"Nevada quietly signed an agreement earlier this year with a company that collects location data from cellphones, allowing police to track a device virtually in real time," reports the Associated Press. "All without a warrant."

The software from Fog Data Science, adopted this January in Nevada through a Department of Public Safety contract, pulls information from smartphone apps in order to let state investigators identify the location of mobile devices. The state is allowed more than 250 queries a month using the tool, which allows officers to track a device's location over long stretches of time and enables them to see what Fog calls "patterns of life," according to company documents from...