He added: "When people feel confident to come forward to report crimes in our communities or participate in policing efforts without fear of deportation, they are more likely to cooperate with the criminal justice system".
"Here's my message to Mayor Schaaf: 'How dare you!'" the attorney general said.
California sheriffs have called on the GOP-controlled Congress to intervene and pass federal law to change the state's sanctuary status, arguing that the law ties their hands too tightly and will only increase the chances of another high-profile tragedy.
California Governor Edmund G. Brown and Attorney General Xavier Becerra, both named defendants in the lawsuit, sharply condemned it as a meritless. Note: As a result, the Justice Department says, immigration agents face greater danger in re-arresting the former prisoners once they're back on the streets.
The demand may end up being definitive case where role of local and state administrations in immigration policy is dirimad. "What Jeff Sessions said is completely not true", said Brown.
In suing, Sessions is citing the same principle that allowed former President Barack Obama's administration to block state laws in Arizona and Alabama that targeted illegal immigrants. California legislature and the governor by signing the bill, put us on a position that we have to go to court.
Sessions on Wednesday announced a Department of Justice (DOJ) lawsuit against California on Wednesday during a speech to the California Peace Officers' Association in Sacramento. Jeff, se political stunts may be norm in Washington, but y don't work here. SAD! It calls AB 103 an "improper, significant intrusion into federal enforcement of immigration laws" and again a violation of the Supremacy Clause.
In addition, California's state budget bill also banned new contracts for immigration detention and gave the state attorney general power to monitor all state immigration detention centers.
California Gov. Jerry Brown blasted Sessions' announcement, accusing the administration of trying to "polarize America".
Demonstrators are blocking traffic outside a hotel where Sessions will deliver a speech to law enforcement officials.
Sessions has blamed sanctuary city policies for crime and gang violence.
The attorney general took sharp aim at California's Democratic political leadership, including Oakland Mayor Elizabeth Schaff, for actions he claimed have shielded 800 criminal immigrants from federal immigration officers.
In a statement previous year the association's president, Gardena Police Chief Ed Madrano, said the compromise "addresses the significant public safety concerns we raised during this debate, and it reaffirms what we have held since the beginning, which is that California law enforcement should not be used to assist in mass deportations".