(January 2017) - Immigration and Customs Enforcement (ICE)'s use of detainers is increasingly in the spotlight as states and localities that restrict their cooperation with federal immigration enforcement efforts come under fire. This joint policy brief by the American Immigration Lawyers Association and NIJC summarizes the legal and constitutional requirements governing ICE's detainer practice and the ways in which ICE's current practice routinely violates these constraints. At a time when ICE issues more than 5,000 detainers in violation of federal law and the Constitution every month, states and localities that have restricted or are considering restricting their cooperation are well within their rights to question participation in an unlawful program. NIJC demands that ICE be held accountable in the design and implementation of its detainer program.