49 CFR 604.38: Discovery.

(a) Permissible forms of discovery shall be within the discretion of the PO.

(b) The PO shall limit the frequency and extent of discovery permitted by this section if a party shows that:

(1) The information requested is cumulative or repetitious;

(2) The information requested may be obtained from another less burdensome and more convenient source;

(3) The party requesting the information has had ample opportunity to obtain the information through other discovery methods permitted under this section; or

(4) The method or scope of discovery requested by the party is unduly burdensome or expensive.