They can track you via your phone already. The dedicated devices are presumably more reliable for them and were used so they didn't have to get a warrant for phone tracking.
Good point. Considering that the phone companies have a long history of secretly sharing foreign call data with the NSA, and a recent history of secretly sharing domestic call data as well, we can expect more of the same.
Rather than fighting this Supreme Court Ruling, maybe law enforcement will instead push for real-time access to GPS data from the carriers.
