Congress has a long-standing interest in seeing that immigration enforcement agencies identify and deport serious criminal aliens. The expeditious removal of such aliens has been a statutory priority since 1986, and the Department of Homeland Security (DHS) and its predecessor agency have operated programs targeting criminal aliens for removal since 1988. This book examines the four programs the DHS operates to target criminal aliens with a focus on the merits of jail enforcement programs and the role of state and localities in immigration enforcement.