U.S. Immigration and Customs Enforcement (ICE) works in partnership with many federal, state and local law enforcement agencies to authorize immigration enforcement within an agency's jurisdiction. The Delegation of Immigration Authority Section 287(g) of the Immigration and Nationality Act lays out the requirements for such a partnership.
ICE enforces federal immigration laws in the United States. The 287(g) program exists to delegate authority to local law enforcement officers to discover information on potential illegal aliens and then arrest or detain those in violation of immigration laws. As of 2014, 35 law enforcement agencies across 18 states participate in the 287(g) program, with more than 1,500 officers certified by ICE, according to the ICE fact sheet on 287(g).