Sec.  1.331   Who may sign and issue.

   Subpenas requiring the attendance and testimony of witnesses, and subpenas
   requiring the production of any books, papers, schedules of charges,
   contracts, agreements, and documents relating to any matter under
   investigation or hearing, may be signed and issued as follows:

   (a) Hearings before the Commission en banc, an individual commissioner, or a
   panel of commissioners: By any commissioner participating in the conduct of
   the hearing.

   (b) Hearings before an administrative law judge: By the administrative law
   judge or, in his absence, by the Chief Administrative Law Judge.