US: Government agents in some US states can sneak onto any individual’s property in the middle of the night, put a GPS device on the bottom of his/her car and keep track of everywhere he/she goes. This doesn’t violate Fourth Amendment rights. The rule has been applied in California and eight other Western states.
The US Court of Appeals for the Ninth Circuit, which covers this vast jurisdiction, recently decided the government can monitor any individual in this way virtually anytime it wants — with no need for a search warrant.
However, other courts are coming to a different conclusion from the Ninth Circuit’s — including the influential US Court of Appeals for the District of Columbia Circuit. That court ruled, also this month, that tracking for an extended period of time with GPS is an invasion of privacy that requires a warrant. The issue is likely to end up in the Supreme Court.