This is the applicable law.
50 U.S. Code § 1809 - Criminal sanctions
(a) Prohibited activities
A person is guilty of an offense if he intentionally—
(1) engages in electronic surveillance under color of law except as authorized by this chapter, chapter 119, 121, or 206 of title 18, or any express statutory authorization that is an additional exclusive means for conducting electronic surveillance under section 1812 of this title;
An offense described in this section is punishable by a fine of not more than $10,000 or imprisonment for not more than five years, or both.https://www.law.cornell.edu/uscode/text/50/1809