Without any probable cause for search, this is a violation of the Fourth Amendment.

FORBES: Connect

Police were free to employ the tactic for any reason without showing probable cause to a magistrate and getting a search warrant, the government said.

WSJ: Supreme Court Reins In Police on GPS Trackers

This case and a separate and still pending appeal over police intrusions into homes and cars could have a far-reaching impact on when a person's private contents can be subjected to a search without clear probable cause or a valid warrant.

CNN: Supreme Court sides with dog in search case

Taken together, the government argued that it could track a cellphone's location without having to show probable cause.

WSJ: Judges Challenge Phone Location Tracking

Congress should resist any proposal to give the government power to wiretap with or without a warrant on any standard less than probable cause to believe that a crime is being committed.

CENTERFORSECURITYPOLICY: The Case Against the Halperin Nomination �� First Edition