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Title 18, Crimes and Criminal ProcedureRelease 119-110

§3121 General Prohibition on Pen Register and Trap and Trace Device Use; Exception

Title 18 › PART II — CRIMINAL PROCEDURE › CHAPTER 206 — PEN REGISTERS AND TRAP AND TRACE DEVICES › § 3121

Last updated Sep 22, 2026|Official source

Summary

People may not install or use a pen register or trap and trace device without a court order under section 3123, an order under the Foreign Intelligence Surveillance Act of 1978 (50 U.S.C. 1801 et seq.), or a foreign government order tied to an executive agreement the Attorney General certifies meets section 2523. Communication providers may still use these devices to run, maintain, or test systems, to protect their rights, property, or users, to log that a call or message began or ended to prevent fraud, or when a user agrees. Government agencies must use available technology that only collects dialing, routing, addressing, and signaling information and must not record the contents of communications. Anyone who knowingly breaks the rule about needing an order can be fined, jailed for up to one year, or both.

Full Legal Text

Title 18, §3121

Crimes and Criminal Procedure, Source: USLM XML via OLRC

(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.

Legislative History

Notes & Related Subsidiaries

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].”

Reference

Citations & Metadata

Citation

18 U.S.C. § 3121

Title 18, Crimes and Criminal Procedure

Last Updated

Sep 22, 2026

Release point: 119-110