Crime is costly, yet we understand little about it. The United States justice system costs $280 billion per year, but compared to other areas, such as medicine and agriculture, we have few answers for the field's fundamental questions, like what causes crime and how we can best use our justice...

Several cities have recently adopted civil injunctions as a means to reduce gang violence. To evaluate the effectiveness of such injunctions, I develop an extensive database of neighborhood-level reported crime counts from four police jurisdictions within Los Angeles County. I construct two...

Despite widespread popular accounts linking crack cocaine to inner-city decay systematic research has analyzed the effect of the introduction of crack on urban crime. We" study this question using FBI crime rates for 27 metropolitan areas and two sources of" information on the date at which...