Okla. Stat. tit. 76, § 84

DISCOVERY; USE OF MATERIALS. A. Trust claims materials and trust governance documents shall be presumed to be relevant and authentic, subject to the Rules of Evidence governing admissibility. Any party may present trust claims materials to prove alternative causation for a plaintiff's injuries or to allocate liability for the plaintiff's injury. No claims of privilege may apply to trust claims materials or trust governance documents. B. A defendant in a personal injury claim may seek discovery against a personal injury trust identified under Section 3 of this act. The plaintiff may not claim privilege or confidentiality to bar discovery under this subsection and shall provide consent or other expression of permission that may be required by the personal injury trust to release information and materials sought by the defendant.