Brown and California Attorney General Xavier Becerra held a press conference at the Capitol to defend the laws following a speech by Sessions to a law enforcement conference in downtown Sacramento on Wednesday morning.
Sessions' lawsuit hits directly on Senate Bill 54 - the centerpiece of California's "resistance" on immigration - which aims to prevent state and local police officers from helping to carry out the president's promised crackdown on undocumented immigrants.
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Sessions told those in attendance at the California Peace Officers Association's Legislative Day that the state has "a problem" and told state officials to "stop actively obstructing law enforcement ... stop protecting lawbreakers".
But there is a federal law that prohibits states and cities from interfering or prohibiting communication between local law enforcement and the feds about a person's immigration status.
The statement also reiterated some of Schaaf's criticism of the Trump administration.
Sessions has blamed sanctuary city policies for crime and gang violence.
Larger US cities, including Los Angeles, Chicago and NY ruled by the opposition Democrats, adopted policies that hinder the sharing of information between the local police and immigration officers. He also said that he spoke with former U.S. Attorney General Eric Holder on possible responses to the DOJ's lawsuit, and said that Legislature will have a response later today.
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".
It is the first legal action against a state or local government over its immigration policies by Mr Sessions' justice department.
His plans on immigration have put him at odds with sanctuary cities and the state of California, which in October was declared a sanctuary state by legislation signed by Brown.
"So here's my message to Mayor Schaaf: How dare you!" Jeff, these political stunts may be the norm in Washington, but they don't work here. "Bragging about and encouraging obstruction of our law enforcement, and, the law-I am afraid that this is an embarrassment to the proud state of California". "We will do everything in our power to stand up for and protect Dreamers, hard-working families, immigrants - people who are just doing their best to work, to learn, and to have a part of the Sacramento and California dream", Steinberg said.
The U.S. Supreme Court reinforced the federal government's primacy in enforcing immigration law when it blocked much of Arizona's tough 2010 immigration law on similar grounds.