Scholars have widely criticized the Supreme Court’s Fourth Amendment jurisprudence as incoherent, especially in cases involving emerging technologies. This Article argues that to understand Fourth Amendment doctrine, one must consider how the values that underlie the Court’s decisions are balanced against each other and shift over time. To do so, this Article first proposes a novel, bottom-up approach to identifying the relevant values that focuses on the specific evidence that the Court considers in each case. Distilling the values underlying the Fourth Amendment provides a more coherent understanding of Fourth Amendment doctrine. This Article then applies this framework to three biometric technologies: facial recognition, iris recognition, and DNA profiling. Law enforcement use of these technologies may all raise Fourth Amendment challenges, but the framework shows how these challenges implicate different values. Recognition and application of this framework can result in a better appreciation of the impact of emerging technologies on Fourth Amendment doctrine.
