Law enforcement organizations around the country are desperate to keep the public unaware of the use of Stringrays, a surveillance technology that secretly monitors cell phones, even as courts and lawmakers are starting to fight back.

That’s the conclusion of the Electronic Frontier Foundation (EFF), which tallied up a year’s worth of public records requests by American media organizations, as well as court and legislative actions, related to the government’s use of the technology, also known as IMSI catchers.

“We’ve long worried about the government’s use of [Stingrays, which] masquerade as a legitimate cell phone tower, tricking phones nearby to connect to the device in order to track a phone’s location in real time,” the EFF wrote in a blog post today. “We’re not just worried about how invasive these devices can be, but also that the government has been less than forthright with judges about how and when they use IMSI catchers. This year, the public learned just how desperately law enforcement wanted to keep details about Stingrays secret. … The results are shocking.”

Stingrays became a big part of the public conversation this year. Last summer, as VentureBeat reported, the CEO of ESD America, which builds a highly secure phone for clients who demand military-grade security, revealed that in the course of testing their phone, the company discovered cell towers capable of intercepting calls and then handing them off to carriers’ networks, a tool that allows the government to listen in or add spyware to mobile devices.

Made by the Harris Corporation, a Florida multinational, Stringrays are designed to obtain the cell number of people targeted in criminal or intelligence investigations and then mimic the nearest cell tower so that any calls from the target phone are routed through the device instead.

Those interested in ensuring that criminals or terrorists can’t safely use cell phone networks without being monitored by the government will no doubt applaud the use of the technology. But the EFF and other privacy groups, as well as media organizations and an increasing number of courts and legislatures around the country, are concerned that members of the public who have never committed any crimes are also having their calls intercepted.

Long list of obfuscation

The list of government attempts to keep information about Stingrays away from the public is long.

To begin with, much of police use of Stingrays is done without obtaining warrants, the EFF alleges. But according to Wired, that’s in part because the Harris Corporation makes law enforcement organizations sign non-disclosure agreements that preclude them from revealing their use of the technology to the courts.

Harris did not immediately respond to a request for comment by VentureBeat.

At the same time, police departments have been fighting lawsuits demanding information about the use of Stingrays by claiming, according to the San Diego Union-Tribune, that making public such details about IMSI catchers, “‘would reveal security or intelligence information’ and was exempt from disclosure … ‘because to do so would potentially endanger the lives and physical safety of law enforcement officers and adversely impact criminal and national security investigations.'”

Similarly, the American Civil Liberties Union asserted in June that law enforcement agencies have been “deliberately concealing the use of Stingrays in court documents submitted to judges in criminal investigations.”

Indeed, in one case, the U.S. Marshals Service even intervened in an attempt by the ACLU to find out how the Sarasota (Florida) Police Department uses Stingrays. “The US Marshals suddenly moved the stack of paper records hundreds of miles away,” according to Ars Technica. “It’s a move that will frustrate ongoing efforts by the … ACLU to access the documents in question.”

For its part, the ACLU argues that Sarasota police “hide behind the sham cloak of the U.S. Marshals office to keep the information about Stingray use out of court files — and beyond even a court’s custody and reach.” In Sarasota, the ACLU claimed, and the EFF highlighted, the police “revealed officers concealed their use of Stingrays from judges, having one officer withdraw a warrant affidavit that mentioned the use of an IMSI catcher, and describing a policy of referring to Stingrays as a ‘source’ in official documents.”

Police have used similar tactics in other parts of the country as well, the EFF argued. In Tacoma, Wash., police hid their use of Stingrays from judges dozens of times over five years. “From 2009 to earlier this year,” wrote Tacoma’s News Tribune, “the county’s Superior Court judges unwittingly signed more than 170 orders that Tacoma police and other local law enforcement agencies say authorized them to use” Stingrays.

And the pattern of law enforcement obfuscation about agencies’ use of the technology goes on. In Baltimore, the EFF said, prosecutors gave up on use of evidence gathered through a Stingray after “a judge threatened to hold a police officer in contempt for refusing to testify about the device.”

Courts and legislatures fighting back

But while police and other law enforcement agencies are stepping up their campaigns to keep the use of Stingrays secret, the courts and legislatures are fighting back. According to the EFF, Tacoma judges are now requiring police say when they plan to implement the technology in surveillance and that they commit to not keep data related to people who aren’t part of an investigation. State Supreme Courts in Florida and Massachusetts ruled that police must get warrants for any real-time cell phone monitoring, as did lawmakers in nine states — Wisconsin, Illinois, Indiana, Colorado, Minnesota, Maryland, Utah, Virginia, and Tennessee.

Whether or not actions by the courts and legislators, or increased sunlight on law enforcement use of Stingrays brought on by public records requests, has any effect on such usage is still unknown. But to organizations like the EFF and ACLU, it’s essential that the public not be kept in the dark by police about the use of such technology. And the battle is just getting underway.

“As we continue to learn about Stingrays in 2015,” the EFF wrote, “we hope more courts and legislatures confront these dangerous tools and work to enact privacy safeguards to protect the data of innocent people who have the bad fortune of being nearby when the police use one.”