Section 4.1042 - Who may testify?(a) Except as provided in paragraph (b) of this section, each party may present as witnesses the following persons only:(1) Persons who qualify as expert witnesses; and(2) OFA staff who participated in the preparation of the negative proposed finding, except that if the OFA employee is a senior Department employee, any party other than OFA must first obtain a subpoena for that employee under § 4.1035 .(b) The ALJ may authorize testimony from witnesses in addition to those identified in paragraph (a) of this section only under extraordinary circumstances.