by Annemarie Ardy*
Cell phones have become ubiquitous in modern life; they are often carried everywhere and used to facilitate nearly every activity. Yet their incredible convenience is a double-edged sword: when searched by law enforcement, the wealth of information contained on a cell phone can paint a more intimate and fine-grained portrait of a person’s life than 24/7 surveillance. Passcodes and biometric scanners—mechanisms that permit a user to unlock a device through its recognition of the user’s face or fingerprint—stand in the government’s way, but only so long as courts do not permit the government to compel people to unlock their phones. Although the compulsion of a passcode clearly violates the Fifth Amendment’s Self-Incrimination Clause, courts have split on the question of whether compulsion of biometric scanning receives similar protections. This Contribution argues that courts should treat the use of biometric scanners as categorically testimonial and therefore protected by the Self-Incrimination Clause. Biometric scanners convey information that is classically testimonial, and to hold otherwise would pose unacceptable risks to personal privacy.