The Questionable Objectivity of Fourth Amendment Law

Abstract

The Supreme Court often insists that Fourth Amendment rules must be objective. The doctrine should focus on what police officers do, not what they are thinking when they do it. Recently, however, Fourth Amendment law’s objective façade has begun to crack. In a series of cases, the Supreme Court has introduced subjective tests. Fourth Amendment law is now best understood as a complex mix of subjective and objective tests. The Justices have not offered a clear explanation for why they use objective rules in some cases and subjective rules in others. But it should be clear that the Justices are making a choice, and that both subjective and objective approaches are in play.

This Article identifies the Supreme Court’s recent turn to subjective rules and offers a normative framework for the choice between subjective and objective tests in Fourth Amendment law. It begins by reviewing existing caselaw and showing how it often hinges on an officer’s subjective state of mind. The Article then offers a framework for choosing between objective and subjective tests. Subjective approaches can permit courts to craft narrower rules that better distinguish harmful from beneficial police practices. But the benefits of subjectivity depend on whether harms track subjectivity and whether states of mind can be determined reliably. To best achieve the aims of Fourth Amendment law, courts should consider in each context the civil liberties benefit of narrowing doctrine in light of the risk that a subjective test will be misapplied.