Chapter 3: Introduction to Technological Aspects of Privacy
Location Tracking: Technologies and Carpenter
Location is tracked via cell-tower/Wi-Fi triangulation, GPS, and photo metadata. The U.S. has historically had few restrictions, but Carpenter v. United States requires a warrant for long-term tracking; states now treat location as sensitive and COPPA includes location in personal data.
- Cell-tower and Wi-Fi triangulation: position computed geometrically from signal timing/strength to known towers.
- GPS: device determines longitude, latitude, and altitude; smartphones often automatically share this with apps or the provider.
- Metadata: photos from GPS-enabled devices often store location (and time) automatically, sometimes without user awareness.
Carpenter and the warrant rule
Historically the U.S. had few restrictions on businesses using location data. In Carpenter v. United States, the Supreme Court held police need a warrant for long-term tracking of an individual's movements. For shorter periods, data holders may respond voluntarily to police requests. State comprehensive laws now often classify location as sensitive data, and COPPA includes location in its definition of personal data.
Key terms - quick answers
What is “Triangulation”?
Determining a phone's position geometrically from its signal timing and strength relative to several cell towers whose locations are known.
What is “GPS”?
Global positioning satellites that let a device determine its longitude, latitude, and altitude from differences in message arrival times.
What is “Metadata”?
Data such as location and time automatically stored within content like photos, often without the user's awareness.
What is “Carpenter v. United States”?
U.S. Supreme Court decision holding that police need a warrant to conduct long-term tracking of an individual's movements.