 United States Court of Appeals
     for the Federal Circuit
            ______________________

 SALMA ACEVEDO, JAIME A. ALVARADO, PETER
   J. APPELT, JOHN BILOTTI, JR., WILLIAM W.
   BRADLEY, JEFFREY BRODACK, JOHNNY R.
     CISNEROS, PIERRE DE BONO, JAMES E.
    DEZENDORF, ROBERT DOBIECKI, CESAR
   ESPEJO, TARA FIONDA, LISA FOOSE, JUAN
        ANTONIO GALLARDO, CATHERINE
   GIARRAPUTO, SERGIO PIMENTA GODINHO,
   BRIAN HERLIHY, CRISTOBAL HERNANDEZ,
 TRACEY HILL, CHERYL LISE JACOBO, DAVID F.
  JONES, DAVID R. KAISER, DAVID LANDERER,
      ANDREW J. LONG, RICHARD J. LORIA,
  JEANNETTE POZO, GUILLERMO C. SALOMON,
JESSICA ALFRED, ADELA T. ARGUELLO, MARITA
      BAEZ, DANIEL E. BAUTISTA, PABLO R.
   CARDENAS, OLGA L. CASEY, CHRISTINE M.
    COOPER, TOMMY L. COOPER, GEORGE O.
DORADO, KEITH R. DURHAM, JOSEFINA FARIAS,
    KENNETH P. KELLY, RAYMOND F. KNOPP,
 TAMARA T. LACY, FRANK MADDALENA, RALPH
  MARTINEZ, CLAUDIA MONISTROL, RAYMOND
      MONZON, RAYMOND MORABITO, TODD
 NICHOLAS, KAREN O'NEILL, THOMAS O'SHEA,
  DENNYSON F. PADILLA, JOSE E. PORRONDO,
 JEANNINE PERNICIARO, CHRISTINE POWERS,
EMA QYTEZA, DEBORAH ANN REINOA, GONZALO
    REINOSA, JOHN RIOMAO, DULCE MARIA
    RODRIGUEZ, KARLA RODRIGUEZ, KERRI
   ROONEY, NORMAN A. ROY, GEORGE RUDY,
   DEBRA K. RUTTER, JACQUELINE SALAMON,
    MICHAEL B. SAUER, KENNETH J. SCOTT,
 CHARLES SHEGOG, LINDA SHOUPE, MICHAEL
2                                          ACEVEDO   v. US



   SILVA, STACEY SIMON, ADRIAN SMITH,
MICHAEL J. SMITH, RONALD M. SMITH, PHILLIP
THOMPSON, PETER TOUHY, WAYNE T. WILSON,
     JOHN F. YOUNG, ROBERT ZYLSTRA,
             Plaintiffs-Appellants

                           v.

                  UNITED STATES,
                  Defendant-Appellee
                ______________________

                      2015-5126
                ______________________

    Appeal from the United States Court of Federal
Claims in No. 1:11-cv-00768-EDK, Judge Elaine Kaplan.
                 ______________________

                 Decided: June 9, 2016
                ______________________

    JULES BERNSTEIN, Bernstein & Lipsett, P.C., Wash-
ington, DC, argued for plaintiffs-appellants. Also repre-
sented by LINDA LIPSETT; EDGAR N. JAMES, James &
Hoffman, P.C., Washington, DC.

    LAUREN MOORE, Commercial Litigation Branch, Civil
Division, United States Department of Justice, Washing-
ton, DC, for defendant-appellee. Also represented by
BENJAMIN C. MIZER, ROBERT E. KIRSCHMAN, JR., REGINALD
T. BLADES, JR.
                 ______________________

Before PROST, Chief Judge, LOURIE and TARANTO, Circuit
                       Judges.
PROST, Chief Judge.
ACEVEDO   v. US                                         3



    Plaintiffs-Appellants Salma Acevedo et al. (“Appel-
lants”) allege that the United States violated 5 U.S.C.
§ 5928 by refusing to provide them with danger pay
allowances.     The Court of Federal Claims (“Claims
Court”) held that it lacked jurisdiction over the case
because § 5928 and its implementing regulations are not
money-mandating, as required for the court to possess
jurisdiction under the Tucker Act, 28 U.S.C. § 1491(a)(1).
Acevedo v. United States, 121 Fed. Cl. 57, 59 (2015). For
the reasons stated below, we affirm the Claims Court’s
ruling.

                      BACKGROUND
    The Appellants in this case are employed by the U.S.
Customs and Border Protection, Department of Homeland
Security (“CBP”), as present and former Supply Chain
Security Specialists in its Customs-Trade Protection
Against Terrorism (“C-TPAT”) program. The purpose of
the C-TPAT program is to improve the security of the
importation of goods into the United States. Pursuant to
this mission, C-TPAT employees, including the Appellants
in this case, travel and work at foreign posts designated
by the Secretary of State as “danger pay posts” in an
attempt to prevent terrorists and terrorist weapons from
entering the United States.
    In Count I of their complaint against the government,
the Appellants alleged that they did not receive overtime
pay as required by the Fair Labor Standards Act and thus
sought back pay, liquidated damages, attorney fees and
other relief pursuant to 29 U.S.C. § 216(b). In Count II,
the Appellants alleged violations of 5 U.S.C. § 5928,
contending that CBP refused to provide them with danger
pay allowances for work performed in posts of duty that
the Department of State has designated as eligible for
such allowances.
4                                             ACEVEDO   v. US



   Section 5928 (“the danger pay statute”) is part of the
Overseas Differentials and Allowances Act of 1960
(“ODAA” or “the Act”). Section 5928 provides as follows:
    An employee serving in a foreign area may be
    granted a danger pay allowance on the basis of
    civil insurrection, civil war, terrorism, or wartime
    conditions which threaten physical harm or im-
    minent danger to the health or well-being of the
    employee. A danger pay allowance may not exceed
    35 percent of the basic pay of the employee, except
    that if an employee is granted an additional dif-
    ferential under section 5925(b) of this title with
    respect to an assignment, the sum of that addi-
    tional differential and any danger pay allowance
    granted to the employee with respect to that as-
    signment may not exceed 35 percent of the basic
    pay of the employee. The presence of nonessential
    personnel or dependents shall not preclude pay-
    ment of an allowance under this section. In each
    instance where an allowance under this section is
    initiated or terminated, the Secretary of State
    shall inform the Speaker of the House of Repre-
    sentatives and the Committee on Foreign Rela-
    tions of the Senate of the action taken and the
    circumstances justifying it.
5 U.S.C. § 5928 (emphasis added).
    Pursuant to Executive Order No. 10,903, the Presi-
dent delegated to the Secretary of State the authority to
promulgate regulations governing the payment of allow-
ances under § 5928. Exec. Order No. 10,903, 26 Fed. Reg.
217 (Jan. 9, 1961); see also Department of State Standard-
ized Regulations (“DSSR”) §§ 011(a), 650. The regulations
state that the “danger pay allowance prescribed in Chap-
ter 650 may be granted to employees defined in Section
040i.” DSSR § 031.2 (emphasis added).
ACEVEDO   v. US                                             5



   The DSSR also prescribes the basis for danger pay al-
lowance:
   A danger pay allowance is established by the Sec-
   retary of State when, and only when, civil insur-
   rection, civil war, terrorism or wartime conditions
   threaten physical harm or imminent danger to the
   health or well being of a majority of employees of-
   ficially stationed or detailed at a post or coun-
   try/area in a foreign area. To determine whether
   the situation meets the danger pay criteria, a post
   usually must submit the Danger Pay Factors
   Form (FS–578) along with pertinent supporting
   information to the Department of State (Office of
   Allowances) for review. The Director of the Office
   of Allowances will chair a working group which
   will make a recommendation to the Assistant Sec-
   retary of State for Administration concerning a
   danger pay designation.
DSSR § 653.1. Moreover, section 013 of the DSSR, enti-
tled “Authority of Head of Agency,” provides, in relevant
part:
   When authorized by law, the head of an agency
   may defray official residence expenses for, and
   grant . . . danger pay . . . to an employee of his/her
   agency and require an accounting therefor, sub-
   ject to the provisions of these regulations and the
   availability of funds. Within the scope of these
   regulations, the head of an agency may issue such
   further implementing regulations as he/she may
   deem necessary for the guidance of his/her agency
   with regard to the granting of and accounting for
   these payments.
    The government moved to dismiss Count II of the Ap-
pellants’ complaint, contending that the Claims Court
lacks jurisdiction on the grounds that 5 U.S.C. § 5928 is
not a money-mandating statute, that the DSSR is not
6                                            ACEVEDO   v. US



money-mandating, and that CBP has not adopted a policy
of paying danger pay to all eligible employees. The
Claims Court agreed with the government and granted its
motion to dismiss Count II. The Claims Court then
granted the Appellants’ motion pursuant to Court of
Federal Claims Rule 54(b) and entered final judgment
with respect to the danger pay claim. The Appellants
timely appealed to us.

                       DISCUSSION
    We review de novo the Claims Court’s decision to
dismiss a case for lack of subject matter jurisdiction.
Bianchi v. United States, 475 F.3d 1268, 1273 (Fed. Cir.
2007). The Appellants bear the burden of establishing the
court’s jurisdiction by a preponderance of the evidence.
Trusted Integration, Inc. v. United States, 659 F.3d 1159,
1163 (Fed. Cir. 2011). “In determining jurisdiction, a
court must accept as true all undisputed facts asserted in
the plaintiff’s complaint and draw all reasonable infer-
ences in favor of the plaintiff.” Id.
    The Tucker Act provides the Claims Court with juris-
diction over claims “against the United States founded
either upon the Constitution or any Act of Congress or
any regulation of an executive department, or upon any
express or implied contract with the United States or for
liquidated or unliquidated damages in cases not sounding
in tort.” 28 U.S.C. § 1491(a)(1). However, the Tucker Act
is “only a jurisdictional statute; it does not create any
substantive right enforceable against the United States
for money damages.” United States v. Testan, 424 U.S.
392, 398 (1976). “Instead, to invoke jurisdiction under the
Tucker Act, a plaintiff must identify a contractual rela-
tionship, constitutional provision, statute, or regulation
that provides a substantive right to money damages.”
Khan v. United States, 201 F.3d 1375, 1377 (Fed. Cir.
2000).
ACEVEDO   v. US                                          7



    Here, the Appellants argue that “[t]he CBP policy and
practice of paying danger pay to its employees, the rele-
vant statutory provisions of 5 U.S.C. §§ 5921–5928, their
legislative history, and the provisions of the DSSR serve
to establish 5 U.S.C. § 5928 to be money-mandating.”
Appellants’ Br. 11–12. As the Claims Court properly
determined, however, the Appellants are incorrect.
    In a thorough and well-reasoned decision, the Claims
Court concluded that the danger pay statute and the
DSSR, taken individually or together, are merely money-
authorizing and not money-mandating. Acevedo, 121 Fed.
Cl. at 63–66. The Claims Court also determined that the
Appellants had “failed to establish the existence of agency
regulations or a formal agency policy by which all em-
ployees eligible to receive danger pay allowances under
the DSSR must be provided such allowances.” Id. at 66.
We agree.
    The Appellants rely on the purpose and legislative
history of § 5928 to argue that it is money-mandating.
They acknowledge that § 5928 says that “[a]n employee
serving in a foreign area may be granted a danger pay
allowance” but they argue that this is a case where the
presumption that “may” means money-authorizing and
not money-mandating can be rebutted. For support, the
Appellants cite to Doe v. United States where we held that
the moiety statute—which authorizes the Secretary of the
Treasury to compensate informants in customs investiga-
tions with a portion of the recovery—is money-mandating,
even though the statute uses the word “may.” 100 F.3d
1576, 1582 (Fed. Cir. 1996); 19 U.S.C. § 1619(a) (2000)
(stating that “the Secretary may award and pay such
person an amount that does not exceed 25 percent of the
net amount so recovered”). But in Doe, we specifically
noted that we were not “writ[ing] on a clean slate,” and
explained that prior cases had interpreted the moiety
statute as requiring some award, although it left to the
Secretary’s discretion the amount of the award. 100 F.3d
8                                             ACEVEDO   v. US



at 1582. We also relied on our understanding that Con-
gress did not intend to vest complete discretion with the
Secretary in awarding the compensation. Id. Here, we do
not have the same legislative history or understanding
that § 5928 was intended to require some type of danger
payment, and only the amount was up to the discretion of
the agency.
    Indeed, that is precisely what we concluded in Roberts
v. United States, 745 F.3d 1158, 1162 (Fed. Cir. 2014).
Looking at the same Act and evaluating similar argu-
ments, we determined that § 5928, standing alone, is not
money-mandating. We also determined that the DSSR is
not money-mandating, at least with respect to living
quarters allowances (“LQA”). Id. at 1164–65. Much of
the same analysis from Roberts is applicable here. For
example, in Roberts, we noted that section 013 of the
DSSR contemplates further regulations, because it states:
    When authorized by law, the head of an agency
    may defray official residence expenses for, and
    grant . . . [danger pay and LQA] . . . to an employ-
    ee of his/her agency . . . . Within the scope of
    these regulations, the head of an agency may issue
    such further implementing regulations as he/she
    may deem necessary for the guidance of his/her
    agency with regard to the granting of and account-
    ing for these payments.
DSSR § 013 (emphasis added). Similarly, the definition of
“employee” in the danger pay and LQA regulations con-
templates further regulations, stating: “‘Employee’ means
an individual . . . who is . . . eligible for allowances and
differential under subchapter 030 . . . as determined by
relevant agency authority.” DSSR § 040(i)(4) (emphasis
added).
    The Appellants contend that the danger pay regula-
tions are different from the LQA regulations in key ways,
such that our conclusion in Roberts is not applicable here.
ACEVEDO   v. US                                            9



The Appellants argue that in the case of danger pay,
unlike LQA, the eligibility requirements are “fully and
completely set forth in the DSSR and no further imple-
menting regulations or agency decisions are needed or
contemplated.” Appellants’ Br. 39–40. But the Appel-
lants fail to specifically indicate the differences between
the regulatory schemes that would support that broad
proposition. In contrast, as the government notes, the
LQA provisions and danger pay provisions are “equally
detailed.” Appellee’s Br. 24. For example, the DSSR
provides the specific costs that LQA is designed to cover,
DSSR § 131.3 (“LQA rates are designed to cover substan-
tially all of the rent, heat, light, fuel, gas, electricity,
water, taxes . . . insurance, and agent’s fee . . . .”); what
qualifies as “rent” under the provision, DSSR § 131.2;
when and how LQA grants commence, DSSR § 132.1;
when and how LQA grants terminate, DSSR § 132.4; how
to determine the LQA rate, DSSR § 134; and how LQA is
paid, DSSR § 135. Notably, what is not in the DSSR is
any requirement that LQA be paid; instead the regula-
tions merely set forth a framework for LQA when an
agency exercises its discretion to provide such allowances.
That is equally true for the danger pay allowance. Thus,
our conclusion in Roberts that § 5928 and the DSSR
“standing alone, are only money-authorizing, not money-
mandating,” is also applicable in this case. 745 F.3d at
1162.
    Finally, the Appellants argue that the CBP has an
unwritten policy of paying danger pay and that policy, in
conjunction with the statute and regulations, confers
Tucker Act jurisdiction. They note that in Roberts, alt-
hough we concluded that § 5928 and the DSSR were not
money-mandating, we nonetheless ultimately held that
the Claims Court had jurisdiction over the case. We
relied on the fact that there were “[f]urther implementing
regulations,” id. at 1160, which, together with the statute
10                                            ACEVEDO   v. US



and DSSR, were “fairly construed as money-mandating,”
id. at 1166. Here, we have no such regulations.
    The Appellants point only to a number of letters and
emails from various officials—including CBP’s Assistant
Commissioner for Legislative Affairs, individuals from
CBP’s Office of Congressional Affairs, and individuals
from CBP’s Office of Human Resources Management—
which state that CBP provides danger pay to all eligible
employees. But as the Claims Court noted, “[a]t best”
these letters show “that CBP has had a practice of provid-
ing such pay to employees, in at least some cases, upon
the request of their supervisors.” Acevedo, 121 Fed. Cl. at
66. The Appellants have not, however “identified any
agency-wide policy or directive that requires supervisors
to request such allowances for employees who meet the
State Department’s eligibility criteria.” Id. Moreover,
such letters and emails are not akin to formal agency
rules or binding written directives and therefore cannot
constitute a “source of substantive law [that] can fairly be
interpreted as mandating compensation by the Federal
Government for the damages sustained.” United States v.
Mitchell, 463 U.S. 206, 218 (1983).
    Because § 5928, the DSSR, and the alleged unwritten
policy of providing danger pay, cannot reasonably be
construed as “money-mandating,” we conclude that the
Appellants have failed to establish jurisdiction over their
complaint.
                       CONCLUSION
   For the foregoing reasons, we affirm the Claims
Court’s dismissal for lack of subject matter jurisdiction.
                       AFFIRMED
