Us Code § 3121 - General prohibition on pen register and trap and trace device use; exception

Full text of Us Code United States Code § 3121 — General prohibition on pen register and trap and trace device use; exception, with citation guidance and answers to common questions.

§ 3121. General prohibition on pen register and trap and trace device use; exception

(a) In General.—Except as provided in this section, no person may install or use a pen register or a trap and trace device without first obtaining a court order under section 3123 of this title or under the Foreign Intelligence Surveillance Act of 1978 (50 U.S.C. 1801 et seq.) or an order from a foreign government that is subject to an executive agreement that the Attorney General has determined and certified to Congress satisfies section 2523.

(b) Exception.—The prohibition of subsection (a) does not apply with respect to the use of a pen register or a trap and trace device by a provider of electronic or wire communication service—

(1) relating to the operation, maintenance, and testing of a wire or electronic communication service or to the protection of the rights or property of such provider, or to the protection of users of that service from abuse of service or unlawful use of service; or

(2) to record the fact that a wire or electronic communication was initiated or completed in order to protect such provider, another provider furnishing service toward the completion of the wire communication, or a user of that service, from fraudulent, unlawful or abusive use of service; or (3) where the consent of the user of that service has been obtained.


(c) Limitation.—A government agency authorized to install and use a pen register or trap and trace device under this chapter or under State law shall use technology reasonably available to it that restricts the recording or decoding of electronic or other impulses to the dialing, routing, addressing, and signaling information utilized in the processing and transmitting of wire or electronic communications so as not to include the contents of any wire or electronic communications.

(d) Penalty.—Whoever knowingly violates subsection (a) shall be fined under this title or imprisoned not more than one year, or both.

(Added Pub. L. 99–508, title III, §301(a), Oct. 21, 1986, 100 Stat. 1868; amended Pub. L. 103–414, title II, §207(b), Oct. 25, 1994, 108 Stat. 4292; Pub. L. 107–56, title II, §216(a), Oct. 26, 2001, 115 Stat. 288; Pub. L. 115–141, div. V, §104(3)(A), Mar. 23, 2018, 132 Stat. 1217.)


Editorial Notes

References in Text

The Foreign Intelligence Surveillance Act of 1978, referred to in subsec. (a), is Pub. L. 95–511, Oct. 25, 1978, 92 Stat. 1783, which is classified principally to chapter 36 (§1801 et seq.) of Title 50, War and National Defense. For complete classification of this Act to the Code, see Short Title note set out under section 1801 of Title 50 and Tables.

Amendments

2018—Subsec. (a). Pub. L. 115–141 inserted before period at end "or an order from a foreign government that is subject to an executive agreement that the Attorney General has determined and certified to Congress satisfies section 2523".

2001—Subsec. (c). Pub. L. 107–56 inserted "or trap and trace device" after "pen register" and ", routing, addressing," after "dialing" and substituted "the processing and transmitting of wire or electronic communications so as not to include the contents of any wire or electronic communications" for "call processing".

1994—Subsecs. (c), (d). Pub. L. 103–414 added subsec. (c) and redesignated former subsec. (c) as (d).


Statutory Notes and Related Subsidiaries

Effective Date

Pub. L. 99–508, title III, §302, Oct. 21, 1986, 100 Stat. 1872, provided that:

"(a) In General.—Except as provided in subsection (b), this title and the amendments made by this title [enacting this chapter and section 1367 of this title] shall take effect ninety days after the date of the enactment of this Act [Oct. 21, 1986] and shall, in the case of conduct pursuant to a court order or extension, apply only with respect to court orders or extensions made after this title takes effect.

"(b) Special Rule for State Authorizations of Interceptions.—Any pen register or trap and trace device order or installation which would be valid and lawful without regard to the amendments made by this title shall be valid and lawful notwithstanding such amendments if such order or installation occurs during the period beginning on the date such amendments take effect and ending on the earlier of—

"(1) the day before the date of the taking effect of changes in State law required in order to make orders or installations under Federal law as amended by this title; or

"(2) the date two years after the date of the enactment of this Act [Oct. 21, 1986]."

About This Section

18 U.S.C. § 3121 is part of Title 18 of the United States Code. The United States Code is the official codification of federal statutes maintained by the Office of the Law Revision Counsel of the U.S. House of Representatives. Congress amends the Code through new public laws, which are eventually incorporated into the relevant title.

This section may be cited in legal writing as 18 U.S.C. § 3121. For the most current official text, including any recent amendments, use the official source links below. Do not rely on this page as the sole authority for legal citation or litigation.

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Sources

Source: official Us Code text · Last verified 2026-08-27

Frequently Asked Questions About Us Code § 3121

What does United States Code § 3121 cover?

Section 3121 ("General prohibition on pen register and trap and trace device use; exception") is part of the United States Code, the codified statutory law of Us Code. It sets out the legal rule or procedure described in the text above. Statutes are amended regularly, so always verify against the official source.

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Is this the official text of Us Code law?

No. This page is for research and education and may not include the most recent amendments. For official current law, check the Us Code official source linked on this page or consult a licensed Us Code attorney.

How does Us Code § 3121 apply to my situation?

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Sources & Verification

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