Fourth Amendment cases are replete with references to “purpose.” Typically, these references pertain to the motivations of individual officers and occasionally to those of public institutions. That courts pay attention to purpose is unsurprising. Across many areas of law, an alleged wrongdoer’s intentions are often critical to determining liability, a remedy, or both. Purpose analysis in Fourth Amendment cases however, is surprisingly confused. The Supreme Court has, without explanation, advanced separate frameworks for analyzing purpose – objective, subjective, and programmatic. The only consistent thing about the three approaches is that they all fail to ensure that law enforcement agents behave transparently and honestly. The failure is particularly worrisome because of the increasingly salient role that purpose analysis has played in recent Supreme Court cases.
This Article contends that purpose should be an ex ante institutional design principle rather than what it currently is, a judicial device for ascertaining an actor’s past motivations. A single enforcement bureaucracy should not be responsible for too broad a range of functions, particularly if those functions implicate very different levels of state coercion – for example, enforcing felony narcotics laws as opposed to traffic laws. Modern police departments tend to have sprawling mandates that sometimes make it impossible for policy makers and officers to differentiate and rank distinct goals. Mandate sprawl is particularly problematic because it creates opportunities for pretextual searches and seizures – police have access to a broad range of rationales to justify conduct that was actually carried out for an impermissible motive. Were enforcement bureaucracies required to differentiate enforcement activities by purpose, it would go a long way in curing this problem.