37 C.F.R. § 41.150 – Discovery.

(a) Limited discovery. A party is not entitled to discovery except as authorized in this subpart. The parties may agree to discovery among themselves at any time.
(b) Automatic discovery.
1. (1) Within 21 days of a request by an opposing party, a party must:
  1. (i) Serve a legible copy of every requested patent, patent application, literature reference, and test standard mentioned in the specification of the party's involved patent or application, or application upon which the party will rely for benefit, and, if the requested material is in a language other than English, a translation, if available, and
  2. (ii) File with the Board a notice (without copies of the requested materials) of service of the requested materials.
2. (2) Unless previously served, or the Board orders otherwise, any exhibit cited in a motion or in testimony must be served with the citing motion or testimony.
(c) Additional discovery.
1. (1) A party may request additional discovery. The requesting party must show that such additional discovery is in the interests of justice. The Board may specify conditions for such additional discovery.
2. (2) When appropriate, a party may obtain production of documents and things during cross examination of an opponent's witness or during testimony authorized under § 41.156.