"U.S. Immigration and Customs Enforcement (ICE), the largest investigative agency in the Department of Homeland Security (DHS), is responsible for enforcing federal immigration laws as part of its homeland security mission. ICE works closely with federal, state and local law enforcement partners in this mission. The 287(g) Program, one of ICE's top partnership initiatives, allows state and local law enforcement entities to enter into a partnership with ICE, under a joint Memorandum of Agreement (MOA), in order to receive delegated authority for immigration enforcement within their jurisdictions. The 287(g) Program has emerged as one of the agency's most successful and popular partnership initiatives as more state and local leaders have come to understand how a shared approach to immigration enforcement can benefit their communities."
U.S. Immigration and Customs Enforcement: http://www.ice.gov/