Law enforcement agencies across the country already subpoena phone location data regularly. The district attorney for Suffolk County, Mass., regularly asks phone companies for cellphone location information.
The subpoenas are “part of almost every major case, including homicide, in some cases, sexual assault, drug trafficking cases,” says Jake Wark, a spokesman for the office.
While the National Security Agency has conceded that it does collect records of U.S. phone traffic, it says it does not currently track the location of cellphones. But the agency also says that it would be legal to collect that information.