Section 104.23 - Expert or opinion testimony(a)(1) If the General Counsel authorizes an employee to give testimony in a legal proceeding not involving the United States, the testimony, if otherwise proper, shall be limited to facts within the personal knowledge of the employee. Employees, with or without compensation, shall not provide expert testimony in any legal proceedings regarding Office information, subjects, or activities except on behalf of the United States or a party represented by the United States Department of Justice.(2) The General Counsel may authorize an employee to appear and give the expert or opinion testimony upon the requester showing, pursuant to § 104.3 of this part, that exceptional circumstances warrant such testimony and that the anticipated testimony will not be adverse to the interest of the Office or the United States.(b)(1) If, while testifying in any legal proceeding, an employee is asked for expert or opinion testimony regarding Office information, subjects, or activities, which testimony has not been approved in advance in writing in accordance with the regulations in this subpart, the witness shall:(i) Respectfully decline to answer on the grounds that such expert or opinion testimony is forbidden by this subpart;(ii) Request an opportunity to consult with the General Counsel before giving such testimony; and(iii) Explain that upon such consultation, approval for such testimony may be provided.(2) If the tribunal conducting the proceeding then orders the employee to provide expert or opinion testimony regarding Office information, subjects, or activities without the opportunity to consult with the General Counsel, the employee shall respectfully refuse to provide such testimony, citing United States ex rel. Touhy v. Ragen, 340 U.S. 462 (1951).(c) If an employee is unaware of the regulations in this subpart and provides expert or opinion testimony regarding Office information, subjects, or activities in a legal proceeding without the aforementioned consultation, the employee shall, as soon after testifying as possible, inform the General Counsel that such testimony was given and provide a written summary of the expert or opinion testimony provided.(d)Proceeding where the United States is a party. In a proceeding in which the United States is a party or is representing a party, an employee may not testify as an expert or opinion witness for any party other than the United States.