40 CFR §209.22

1. (a)Further discovery under this section shall be undertaken only upon order of the administrative law judge or upon agreement of the parties, except as provided in § 209.21. The administrative law judge shall order further discovery only after determining:
   1. (1)That such discovery will not delay the proceeding unreasonably;
   2. (2)That the information to be obtained is not obtainable voluntarily; and
   3. (3)That such information is relevant to the subject matter of the hearing.
2. (b)The administrative law judge shall order depositions upon oral questions only upon a showing of good cause and a finding that:
   1. (1)The information sought cannot be obtained by alternative methods; or
   2. (2)There is a substantial reason to believe that relevant and probative evidence may otherwise not be preserved for presentation by a witness at the hearing.
3. (c)Any party to the proceeding may make a motion or motions for an order of discovery. The motion shall set forth:
   1. (1)The circumstances which require the discovery;
   2. (2)The nature of the information expected to be discovered; and
   3. (3)The proposed time and place where it will be taken. If the administrative law judge determines the motion should be granted, he or she shall issue an order for the taking of such discovery together with the conditions and terms thereof.
4. (d)A person's or party's failure to comply with a discovery order may lead to the inference that the information to be discovered is adverse to the person or party who failed to provide it.