45 CFR §1149.50

1. (a)Except as provided in paragraph (b) of this section, testimony at the hearing must be given orally by witnesses under oath or affirmation.
2. (b)At the discretion of the ALJ, testimony may be admitted in the form of a written statement or deposition.
   1. (1)Any such statement must be provided to all other parties along with the last known address of such witness, in a manner which allows sufficient time for other parties to subpoena the witness for cross-examination at the hearing.
   2. (2)Prior written statements of witnesses proposed to testify at the hearing and deposition transcripts must be exchanged.
3. (c)The ALJ must exercise reasonable control over the mode and order of interrogating witnesses and presenting evidence so as to:
   1. (1)Make the interrogation and presentation effective for ascertaining the truth;
   2. (2)Avoid needless consumption of time; and
   3. (3)Protect witnesses from harassment and undue embarrassment.
4. (d)The ALJ must permit the parties to conduct such cross examination as may be required for a full and true disclosure of the facts.
5. (e)At the discretion of the ALJ, a witness may be cross examined on matters relevant to the proceeding without regard to the scope of his or her direct examination. To the extent permitted by the ALJ, cross-examination on matters outside the scope of direct examination must be conducted in the manner of direct examination. Leading questions may be used only if the witness is a hostile witness, an adverse party, or a witness identified with an adverse party.