Immigration, Sanctuary Policies, and Public Safety

US Immigration and Customs Enforcement (ICE) detainers-the requests from ICE to a state or local law enforcement agency to hold someone until the person can be taken into immigration custody-have been instrumental in supporting the growing number of deportations from the United States. However, as migrant detentions expanded after 9/11, law enforcement agencies have been increasingly reluctant to comply with ICE's detainers, due to the cost incurred by detention centers when holding immigrants for an extended period and the possible violation of migrants' civil rights. Such reluctance has earned these law enforcement agencies the label of "sanctuary cities." ICE has denounced this behavior, arguing that it interferes with the agency's ability to obtain custody of convicted criminals and makes communities less safe. Using data on detainers at the local law enforcement-agency level, we assess ICE's claims. We find that sanctuary policies do not hinder ICE's ability to obtain custody of convicted criminals and question the argument that such policies might make communities less safe. These findings are relevant for migration scholars and policymakers interested in gaining a better understanding of the public-safety implications of sanctuary policies aimed at immigrants in various receiving nations, including Canada, the UK, and the United States.