The Baltimore Police Department has used an invasive and controversial cellphone tracking device thousands of times in recent years while following instructions from the FBI to withhold information about it from prosecutors and judges, a detective revealed in court testimony Wednesday.
The testimony shows for the first time how frequently city police are using a cell site simulator, more commonly known as a "stingray," a technology that authorities have gone to great lengths to avoid disclosing.
The device mimics a cellphone tower to force phones within its range to connect. Police use it to track down stolen phones or find people.
Until recently, the technology was largely unknown to the public. Privacy advocates nationwide have raised questions whether there has been proper oversight of its use.
Baltimore has emerged in recent months as a battleground for the debate. In one case last fall, a city detective said a nondisclosure agreement with federal authorities prevented him from answering questions about the device. The judge threatened to hold him in contempt if he didn't provide information, and prosecutors withdrew the evidence.
The nondisclosure agreement, presented for the first time in court Wednesday, explicitly instructs prosecutors to drop cases if pressed on the technology, and tells them to contact the FBI if legislators or judges are asking questions.
Detective Emmanuel Cabreja, a member of the Police Department's Advanced Technical Team, testified that police own a Hailstorm cell site simulator — the latest version of the stingray — and have used the technology 4,300 times since 2007.
Cabreja said he had used it 600 to 800 times in less than two years as a member of the unit.
Nate Wessler, an attorney with the American Civil Liberties Union, said 4,300 uses is "huge number." He noted that most agencies have not released data.
The Florida Department of Law Enforcement says its officers have used the device about 1,800 times. Police in Tallahassee say they have used it more than 250 times; police in Tacoma, Wash., 170 times.
Former U.S. Judge Brian L. Owsley, a law professor at Indiana Tech, said he was "blown away" by the Baltimore figure and the terms of the nondisclosure agreement. "That's a significant amount of control," he said.
Agencies have invoked the nondisclosure agreement to keep information secret. At a hearing last year, a Maryland State Police commander told state lawmakers that "Homeland Security" prevented him from discussing the technology.
Baltimore Police Stingray non-disclosure agreement
Wessler said the secrecy is upending the system of checks and balances built into the criminal justice system.
"In Baltimore, they've been using this since 2007, and it's only been in the last several months that defense attorneys have learned enough to start asking questions," he said. "Our entire judicial system and constitution is set up to avoid a 'just trust us' system where the use of invasive surveillance gear is secret."
Cabreja testified Wednesday during a pretrial hearing in the case of Nicholas West, 21, and Myquan Anderson, 17. West and Anderson were charged in October 2013 with armed carjacking, armed robbery, theft and other violations stemming from an attack on a man in Federal Hill.
Cabreja took what he said was a copy of the nondisclosure agreement to court. It was dated July 2011 and bore the signatures of then-Police Commissioner Frederick H. Bealefeld III and then-State's Attorney Gregg Bernstein.
Defense attorney Joshua Insley asked Cabreja about the agreement.
"Does this document instruct you to withhold evidence from the state's attorney and Circuit Court, even upon court order to produce?" he asked.
"Yes," Cabreja said.
Cabreja did not comply with a defense subpoena to produce the device in court. He said he was barred from doing so by the nondisclosure agreement.
An FBI spokesman declined to comment on the technology or the document.
The signatories to the document agree that disclosing the existence of the stingray would "reveal sensitive technological capabilities possessed by the law enforcement community and may allow individuals who are the subject of investigation … to avoid detection."
They agree that "disclosure of this information could result in the FBI's inability to protect the public from terrorism and other criminal activity" by rendering the technology useless for investigations.
Document: Government's Response for Motion to Suppress Stingray evidence