The United States Supreme Court issued a unanimous decision instructing police that they must get a warrant if they want to search an arrested person’s cell phone.

“Our answer to the question of what police must do before searching a cell phone seized incident to an arrest is accordingly simple—get a warrant,” Chief Justice John Roberts wrote in the court’s opinion [PDF].

The decision applied to two cases. In one case, Riley v. California, involves an officer who seized a “smartphone” from a person who was under arrest and began to scroll through its contents at the scene of the arrest. He was looking through text messages and the phone’s contact list. In the second case, United States v. Wurie, an officer believed the person arrested had used a cell phone to arrange a drug deal. At the police station, an officer noticed that a “flip” phone was repeatedly receiving calls from a number labeled “my house.” The officer searched through the call log on the phone in order to obtain the home phone number.

The Supreme Court solidly affirmed that Americans have a Fourth Amendment privacy interest in keeping their cell phones from being subject to warrantless searches.

“These decisions are huge for digital privacy,” EFF Staff Attorney Hanni Fakhoury reacted. “The court recognized that the astounding amount of sensitive data stored on modern cell phones requires heightened privacy protection, and cannot be searched at a police officer’s whim. This should have implications for other forms of government electronic searches and surveillance, tightening the rules for police behavior and preserving our privacy rights in our increasingly digital world.”

Steven R. Shapiro, national legal director for the ACLU, reacted, “By recognizing that the digital revolution has transformed our expectations of privacy, today’s decision is itself revolutionary and will help to protect the privacy rights of all Americans. We have entered a new world but, as the court today recognized, our old values still apply and limit the government’s ability to rummage through the intimate details of our private lives.”

Remarkably, the Supreme Court rejected some key arguments that may have sounded good but simply did not convince the justices that they were significant enough to undermine a person’s right to privacy.

“The United States and California had argued that information on a cell phone may nevertheless be vulnerable to two types of evidence destruction unique to digital data—remote wiping and data encryption,” Roberts wrote.

He described, “Remote wiping occurs when a phone, connected to a wireless network, receives a signal that erases stored data. This can happen when a third party sends a remote signal or when a phone is preprogrammed to delete data upon entering or leaving certain geographic areas.”

“Encryption is a security feature that some modern cell phones use in addition to password protection,” Roberts also explained. “When such phones lock, data becomes protected by sophisticated encryption that renders a phone all but ‘unbreakable’ unless police know the password.”

The court noted that neither remote wiping nor encryption involved an “active attempt by a defendant or associates to conceal or destroy evidence upon arrest.” These are both “ordinary” operations of a cell phone’s “security features.” Neither of the justices seemed to be convinced that an appropriate answer to overcoming either of these “features” was to conduct a warrantless search because police may still be unable to get to the data if the phone had already locked or the data had already been wiped.

Roberts’ opinion suggested that, rather than grant the police broad authority to conduct warrantless searches on any American who is under arrest, police could disconnect a phone from a network to prevent remote wiping. They could turn the phone off or remove the battery. They could also place the phone in an enclosure that isolated it from radio waves (like a Faraday bag). And Roberts further acknowledged that the police may be able to claim “exigent circumstances” if they knew there would be an “imminent remote-wipe attempt” and search the phone immediately.

The US government had proposed that police be able to search a cell phone without a warrant but “restrict the cell phone search to those areas of the phone where an officer reasonably believes that information relevant to the crime, the arrestee’s identity or officer safety will be discovered.” That was rejected by the court as well.

“This approach would again impose few meaningful constraints on officers,” Roberts contended. “The proposed categories would sweep in a great deal of information, and officers would not always be able to discern in advance what information would be found where.”

The court rejected the suggestion that police be able to search “call logs.” They also rejected a suggestion from California officers only search “cell phone data if they could have obtaine the same information from a pre-digital counterpart.”

“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,” Roberts argued. “The fact that someone could have tucked a paper bank statement in a pocket does not justify a search of every bank statement from the last five years. And to make matters worse, such an analog test would allow law enforcement to search a range of items contained on a phone, even though people would be unlikely to carry such a variety of information in physical form.”

As one may have noticed, there’s a bit of a dumbfounded tone that runs throughout the Supreme Court opinion, as if the justices could not believe attorneys from California and the US government were actually proposing some of these ideas to defend giving police such wide discretion. The justices were also clearly astonished by some of the language the US government used to argue the case.

“The United States asserts that a search of all data stored on a cell phone is ‘materially indistinguishable’ from searches of these sorts of physical items,” Roberts stated. “That is like saying a ride on horseback is materially indistinguishable from a flight to the moon. Both are ways of getting from point A to point B, but little else justifies lumping them together.”

The court ultimately concluded, “Modern cell phones are not just another technological convenience. With all they contain and all they may reveal, they hold for many Americans ‘the privacies of life.'”

Creative Commons-Licensed Photo by Neilpcronin

Kevin Gosztola

Kevin Gosztola

Kevin Gosztola is managing editor of Shadowproof. He also produces and co-hosts the weekly podcast, "Unauthorized Disclosure."