The Supreme Court’s recent decision in Riley v. California held that cell phones cannot be subject to warrantless searches incident to arrest, a strong statement that digital devices are entitled to the protections of the Fourth Amendment. But the opinion leaves many questions unanswered. One of the most important is what expectation of privacy individuals and businesses maintain in the separate digital “subcontainers” on their devices: the discrete files, folders, and application data that police may try to search within a given computer or cell phone. This question has important implications for the scope of warrantless searches in the digital age and has been the subject of a longstanding circuit conflict.

In this Note, I argue that Riley’s reasoning, as well as the text and history of the Fourth Amendment, suggest that digital subcontainers should be accorded robust privacy protections when they are subject to warrantless searches. Analyzing the Court’s reasons for its holding in Riley, this Note demonstrates that those reasons apply with equal force to warrantless searches of all files and folders on a digital device, not just to the government’s initial intrusion. On this reasoning, I propose that even if the government has authorization to conduct a search of some portion of the files on a device, the suspect maintains a constitutionally protected privacy interest in the other files that prevents the government from expanding its search without authorization. This bright-line rule is consistent with Riley, helps resolve unsettled questions how certain search doctrines apply to digital searches, and furthers the goal of providing a reasonable and administrable rule for law enforcement and courts to apply to warrantless digital searches.