The U.S. Justice Department has plans to launch a review of technology that allows law enforcement and other government agencies to secretly track cell phones, along with the policies surrounding it, the Wall Street Journal reported Sunday. The review is to result in the release of more information publicly about how the devices work and more stringent standards. 

The policy review comes at a time when the FBI has been obtaining more search warrants to use the technology. The devices are called various names including Stingway and dirtbox. With the technology, people are able to uncover the last known location of a cell phone by determining where the phone last transmitted a call or text message.

The technology is increasingly being used by police. A Baltimore police official said his department had used them 4,300 times since 2007, and more police departments are exploring the technology.

The systems also have been under more scrutiny by politicians and the public. For example, in January, a bill for the Geolocation Privacy and Survelliance Act, which would require police to get a warrant before using the surveillance technology, was introduced in Congress. “At some point, it becomes more harmful to try to keep it secret than to acknowledge it,” a law enforcement official told the Journal.

The FBI, the U.S. Marshals Service and the Drug Enforcement Administration all use the technology, and each is governed by different procedures. The Justice Department will conduct a review of each agency’s policy and could create standards, officials who chose to remain anonymous told the Journal.

It is unclear how much information will be revealed to the public about how the system works. Local police departments must sign nondisclosure agreements with the FBI before receiving access to the technology. Officials told the Journal they do not want to reveal too much and render the devices ineffective. The devices have helped the government track down terrorists for decades.