12 U.S.C. § 3420

(a) Financial records about a customer obtained from a financial institution pursuant to a subpena issued under the authority of a Federal grand jury— (1) shall be returned and actually presented to the grand jury unless the volume of such records makes such return and actual presentation impractical in which case the grand jury shall be provided with a description of the contents of the records.; 1 1 So in original. (2) shall be used only for the purpose of considering whether to issue an indictment or presentment by that grand jury, or of prosecuting a crime for which that indictment or presentment is issued, or for a purpose authorized by rule 6(e) of the Federal Rules of Criminal Procedure, or for a purpose authorized by section 3412(a) of this title ; (3) shall be destroyed or returned to the financial institution if not used for one of the purposes specified in paragraph (2); and (4) shall not be maintained, or a description of the contents of such records shall not be maintained by any Government authority other than in the sealed records of the grand jury, unless such record has been used in the prosecution of a crime for which the grand jury issued an indictment or presentment or for a purpose authorized by rule 6(e) of the Federal Rules of Criminal Procedure. (b) (1) No officer, director, partner, employee, or shareholder of, or agent or attorney for, a financial institution shall, directly or indirectly, notify any person named in a grand jury subpoena served on such institution in connection with an investigation relating to a possible— (A) crime against any financial institution or supervisory agency or crime involving a violation of the Controlled Substance Act [ 21 U.S.C. 801 et seq.], the Controlled Substances Import and Export Act [ 21 U.S.C. 951 et seq.], section 1956, 1957, or 1960 of title 18, sections 5313, 5316, 5322, 5324, 5331, and 5332 of title 31, or section 6050I of title 26 ; or (B) conspiracy to commit such a crime, about the existence or contents of such subpoena, or information that has been furnished to the grand jury in response to such subpoena. (2) Section 1818 of this title and section 1786(k)(2) of this title shall apply to any violation of this subsection.