For years, the FBI and other federal, state, and local law enforcement agencies have been using invasive cell phone surveillance equipment, called Stingrays or cell site simulators, in secret and without abiding by the requirements of the Fourth Amendment. After sustained advocacy by the ACLU and others, that may be changing. The Wall Street Journal reports today that the “Justice Department will start revealing more about the government’s use of secret cellphone tracking devices and has launched a wide-ranging review into how law-enforcement agencies deploy the technology.” According to the Journal, “in recent months, the Federal Bureau of Investigation has begun getting search warrants from judges to use the devices,” an improvement over prior policy.

Stingrays mimic legitimate cell phone towers and force all phones in the area to transmit their unique identifying information, which lets law enforcement precisely locate people’s cell phones, including inside homes and other private spaces. Even when police are searching for a particular suspect’s phone, the devices conduct a dragnet search of all bystanders’ phones in the area, raising serious Fourth Amendment concerns.

We know that at least a half dozen federal law enforcement agencies and more than 50 state and local police departments own Stingrays. In most cases, police have been using the technology without getting a probable cause warrant from a judge. Instead, they have been applying for lesser orders on a mere relevance standard, or not seeking judicial approval at all. And they have been engaged in a sustained campaign of excessive and corrosive secrecy, hiding even the mere fact of Stingray use from judges and defense attorneys in thousands of cases.

Federal law enforcement’s move toward using warrants for this invasive technology is welcome and long overdue, as is the promise of increased transparency. But major questions remain.

First, the Wall Street Journal reports that the Justice Department is slow-walking the move toward decreased secrecy around Stingrays because it doesn’t “want to reveal information that would give new ammunition to defense lawyers in prosecutions where warrants weren’t used.” If that is so, the promise of greater transparency is a sham. Law enforcement agencies have been violating the rights of defendants and non-suspects for years by failing to get warrants and then hiding the fact and details of Stingray use from defense attorneys and courts. Trying to insulate these violations from challenge by maintaining secrecy until pending cases have concluded will perpetuate the government’s outrageous conduct, not ameliorate it.

Moreover, the foundations of the government’s Stingray secrecy regime have already crumbled. In public records cases brought by the ACLU, judges have rejected the government’s half-baked rationales for extreme secrecy and ordered basic and accurate information about Stingray use released. Judges in criminal cases have also pushed back, ordering disclosure of information to defense attorneys and threatening to hold police officers in contempt of court for refusing to answer questions under oath. As my colleague Chris Soghoian and West Point professor Stephanie Pell have meticulously demonstrated, extensive information about Stingrays is already public, making the government’s arguments for secrecy nonsensical. The time to end the charade of concealment is now. The FBI should begin by releasing unredacted copies of the nearly 5,000 pages of whited-out Stingray documents it recently made public in response to Freedom of Information Act requests. Other federal agencies that make heavy use of Stingrays, including the U.S. Marshals Service and the DEA, must also come clean.

Second, the FBI must take steps to ensure that local police also change their policies. Litigation by the New York Civil Liberties Union recently forced release of the non-disclosure agreement that the FBI makes local police sign when they purchase Stingrays. That agreement requires police to withhold information from judges, defense attorneys, and the public, and even to dismiss prosecutions if the government may be required to disclose information about Stingrays during the case. But as the Wall Street Journal explains, while requiring secrecy about Stingrays, “the FBI doesn’t require or provide legal standards to police on best practices for how to use the devices.” As a result, in cities across the country, from Tallahassee, to Baltimore, to St. Louis, to Tacoma, police have been riding roughshod over the Constitution by failing to get warrants before using Stingrays and hiding relevant information from courts. The FBI should immediately withdraw the non-disclosure agreements and replace them with guidance mandating that local police get probable cause warrants and directing them to begin disclosing accurate information to the public and the courts.

Finally, the Journal reports that there has been a spike in emergency requests to cell service providers for cell phone location information, motivated in part by the desire to get easy access to general data about where suspects’ cell phones are so police know where to set up their Stingrays. This suggests abuse of these requests, which do not involve a court’s approval. The Justice Department should take action to ensure that these violations end by limiting such exigency requests only to actual emergencies, as required by the federal Stored Communications Act and the Fourth Amendment.

The reported changes in policy around Stingrays are promising. The proof of the pudding is in the eating, however, and the real reach of these developments remains to be seen.