DOJ to review secret cell phone tracking programs, reveal information on usage

The review will result in the implementation of new guidelines for the use of these devices by the Drug Enforcement Administration, the U.S. Marshals, and the FBI, according to the Wall Street Journal. Officials will also explain why and how the secretive boxes are used, but the extent of those disclosures has not yet been decided.

"We know it's got to come out," one law enforcement official told the publication. "At some point, it becomes more harmful to try to keep it secret than to acknowledge it. We just want to acknowledge it carefully and slowly, so we don't lose what is a very effective tool."

Currently, each agency has their own rules and procedures for deploying so-called stingrays —  including whether an operation requires a warrant — and those with access are prohibited from describing the devices' technical capabilities, even if called to do so in court.

Stingray devices masquerade as cell towers, scanning mobile phones as they attempt to connect. Their widespread use has angered privacy advocates, who argue that the boxes facilitate illegal mass surveillance, especially since they are often used without a warrant.

In addition to legal and privacy concerns, stingrays can affect the operation of mobile networks. Though non-target devices are quickly "let go," or told to search for another tower, the FBI has recently acknowledged that it can cause interference over a large area.

"Because of the way, the Mobile Equipment sometimes operates," an FBI agent recently testified, "its use has the potential to intermittently disrupt cellular service to a small fraction of Sprint's wireless customers within its immediate vicinity. Any potential service disruption will be brief and minimized by reasonably limiting the scope and duration of the use of the Mobile Equipment."