A Government authority may request financial records under pursuant to a formal written request only if—
((1)) no administrative summons or subpena authority reasonably appears to be available to that Government authority to obtain financial records for the purpose for which such records are sought;
((2)) the request is authorized by regulations promulgated by the head of the agency or department;
((3)) there is reason to believe that the records sought are relevant to a legitimate law enforcement inquiry; and
((4))
((A)) a copy of the request has been served upon the customer or mailed to his last known address on or before the date on which the request was made to the financial institution together with the following notice which shall state with reasonable specificity the nature of the law enforcement inquiry:
((B)) ten days have expired from the date of service or fourteen days from the date of mailing of the notice by the customer and within such time period the customer has not filed a sworn statement and an application to enjoin the Government authority in an appropriate court, or the customer challenge provisions of have been complied with.
