In a unanimous opinion filed today (June 25, 2014) The United States Supreme Court has ruled that a warrant is required before police may search information on a cell phone even when the cell phone was seized incident to arrest.
The opinion, Riley v. California, authored by Chief Justice Roberts, declined to follow the reasoning of United States v. Robinson, 414 U.S. 218 (1973) (in which a cigarette pack found on Robinson after his arrest was searched and drugs were found). "Digital data stored on a cell phone cannot itself be used as a weapon to harm an arresting officer or to effectuate the arrestee's escape."
Chief Justice Robert's opinion is worth a read. Here is an excerpt:
The United States asserts that a search of all data stored on a cell phone is "materially indistinguishable" from searches of these sorts of physical items (billfolds and address books, etc.). (citing to the brief for the United States). That is like saying a ride on horseback is materially indistinguishable from a flight to the moon. Both are ways of getting from point A to point B, but little else justifies lumping them together. Modern cell phones, as a category, implicate privacy concerns far beyond those implicated by the search of a cigarette pack, a wallet, or a purse.
So keep on rocking in the free world!