Legal Status and the Criminal Activity of Immigrants
利用2007年欧盟东扩后合法身份的外生变化，通过双重差分法估计合法身份对移民再犯罪率的影响，发现合法身份使再犯罪率降低50%。
We exploit exogenous variation in legal status following the January 2007 European Union enlargement to estimate its effect on immigrant crime. We difference out unobserved time-varying factors by (i) comparing recidivism rates of immigrants from the “new” and “candidate” member countries; and (ii) using arrest data on for eign detainees released upon a mass clemency that occurred in Italy in August 2006. The timing of the two events allows us to setup a difference-in-differences strategy. Legal status leads to a 50 percent reduction in recidivism, and explains one-half to two-thirds of the observed differences in crime rates between legal and illegal immigrants.