32 CFR 97.11: Procedures—expert or opinion testimony.

(a) Personnel may not present expert or opinion testimony involving official information, except when:

(1) The testimony is presented on behalf of the United States, a Federal agency, or any party represented by the Department of Justice.

(2) The chief legal advisor of the DoD Component with primary equity has granted special written approval upon a showing of exceptional need or unique circumstances, but only if the anticipated testimony is not adverse to the interests of the DoD or the United States and is presented at no expense to the Government.

(b) If a court orders the presentation of testimony disallowed by paragraph (a) of this section, personnel must respectfully decline to comply with the court's order unless the chief legal advisor directs otherwise.