Sanctuary Cities and Crime

A sanctuary policy is a policy that inhibits local law enforcement from cooperating with immigration authorities. Sanctuary policies have gained more attention in recent U.S. policy debates. Opponents claim that sanctuary policies attract criminals and lower the opportunity cost of crime through weaker sanctions and lower apprehension probability. Supporters counter that these policies produce a spiral of trust that supports police and raises informal social control over crime. Using city crime data from 1999 to 2010, I estimate the effect of sanctuary policies on crime. Using a difference-in-differences approach, this paper finds no evidence that sanctuary policies cause an increase in crime and some evidence that they may lead to a decrease in property crime. Moreover, further analysis confirms no pre-trend before the policy adoption and finds the effect strengthened over time after the adoption. The increased trust between residents and police is likely the reason for the negative effect.