7 CFR §1.331

1. (a)Except as provided in paragraph (b) of this section, testimony at the hearing shall 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. Any such written 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 such witness for cross-examination at the hearing. Prior written statements of witnesses proposed to testify at the hearing and deposition transcripts shall be exchanged as provided in § 1.322(g) of this part.
3. (c)The ALJ shall permit the parties to conduct such cross-examination as may be required for a full and true disclosure of the facts.
4. (d)A witness may be cross-examined on any matter relevant to the proceeding without regard to the scope of his or her direct examination.
5. (e)Upon motion of any party, the ALJ shall order witnesses excluded so that they cannot hear the testimony of other witnesses. This rule does not authorize exclusion of—
   1. (1)A party who is an individual;
   2. (2)In the case of a party that is not an individual, an officer or employee of the party designated by the representative; or
   3. (3)An individual whose presence is shown by a party to be essential to the presentation of its case, including an individual employed by the USDA engaged in assisting the representative for USDA.