Departmental units are authorized to request financial records of any customer from a financial institution pursuant to a formal written request under the Act only if:

(a) No administrative summons or subpoena authority reasonably appears to be available to the Departmental unit to obtain financial records for the purpose for which the records are sought;

(b) There is reason to believe that the records sought are relevant to a legitimate law enforcement inquiry and will further that inquiry;

(c) The request is issued by a supervisory official of a rank designated by the head of the requesting Departmental unit. The officials so designated shall not delegate this authority to others;

(d) The request adheres to the requirements set forth in § 47.4; and

(e) The notice requirements set forth in section 1108(4) of the Act, or the requirements pertaining to delay of notice in section 1109 of the Act, are satisfied, except in situations (e.g., section 1113(g)) where no notice is required.