Federal Immigration Law Making Sanctuary States And Cities Illegal–Title 8, Sec. 1373 Along With Aiding And Abetting Law, Sec. 1324
(a) In general
Notwithstanding any other provision of Federal, State, or local law, a Federal, State, or local government entity or official may not prohibit, or in any way restrict, any government entity or official from sending to, or receiving from, the Immigration and Naturalization Service information regarding the citizenship or immigration status, lawful or unlawful, of any individual.
Here’s Title 8, Sec. 1324:
Section 274 felonies under the federal Immigration and Nationality Act, INA 274A(a)(1)(A):
A person (including a group of persons, business, organization, or local government) commits a federal felony when she or he:
* assists an alien s/he should reasonably know is illegally in the U.S. or who lacks employment authorization, by transporting, sheltering, or assisting him or her to obtain employment, or
* encourages that alien to remain in the U.S. by referring him or her to an employer or by acting as employer or agent for an employer in any way, or
* knowingly assists illegal aliens due to personal convictions.
Many thanks to Joe Guzzardi for quoting the 1373 law and posting it!