  United States Court of Appeals
      for the Federal Circuit
                ______________________

  ROBERT M. ATHEY, MICHAEL R. CLAYTON,
  THELMA R. CURRY, RICHARD S. DROSKE,
RALPH L. FULLWOOD, PAUL D. ISING, CHARLES
       A. MILBRANDT, TROY E. PAGE,
             Plaintiffs-Appellants

                           v.

                  UNITED STATES,
                  Defendant-Appellee
                ______________________

                      2017-2277
                ______________________

    Appeal from the United States Court of Federal
Claims in No. 1:99-cv-02051-PEC, Judge Patricia E.
Campbell-Smith.
                ______________________

               Decided: October 31, 2018
                ______________________

    IRA MARK LECHNER, Washington, DC, argued for
plaintiffs-appellants.

    MIKKI COTTET, Commercial Litigation Branch, Civil
Division, United States Department of Justice, Washing-
ton, DC, argued for defendant-appellee. Also represented
by HILLARY STERN, CHAD A. READLER, ROBERT E.
KIRSCHMAN, JR., REGINALD T. BLADES, JR.
                 ______________________
2                                   ATHEY   v. UNITED STATES




        Before REYNA, SCHALL, and STOLL, Circuit Judges.
SCHALL, Circuit Judge.
    Robert M. Athey, Michael R. Clayton, Thelma R. Cur-
ry, Richard S. Droske, Ralph L. Fullwood, Paul D. Ising,
Charles A. Milbrandt, and Troy E. Page (“Appellants”) are
former employees of the Department of Veterans Affairs
(“VA”). Appellants were employed by the VA under title
38 of the United States Code. 1 During the period from
1993 through 1999, Appellants retired or separated from
their positions with the VA with accrued but unused
leave.
    The Lump Sum Pay Act (“LSPA”), 5 U.S.C.
§§ 5551-5552, which covers Appellants, provides that an
employee “who is separated from the service . . . is enti-
tled to receive a lump-sum payment for accumulated and
current accrued annual or vacation leave to which he is
entitled by statute.” 5 U.S.C. § 5551(a). The lump-sum
payment must be equal to the pay the separated employee
would have received had he or she remained in federal
service until the expiration of the period of annual or
vacation leave. Id. It is undisputed that Appellants
received lump-sum payments for their accrued and un-
used annual leave pursuant to the LSPA. It also is un-
disputed that, after Appellants left the VA, they received
supplemental lump-sum payments. These supplemental
lump-sum payments reflected statutory pay increases and
general system-wide pay increases that became effective


    1   Appellants fall into one of three categories of em-
ployees under the title 38 system: registered nurses and
nurse anesthetists under 38 U.S.C. § 7401(1); physicians
assistants and expanded-function dental auxiliaries under
38 U.S.C. § 7401(1); and so-called “hybrid” employees
under 38 U.S.C. §§ 7401(3) and 7403(f)(1)(a).
ATHEY   v. UNITED STATES                                  3



prior to the expiration of Appellants’ accrued annual
leave.
    Appellants are members of a class of former VA em-
ployees. On June 21, 2006, the class filed a complaint in
the United States Court of Federal Claims, alleging that
the VA improperly omitted certain pay increases from
class members’ supplemental lump-sum payments. The
allegedly omitted increases included Cost of Living Ad-
justments (“COLAs”) and Locality Pay Adjustments. The
complaint additionally alleged that lump-sum payments
made to certain members of the class improperly omitted
non-overtime Sunday premium pay that the members
would have received had they remained in federal service
until the expiration of their periods of annual or vacation
leave. Certain class members also alleged that their
lump-sum payments improperly omitted evening and
weekend “additional pay” that they would have received
had they remained in federal service until the expiration
of their periods of annual or vacation leave. 2 Finally, all
members of the class sought pre-judgment interest on
their claims under the Back Pay Act (“BPA”), 5 U.S.C.
§ 5596, as in effect during the years 1993 through 1999.
In pertinent part, the BPA provides that interest is au-
thorized for “an amount equal to all or any part of the
pay, allowances, or differentials” lost by an “employee”




   2    Section 7453(a) of title 38 of the United States
Code states that, “[i]n addition to the rate of basic pay
provided for nurses, a full-time nurse or part-time nurse
shall receive additional pay as provided by this section.”
Evening and weekend “additional pay” are provided for in
38 U.S.C. § 7453(b) and (c), respectively.
4                                   ATHEY   v. UNITED STATES



who has been subjected to “an unjustified or unwarranted
personnel action.” Id. 3
    Appellants’ claims for additional COLAs, Locality Pay
Adjustments, and non-overtime Sunday premium pay
have been resolved. Before us now is Appellants’ appeal
of two decisions of the Court of Federal Claims. In those
decisions, the court held that, as members of the class,
Appellants were not entitled to have evening and week-
end “additional pay” included in their lump-sum pay-
ments. The court also held that Appellants were not
entitled to receive pre-judgment interest on amounts
improperly withheld from their lump-sum payments. 4
Appellants have timely appealed. We have jurisdiction
pursuant to 28 U.S.C. § 1295(a)(3). For the reasons set
forth below, we affirm.
                      BACKGROUND
        Proceedings in the Court of Federal Claims
    Three decisions of the Court of Federal Claims are
relevant to this appeal. In the first decision, Athey v.
United States, 78 Fed. Cl. 157, 161 (2007) (“Athey I”), the
court addressed the claim that additional pay, in the form
of evening and weekend pay, should have been included
in lump sum payments received pursuant to 5 U.S.C.
§ 5551(a). On this issue, the government moved for
dismissal pursuant to Rule 12(b)(6) of the Rules of the
U.S. Court of Federal Claims (“RCFC”) for failure to state
a claim upon which relief could be granted. The govern-
ment argued that title 38 entitles Appellants to a lump-
sum payment of accrued annual leave, calculated based


    3   The present version of the BPA is the same as the
version in effect during the period of 1993–1999.
    4   Hereafter, for ease of reference in discussing Ap-
pellants’ BPA claim, we refer to “Appellants’ claims to
interest on their LSPA claims.”
ATHEY   v. UNITED STATES                                    5



on the basic rate of pay they were earning prior to separa-
tion, but that 38 U.S.C. § 7453(i) prohibits the inclusion of
“additional pay” (pay for evening and weekend work) in
the payout amount. 78 Fed. Cl. at 161. Section 7453(i)
states:
    Any additional pay paid pursuant to this section
    shall not be considered as basic pay for the pur-
    poses of the following provisions of title 5 (and any
    other provision of law relating to benefits based on
    basic pay):
    (1) Subchapter VI of chapter 55.
    (2) Section 5595.
    (3) Chapters 81, 83, 84, and 87.
38 U.S.C. § 7453(i). Relevant to this appeal, subchapter
VI of Chapter 55 encompasses 5 U.S.C. §§ 5551–52, the
LSPA. Section 5595 covers severance pay.
    Appellants countered with the argument that the
term “pay” in 5 U.S.C. § 5551(a) is not limited to “basic
pay” (referenced in § 7453(i)), but also includes premium
pay. 78 Fed. Cl. at 161. They further argued that
§ 7453(i) is properly understood to simply mean that
“additional pay” is not part of “basic pay” rather than as
excluding it from the calculation of “pay” under the LSPA
for purposes of a lump-sum payment. Id. at 162.
    In granting the government’s motion, the court held
that “additional pay” as part of a lump-sum payment is
prohibited under 38 U.S.C. § 7453(i). As seen, § 7453(i)
states in pertinent part that “[a]ny additional pay paid
pursuant to this section shall not be considered as basic
pay for the purposes of . . . Subchapter VI of chapter 55
[LSPA] [and] Section 5595 [Severance Pay].” Citing
§ 7453(i), the court stated that, in § 7453(i), Congress
determined “with clarity” that lump-sum separation pay
should not include “additional pay,” even if title 5 pro-
6                                   ATHEY   v. UNITED STATES



vides it to other civil service employees. Athey I, 78 Fed.
Cl. at 163.
     In Athey v. United States, 108 Fed. Cl. 617 (2013)
(“Athey II”), the Court of Federal Claims, in an opinion by
the same judge who had issued the court’s opinion in
Athey I, determined that it had jurisdiction over Appel-
lants’ claims for interest and that, in seeking interest
under the BPA, Appellants had stated a claim upon which
relief could be granted. The court thus denied the gov-
ernment’s motion to dismiss under RCFC 12(b)(1) for lack
of jurisdiction or, in the alternative, under RCFC 12(b)(6)
for failure to state a claim upon which relief could be
granted.
    On the jurisdictional issue, the Court of Federal
Claims rejected the government’s argument that Appel-
lants had failed to plead a money-mandating statute that
would provide the court with jurisdiction under the Tuck-
er Act, 28 U.S.C. § 1491. The court held that, when pled
together, the LSPA and the BPA provided the court with
jurisdiction to hear Appellants’ claims. See 108 Fed. Cl.
at 619 (citing Worthington v. United States, 168 F.3d 24,
26 (Fed. Cir. 1999) (stating that, in order to “fall within
the Tucker Act’s jurisdictional grant, a claim must invoke
a statute that mandates the payment of money damages”
and that the BPA is such a “money-mandating” statute
when based on violations of statutes or regulations cov-
ered by the Tucker Act)). The court reasoned that, in this
case, Appellants’ claims under the BPA were based upon
the LSPA, which the court found to be a money-
mandating statute providing “separated federal employ-
ees accumulated annual pay when entitled by law.” Id.
    The Court of Federal Claims next addressed the gov-
ernment’s argument that Appellants had failed to state a
claim upon which relief could be granted because Appel-
lants had not suffered a loss of “pay” as required by the
BPA and were not “employees” for purposes of the BPA.
ATHEY   v. UNITED STATES                                 7



The court turned first to the question of whether Appel-
lants could satisfy the definition of “pay” under the BPA
and under the accompanying regulations promulgated by
the Office of Personnel Management (“OPM”) that were in
effect during the period 1993–1999. 108 Fed. Cl. at 620. 5
The court noted that, in December 1981, OPM promulgat-
ed regulations interpreting the BPA and authorizing the
payment of back pay, mandatory pre-judgment interest,
and reasonable attorney fees “for the purpose of making
an employee financially whole (to the extent possible).”
46 Fed. Reg. 58,271, 58,273 (Dec. 1, 1981); see 5 C.F.R.
§ 550.801 (1981). The court also noted that the 1981
regulations defined “pay” broadly as “monetary and
employment benefits to which an employee is entitled by
statute or regulation by virtue of the performance of a
Federal function.” 46 Fed. Reg. at 58,272; see 5 C.F.R.
§ 550.803 (1981). The court determined that because the
1981 regulation defined “pay” so broadly and because
OPM comments specifically excluded from that broad
definition only retirement benefits and not lump-sum
payments, lump-sum payments constituted pay under the
BPA. 108 Fed. Cl. at 620 (citing 46 Fed. Reg. 58,271–02).
Acknowledging that later OPM regulations, which became
effective in 2000, narrowed the definition of “pay,” the
court found that using the 2000 definition to retroactively
modify the 1981 regulations would be impermissible. Id.
(citing Bowen v. Georgetown Univ. Hosp., 488 U.S. 204,
208 (1988)). 6 Accordingly, the court concluded that Appel-


   5    5 U.S.C. § 5596(c) authorizes OPM to promulgate
regulations implementing the BPA.
    6   5 C.F.R. § 550.803 (2000) defines pay, allowances,
and differentials as “pay, leave, and other monetary
employment benefits to which an employee is entitled by
statute or regulation and which are payable by the em-
ploying agency to an employee during periods of Federal
employment. Agency and employee contributions to a
8                                   ATHEY   v. UNITED STATES



lants’ claims for payments under the LSPA fell within the
applicable statutory and regulatory definitions of “pay”
under the BPA.
    The court also found that Appellants qualified as
“employees” for purposes of the BPA. Id. at 620–22. The
court thus denied the government’s alternative motion to
dismiss pursuant to RCFC (12)(b)(6). Id. at 622.
    After the decision of the Court of Federal Claims in
Athey II, the government and Appellants cross-moved for
summary judgment on the issue of entitlement to interest
under the BPA on class members’ lump-sum payments.
These motions were decided in Athey v. United States, 123
Fed. Cl. 42 (2015) (“Athey III”). In Athey III, a Court of
Federal Claims judge different from the judge who had
decided Athey I and Athey II granted the government’s
motion for summary judgment that Appellants were not
entitled to interest under the BPA. As seen, the BPA
provides that interest is authorized for “an amount equal
to all or any part of the pay, allowance, or differentials”
lost by an “employee” who has been subjected to “an
unjustified or unwarranted personnel action.” 5 U.S.C.
§ 5596. The court held, among other things, that lump-
sum payments do not, in fact, qualify as “pay, allowance,
or differentials” under the BPA, so as to entitle Appel-
lants to pre-judgment interest. 123 Fed. Cl. at 59–61.
    The Court of Federal Claims first addressed Appel-
lants’ argument that Athey II, which denied the govern-
ment’s earlier 12(b)(6) motion to dismiss, ipso facto also



retirement investment fund, such as the Thrift Savings
Plan, are not covered. Monetary benefits payable to sepa-
rated or retired employees based upon a separation from
service, such as retirement benefits, severance payments,
and lump-sum payments for annual leave, are not cov-
ered.” (Emphasis added.)
ATHEY   v. UNITED STATES                                   9



found liability to Appellants for BPA interest without the
need for further argument or decision. Id. at 50. The
court rejected this argument, pointing out that “[a]n
initial denial of a motion to dismiss does not foreclose, as
the law of the case, the court’s later consideration of those
claims on summary judgment.” Id. (first citing Behrens v.
Pelletier, 516 U.S. 299, 309 (1996); then citing Gould, Inc.
v. United States, 66 Fed. Cl. 253, 266 (2005)).
    “In any event,” the court continued, “whether BPA in-
terest is available for violations of the lump-sum payment
statute is an issue of largely first impression; thus, this
court will not so woodenly apply the law of the case doc-
trine to preclude a thorough review of the claim.” Id. at
51 (citing Jamesbury Corp. v. Litton Indus. Prods., Inc.,
839 F.2d 1544, 1551 (Fed. Cir. 1988)). The court stated
that this was “especially true” in the instant case because
the court found “clear error in one of Athey II’s principle
findings that otherwise might have qualified for deference
as law of the case.” Id. Specifically, the court concluded
that “Athey II erroneously held that the lump-sum pay-
ment for annual leave was ‘pay’ for purposes of the Back
Pay Act.” Id.
    Pointing to the language of 5 U.S.C. § 5551(a), which
states that “[t]he lump-sum payment is considered pay for
taxation purposes only,” the court observed that the LSPA
“plainly and unambiguously states that the ‘lump-sum
payment is considered pay for taxation purposes only.’”
123 Fed. Cl. at 51. Further, the court noted that Appel-
lants conceded that, by virtue of the specific limitation to
taxation included in § 5551(a), a lump-sum payment does
not constitute “pay.” Id. The court also noted that the
LSPA has defined the lump sum as “pay for taxation
purposes only” since lump-sum payments were first
authorized by Congress in 1944. Id. at 52 (citing Act of
Dec. 21, 1944, ch. 632 § 1, 58 Stat. 845). The clear com-
mand of the LSPA, the court concluded, could not be
10                                    ATHEY   v. UNITED STATES



overcome by the reference in the BPA to “pay, allowances,
or differentials.”
    First, relying upon the rule that “[s]pecific terms pre-
vail over the general in the same or another statute which
otherwise might be controlling,” the Court of Federal
Claims reasoned that “even if the lump-sum payment
statute and the BPA were found to be in conflict, . . . the
lump-sum payment statute’s specific definition of the
lump sum would take precedence over the Back Pay Act’s
more general use of the term ‘pay.’” Id. (quoting Thiess v.
Witt, 100 F.3d 915, 919 (Fed. Cir. 1996)). Second, the
court stated that “[t]he later-adopted BPA cannot be
interpreted to supersede the earlier lump-sum payment
statute because the law is clear that ‘repeals by implica-
tion are not favored’ absent clear congressional intent, . . .
and there is no evidence of such intent here.” Id. at 52
(quoting Canadian Lumber Trade All. v. United States,
517 F.3d 1319, 1343 (Fed. Cir. 2008)).
    Having concluded that a lump-sum payment for an-
nual leave is not “pay” for purposes of the BPA, the court
stated that it could not “defer to Athey II’s contrary con-
clusion as the law of the case.” Id. 7 The court, however,
did rule that Athey II’s conclusion that Appellants were
“employees” for purposes of the BPA was law of the case.
Id. at 52–53.
    After addressing the question of law of the case with
regard to Athey II, the Court of Federal Claims turned to
the government’s motion for summary judgment. The
court began by considering principles of sovereign immun-
ity. Those principles are well-settled.




     7 On appeal, Appellants do not challenge the ruling
of the Court of Federal Claims on the law-of-the-case
issue.
ATHEY   v. UNITED STATES                                    11



    “The United States, as sovereign, is immune from suit
save as it consents to be sued.” United States v. Sher-
wood, 312 U.S. 584, 586 (1941). Further, “[a] waiver of
the Federal Government’s sovereign immunity must be
unequivocally expressed in statutory text, and will not be
implied. Moreover, a waiver of the Government’s sover-
eign immunity will be strictly construed, in terms of its
scope, in favor of the sovereign.” Lane v. Pena, 518 U.S.
187, 192 (1996) (citations omitted). Arising from this
latter principle is the corollary “no-interest rule[,] . . . to
the effect that interest cannot be recovered in a suit
against the Government in the absence of an express
waiver of sovereign immunity from an award of interest.”
Library of Congress v. Shaw, 478 U.S. 310, 311 (1986);
Doyle v. United States, 931 F.2d 1546, 1550 (Fed. Cir.
1991). “Thus,” the Court of Federal Claims observed, “the
waiver [of sovereign immunity] as to interest must be
separate from the waiver as to underlying liability.”
Athey III, 123 Fed. Cl. at 54 (first citing Shaw, 478 U.S. at
314; then citing England v. Contel Adv. Sys., Inc., 384
F.3d 1372, 1379 (Fed. Cir. 2004)). The court concluded
that “while it is plain that the lump-sum payment statute
lacks a waiver [of sovereign immunity] for pre-judgment
interest, the question remains whether the Back Pay Act
might provide the requisite waiver based on the facts of
this case.” Id. at 55 (citations omitted). Noting that
interest under the BPA could be available to Appellants if
the statutory requirements were met, the Court of Feder-
al Claims turned to the task of “analyz[ing] liability under
the [BPA] element by element.” Id.
    The Court of Federal claims noted that the BPA al-
lows interest on an amount payable to “[a]n employee of
an agency who . . . is found by appropriate authority . . . to
have been affected by an unjustified or unwarranted
personnel action which ha[s] resulted in the withdrawal or
reduction of all or part of the pay, allowances, or differen-
tials of the employee.” Id. at 55 (quoting 5 U.S.C.
12                                   ATHEY   v. UNITED STATES



§ 5596(b)(1)(A), (2)(A)). The court found that, for the
reasons set forth in Athey II, Appellants met the defini-
tion of “employee” for purposes of the BPA. Id. at 55–56
(citing Athey II, 108 Fed. Cl. at 620–22). The court also
found that, for purposes of the BPA, it (the Court of
Federal Claims) was an “appropriate authority” to consid-
er Appellants’ claims that they had suffered an unjusti-
fied or unwarranted personnel action by being improperly
deprived of supplemental lump-sum payments for annual
leave. Id. at 57. In addition, the court found that the “the
government’s failure to properly calculate lump-sum
payments for annual leave qualifies as an ‘unjustified or
unwarranted personnel action’ within the meaning of the
[BPA].” Id. at 59.
    However, referring to Appellants, the Court of Federal
Claims stated that “[e]ven if plaintiffs qualify as ‘employ-
ee[s]’ who suffered an ‘unjustified or unwarranted per-
sonnel action,’ they can only recover under the Back Pay
Act if they also establish that the result was a ‘withdraw-
al or reduction of all or part of [their] pay, allowances, or
differentials.’” Athey III, 123 Fed. Cl. at 59 (quoting 5
U.S.C. § 5596(b)(1)). The court, citing DeOcampo v.
Department of the Army, 551 F. App’x 1000, 1003 (Fed.
Cir. 2014), noted that the Federal Circuit has held that
lump-sum payments for annual leave do not qualify as
“pay, allowances, or differentials” for purposes of the BPA
based upon the OPM revisions to the BPA regulations
that took effect in 2000. Id. at 59. The court pointed out,
though, that the Federal Circuit has not “directly consid-
ered whether the lump-sum payment for annual leave
qualified as ‘pay, allowances, or differentials’ before
[the] . . . 2000 amendments took effect.” Id.
    Ultimately, the Court of Federal Claims determined
that it could not conclude that Appellants’ lump-sum
payments fell within the BPA’s definition of “pay, allow-
ances, or differentials.” Id. at 61. The court rested its
determination on several grounds.
ATHEY   v. UNITED STATES                                 13



     The court began by examining American Federation of
Government Employees, AFL-CIO v. United States, 622 F.
Supp. 1109, 1115 (N.D. Ga. 1984), aff’d sub nom. Am.
Fed’n of Gov’t Employees v. United States, 780 F.2d 720
(Fed. Cir. 1986). Id. at 59–60. In that case, the United
States District Court for the Northern District of Georgia
considered “whether the lump-sum payment for military
leave,” payable under 37 U.S.C. § 501(b)(1), “constitute[d]
deferred compensation, or [was] an ancillary fringe bene-
fit afforded to persons employed by the military.” 622 F.
Supp. at 1115. Recognizing the similarities between
§ 501(b)(1) and the civilian equivalent at 5 U.S.C.
§ 5551(a), the district court compared the two statutes
and concluded that they both authorized “a benefit, and
not deferred compensation, to government and military
employees.” 123 Fed. Cl. at 59–60. First, the district
court noted that, per the terms of § 5551(a), a lump-sum
payment is “pay for taxation purposes only.” Id. Second,
the district court pointed out that both § 501(b)(1) and
§ 5551(a) provide that the lump-sum amount may be paid
only upon discharge or separation and that, in that sense,
both statutes are unlike salary. Id. And third, the dis-
trict court observed that “[b]oth statutes provide limita-
tions, 37 U.S.C. § 501(b)(3) (payment for no more than
sixty days); 5 U.S.C. § 5551(a) (period of leave not extend-
ed due to post-separation holiday),” and that salary is not
generally subject to such limitations or potential for
reduction. See id.
    The Court of Federal Claims also considered the deci-
sion of the Court of Claims in Polos v. United States, 231
Ct. Cl. 929 (1982). Athey III, 123 Fed. Cl. at 60. In Polos,
the Court of Claims ruled that the plaintiff before it was
not entitled to recover under the BPA for lost opportuni-
ties to life and disability insurance because these were not
“allowance[s]” to which he was entitled while an employ-
ee. 231 Ct. Cl. at 931. In arriving at its decision, the
court reasoned that lost opportunities for insurance
14                                  ATHEY   v. UNITED STATES



benefits “fall[ ] within the general category of claims for
the monetary equivalent of annual leave, or for per diem
expenses, or for interest, which have been denied in other
cases as not being lost ‘pay, allowances, or differentials’
the employee would have earned, but for the wrongful
personnel action.” Athey III, 123 Fed. Cl. at 60 (quoting
Polos, 231 Ct. Cl. at 931).
    Next, the Court of Federal Claims turned to the 1981
OPM regulations, which broadly define “pay, allowances,
or differentials” as “monetary and employment benefits to
which an employee is entitled by statute or regulation by
virtue of the performance of a Federal function.” See 5
C.F.R. § 550.803 (1981). The court noted that, in com-
ments accompanying the 1981 regulations, “OPM express-
ly excluded retirement benefits, but made no mention of
lump-sum payments (either including them or excluding
them from ‘pay, allowances or differentials’).” Athey III,
123 Fed. Cl. at 60; see also 46 Fed. Reg. at 58,271–72.
The court observed that Athey II “construed this silence
and potential ambiguity in favor of including lump-sum
payments within the BPA.” 123 Fed. Cl. at 60. The court
continued, however, that, “on further reflection, . . . the
better interpretation excludes lump sums from coverage
under the BPA.” Id. “Under well-established principles
of sovereign immunity,” the court stated, “waivers of
sovereign immunity cannot be implied, and ambiguities
must be construed in favor of the United States.” Id.
    The Court of Federal Claims concluded its analysis by
stating that the BPA “itself distinguishes annual leave
and the lump-sum payment for annual leave from ‘pay,
allowances, and differentials.’” Id. In that regard, the
back payment of “pay, allowances, and differentials” is
covered in 5 U.S.C. § 5596(b)(1)(A)(i). That provision
authorizes a monetary benefit in “an amount equal to all
or any part of the pay, allowances, or differentials, as
applicable which the employee normally would have
earned or received during the period if the personnel
ATHEY   v. UNITED STATES                                 15



action had not occurred.” Payments due under paragraph
(b)(1)(A)(i) “shall be payable with interest.” 5 U.S.C.
§ 5596(b)(2)(A). Annual leave lost as a result of an ad-
verse personnel action, on the other hand, is addressed in
a separate paragraph, at 5 U.S.C. § 5596(b)(1)(B). That
paragraph “authorizes a re-crediting or restoration of that
leave to an employee’s leave account following correction
of the adverse personnel action if the individual is still
employed, or a lump-sum payment for annual leave
pursuant to the lump-sum payment statute if and when
[the individual] separate[s] from federal civilian service.
Athey III, 123 Fed. Cl. at 61. “No interest is authorized on
payments of [that] lump sum,” the court pointed out. Id.
    Having explained why it could not conclude that Ap-
pellants’ lump-sum payments fell within the BPA’s defini-
tion of “pay, allowances or differentials,” the court stated
that, “since plaintiffs fail to meet one of the essential
criteria for relief under the Back Pay Act, their claim for
interest under the BPA must fail.” Id. Accordingly, the
court entered summary in favor of the government on
Appellants’ claim for interest under the BPA. Id. at 62.
     In due course, the class and the government negotiat-
ed a settlement agreement providing that the government
would pay “one-hundred percent (100%) of the govern-
ment’s estimated exposure of back lump-sum pay as
calculated by the VA.” J.A. 5. The settlement amount
included COLAs, Locality Pay Adjustments, and differen-
tial Sunday premium pay owed to the class members. It
did not, however, include evening and weekend “addition-
al pay” under 38 U.S.C. § 7453(a). Nor did it include
interest under the BPA on their LSPA claims. After
conducting a fairness hearing, the Court of Federal
Claims approved the agreement on June 28, 2017, and on
June 30, the court entered final judgment. J.A. 1–11.
16                                   ATHEY   v. UNITED STATES



    Appellants now appeal from the Court of Federal
Claims’s final judgment insofar as it incorporates the
court’s decisions in Athey I and Athey III.
                        DISCUSSION
                             I.
                    Standard of Review
    In Athey I, the Court of Federal Claims granted the
government’s motion to dismiss pursuant to RCFC
12(b)(6). “This court reviews the grant of a motion to
dismiss de novo.” Call Henry, Inc. v. United States, 855
F.3d 1348, 1354 (Fed. Cir. 2017) (citing Bell/Heery v.
United States, 739 F.3d 1324, 1330 (Fed. Cir. 2014)). “To
survive a motion to dismiss, a complaint must contain
sufficient factual allegations that, if true, would ‘state a
claim to relief that is plausible on its face.’” Id. (quoting
Bell/Heery, 739 F.3d at 1330). “The court must accept
well-pleaded factual allegations as true and must draw all
reasonable inferences in favor of the claimant.” Id.
    In Athey III, the Court of Federal Claims granted the
government’s cross-motion for summary judgment. “We
review a grant of summary judgment by the Court of
Federal Claims de novo.” FastShip, LLC v. United States,
892 F.3d 1298, 1302 (Fed. Cir. 2018) (quoting Wells Fargo
& Co. v. United States, 827 F.3d 1026, 1032 (Fed. Cir.
2016)). Summary judgment is appropriate “if the movant
shows that there is no genuine dispute as to any material
fact and the movant is entitled to judgment as a matter of
law.” Id. (quoting RCFC 56(a)). In this case, the perti-
nent facts are not in dispute. Consequently, our sole task
on review is to determine whether, in granting the gov-
ernment’s cross-motion, the Court of Federal Claims erred
as a matter of law. We review the Court of Federal
Claims’s legal conclusions de novo. Shell Oil Co. v. United
States, 896 F.3d 1299, 1306 (Fed. Cir. 2018) (citing John
ATHEY   v. UNITED STATES                                  17



R. Sand & Gravel Co. v. United States, 457 F.3d 1345,
1353 (Fed. Cir. 2006) aff’d, 552 U.S. 130 (2008)).
   We address in turn the issues of evening and weekend
additional pay and interest under the BPA.
                             II.
           Evening and Weekend Additional Pay
                             A.
    Appellants contend that the LSPA mandates that a
lump-sum payment for unused annual leave “shall equal”
the entire compensation an employee would have received
while at work until the expiration of his or her leave.
Appellants Br. 14–21. In that connection, Appellants
argue that additional pay is part of an employee’s entire
compensation. Id. at 46–52. Thus, Appellants urge, to
equal the compensation they would have received, the
government must pay them evening and weekend addi-
tional pay. Id.
    Appellants also argue that a lump-sum payment un-
der the LSPA should include “additional pay” for evening
and weekend work because of the interplay between 5
U.S.C. § 5551(a) and 38 U.S.C. § 7453(i). As they did in
the Court of Federal Claims, Appellants argue that the
term “pay” in § 5551(a) is not limited to “basic pay” (refer-
enced in § 7453(i)), but also includes premium pay.
According to Appellants, neither § 5551(a) nor § 7453(i)
contemplates that the generic term “pay” found in the
LSPA should not include additional pay. Appellants Br.
49–50.
     The government responds that Appellants are not en-
titled to have “additional pay” included in their lump-sum
payments. It argues that the “plain language and legisla-
tive history of 38 U.S.C. [§] 7453(i) clearly indicate[ ]
Congress’s intention to limit the lump sum pay of title 38
and hybrid employees by excluding ‘additional pay.’”
18                                    ATHEY   v. UNITED STATES



Gov’t Br. 39. In addition, the government urges that, in
the event of any conflict between § 5551 of title 5 and
§ 7453(i) of title 38, the latter controls, because Congress
has made clear that title 38 overrides title 5 unless oth-
erwise stated. See 38 U.S.C. § 7425(b) (“Notwithstanding
any other provision of law, no provision of title 5 or any
other law pertaining to the civil service system which is
inconsistent with any provision of section 7306 of this title
or this chapter shall be considered to supersede, override,
or otherwise modify such provision of that section or this
chapter except to the extent that such provision of title 5
or of such other law specifically provides, by specific
reference to a provision of this chapter, or such provision
to be superseded, overridden, or otherwise modified.”).
                             B.
     The pertinent rules of statutory construction are well-
settled. “Our review of questions of statutory interpreta-
tion is de novo, except to the extent deference to an agen-
cy’s construction of a statute it administers is required
under the two-step analysis set forth in Chevron . . . .”
NSK Ltd. v. United States, 390 F.3d 1352, 1354 (Fed. Cir.
2004) (citing Chevron, U.S.A., Inc. v. Nat. Res. Def. Coun-
cil, Inc., 467 U.S. 837, 842–43 (1984)); see also Vassallo v.
Dep’t of Def., 797 F.3d 1327, 1330 (Fed. Cir. 2015) (ex-
plaining that we generally review an agency’s statutory
interpretation using the two-pronged framework estab-
lished by Chevron). The first prong of Chevron requires
us to assess “whether Congress has directly spoken to the
precise question at issue”; if so, we “must give effect to the
unambiguously expressed intent of Congress.” Chevron,
467 U.S. at 842–43. If the statute does not answer the
precise question at issue, however, meaning that it is
“silent or ambiguous,” then, under prong two of Chevron,
we must determine whether the agency provided “a
permissible construction of the statute.” Id. at 843;
Hymas v. United States, 810 F.3d 1312, 1318 (Fed. Cir.
2016). In this case, the “precise question at issue” is
ATHEY   v. UNITED STATES                                   19



whether “additional pay” under 38 U.S.C. § 7453(a) in the
form of evening and weekend pay under § 7453(b) and (c)
is to be included in lump sum payments under 5 U.S.C.
§ 5551(a). “If the statute is clear and unambiguous, then
the plain meaning of the statute is generally conclusive,
and we give effect to the unambiguously expressed intent
of Congress.” Indian Harbor Ins. Co. v. United States, 704
F.3d 949, 954 (2013) (citing Sullivan v. Stroop, 496 U.S.
478, 482 (1990)). We agree with the parties that, in this
case, the statutory language is clear as to “the precise
question at issue,” so that resorting to step two of Chevron
is not necessary.
     It is undisputed that the evening and weekend pay
that Appellants seek constitute “additional pay” under 38
U.S.C. § 7453(a), (b), (c). Section 7453(i), in turn, express-
ly states that “[a]ny additional pay paid pursuant to
[§ 7453] shall not be considered as basic pay for the pur-
poses of [5 U.S.C. § 5551 (the LSPA)].” This language is
clear. As the Court of Federal Claims stated in Curry v.
United States, “Congress has ‘with clarity’ determined via
section 7453(i) that lump-sum separation pay should not
include additional pay.” 66 Fed. Cl. 593, 600 (2005),
(quoting Lanehart v. Horner, 818 F.2d 1574, 1582 (Fed.
Cir. 1987)). Appellants’ argument that we should draw a
distinction between “basic pay” in § 7453(i) and “pay” in 5
U.S.C. § 5551 and thereby prevent the application of
§ 7453(i)’s bar to their case is unavailing. Not only is the
argument not supported by the statutory language, but it
is contrary to the pertinent legislative history:
    [Section 7453(i)] provides that additional pay un-
    der this new subsection will not count as basic
    compensation for lump-sum leave payments, sev-
    erance pay, and other benefits relating to basic
    compensation.
H.R.Rep. No. 93-368, at 1708 (1973), reprinted in 1973
U.S.C.C.A.N. 1688, 1708, 1973 WL 12602.
20                                  ATHEY   v. UNITED STATES



    In sum, the plain language of 38 U.S.C. §7453(i) com-
pels the conclusion that Appellants are not entitled to
have evening and weekend “additional pay” included in
their lump-sum payments under the LSPA.
                            III.
                  Pre-Judgment Interest
                            A.
    Appellants contend that lump-sum payments consti-
tute “pay, allowances, or differentials” for purposes of the
BPA and its provision for pre-judgment interest. Appel-
lants argue that the legislative history of the BPA demon-
strates that Congress acted to ensure that federal
employees wrongly deprived of compensation through
unwarranted or unjustified personnel action be made
entirely “whole” as if the unlawful action had never
happened. See Appellants Br. 22–23 (citing Restoration of
Excess Annual Leave Lost Due to Certain Personnel
Action: Hearing Before the Subcomm. on Retirement and
Employee Benefits of the H. Comm. on Post Office and
Civil Service, 94th Cong. 1–2 (1975)). Appellants also
argue that Congress has come to realize that being made
“whole” includes interest on any back pay awarded. See
Appellants Br. 26–27 (quoting H. Comm. on Post Office
and Civil Service, 96th Cong. Legislative History of the
Civil Service Reform Act of 1978, Vol. I at 697–98, 1054
(Comm. Print 1979) (“As revised by the bill, section
5596(b)(1) of title 5 entitles the employee to the recovery
of an amount equal to all or any part of the pay, allowanc-
es, or differentials, as applicable[,] that the employee
normally would have earned or received if the personnel
action had not occurred, less any amounts earned by him
through other employment during that period[,] plus
interest on the amount payable.”)); see also 5 C.F.R.
§ 550.803 (1981).
ATHEY   v. UNITED STATES                                 21



     Appellants further contend that OPM’s 1981 regula-
tions support their claim. As seen, the regulation set
forth at 5 C.F.R. § 550.803 defined “[p]ay, allowances, and
differentials” to mean “monetary and employment bene-
fits to which an employee is entitled by statute or regula-
tion by virtue of the performance of a Federal function.”
46 Fed. Reg. 58,275 (1981). Appellants argue that the
1981 regulation demonstrates that OPM interpreted the
BPA as “making the employee financially whole,” which
includes interest on lump-sum payments. Appellants Br.
28 (quoting 5 C.F.R. § 550.801), 42–43. Appellants urge
that the Court of Federal Claims should have deferred to
OPM’s interpretation of the terms “pay, allowances, and
differentials” under Chevron step two. Id. at 33–40. The
relevant interpretation, according to Appellants, is in-
cluded in the 1981 regulations that defined “pay” much
more broadly than the 2000 revisions, so as to include
lump-sum payments. Id. at 38–39.
    The government responds that the BPA itself bars the
payment of interest on lump-sum payments for accrued
and unused leave. Gov’t Br. 11–13. The government
points to the fact that the LSPA expressly states that a
lump-sum payment is considered pay for taxation purpos-
es only, and urges that any conflict between the LSPA
and BPA should be resolved by using the LSPA’s specific
reference to “lump sum” over the BPA’s general use of
“pay.” Id. at 14–15. To the extent that the BPA’s lan-
guage is ambiguous about whether lump-sum payments
are included in its coverage, the government argues,
Appellants’ claim must fail because, as Athey III stated,
123 Fed. Cl. at 54–55, a waiver of sovereign immunity to
consent to being sued cannot be ambiguous. Gov’t Br. 19–
20 (citing Shaw, 478 U.S. at 318). Finally, while the
government agrees with Appellants that OPM’s 1981
regulation is entitled to Chevron deference, it asserts that
OPM “has consistently defined [pay, allowances, and
22                                  ATHEY   v. UNITED STATES



differentials] to exclude post-retirement payments such as
‘lump sum payments for accrued annual leave.’” Id. at 23.
    In the alternative, the government argues that Appel-
lants are not entitled to interest on their lump-sum pay-
ments because the BPA covers only “employees” who have
been subjected to “unjustified or unwarranted personnel
actions.” According to the government, Appellants do not
qualify as “employees” under the statute. Id. at 27–34.
                            B.
    We hold that the Court of Federal Claims did not err
in ruling that Appellants are not entitled to pre-judgment
interest on the lump-sum payments they received for
accrued and unused leave. As the Court of Federal
Claims recognized, the starting point in the analysis is
the proposition that “[t]he United States, as sovereign, is
immune from suit save as it consents to be sued.” Sher-
wood, 312 U.S. at 586. Moreover, “[a] waiver of the
Federal Government’s sovereign immunity must be
unequivocally expressed in statutory text and will not be
implied.” Lane, 518 U.S. at 192 (citations omitted).
Finally, as the Court of Federal Claims also recognized,
pertinent to this case is the “no-interest rule,” which
states that “interest cannot be recovered in a suit against
the Government in the absence of an express waiver of
sovereign immunity from an award of interest,” Shaw,
478 U.S. at 311. We agree with the Court of Federal
Claims that neither the LSPA nor the BPA provides the
required waiver of sovereign immunity for Appellants’
claims for interest on their lump-sum payments.
   To begin with, the LSPA plainly and unambiguously
supports the Court of Federal Claims’s conclusion that
Appellants’ lump-sum payments are not “pay” under the
BPA. See Athey III, 123 Fed. Cl. at 52. As the Court of
Federal Claims pointed out in the portion of Athey III in
which it declined to accord law-of-the-case deference to
Athey II, see id. at 51, the LSPA states that only for the
ATHEY   v. UNITED STATES                                   23



purposes of taxation will lump-sum payments be consid-
ered pay. In this case, the critical word “only” appears at
the end of the pertinent sentence in § 5551(a). Thus, the
unambiguous meaning is that for any purposes other than
taxation, a lump-sum payment is not considered pay, a
point Appellants conceded before the Court of Federal
Claims. Athey III, 123 Fed. Cl. at 51. There is no other
way to read the statute; this reading is conclusive. And
since the BPA is not for purposes of taxation, a lump-sum
payment is not considered “pay” under that statute, as the
Court of Federal Claims found.
    Neither does the BPA itself provide the express waiv-
er of sovereign immunity required for an award of interest
on Appellants’ lump-sum payments. Though the Court of
Federal Claims found that the language of the LSPA
makes it clear that a lump-sum payment does not consti-
tute “pay” for purposes of the BPA, the court nevertheless
examined both the BPA and OPM’s 1981 regulations in
order to determine whether, for purposes of the BPA,
Appellants could establish that they had suffered a “with-
drawal or reduction of all or part of [their] pay, allowances
or differentials.” 123 Fed. Cl. at 59. We have recited at
length the court’s analysis.
     As discussed above, the BPA waives sovereign im-
munity as to interest when “[a]n employee of an agen-
cy . . . is found by appropriate authority . . . to have been
affected by an unjustified or unwarranted personnel
action which has resulted in the withdrawal or reduction
of all or part of the pay, allowances, or differentials of the
employee.” 5 U.S.C. § 5596(b)(1)(A), (2)(A) (emphasis
added). Assuming without deciding that Appellants meet
the requirements of “employee,” “appropriate authority,”
and “unjustified personnel action,” we agree with the
Court of Federal Claims that they fail to meet the re-
quirement of “withdrawal or reduction of all or part of
[their] pay, allowances, or differentials.” Quite simply, as
the court’s thorough analysis demonstrates, there is
24                                  ATHEY   v. UNITED STATES



nothing in the BPA that reveals the required express
waiver of sovereign immunity for an award of interest on
Appellants’ lump-sum payments. Appellants’ reliance on
general legislative history statements is misplaced. These
statements cannot alter the fact that the express waiver
required in the statutory language is missing. See Lane,
518 U.S. at 192 (“A statute’s legislative history cannot
supply a waiver that does not appear clearly in any statu-
tory text.”); United States v. Nordic Vill., Inc., 503 U.S.
30, 37 (1992) (“[T]he ‘unequivocal expression’ of elimina-
tion of sovereign immunity that we insist upon is an
expression in the statutory text. If clarity does not exist
there, it cannot be supplied by a committee report.”); De
Archibold v. United States, 499 F.3d 1310, 1313–14 (Fed.
Cir. 2007) (“We cannot resort to the legislative history to
find a waiver not otherwise unequivocally expressed in
the statute.”).
    Also misplaced is Appellants’ reliance on its view of
OPM’s 1981 regulation defining “pay, allowances, and
differentials.” Language in a regulation cannot take the
place of the statutory language needed in order to meet
the requirement of an express waiver of sovereign immun-
ity. “Only an express statute suffices to waive the sover-
eign immunity of the United States.” Former Emps. of
Quality Fabricating, Inc. v. U.S. Sec’y of Labor, 448 F.3d
1351, 1354 (Fed. Cir. 2006) (emphasis added) (citing West
v. Gibson, 527 U.S. 212, 217 (1999)).
    In any event, even if the 1981 regulation could, as a
matter of law, provide the required waiver, it fails to do
so. We agree with the Court of Federal Claims in Athey
III that while the 1981 OPM regulation defined “pay,
allowances, or differentials” broadly, a broad definition
cannot overcome the settled requirement that waivers of
sovereign immunity be explicit, with any ambiguity
construed in favor of the United States. See Shaw, 478
U.S. at 318. In this case, since the 1981 regulation never
explicitly mentioned lump-sum payments either way, we
ATHEY   v. UNITED STATES                               25



construe that ambiguity in favor of the United States and
conclude that the regulation did not authorize the pay-
ment of BPA interest.
    In sum, since Appellants’ lump-sum payments do not
constitute “pay, allowances, or differentials,” Appellants
have failed to demonstrate the required waiver of sover-
eign immunity. We therefore affirm the Court of Federal
Claims’s holding that the United States is not liable for
pre-judgment interest under the BPA.
                           CONCLUSION
     For the foregoing reasons, the decisions of the Court
of Federal Claims in Athey I and Athey III, as incorpo-
rated in the court’s final judgment of June 30, 2017, are
affirmed.
                           AFFIRMED
                             COSTS
   No costs.
