Law Commons^™

Are Police Officers Bayesians? Police Updating In Investigative Stops, Jeffrey A. Fagan, Lila J.E. Nojima

Faculty Scholarship

Theories of rational behavior assume that actors make decisions where the benefits of their acts exceed their costs or losses. If those expected costs and benefits change over time, behavior will change accordingly as actors learn and internalize the parameters of success and failure. In the context of proactive policing, police stops that achieve any of several goals — constitutional compliance, stops that lead to “good” arrests or summonses, stops that lead to seizures of weapons, drugs, or other contraband, or stops that produce good will and citizen cooperation — should signal to officers the features of a stop that …

No Runs, Few Hits And Many Errors: Street Stops, Bias And Proactive Policing, Jeffrey A. Fagan

Faculty Scholarship

Equilibrium models of racial discrimination in law enforcement encounters suggest that in the absence of racial discrimination, the proportion of searches yielding evidence of illegal activity (the hit rate) will be equal across races. Searches that disproportionately target one racial group, resulting in a relatively low hit rate, are inefficient and suggest bias. An unbiased officer who is seeking to maximize her hit rate would reduce the number of unproductive stops toward a group with the lower hit rate. An unbiased policing regime would generate no differences in hit rates between groups.

We use this framework to test for racial …

Terry'S Original Sin, Jeffrey Fagan

Faculty Scholarship

In Mapp v. Ohio, the U.S. Supreme Court extended the due process protections of the exclusionary rule to include all "constitutionally unreasonable searches" that were done without a basis of probable cause. In the seven years after Mapp, when homicide rates in the U.S. nearly doubled, riots broke out in at least forty-seven U.S. cities. During the same era, a heroin epidemic gripped the nation's urban centers, giving rise to street drug markets and associated violence and pressures on law enforcement to curb those markets. As violence increased, a turn in the nation's political culture questioned Mapp's restraints on …

Probabilities, Perceptions, Consequences And "Discrimination": One Puzzle About Controversial "Stop And Frisk", Kent Greenawalt

Faculty Scholarship

A troubling aspect of the practice of "stop and frisk" in New York and other cities is the evidence that this police tactic is employed predominantly against young men in racial minorities. On August 12, 2013, the federal district court ruled in Floyd v. City of New York that New York's practices and policies regarding stop and frisk violated the Equal Protection Clause of the Fourteenth Amendment and its Due Process Clause, which makes the Fourth Amendment ban on "unreasonable searches and seizures" applicable against the states. Judge Shira A. Scheindlin found that a number of specific stops and subsequent …