Federal surveillance authority has grown substantially since 9/11. Key authorities and debates:
- FISA Section 702: Authorizes warrantless surveillance of non-U.S. persons abroad; "incidental" collection of Americans communicating with foreign targets has produced ongoing reform debates.
- Geofence and reverse-warrant practices: Compelling tech companies to identify all devices in a geographic area or all users searching for specific terms.
- Third-party doctrine (Smith v. Maryland, 1979): Records held by third parties (banks, phone companies) get less Fourth Amendment protection. Carpenter v. United States (2018) limited this for cell-site location data.
- Stingray / IMSI-catcher use by local police.
- Section 215 / "business records" authority and its successor regimes.
Reform proposals include warrant requirements for U.S.-person queries, sunset of broad authorities, and codification of Carpenter to broader records categories.