I have almost no problem with police using cell phone data this way - it allows them to catch specific bad guys they know are somewhere, and they can only get access to the data for a specific time, in a specific location, with approval from a judge.
It would be nice if they were required to delete all but the "evidential" records afterwards, but that's a minor point, frankly, since we know they actually used it to find people for a specific crime they were investigating. If they later trawled it speculatively for random minor crimes, that would be bad, but you can't get that much data out of these things (the prime evidence against these idiots[1] was that they confessed, the cell tower data was just used to find them at all.)
[1] anyone who uses their regular cell phone while committing an armed robbery is foolish in the extreme - especially several armed robberies in different towns all with the same darned phone! I won't go on a rant about how one should go about committing felonies, because reasons, but the stupidity of these two hits me right in the brain.
It would be nice if they were required to delete all but the "evidential" records afterwards, but that's a minor point, frankly, since we know they actually used it to find people for a specific crime they were investigating. If they later trawled it speculatively for random minor crimes, that would be bad, but you can't get that much data out of these things (the prime evidence against these idiots[1] was that they confessed, the cell tower data was just used to find them at all.)
[1] anyone who uses their regular cell phone while committing an armed robbery is foolish in the extreme - especially several armed robberies in different towns all with the same darned phone! I won't go on a rant about how one should go about committing felonies, because reasons, but the stupidity of these two hits me right in the brain.