In one of the most significant Fourth Amendment rulings everhanded down by the Supreme Court, all nine justices agreed in an opinion involving two companion cases, Riley v. California [PDF] and United States v. Wurie, that police generally need a warrant before reading data on the cell phone of an arrestee. This decision may well presage how the court will rule on the constitutionality of the National Security Agency (NSA) metadata collection program when that issue inevitably comes before it.
Warrants Needed to Search Cell Phone Data
There has always been a preference for search warrants when the police conduct a Fourth Amendment search or seizure. But, over the years, the court has carved out certain exceptions to the warrant requirement, including the search incident to a lawful arrest. The 1969 case of Chimel v. California defined the parameters of this exception. Upon a lawful arrest, police can search the person of the arrestee and areas within his immediate control from which he could secure a weapon or destroy evidence.
Four years later, in United States v. Robinson, the court confirmed that the search incident to a lawful arrest is a bright-line rule. These types of searches will not be analyzed on a case-by-case basis. If the arrest is lawful, a search incident to it needs no further justification. It does not matter whether the officer is concerned in a given case that the arrestee might be armed or destroy evidence.
In Riley/Wurie, the court declined to apply the search incident to a lawful arrest exception to searches of data contained on an arrestee’s cell phone. Chief Justice John Roberts wrote for the court that the dual rationales for applying the exception to the search of physical objects–protecting officers and preventing destruction of evidence–do not apply to the digital content on cell phones: “There are no comparable risks when the search is of digital data.”