The American Civil Liberties Union this weekend released the results of public records requests filed last August to hundreds of local police departments across the country, asking them about their policies, practices, and procedures for tracking cell phone records.
 
As The New York Times reported on Sunday, the records show that the practice of tracking cell phones “has become a powerful and widely used surveillance tool for local police officials, with hundreds of departments, large and small, often using it aggressively with little or no court oversight.”
Many of the approximately 200 law enforcement agencies that responded in North Carolina and around the country said they track cell phones without a warrant. In Wilson County, N.C., for example, police obtain cell phone tracking data where it is “relevant and material” to an ongoing investigation — a standard much lower than probable cause.
“These findings raise tremendous privacy concerns for individuals,” said Katy Parker, Legal Director of the ACLU of North Carolina Legal Foundation. “In order to preserve Americans’ constitutional right to privacy, the government should have to obtain a warrant before tracking people’s cell phones. While the inconsistency of legal standards among different jurisdictions in North Carolina is disturbing, the fact that some agencies do obtain warrants when they have probable cause to track a cell phone shows that such a practice is both reasonable and workable.”
The ACLU supports bipartisan legislation currently pending in both the House of Representatives and the Senate that would address this problem called the Geolocation Privacy and Surveillance (GPS) Act. It would require law enforcement officers to obtain a warrant to access location information from cell phones or GPS devices. 
It would also mandate that private telecommunications companies obtain their customers’ consent before collecting location data.
The U.S. Supreme Court in January held in U.S. v. Jones that prolonged location tracking is a search under the Fourth Amendment, but the effects of that ruling on law enforcement have yet to be seen.