The US Supreme Court justices heard oral arguments on Tuesday morning in two companion cases revolving around whether police officers need a warrant to search a suspect's cell phone upon arrest: United States v. Wurie involves an old-fashioned flip-phone, while Riley v. California centers on a modern smartphone.

The specific issue before the court in Riley is currently the more interesting debate. Does an arrest alone allow a police officer to search the vast troves of data available on a person's smartphone? In David Riley's case, his phone held a potentially incriminating photo: Riley was standing next to a red Oldsmobile allegedly involved in a prior shooting, but the car was not directly connected to the reason for Riley’s current arrest.

So during two spirited hours today, justices and counsel alike name-dropped a host of technologies and digital platforms, including Twitter, Facebook, Fitbits, GPS, airplane mode, Faraday bags, encryption, online dating apps, and several others in an effort to craft what amounts to an appropriate search and seizure rule for the digital age. And while justices appeared all too willing to try to strut their technological proficiency—some more successfully than others—the task at hand was to determine whether warrantless searches of cell phones and other devices in a suspect’s proximity "incident to arrest" are acceptable under the US Constitution’s Fourth Amendment, which forbids “unreasonable” searches and seizures.

New rule for a new world

Most of the justices during the Riley argument appeared to agree that computers have changed the world to such an extent that a new computer-specific rule is now necessary for searches incident to arrest. They seemed to further agree that police should not have unfettered access to all of the information on one’s cell phone just because it is on one's person during an arrest.

Justices Elena Kagan and Sonia Sotomayor came off as most sympathetic to a so-called “seize-and-hold” bright line rule, whereby a warrant would always be required before a cell phone on one’s person could be searched after an arrest. But as Constitutional law scholar Orin Kerr argues in a Washington Post opinion piece, “I’m not sure there were other votes on the court for that.”

“People carry their entire lives on cell phones...That’s the world we live in,” Justice Kagan argued. Kagan later rhetorically asked the Government’s attorney—Edward C. Dumont, Solicitor General for California—if things should swing the exact opposite way where warrants are unnecessary. “Mr. Dumont… are you saying… in other words, one has to keep one’s cell phone at home to have an expectation of privacy in it?”

Jeffrey Fisher, Riley’s attorney, echoed Kagan’s sentiments. “The modern reality of smartphones is that it is an indispensable item for everyday life of a modern professional and, indeed, most anyone… [We live in] a world where everybody has everything with them at all times.”

Other justices seemed to prefer a middle ground rule, whereby some warrantless cell searches incident to arrest are permissible while others are not.

Kerr suggests that the majority of the court seeks a rule that would bring about what he calls an “equilibrium-adjustment,” whereby the present balance of government power is shifted from physical evidence to digital evidence. Kerr however, argues that such a middle-ground approach would not be easy to achieve in reality because of how difficult it'd be to apply.

Chief Justice John Roberts, in looking to craft such a middle-ground rule for cell phone searches, suggested that the court might seek to draw a distinction between “public” versus “private” search information on a cell phone, hoping to determine what the proper line is for an appropriate search incident to arrest. Roberts asked:

What about something like Facebook or a Twitter account?… Any privacy interest in a Facebook account is at least diminished because the point is you want these things to be public and seen widely… Could you have a rule that the police are entitled to search those apps that, in fact, don’t have an air of privacy about them?

Fisher, echoing Kerr's concern, responded that this would be an incredibly difficult rule to administer in the real world. Thus, Fisher believes it would fail as a practical solution. And, as he went on to note, social media accounts are usually semi-private. Since they are typically only accessible to a certain audience, it further complicates this distinction.

Roberts, seeking an alternative limiting principle based on the type of device searched—and perhaps also revealing some information about his own preferred fitness tracking tool—further inquired:

What if you have a device that doesn't have the broad information that a smartphone has but, only very limited like a Fitbit, that tells you how many steps you've taken, and the defendant says, I've been in my house all afternoon and they want to check and see if he's walked four miles... Is that something they can look at?

Fisher responded that such a distinction would be a faulty one as well, arguing that under prior precedent, information like how many steps someone takes in the privacy of their home is just the type of constitutionally protected detail that should not be in the hands of law enforcement absent a search warrant.

Decisions in both Riley and Wurie are expected to be issued by late-June. In light, the justices must quickly bridge the gap between the tech-savvy and tech-averse among them and reach a difficult, closely watched conclusion soon.