A New York federal judge has suppressed evidence obtained without a warrant by DEA agents using a Stingray, a cellphone-tower-spoofing device that allows law enforcement to pinpoint cellphone users' locations, and can be used to intercept information about their calls and text messages, or even the calls and messages themselves. The decision, made yesterday in Southern District federal court, is the first time a federal jurist has weighed in on the issue.

The decision came in the case of Raymond Lambis, who the feds charged with conspiracy to distribute narcotics after a search of his apartment turned up 1,005 grams of a mixture that contains cocaine. Lambis's lawyer didn't dispute the presence of the drugs, though Lambis allegedly told agents the white powder was fake cocaine. Instead, the lawyer objected to the way DEA agents came to search the apartment.

Last August, the DEA said it was investigating a drug-trafficking organization importing large amounts of narcotics from South America when it obtained a warrant for cell tower data from Lambis's phone. In a motion, Lambis's lawyer Bernard Seidler wrote that agents had "only a hunch that Lambis was involved in criminal activity because his [cellphone] number came up in a separate investigation of another person." With the cell tower data, investigators were able to trace the phone to West 177th Street and Broadway, but could not pinpoint it any more specifically.

From there, without consulting a judge, they brought in a Stingray, which simulates a cellphone tower and forces phones in the area to connect to it. An agent combed the block with the device, then the inside of Lambis's building until finding that the strongest signal was coming from his apartment. The same evening, DEA agents knocked on the apartment door, talked their way in, and searched Lambis's apartment without a warrant, turning up the drugs, digital scales, Ziploc bags, and eight phones.

"Without the enhancement simulator the agents did not even have a reasonable suspicion to justify knocking," Seidler wrote in a motion to suppress the evidence.

Judge William Pauley agreed, writing, "The use of a cell-site simulator constitutes a Fourth Amendment search...Absent a search warrant, the Government may not turn a citizen’s cell phone into a tracking device."

As Pauley noted in his decision, the DEA changed its policy on Stingray use the week after Lambis's arrest, requiring agents to obtain a warrant before using the device.

In his decision, Pauley compares use of the cell-tower simulator to thermal-imaging devices, which the Supreme Court has ruled can't be used to peer into people's homes without a warrant, in part because the technology is not readily available to the public. Similarly, he wrote, a federal appeals court has rejected similar arguments to those made by federal prosecutors—that the Stingray reveals no intimate details of the apartment—in a case involving drug-sniffing dogs. In this situation, the privacy protections should be even stronger than in cases where drug-sniffing dogs have been found to have been used improperly, he said.

"An electronic search for a cell phone inside an apartment is far more intrusive than a canine sniff because, unlike narcotics, cell phones are neither contraband nor illegal," Pauley wrote. "In fact, they are ubiquitous."

The ACLU and other civil liberties and electronic privacy groups have called for restrictions on Stingray use, and a public accounting of the technology, which law enforcement agencies are trying to keep secret. ACLU Speech, Privacy, and Technology Project lawyer Nathan Freed Wessler praised the recent decision.

"After decades of secret and warrantless use of Stingray technology by federal law enforcement to track phones, a federal court has finally held the authorities to account," he said in a statement. "The feds are now firmly on notice that when they hide their intent to use invasive surveillance technology from courts and fail to get a warrant, their evidence will be suppressed. This opinion strongly reinforces the strength of our constitutional privacy rights in the digital age."

The ACLU has identified 66 agencies in 24 states and the District of Columbia that own Stingrays, and due to the secrecy around the devices, believes their use is much more widespread. Earlier this year, the NYCLU showed conclusively for the first time that the NYPD is using Stingrays.

Seidler told Reuters he is not sure whether federal prosecutors will now drop the charges against his client.