Lawful Interception

Lawful interception (LI) is obtaining communications network data pursuant to lawful authority for the purpose of analysis or evidence. Such data generally consist of signalling or network management information or, in fewer instances, the content of the communications. If the data are not obtained in real-time, the activity is referred to as access to retained data (RD).

There are many bases for this activity that include infrastructure protection and cybersecurity. In general, the operator of public network infrastructure can undertake LI activities for those purposes. Operators of private network infrastructures have an inherent right to maintain LI capabilities within their own networks unless otherwise prohibited.

One of the bases for LI is the interception of telecommunications by law enforcement agencies (LEAs), regulatory or administrative agencies, and intelligence services, in accordance with local law. Under some legal systems, implementations—particularly real-time access to content—may require due process and receiving proper authorization from competent authorities—an activity that was formerly known as "wiretapping" and has existed since the inception of electronic communications. The material below primarily treats this narrow segment of LI.

With the legacy public switched telephone network (PSTN), wireless, and cable systems, lawful interception (LI) was generally performed by accessing the mechanical or digital switches supporting the targets' calls. The introduction of packet switched networks, softswitch technology, and server-based applications the past two decades fundamentally altered how LI is undertaken.