If police officers arrest you, they can search you, including your pockets, and the area within your immediate control. (See Search Incident to Arrest.) But what happens if they come across your iPhone or Android, or even your old-school flip phone? Are they free to dive into your phone and all its data, or do they first need a warrant?
The U.S. Supreme Court sets the basic rules on search and seizure through interpretation of the Fourth Amendment, which protects against unreasonable government intrusion. But since it takes so long for a case to get all the way to the Supreme Court, search-and-seizure law relating to new technology often remains uncertain for many years.
Uncertainty about cellphone searches prevailed until June of 2014, when the U.S. Supreme Court held that police officers generally need warrants to search the cellphones of arrestees.
After an arrest, officers are allowed to search people and any containers on or immediately around them. But lower courts across the country couldn’t agree whether this kind of search reasonably extended to cellphones. Some said that mobile-phone searches required warrants, while others said they didn't.
The Supreme Court found that a cellphone is entirely unlike a typical container—for instance, a cigarette pack. Sure, both might contain evidence, but that evidence is physical in one instance and digital in the other. And the digital evidence that cellphones hold is both vast and tremendously personal. Today's smart phones hold anything from bank and medical records to intimate text messages to data that tracks the owner's location.
Plus, as the Court explained, data revealed by a cellphone may not actually be stored on it. With cloud computing, the information might actually live on a remote server. The fact that cellphones may not even "contain" the information they display is another way in which the cigarette-pack analogy falls short.
Prosecutors expressed a series of objections to the requirement that officers obtain warrants before searching arrestees' cellphones. They mentioned "remote wiping," by which a third party could delete a phone's data after police officers take it, or by which the data might erase if the phone enters or exits a particular geographic area. They also discussed data encryption, which makes information nearly impossible to get to without a password. They even invoked extreme scenarios, as where a phone has the location of an about-to-explode bomb or a missing child.
First, to the extent that a cellphone might be usable as a weapon, the Supreme Court said that officers can search it without a warrant—for example, they can retrieve a razor blade hidden between the phone and its case. Second, officers can probably take "preventive measures" to avoid the loss of a phone's data. Without delving into it, they could turn off the phone, place it in a bag that protects against radio waves, or disable its automatic encryption lock, for example. Third, with today's technology, it may take officers as little as 15 minutes to get a warrant that authorizes a search. And fourth, officers can dig into the phone when there's an emergency.
The "exigent circumstances" doctrine allows officers to act without warrants when the circumstances are severe. For example, if the officers have reason to believe that they can do nothing to stop the loss of a phone's data and must search it now or never, they likely can do so. They certainly can go into the phone if there's a basis to suspect that it can help them avert a disaster involving a ticking bomb or missing child.
The Supreme Court ultimately decided that cellphones are most like homes, which police officers need warrants to search. If anything, Chief Justice Roberts wrote, a contemporary cellphone—with its immense storage capacity—contains more private, sensitive information than a house. So, officers who plan to search cellphones will usually have to get court approval before having at it.