Supreme Court Issues Bold Decision On Cell Phone Privacy


As of yesterday, America’s Fourth Amendment law was an antique. It was the legal equivalent of trying to solve complicated differential equations with an abacus. It took little account of how much data government can gather or store with modern day computers, and even less account of technological advances such as the smart phone.

Today, there are still many questions courts must consider about how our understanding of privacy should evolve to meet the challenges of an era where millions of people carry computers in their pockets that are more powerful than anything that existed 50 years ago. Yet, with its decision in Riley v. United States, the justices took an important step towards lifting our Constitution out of what President Franklin Delano Roosevelt used to call the “horse-and-buggy age.” As of today, in nearly all circumstances, the police must obtain a warrant before they can search through your cell phone.

Although the Fourth Amendment generally provides that a person’s possessions may not be searched unless a judicially issued warrant authorizes the search, the Court has long recognized an exception to this rule for what is known as searches incident to an arrest. When a suspect is taken into police custody, that suspect may carry evidence of a crime that they will quickly try to destroy if it remains in their possession — or, worse, they may carry a weapon that could endanger the officer’s safety. Thus, police are allowed to search a suspect when they are placed under arrest, and evidence uncovered during this search can typically be used against the suspect even if the police make this search without first obtaining a warrant.

This general rule allowing searches incident to an arrest dates back about a century, long before the era of computers and the iPhone. So the justices who created and fleshed out this rule had no concept of what it would mean when many people carry a small device in their pocket that can access years worth of their emails and text messages, that can reveal a suspects’ finances and romantic partners, and that may contain extensive photo and video evidence of how they lead their lives. Riley teed up this question for the modern-day Supreme Court: when police arrest someone carrying a cell phone, does that arrest give law enforcement license to cull through the device and access whatever information they choose?


The answer, according to a nearly unanimous opinion by Chief Justice John Roberts, is no. “Cell phones,” Roberts explained, “place vast quantities of personal information literally in the hands of individuals. A search of the information on a cell phone bears little resemblance to the type of brief physical search” authorized by previous cases.

As Roberts lays out, few of the traditional justifications for a search incident to arrest authorize a full search of a suspect’s cell phone. The data stored on a phone “cannot itself be used as a weapon to harm an arresting officer or to effectuate the arrestee’s escape.” If the phone conceals a weapon, officers can search the physical phone itself without actually accessing its electronic contents. And, if police fear that a suspect may delete incriminating evidence on the phone, in most cases they can alleviate this fear by taking the phone from the suspect and waiting until they obtain a warrant to search it. If they fear that any data on the phone may be remotely wiped, they can store the phone in a place where cell phone signals cannot reach it.

These reasons, combined with the distinct character of cell phones as compared to the kind of objects people used to carry on their person when the Court’s Fourth Amendment doctrines developed, justify requiring police to obtain a warrant before they may search a cell phone. As Roberts lays out, “[p]rior to the digital age, people did not typically carry a cache of sensitive personal information with them as they went about their day. Now it is the person who is not carrying a cell phone, with all that it contains, who is the exception.”

It should be noted that Riley does not rule out the possibly that, in extraordinary cases, police may be justified in searching a cell phone without a warrant. Thus, for example, in the rare case where a suspect is “texting an accomplice who, it is feared, is preparing to detonate a bomb,” or when a suspect is a “child abductor who may have information about the child’s location in his cell phone,” a warrantless search would be justified. Nevertheless, in the vast majority of cases, the Constitution now requires police to get a warrant before they can search a cell phone.

America’s privacy law, in other words, took a significant step into the modern era with Riley. It remains to be seen, however, how the Court will answer similar questions about whether new technologies require a rethinking of longstanding privacy doctrines — such as when the National Security Agency builds a database of millions of phone calls made over many years.