8 U.S.C. § 1252c : US Code - Section 1252C: Authorizing State and local law enforcement officials to arrest and detain certain illegal aliens

    (a) In general
      Notwithstanding any other provision of law, to the extent
    permitted by relevant State and local law, State and local law
    enforcement officials are authorized to arrest and detain an
    individual who - 
        (1) is an alien illegally present in the United States; and
        (2) has previously been convicted of a felony in the United
      States and deported or left the United States after such

    but only after the State or local law enforcement officials obtain
    appropriate confirmation from the Immigration and Naturalization
    Service of the status of such individual and only for such period
    of time as may be required for the Service to take the individual
    into Federal custody for purposes of deporting or removing the
    alien from the United States.
    (b) Cooperation
      The Attorney General shall cooperate with the States to assure
    that information in the control of the Attorney General, including
    information in the National Crime Information Center, that would
    assist State and local law enforcement officials in carrying out
    duties under subsection (a) of this section is made available to
    such officials.