34 C.F.R. § 81.16 – Discovery.

(a) The parties to a case are encouraged to exchange relevant documents and information voluntarily.
(b) The ALJ, at a party's request, may order compulsory discovery described in paragraph (c) of this section if the ALJ determines that—
1. (1) The order is necessary to secure a fair, expeditious, and economical resolution of the case;
2. (2) The discovery requested is likely to elicit relevant information with respect to an issue in the case;
3. (3) The discovery request was not made primarily for the purposes of delay or harassment; and
4. (4) The order would serve the ends of justice.
(c) If a compulsory discovery is permissible under paragraph (b) of this section, the ALJ may order a party to do one or more of the following:
1. (1) Make relevant documents available for inspection and copying by the party making the request.
2. (2) Answer written interrogatories that inquire into relevant matters.
3. (3) Have depositions taken.
(d) The ALJ may issue a subpoena to enforce an order described in this section and may apply to the appropriate court of the United States to enforce the subpoena.
(e) The ALJ may not compel the discovery of information that is legally privileged.
(f)
1. (1) The ALJ limits the period for discovery to not more than 90 days but may grant an extension for good cause.
2. (2) At a party's request, the ALJ may set a specific schedule for discovery.
  (Authority: 20 U.S.C. 1234(f)(1) and (g))