45 C.F.R. § 615.5

(a) No employee may produce official records and information or provide any testimony in response to a demand or request unless authorized to do so by the General Counsel in accordance with this part.

(b) The General Counsel, in his or her discretion, may grant an employee permission to testify or produce official records and information in response to a demand or request. In making this decision, the General Counsel shall consider whether:

(1) The purposes of this part are met;

(2) Allowing such testimony or production of records would be necessary to prevent a miscarriage of justice;

(3) NSF has an interest in the decision that may be rendered in the legal proceeding; and

(4) Allowing such testimony or production of records would be in the best interest of NSF or the United States.

(c) If authorized to testify pursuant to this part, an employee may testify as to facts within his or her personal knowledge, but, unless specifically authorized to do so by the General Counsel, shall not:

(1) Disclose confidential or privileged information;

(2) Testify as to facts when the General Counsel determines such testimony would not be in the best interest of the Foundation or the United States; or

(3) Testify as an expert or opinion witness with regard to any matter arising out of the employee's official duties or the functions of the Foundation.