New Illinois Law Limits Police Use Of Cellphone-Tracking Stingray

An anonymous Slashdot reader quotes a report from ABC News:
A new Illinois law limits how police can use devices that cast a wide net in gathering cellphone data... [Stingray] gathers phone-usage data on targets of criminal investigations, but it also gathers data on other cellphones -- hundreds or even thousands of them -- in the area. The new law requires police to delete the phone information of anyone who wasn't an investigation target within 24 hours. It also prohibits police from accessing data for use in an investigation not authorized by a judge.

A dozen other states have adopted such regulations, and Congress is considering legislation that would strengthen federal guidelines already in place... Privacy advocates worry that without limits on how much data can be gathered or how long it can be stored, law enforcement could use the technology to build databases that track the behavior and movement of people who are not part of criminal investigations.
Earlier this month a U.S. judge threw out evidence gathered with Stingray for the first time, saying that without a search warrant, "the government may not turn a citizen's cell phone into a tracking device." The ACLU has identified 66 agencies in 24 states using Stingray technology, "but because many agencies continue to shroud their purchase and use of stingrays in secrecy, this map dramatically underrepresents the actual use of stingrays by law enforcement agencies nationwide."