5 CFR § 1201.72 - Explanation and scope of discovery.
(a) Explanation. Discovery is the process, apart from the hearing, by which a party may obtain relevant information, including the identification of potential witnesses, from another person or a party, that the other person or party has not otherwise provided. Relevant information includes information that appears reasonably calculated to lead to the discovery of admissible evidence. This information is obtained to assist the parties in preparing and presenting their cases. The Federal Rules of Civil Procedure may be used as a general guide for discovery practices in proceedings before the Board. Those rules, however, are instructive rather than controlling.
(b) Scope. Discovery covers any nonprivileged matter that is relevant to the issues involved in the appeal, including the existence, description, nature, custody, condition, and location of documents or other tangible things, and the identity and location of persons with knowledge of relevant facts. Discovery requests that are directed to nonparties and nonparty Federal agencies and employees are limited to information that appears directly material to the issues involved in the appeal.
(c) Methods. Parties may use one or more of the methods provided under the Federal Rules of Civil Procedure. These methods include written interrogatories to parties, depositions, requests for production of documents or things for inspection or copying, and requests for admission.
(1) The discovery sought is cumulative or duplicative, or is obtainable from some other source that is more convenient, less burdensome, or less expensive;
(2) The party seeking discovery has had sufficient opportunity by discovery in the action to obtain the information sought; or
(3) The burden or expense of the proposed discovery outweighs its likely benefit.