When an investigation into a Virginia bank robbery went cold a few years back, local police turned to Google. Authorities served the tech giant with a “geofence warrant,” which required the company to parse location data on millions of people to find a handful whose cellphones pegged them within 300 meters of the bank at the time of the robbery.

When the Call Federal Credit Union outside Richmond, Va., was robbed at gunpoint in 2019, the suspect took $195,000 from the bank’s vault and fled before the police arrived.

The justices are debating Monday whether the sweeping warrants, which are directed at tech companies rather than individual suspects, are consistent with the Fourth Amendment’s prohibition on unreason...