On Monday, Washington Gov. Jay Inslee signed a bill into law that requires police officers obtain warrants from a judge stating that there is probable cause that the use of a cell site simulator device, or “Stingray,” will lead to evidence of criminal activity.

The News Tribune in Tacoma reported that when police obtain a warrant from a judge to use a stingray device, they must “disclose the use of the device” and must “discard cellphone data from people who are not the specific target of a police investigation.”

Ars Technica noted that while Washington’s law is not the first of its kind in the US, and there are similar laws in Virginia, Minnesota and Utah, Washington’s law may have the most stringent requirements, because it “imposes extra requirements that compel police to describe the technology and its impact in detail to judges.”

As previously reported by Truth in Media’s Derrick Broze, as long as a cellphone is on, it can be tracked by a Stingray device, even if it is not making or receiving a call. Broze noted that police officers are “likely bringing them to large protests to gather data on those in attendance.”

Broze also noted that Stingrays can be handheld or vehicle-based, and that they extract data from cellphones “at full signal, consuming battery faster,” which might mean that a “constantly dying battery could be a sign that you are being tracked.”

In Aug. 2014, The News Tribune revealed that the Tacoma Police Department has had a Stingray device since 2008, and has used it hundreds of times to find criminal suspects, “without telling judges about its capabilities.”

Jared Friend, the director of the Technology and Liberty program at the American Civil Liberties Union’s Washington office, released a statement calling Stingrays “emblematic of the threats to privacy posed by new technologies and expanding government surveillance activities” and saying that with this new law, Washington state has become a “leader in regulating these invasive devices.”

“Around the country, local police departments and the FBI have engaged in a campaign to conceal the use of cell site simulators from judges and from the public,” Friend said. “These devices epitomize the continuing militarization of local law enforcement and should not be free from judicial and public scrutiny.”