A little ways up the Florida coast, a little-known company in Melbourne makes a device of great concern to civil liberties activists. Called the "Stingray," it allows law enforcement officials to track the whereabouts of a specific cell phone — a useful investigative tool that advocates argue also violates privacy rights when it's used without a warrant.

Activists won a big victory on the issue last week, with the Department of Justice instructing federal agencies including the FBI that they do, in fact, need a warrant to use the cell-phone tracking technology. The bad news? Local police forces are still free to track away at will.

"Disturbingly, the policy does not apply to ... the many state and local police departments that have received federal funds to purchase these devices," says Nathan Freed Wessler, staff attorney for the American Civil Liberties Union’s Speech, Privacy, and Technology Project, in a release.

That certainly includes Miami police forces. Earlier this year, the ACLU released data showing that Miami-Dade Police Department had used the Stingray at least 59 times in the previous calendar year. The department originally bought the equipment, which retails for up to $136,000, back in 2003 to track protestors at the Free Trade of the Americas summit.

The ACLU has challenged cops' ability to use Stingrays without warrants, but so far haven't had much luck in court. Two federal appeals courts ruled earlier this year that cops don't need warrants to use the machines, which work by pretending to be a cell phone tower and then triangulating the signal coming from a specific phone.

The DOJ's new rules at least put a dent in that trend. The feds say the technology is critical to investigations.

“Cell-site simulator technology has been instrumental in aiding law enforcement in a broad array of investigations, including kidnappings, fugitive investigations and complicated narcotics cases," Deputy Attorney General Sally Quillian Yates says in a release. "This new policy ensures our protocols for this technology are consistent, well-managed and respectful of individuals’ privacy and civil liberties.”

But the ACLU says the feds' policy still has disturbing gaps. The new policy doesn't cover all federal agencies, Wessler notes, and allows warrantless use in vaguely defined “exceptional circumstances.”

“The Justice Department must close these loopholes, and Congress should act to pass more comprehensive legislation to ensure that Americans’ privacy is protected from these devices and other location tracking technologies," Wessler says.

