>>benwer+(OP)
> Such data may be useful, it says, to “identify every person who attended a protest or rally based on their smartphone location or ad-tracking records.”
"May"? This is exactly how the January 6th protestors were identified.
>>roarch+E3
doubtful. they were issuing subpoenas to the cell companies for their records of the tower registrations for a certain time frame when crimes were being committed. It doesn't take much to identify the owner of a smartphone via that and then correlate that with driver's license photo ids and correlate that with surveillance camera footage to bring a case. that had nothing to do with peaceful protester tracking but bog standard criminal investigation.