49 C.F.R. § 837.4

(a) Production prohibited unless approved. Except in the case of the material referenced in § 837.3, no employee or former employee of NTSB shall, in response to a demand of a private litigant, court, or other authority, produce any material contained in the files of the NTSB (whether or not agency records under 5 U.S.C. 552) or produce any material acquired as part of the performance of the person's official duties or because of the person's official status, without the prior written approval of the General Counsel.

(b) Procedures to be followed for the production of material under this paragraph. (1) All demands for material shall be submitted to the General Counsel at NTSB headquarters, Washington, DC 20594. If an employee receives a demand, he shall forward it immediately to the General Counsel.

(2) Each demand must contain an affidavit by the party seeking the material or his attorney setting forth the material sought and its relevance to the proceeding, and containing a certification, with support, that the information is not available from other sources, including Board materials described in §§ 837.3 and part 801 of this chapter.

(3) In the absence of General Counsel approval of a demand, the employee is not authorized to comply with the demand.

(4) The General Counsel shall advise the requester of approval or denial of the demand, and may attach whatever conditions to approval considered appropriate or necessary to promote the purposes of this part. The General Counsel may also permit exceptions to any requirement in this part when necessary to prevent a miscarriage of justice, or when the exception is in the best interests of the NSTB and/or the United States.