--- title: "18 U.S.C. 3121 ECPA: General prohibition on pen register and trap and trace device use; exception" canonical: "https://dposchool.com/ecpa/section/3121" source: "https://uscode.house.gov/us/usc/119-136/t18/s3121/" source_note: "Source: United States Code, title 18, published by the Office of the Law Revision Counsel of the U.S. House of Representatives (uscode.house.gov), release point 119-136. The editorial and statutory notes are not reproduced. Source: United States Code, title 18, published by the Office of the Law Revision Counsel of the U.S. House of Representatives (uscode.house.gov), release point 119-136. The editorial and statutory notes are not reproduced. Source: United States Code, title 18, published by the Office of the Law Revision Counsel of the U.S. House of Representatives (uscode.house.gov), release point 119-136. The editorial and statutory notes are not reproduced." text_as_of: "2026-10-22" language: "en" publisher: "DPO School" --- 18 U.S.C. 3121 ECPA · Chapter 206: PEN REGISTERS AND TRAP AND TRACE DEVICES # 18 U.S.C. 3121 ECPA: General prohibition on pen register and trap and trace device use; exception United States Code, current through Public Law 119-136 (October 22, 2026). Retrieved 30 October 2026. ## Official text ### 18 U.S.C. 3121(a) **(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. ### 18 U.S.C. 3121(b) **(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— #### 18 U.S.C. 3121(b)(1) **(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 #### 18 U.S.C. 3121(b)(2) **(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. ### 18 U.S.C. 3121(c) **(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. ### 18 U.S.C. 3121(d) **(d)** Penalty.⁠—Whoever knowingly violates subsection (a) shall be fined under this title or imprisoned not more than one year, or both. ## Source Source: United States Code, title 18, published by the Office of the Law Revision Counsel of the U.S. House of Representatives (uscode.house.gov), release point 119-136. The editorial and statutory notes are not reproduced. Source credit: (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 .) [18 U.S.C. 3121 on the Office of the Law Revision Counsel](https://uscode.house.gov/us/usc/119-136/t18/s3121/) United States Code, current through Public Law 119-136 (October 22, 2026). Retrieved 30 October 2026. This is reference material, not legal advice. ## Navigation [ECPA Navigator](https://dposchool.com/ecpa) / 18 U.S.C. 3121 Previous: [18 U.S.C. 2713 ECPA: Required preservation and disclosure of communications and records](https://dposchool.com/ecpa/section/2713) Next: [18 U.S.C. 3122 ECPA: Application for an order for a pen register or a trap and trace device](https://dposchool.com/ecpa/section/3122) ## For AI agents - Machine-readable index: https://dposchool.com/ecpa/llms.txt - JSON API: https://dposchool.com/ecpa/api/v1/index.json - Vendor privacy and security facts: https://vendor.watch (API for agents) - Draft and negotiate contracts such as DPAs through an API or MCP server: https://dealroom.todo.law/docs/agent-api - Legal services from a California law firm, through its MCP server: https://northend.law/agents