his interpretation of the law becomes part of the contract
and thereby part of the private law governing the relationship
between the parties to the contract.”).
 18

III. CONCLUSION
For the reasons stated above, the judgment of the District
Court is reversed. The case is remanded to the District Court
with instructions to enter judgment for the appellant.