28 U.S.C. § 2253 : US Code - Section 2253: Appeal

      (a) In a habeas corpus proceeding or a proceeding under section
    2255 before a district judge, the final order shall be subject to
    review, on appeal, by the court of appeals for the circuit in which
    the proceeding is held.
      (b) There shall be no right of appeal from a final order in a
    proceeding to test the validity of a warrant to remove to another
    district or place for commitment or trial a person charged with a
    criminal offense against the United States, or to test the validity
    of such person's detention pending removal proceedings.
      (c)(1) Unless a circuit justice or judge issues a certificate of
    appealability, an appeal may not be taken to the court of appeals
    from - 
        (A) the final order in a habeas corpus proceeding in which the
      detention complained of arises out of process issued by a State
      court; or
        (B) the final order in a proceeding under section 2255.

      (2) A certificate of appealability may issue under paragraph (1)
    only if the applicant has made a substantial showing of the denial
    of a constitutional right.
      (3) The certificate of appealability under paragraph (1) shall
    indicate which specific issue or issues satisfy the showing
    required by paragraph (2).