18 U.S. Code § 2705 - Delayed notice
(a)Delay of Notification.—
(1) A governmental entity acting under section 2703(b) of this title may—
where a court order is sought, include in the application a request, which the court shall grant, for an order delaying the notification required under section 2703(b) of this title for a period not to exceed ninety days, if the court determines that there is reason to believe that notification of the existence of the court order may have an adverse result described in paragraph (2) of this subsection; or
where an administrative subpoena authorized by a Federal or State statute or a Federal or State grand jury subpoena is obtained, delay the notification required under section 2703(b) of this title for a period not to exceed ninety days upon the execution of a written certification of a supervisory official that there is reason to believe that notification of the existence of the subpoena may have an adverse result described in paragraph (2) of this subsection.
(2) An adverse result for the purposes of paragraph (1) of this subsection is—
Extensions of the delay of notification provided in section 2703 of up to ninety days each may be granted by the court upon application, or by certification by a governmental entity, but only in accordance with subsection (b) of this section.
(5) Upon expiration of the period of delay of notification under paragraph (1) or (4) of this subsection, the governmental entity shall serve upon, or deliver by registered or first-class mail to, the customer or subscriber a copy of the process or request together with notice that—
(B) informs such customer or subscriber—
that information maintained for such customer or subscriber by the service provider named in such process or request was supplied to or requested by that governmental authority and the date on which the supplying or request took place;
what governmental entity or court made the certification or determination pursuant to which that delay was made; and
As used in this subsection, the term “supervisory official” means the investigative agent in charge or assistant investigative agent in charge or an equivalent of an investigating agency’s headquarters or regional office, or the chief prosecuting attorney or the first assistant prosecuting attorney or an equivalent of a prosecuting attorney’s headquarters or regional office.
(b)Preclusion of Notice to Subject of Governmental Access.—A governmental entity acting under section 2703, when it is not required to notify the subscriber or customer under section 2703(b)(1), or to the extent that it may delay such notice pursuant to subsection (a) of this section, may apply to a court for an order commanding a provider of electronic communications service or remote computing service to whom a warrant, subpoena, or court order is directed, for such period as the court deems appropriate, not to notify any other person of the existence of the warrant, subpoena, or court order. The court shall enter such an order if it determines that there is reason to believe that notification of the existence of the warrant, subpoena, or court order will result in—