The Justice Department on Friday put California and at least seven other jurisdictions on notice about the consequences of so-called sanctuary cities.
The department sent warning letters to the California Department of Corrections and Rehabilitation and local officials in New York, New Orleans, Las Vegas, Miami, Milwaukee, Philadelphia, and Chicago/Cook County, Illinois, the Los Angeles Times reported Friday.
The Times said the letters warn that failure to cooperate might mean the jurisdictions are violating their agreements in terms of grants from the Justice Department. CNBC reached out to the Justice Department for copies of the letters but didn't immediately hear back.
President Donald Trump has previously threatened to take away federal funds from jurisdictions that do not cooperate with federal immigration authorities. Within a few days of taking office, Trump signed an executive order to put teeth into his national crackdown on undocumented immigration.
Last month, the U.S. Department of Homeland Security prepared a list of 118 cities that protected people residing illegally in the country and refused to detain them for immigration enforcement. The controversy has only increased following more federal immigration raids by ICE, or U.S. Immigration and Customs Enforcement, as well as more deportations.
The cities of Los Angeles and San Francisco are among jurisdictions in California considered as "sanctuary cities." For example, San Francisco has a 2013 "Due Process for All" ordinance that limits when local law enforcement may give ICE advance notice on a person's release from local jails. It also bars local police from cooperating on ICE detainer requests.
Similarly, the Los Angeles Police Department has rules in place that restrict officers from cooperating with ICE in immigration enforcement. LAPD also has rules that state officers must not initiate actions to discover the immigration status of a person.