                                                      [DO NOT PUBLISH]


             IN THE UNITED STATES COURT OF APPEALS
                                                                FILED
                     FOR THE ELEVENTH CIRCUIT
                                                U.S. COURT OF APPEALS
                       ________________________   ELEVENTH CIRCUIT
                                                            January 5, 2006
                              No. 05-12857                THOMAS K. KAHN
                          Non-Argument Calendar               CLERK
                        ________________________

                    D. C. Docket No. 04-00055-CV-4-RH

TINA CASTILLO,

                                                           Petitioner-Appellant,

                                   versus

FEDERAL CORRECTIONAL INSTITUTION OF TALLAHASSEE,

                                                                    Respondent,

JOSE VAZQUEZ,

                                                         Respondent-Appellee.

                        ________________________

                 Appeal from the United States District Court
                     for the Northern District of Florida
                       _________________________

                             (January 5, 2006)

Before DUBINA, BLACK and HULL, Circuit Judges.

PER CURIAM:
      Federal prisoner Tina Castillo appeals the district court’s denial of her 28

U.S.C. § 2241 petition for writ of habeas corpus seeking credit against her federal

sentence for time served prior to the imposition of her federal sentence. The

district court did not err, and we affirm.

      In reviewing the denial of a habeas petition, we review the district court’s

factual findings for clear error and review de novo the court’s interpretation of a

statute. Rodriguez v. Lamer, 60 F.3d 745, 747 (11th Cir. 1995). Regarding the

BOP’s decisions concerning the award of credit for time served

      the judiciary retains the final authority on matters of constitutionality
      and statutory construction. Where an administrating agency’s
      construction of a statute is at issue, however, a deferential two-step
      process of review had been established. First, if congressional
      purpose is clear, then interpreting courts and administrative agencies
      must give effect to the unambiguously expressed intent of Congress.
      A second level of review, however, is triggered when the statute is
      silent or ambiguous with respect to the specific issue. Where an
      administrating agency has interpreted the statute, a reviewing court is
      bound by the Chevron rule of deference. A court may not substitute
      its own construction of a statutory provision for a reasonable
      interpretation by an administrating agency. Agency interpretation is
      reasonable and controlling unless it is arbitrary, capricious, or
      manifestly contrary to the statute. Thus, we defer to an agency’s
      reasonable interpretation of a statute it is charged with administering.

 Id. (internal quotations, citations, and footnote omitted).




                                             2
      Section 3585(b) provides:

      A defendant shall be given credit toward the service of a term of
      imprisonment for any time he has spent in official detention prior to
      the date the sentence commences–

             (1) as a result of the offense for which the sentence was
             imposed; or

             (2) as a result of any other charge for which the defendant was
             arrested after the commission of the offense for which the
             sentence was imposed;

      that has not been credited against another sentence.

18 U.S.C. § 3585(b). District courts are not authorized to compute a credit at

sentencing. United States v. Wilson, 112 S. Ct. 1351, 1354 (1992).

      The district court did not err in denying Castillo’s petition because she was

not entitled to credit for time served. Pursuant to the clear terms of § 3585(b), a

defendant can receive credit for time served only if the specified time period has

not been credited against another sentence. See 18 U.S.C. § 3585(b). Castillo does

not dispute the Iowa state court gave her credit against her state sentence for the

period of August 20, 2000, through November 20, 2001. Because this time period

was credited against another sentence, Castillo was not entitled to a second credit




                                           3
against her federal sentence. See Wilson, 112 S. Ct. at 1355-1356 (stating

Congress made clear in § 3585 a defendant could not receive a double credit for his

detention time).

      AFFIRMED.




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