Federal judge declares evidence from cellphone tracker unconstitutional

A federal judge ruled for the first time on Tuesday to suppress evidence obtained using an International Mobile Subscriber Identity (IMSI) catcher, more commonly known as a cell site simulator, or a "Stingray."

The constitutional rights of defendant Raymond Lambis were violated with an "unreasonable search" when the US Drug Enforcement Administration used a Stingray to locate his apartment during a drug-trafficking investigation, ruled US District Judge William Pauley. The controversial devices work by mimicking a nearby cellphone tower, tricking a suspect's phone into connecting to it and thereby making data on the phone accessible to law enforcement agencies. 

Although Stingrays have been used frequently by federal and local agencies in the United States for the past decade, awareness of the technology has only just become widespread in recent years, thanks to the work of privacy groups such as the American Civil Liberties Union (ACLU), who say that collecting such information without a warrant, as many agencies do, is a violation of Fourth Amendment rights. 

According to recent ACLU data, at least 66 agencies in 24 states own the devices. Many of these agencies have used the technology in secret for years without getting warrants, explaining their methods to judges, or disclosing to defense attorneys. But now they've begun to face "significant pushback," as reflected by the ruling Tuesday, says Nathan Freed Wessler, a staff attorney with the ACLU Speech, Privacy, and Technology Project.

"The challenge for a long time was the lack of information," Mr. Wessler explains. "There has been such an extraordinary and extreme level of secrecy around these technologies that legislators just had no idea that this was even in existence, much less that police in their state were using it frequently. As information has become more public, we’ve actually seen that legislation imposing reasonable controls, like a warrant requirement, has deep bipartisan support."

Among the 66 known agencies are a number of federal agencies, including the Federal Bureau of Investigation, the DEA, the Secret Service, and US Marshals Service. Some have already begun to more strictly regulate Stingray use, as the Department of Justice and the Department of Homeland Security adopted policies last year requiring warrants in most search circumstances when using a cell site stimulator and full disclosure to judges. 

In an October 2014 press conference that went largely unnoticed until the following February, when the Charlotte Observer published a video as part of an investigation into Stingray use by local police, FBI Director James Comey defended the agency's use of the technology.

"It’s how we find killers, it’s how we find kidnappers, it’s how we find drug dealers, it’s how we find missing children, it’s how we find pedophiles," Mr. Comey said at a media appearance in Charlotte. "It’s work you want us to be able to do."

While the technology has proved undeniably useful, both liberal and conservative lawmakers largely agree that its use must be more strictly regulated across every level of law enforcement to avoid unconstitutional violations of privacy. The new awareness has prompted legislation at both the state and federal level, such as the F.A.I.R. (Fourth Amendment Integrity Restoration) Surveillance Act, a bill introduced in April and backed by both Republicans and Democrats.

As Joshua Eaton reported for The Christian Science Monitor in May:

The Fair Surveillance Act and the last November's similar Stingray Privacy Act are designed to regulate police use of cell site simulators. Essentially, the bills would require state and local law enforcement agencies to obtain a probable cause warrant before using cell phone tracking technology.

By 2014, 10 states had passed similar legislation. They were joined by California and Washington state last year, according to Jake Lestock, a policy associate at the National Conference of State Legislatures. Stingray legislation is currently pending in Illinois and Rhode Island. 

While it's "hard to predict when Congress might be able to get legislation moving," says Wessler, "it certainly helps to have a respected federal judge explaining that the Fourth Amendment requires more oversight and more protections for people, and I think that could be a motivator for legislators."

The opinion on Tuesday, however, focuses only on the constitutional rights of targeted suspects, he says. The ruling doesn't address another concern of civil libertarians, which is that the devices also inevitably pick up data from the phones of innocent bystanders in the same area.

The nature of the technology makes it impossible to completely eliminate this problem, Wessler says. But there are ways to mitigate the effect, such as warrants mandating that police quickly delete all bystander data or limiting the geographic area and signal strength of the device. 

Pauley's decision on Tuesday marked the first time a federal judge suppressed evidence obtained by a Stingray, but his decision was preceded by a similar ruling by a state appellate court in Maryland in March. The Maryland court was the first in the country to explicitly rule that using a Stingray device constitutes as a search under the Fourth Amendment and requires a warrant, as well as full disclosure of the device's risks and consequences to the judge issuing the warrant. 

"That opinion sent a very strong message to law enforcement, certainly in Maryland but also around the country, that the game of secrecy and deception was up," Wessler says. "And now with yesterday's opinion from the federal judge, that echoes much of the reasoning in the Maryland opinion and that message is even stronger."