The Chicago privacy activist who currently has two pending stingray-related lawsuits against the Chicago Police Department has taken his quest one step further: he has now also sued the Cook County State’s Attorney’s Office (CCSAO).

In a lawsuit filed last Thursday, Freddy Martinez describes how he filed a public records request to the prosecutors in the second-largest county in the United States to hand over "all records showing the case, the information that was used, the charges, the outcome of the case, how the information was obtained and by whom, and any court orders authorizing the use of the equipment."

The case marks a rare instance of when an individual, rather than an organization like the American Civil Liberties Union (as was the case recently in New York), has taken a prosecutorial agency to task for failing to disclose stingray-related records.

Less than a week later, on January 5, 2015, the CCSAO wrote back to Martinez (via his attorney, Matt Topic), saying that it had no such list, and compiling one would be "too burdensome."

Paul A. Castiglione, the executive assistant state's attorney for policy responded to Topic:

I have made inquiries [to] senior attorneys from our Criminal Prosecutions and Narcotics Bureaus and have determined that the SAO has no way of knowing the identity of criminal cases where a cell site simulator was used to obtain evidence in those cases, if any such cases exist. In other words, the SAO has no list of cases where "stingray" equipment, an IMSI catcher or any other cell site simulator was used to obtain information and/or evidence.

Martinez and Topic responded, suggesting a simple query of the CCSAO e-mail system and even proposed limiting it to narcotics and terrorism cases. But both such proposals were still denied—and that ultimately resulted in the suit.

By contrast, just last month, the Mecklenburg County district attorney’s office in North Carolina was able to review such records in its district and had previously distributed the court records to anyone who requested them.

The CCSAO did not immediately respond to Ars’ request for comment.

Stingrays can determine a specific phone’s location, but they also have the ability to intercept calls and text messages. And during the act of locating a phone, stingrays can sweep up information about nearby phones as well. Earlier this year, Ars reported on how the FBI is actively trying to "prevent disclosure" of stingray use in local jurisdictions across America—more recently we reported how the FBI has distributed a pre-written press release to law enforcement agencies.

A font of pen registers

Legal experts roundly applauded Martinez’ efforts to shed some light on how stingrays are being used in actual legal cases.

"Public access to court orders and applications is necessary so the public can assess whether the police are being candid with judges about their use of stingray technology," Nathan Wessler, an attorney with the American Civil Liberties Union, told Ars. "Access to these materials will also reveal whether police are getting probable cause warrants as required by the Fourth Amendment or instead are inappropriately getting orders on a lower standard. Knowing what kinds of orders police are relying on and how frequently they seek them will allow for the kind of informed democratic debate about the stingray use that has been sorely lacking so far."

In many cases, law enforcement agencies use stingrays without a warrant—more often they seek a lower kind of judicial order called a "pen register and trap and trace order," or a "pen/trap order."

In the pre-cellphone era, such an order allowed law enforcement to obtain someone's calling metadata in near-real time from the telephone company. Now, that same data can also be gathered directly by the cops themselves through the use of a stingray. In some cases, police have gone to judges asking for such a device or have falsely claimed the existence of a confidential informant while in fact deploying this particularly sweeping and invasive surveillance tool.

Most judges are likely to sign off on a pen register application not fully understanding that police are actually asking for permission to use a stingray. Under federal law, pen registers are granted under a very low standard: authorities must simply show that the information obtained from the pen register is "relevant to an ongoing criminal investigation."

"A court order will show the legal basis the court is using to authorize the IMSI catcher (stingray)," Susan Freiwald, a law professor at the University of San Francisco, told Ars by e-mail.

"A court order authorizing a stingray device should give a sense of what the court is permitting it to do (which illuminates its capabilities) and the legal threshold for that permission (probable cause, relevance, etc.) as well as any statutory authority. In my experience, prosecutors write out the orders themselves and attach them, unsigned, to their applications so that the judge will sign and date them on approval," Freiwald said.

However, another law professor thought that there is a chance that Martinez could lose on a technicality that was originally brought up in the responses to his attorney.

"I think this sort of case is very important, not only in its own right but as part of a broader set of actions designed to illuminate the use of stingrays," Fred Cate, a law professor at Indiana University, told Ars.

"The FBI has worked mightily to keep information about Stingrays secret, even from courts," Cate said. "As a result, we don’t know how often Stingrays are used, if courts are ever involved in authorizing the use, how often they reveal important evidence, how many cases are settled or dropped because of the FBI’s refusal to let prosecutors level with courts about their use of Stingrays, or how important Stingrays really are to effective law enforcement. The information sought by this suit would help illuminate some of these issues. Unfortunately, the lawsuit seeks information that may not exist as a record and therefore may not be covered by Illinois [Freedom of Information Act] law."