https://arstechnica.com/tech-policy/2020/09/feds-cant-ask-google-for-every-phone-in-a-100-meter-radius-court-says/

Federal courts in the Chicago area have three times rejected government applications for warrants to force Google to produce a list of smartphones near two particular commercial establishments during one of three 45-minute intervals. The most recent ruling was handed down last week and was recently made public.

The decisions are significant because Google has reported massive growth in law enforcement use of such "geofence" searches. Google says there was a 1,500 percent increase between 2017 and 2018 and a further 600 percent jump from 2018 to 2019. That's a hundredfold increase in two years. Google received 180 geofence search requests a week during 2019, according to CNet.