Searching Cell Phones Incident to Arrest

Nearly 90% of American adults have cell phones. When one of those cell phone users is arrested, may police search their mobile phone incident to arrest? The Fourth Circuit recently answered that question in the affimative. See United States v. Murphy, __ F.3d __, 2009 WL 94268 (4th Cir. Jan. 15, 2009). The defendant in Murphy was a passenger in a car that was stopped for speeding. He gave a false name to the police, they figured it out, and he was arrested for obstruction of justice. Counterfeit currency and drug-related items were found in the car. The police searched Murphy's cell phone incident to arrest, and obtained phone numbers they later used to develop additional evidence against Murphy. Murphy was charged with drug and currency offenses, and moved to suppress, arguing that the police should have obtained a warrant to search the phone. Neither the district court nor the court of appeals agreed. The Fourth Circuit said that the "manifest" need to preserve evidence justified police in retrieving "text messages and other information from cell phones and pagers seized incident to an arrest." There's some logic here: over time, new messages and calls will "crowd out" earlier ones from the phone's memory, effectively destroying potentially relevant evidence. Murphy agreed that when a phone has a small storage capacity, the need to preserve evidence justifies a warrantless inspection of a cell phone, but he contended that when a phone has a large storage capacity, the risk of losing critical evidence is reduced, and the privacy interest of the phone's owner is increased, so a warrant should be required. The court rejected this argument as unworkable -- what would count as a "small" or "large" capacity, and how would an officer know the capacity of a phone before searching it? Appellate courts are struggling to apply Fourth Amendment rules to new technologies, and decisions like Murphy often raise as many questions as they provide answers. For example, could the police search the "address book" of Murhpy's phone incident to arrest, even though it is not subject to crowding out? What if Murhphy had been carrying a Blackberry? A laptop? Could those be searched incident to arrest? What if the police can obtain all call information and text messages from the service provider, removing the crowding out/exigency justification? I'm keenly interested in this area of the law, and welcome feedback and comments about what officers are doing in the field and how courts are responding.