On April 29, 2014, the United States Supreme Court heard oral argument in two potentially landmark cases concerning privacy of mobile devices. These are the latest in a series of court challenges addressing how the protections against unreasonable searches and seizures, as stated in the Fourth Amendment, apply to modern technology. The Court’s decisions in these cases will not only define the boundaries of warrantless police searches following an arrest, but will more broadly signal the scope of individual privacy protections for personal data.

In the first case, Riley v. California, David Riley was pulled over for having expired license plates and arrested. When the police later searched Mr. Riley’s smart phone, without a warrant, they found evidence of an attempted murder. Based in part on the warrantless search of his phone, Mr. Riley was later convicted and sentenced to fifteen years in prison. In the second case, United States v. Wurie, police officers observed Boston resident Brima Wuire engaging in a drug deal. After arresting Mr. Wurie, officers opened his phone without a warrant, and used information from it to obtain a search warrant for his residence. That evidence uncovered narcotics and a gun. Mr. Wurie was later convicted of being a felon in possession of a gun and narcotics offenses. 

During oral argument, several Justices appeared unwilling to set a bright-line rule of permitting warrantless searches of all mobile phone contents as part of an arrest. Their reluctance appeared to stem from the vast amounts of personal information on a mobile device. Justice Elena Kagan observed: “A person can be arrested for driving without a seatbelt. And the police could take that phone and could look at every single email that person has written, including work emails, including emails to family members, very intimate communications, could look at all that person’s bank records, could look at all that person’s medical data, could look at that person’s calendar, could look at that person’s GPS.” Other Justices appeared equally reluctant to require a warrant in all circumstances. Justice Anthony Kennedy noted that technology, including mobile devices, has allowed criminals to be “more dangerous, more sophisticated, more elusive.” 

In past decisions, the Court has expanded the protections for individuals by requiring warrants. For example, it required warrants for GPS-extended tracking (United States v. Jones, 132 S. Ct. 945 (2012)) and for thermal imaging of homes (Kyllo v. United States, 533 U.S. 27 (2001)). Here, the Court may be poised to modify that trend by allowing warrantless searches of only some types of data. The difficulty will lie in crafting a rule that clarifies to police, lower court judges and citizens what kind of data can be searched, and when, before a warrant must be obtained.