The lawsuit, filed by the U.S. Justice Department in Los Angeles federal court, alleges that policies barring city resources from aiding in immigration enforcement operations or collecting information about individuals' citizenship status violate federal law.
"We will keep enforcing federal immigration law in Los Angeles, whether or not the city's government or residents agree with it," Chad Mizelle, a senior Justice Department official, said on social media. "And we will not tolerate any interference with the federal government's duty to enforce the law."
The lawsuit comes weeks after Trump deployed California National Guard troops to quell protests in Los Angeles against deportation operations. The demonstrations were limited to a small section of the city, but included some instances of looting, property destruction and attacks on law enforcement.
A spokesperson for Los Angeles Mayor Karen Bass did not immediately respond to a request for comment on the lawsuit.
California officials, including Bass, accused Trump of inflaming tensions and exacerbating a situation local authorities had under control.
California's Democratic Governor, Gavin Newsom, sued the Trump administration over the deployment. A federal appeals court has for now allowed Trump to keep control of the National Guard.
The Justice Department's lawsuit blames Los Angeles' policies for sparking confrontations between activists and federal agents that led to this month's protests. The demonstrations erupted after U.S. Immigration and Customs Enforcement conducted raids on workplaces in and around the city, which has a large immigrant population.
The complaint alleges that Los Angeles' policies, enacted weeks after Trump won last year's election, violate a provision of the U.S. Constitution called the "supremacy clause" that makes federal law supersede conflicting state laws. It asks a federal judge to strike down those policies as unlawful.
The lawsuit marked the latest instance of the Justice Department under Trump challenging so-called sanctuary city policies that prevent local jurisdictions from sharing information or participating in immigration raids.
The department has already sued the Democratic-run states of New York, Illinois and Colorado over policies it argues unlawfully hinder the Trump administration in its effort to deport millions living illegally in the United States. Those cases remain pending.
The Justice Department has also vowed to criminally investigate and prosecute local officials who impede federal immigration enforcement. The Trump administration has sought to revoke federal grant funding from some states over their immigration policies.
Rights groups and Democratic officials have argued that the policies are necessary to build trust in immigrant communities and encourage people who may otherwise be fearful to cooperate with local law enforcement.
BATTLES WITH CALIFORNIA
The lawsuit also marks the latest legal confrontation between the Trump administration and California, the largest U.S. state and a bastion of liberal politics.
The Justice Department is already investigating the state over a law that allows transgender female athletes to compete in girls' school sports and is examining whether faculty hiring practices in the University of California system violate anti-discrimination laws.
Newsom, the state's governor, has long clashed with Trump and recently filed a defamation lawsuit against Fox News over how the network covered a phone call with Trump related to the Los Angeles protests.
