U.S. Supreme Court Tells Police to “Get a Warrant” for Cellphone Searches

By Renee Dopplick, ACM Director of Public Policy
July 7, 2014

The U.S. Supreme Court recently unanimously ruled that law enforcement need to obtain a warrant to search a cellphone seized incident to an arrest. The decision addressed two separate warrantless cellphone search cases before the Court – one involving a smartphone and one involving a flip-lid phone. In the new balancing of law enforcement needs and the rights of arrestees, the Court concluded, “Our answer to the question of what police must do before searching a cell phone seized incident to an arrest is accordingly simple — get a warrant.”

The Court was not clearly convinced that a warrantless search might be necessary to prevent potential evidence destruction of data on the cellphone by remote wiping, geofencing, or data encryption. Geofencing is when the contents of the phone are deleted upon crossing some geographic boundary; this is generally achieved through pre-programmed mechanisms that leverage the device’s GPS location information or the WiFi tower location. When discussing the techniques used to destroy or encrypt data, the Court cited the “Guidelines on Mobile Device Forensics,” published by the National Institute of Standards and Technology in May 2014. The guidelines identify three means to prevent data destruction and encryption, each with tradeoffs for forensics examination: (a) airplane mode, (b) turning off the device, and (c) placing the device in a shielded container, such as a Faraday bag.

Even though the Court asserts a clear rule with a simple answer, warrantless searches of cellphones could still be lawful in certain circumstances. For example, the Court spotlighted the continued applicability of the exigent circumstances exemption, which could allow law enforcement to search the phone immediately without a warrant if they believe an arrestee’s phone is in imminent threat of a data destruction attempt. Presumably, the imminent threat would not be mitigated by disconnecting the cellphone from the network through the “simple” and “reasonable” responses discussed earlier in the opinion. The Court also clarified that law enforcement can disable a phone’s auto-lock security feature to prevent the phone from locking and encrypting data for the purpose of preserving evidence while they obtain the warrant.

“The most significant part of the decision is not the fact that the Supreme Court has limited searches incident to an arrest,” said U.S. Public Policy Council member Mark Rasch. “It’s that it has recognized that data – and digital data in particular – is a different kettle of fish than physical objects and must be treated accordingly. And that’s a big deal. A very big deal.”

Riley v. California; United States. v. Wurie, U.S. Supreme Court Slip Opinion