5 U.S.C. § 7513 : US Code - Section 7513: Cause and procedure

      (a) Under regulations prescribed by the Office of Personnel
    Management, an agency may take an action covered by this subchapter
    against an employee only for such cause as will promote the
    efficiency of the service.
      (b) An employee against whom an action is proposed is entitled to
    - 
        (1) at least 30 days' advance written notice, unless there is
      reasonable cause to believe the employee has committed a crime
      for which a sentence of imprisonment may be imposed, stating the
      specific reasons for the proposed action;
        (2) a reasonable time, but not less than 7 days, to answer
      orally and in writing and to furnish affidavits and other
      documentary evidence in support of the answer;
        (3) be represented by an attorney or other representative; and
        (4) a written decision and the specific reasons therefor at the
      earliest practicable date.

      (c) An agency may provide, by regulation, for a hearing which may
    be in lieu of or in addition to the opportunity to answer provided
    under subsection (b)(2) of this section.
      (d) An employee against whom an action is taken under this
    section is entitled to appeal to the Merit Systems Protection Board
    under section 7701 of this title.
      (e) Copies of the notice of proposed action, the answer of the
    employee when written, a summary thereof when made orally, the
    notice of decision and reasons therefor, and any order effecting an
    action covered by this subchapter, together with any supporting
    material, shall be maintained by the agency and shall be furnished
    to the Board upon its request and to the employee affected upon the
    employee's request.