Well here is an interesting bit of info
(a) Every law enforcement agency in California shall fully cooperate with the United States Immigration and Naturalization Service regarding any person who is arrested if he or she is suspected of being present in the United States in violation of federal immigration laws.(b) With respect to any such person who is arrested, and suspected of being present in the United States in violation of federal immigration laws, every law enforcement agency shall do the following:(1) Attempt to verify the legal status of such person as a citizen of the United States, an alien lawfully admitted as a permanent resident, an alien lawfully admitted for a temporary period of time or as an alien who is present in the United States in violation of immigration laws. The verification process may include, but shall not be limited to, questioning the person regarding his or her date and place of birth, and entry into the United States, and demanding documentation to indicate his or her legal status.(2) Notify the person of his or her apparent status as an alien who is present in the United States in violation of federal immigration laws and inform him or her that, apart from any criminal justice proceedings, he or she must either obtain legal status or leave the United States.(3) Notify the Attorney General of California and the United States Immigration and Naturalization Service of the apparent illegal status and provide any additional information that may be requested by any other public entity.(c) Any legislative, administrative, or other action by a city, county, or other legally authorized local governmental entity with jurisdictional boundaries, or by a law enforcement agency, to prevent or limit the cooperation required by subdivision (a) is expressly prohibited.