18 U.S. Code § 1736. Restrictive use of information

(a)
No information or evidence obtained by reason of compliance by a natural person with any provision of section 3010 of title 39, or regulations issued thereunder, shall, except as provided in subsection (c) of this section, be used, directly or indirectly, as evidence against that person in a criminal proceeding.
(b)
The fact of the performance of any act by an individual in compliance with any provision of section 3010 of title 39, or regulations issued thereunder, shall not be deemed the admission of any fact, or otherwise be used, directly or indirectly, as evidence against that person in a criminal proceeding, except as provided in subsection (c) of this section.
(c)
Subsections (a) and (b) of this section shall not preclude the use of any such information or evidence in a prosecution or other action under any applicable provision of law with respect to the furnishing of false information.
Effective Date

Section effective on first day of sixth month which begins after Aug. 12, 1970, see section 15(b) of Pub. L. 91–375, set out as a note preceding section 101 of Title 39, Postal Service.