You probably know, or should know, that your cellphone is tracking your location everywhere you go. But whether law enforcement officials should have access to that data is at the center of a constitutional debate.
Matt Blaze, a professor of computer and information science at the University of Pennsylvania, says location tracking is key to how the cell system operates.
"As you move around, your phone is constantly checking to see whether the tower that it's currently registered with is the best one, or whether there's a better tower with a stronger signal coming in range," he says. Cellphone companies store that information so they can deliver better service.
That's handy for the police. 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.
In Massachusetts, A Test Case
In many states, the use of that data has led to a movement to protect cellphone location information. One cellphone search, in particular, could serve as a test case for civil liberties groups challenging law enforcement's access to such information.
Shabazz Augustine stands accused of murdering a former girlfriend nine years ago. Massachusetts state prosecutors want to use information they got about the location of his cellphone at the time.
Matt Segal, legal director of the ACLU of Massachusetts, told the state's high court that the evidence should be thrown out, because police got it using a simple subpoena, not a search warrant.
"All the government has to show is that the information they're requesting is relevant and material to an ongoing investigation," Segal says.
“ What we're focused on is the possibility that governments are obtaining this kind of location information on many people who have not committed crimes.