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

Search 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
conviction,
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.