Stingray Devices Pose as Cell Tower For several years, the Chicago Police Department has used cell site simulators (commonly known as IMSI catchers or Stingray devices) to scan cellphones for call logs, which include text messages, which likely will come to and end given the Supreme Court ruling on June 25 that cell phone searches cannot be done without a warrant. Flickr/rmuser

Privacy advocates rejoiced on June 25 when the Supreme Court ruled that law enforcement is not allowed to search cellphones without a warrant. The unanimous ruling brings some legal closure to a longstanding debate at the intersection of privacy and technology.

"The police generally may not, without a warrant, search digital information on a cellphone seized from an individual who has been arrested," states the decision summary, issued by Chief Justice John Roberts. The ruling allows for exceptions under extreme circumstances, such as the case of a kidnapping or bomb threat.

"Modern cellphones are not just another technological convenience," Roberts said about his decision. "With all they contain and all they may reveal, they hold for many Americans the privacies of life."

The ruling overturns a 2011 decision by the California Supreme Court that allowed law enforcement to search cellphones without a warrant. An attempt to overturn that decision was made by the legislature, but vetoed by Gov. Jerry Brown, who said the issue should be determined in the courts.

The prohibition on warrantless cellphone searches follows several high-profile privacy cases in the past several years. The cases of Riley v. California and United States v. Wurie each showed how warrantless cellphone searches cemented the convictions of two criminals, one found guilty in connection with a gang shooting, and the other a purchaser of crack cocaine.

Though the data found in those cases proved the parties to be guilty, the most recent ruling established legal context for an increasingly digital world.

"The United States asserts that a search of all data stored on a cellphone is 'materially indistinguishable' from searches of these sorts of physical items,” Roberts stated in his ruling. “That is like saying a ride on horseback is materially indistinguishable from a flight to the moon. The fact that a search in the pre-digital era could have turned up a photograph or two in a wallet does not justify a search of thousands of photos in a digital gallery."

Reactions to the ruling vary. On the West Coast, SF Gate reported that the California Police Chiefs Association said the ruling was disappointing, but that they would adapt nonetheless. In Texas, the Austin American-Statesman reported that the Austin Police are unfazed by the ruling, likely because in February, the state’s highest criminal court reached a similar conclusion to that of the Supreme Court, and ever since, the agency has sought a warrant or permission from the phone’s owner before inspecting a device. The same goes for the police in Greater New Haven, Conn.

But in the Windy City, the Chicago Police Department will run into trouble -- for several years the department has used cell site simulators (commonly known as IMSI catchers or Stingray devices) to scan cellphones for call logs, which include text messages, the Chicago Tribune reported, also noting that although sources confirm the simulators' use, the city has never publicly acknowledged having the equipment.

An American Civil Liberties Union representative called the decision revolutionary. "Recognizing that a cellphone is a miniature computer that stores enormous amounts of sensitive data is important, as the government continues to develop technological capabilities to gather wide amounts of information,” Electronic Frontier Foundation Staff Attorney Hanni Fakhoury told The Verge. “Whether it be the government’s use of a Stingray, the use of cell site location information to track a person’s location or the NSA’s bulk collection of Internet and phone records."