Departmental units are hereby 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 the Assistant Secretary or Deputy Under Secretary heading the Departmental unit requesting the records, or by a senior agency official designated by the head of the Departmental unit. Officials so designated shall not delegate this authority to others;

(d) The request adheres to the requirements set forth in § 19.4; 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 where no notice is required (e.g., section 1113(g)).