You have an expectation of privacy in location data that reveals your movements in the physical world, and even short-term surveillance of these movements is a search subject to the Fourth Amendment, the U.S. Supreme Court ruled today in Chatrie v. United States. The case involved geofence warrants...
I’m wondering if FBI/NSA/CIA will actually honor the ruling, assuming it holds?
Doubtful. All they have to do is cry “terrorism” and they’re allowed to do whatever they want.
Yup.
Edit: or “espionage.”