45 CFR §1174.19

1. (a)Parties may conduct the following types of discovery:
   1. (1)Requests for production of documents for inspection and copying;
   2. (2)Requests for admissions of authenticity of any relevant document or of the truth of any relevant fact;
   3. (3)Written interrogatories; and
   4. (4)Depositions.
2. (b)For the purpose of this section, the term “documents” includes information, documents, reports, answers, records, accounts, papers, and other data and documentary evidence. Nothing contained herein shall be interpreted to require the creation of a document.
3. (c)Unless the parties mutually agree to discovery, a party may conduct discovery only as ordered by the ALJ. The ALJ shall regulate the timing of discovery.
4. (d)Each party shall bear its own discovery costs.