In a Baltimore trial courtroom on Monday, a local judge threatened to hold a police detective in contempt of court for refusing to disclose how police located a 16-year-old robbery suspect’s phone. Once the Baltimore Police were able to locate Shemar Taylor’s phone, they then searched his house and found a gun as well.

But rather than disclose the possible use of a stingray, also known as a cell site simulator, Detective John L. Haley cited a non-disclosure agreement, likely with a federal law enforcement agency (such as the FBI) and/or the Harris Corporation, since the company is one of the dominant manufacturers of such devices. Stingrays can be used to determine a phone’s location, and they can also intercept calls and text messages.

Baltimore Circuit Judge Barry G. Williams retorted, "You don't have a nondisclosure agreement with the court," according to the Baltimore Sun.

The prosecution then withdrew the evidence of the phone and gun but said it would still pursue the case. Neither Assistant State's Attorney Patrick R. Seidel nor defense attorney Joshua Insley immediately responded to Ars’ request for comment. Angelita Plemmer Williams, a spokeswoman for the State of Maryland Judiciary, told Ars that Judge Williams was prohibited under court rules from speaking to the press “on pending cases that may still be appealed.”

According to the Sun, Haley also told the court that the Baltimore Police was not using a stingray, but Insley “still believes that police used a stingray to find Taylor.”

Pushback begins slowly

Relatively little is known about how stingrays are used by law enforcement agencies nationwide, although documents have surfaced showing how they have been purchased and used in some limited instances.

Last year, Ars reported on leaked documents showing the existence of a body-worn stingray. In 2010, Kristin Paget famously demonstrated a homemade device built for just $1,500.

In recent months, some new information has trickled out as the result of public records lawsuits in various jurisdictions—particularly Florida. In September 2014, new documents released by the City of Oakland, California revealed that it is one of a handful of American jurisdictions attempting to upgrade an existing cellular surveillance system.

Harris Corporation, makers of the StingRay and other related devices, has traditionally refused to speak with Ars about its products. "We do not comment on solutions we may or may not provide to classified Department of Defense or law enforcement agencies," Jim Burke, a spokesman for Harris, previously said.

Earlier this year, the American Civil Liberties Union found that at least in Florida, law enforcement had signed similar agreements with the Harris Corporation. Worse still, cops were actively lying to courts about their use—asking a judge to sign off on a “pen register/trap and trace” order, which is far less invasive than a stingray.

Due to some recent reporting in Tacoma, Washington, judges in Pierce County are now requiring that law enforcement seek specific permission when requesting to use a stingray as of this week.

UPDATE 2:45pm CT: Hanni Fakhoury, a lawyer with the Electronic Frontier Foundation, and former federal public defender, told Ars that judge's typically do not like such evasive action by witnesses.

"It's also a remarkable bit of chutzpah for the officer to refuse to answer the questions when sworn under oath in a proceeding," he wrote by e-mail.

"[The detective] may have been following orders but its ridiculous that superiors, whether police or prosecutors, direct officers to evade answering questions about surveillance technology that is now widely known about. Its even more remarkable the prosecutors simply chose to not use the evidence rather that disclose details about it. That says a few things: first maybe we don’t really need the surveillance if the government can prove a criminal case without the evidence they gather from it (though that remains to be seen in this specific case). Second, that the technology must really be capable of some remarkable things if the government is so desperate to keep it under wraps."

Brian Owsley, a former federal judge and current law professor at Indiana Tech, told Ars he was not aware of another instance of any law enforcement using a non-disclosure agreement "as a shield."

"It is common knowledge that state and local law enforcement agencies are purchasing this technology with grants from the Department of Homeland Security," he wrote. "In exchange for the grants, the agencies must sign the nondisclosure agreement. As courts delve into these Fourth Amendment issues more, there will be more confrontations between the Constitution and the agencies’ obligations pursuant to the agreements. One significant remedy is that prosecutors may lose evidence because judges suppress it due to the lack of a search warrant"