The federal lawsuit is the first by Trump's Justice Department against states or municipalities that have sanctuary city policies.

The Trump administration stepped up its legal fight over the president’s crackdown on undocumented immigrants by suing Illinois and Chicago, claiming their “sanctuary” policies prevent local officials from cooperating with federal immigration enforcement.

The lawsuit appears to be the first the Justice Department has filed after vowing to investigate state and local officials for allegedly interfering with the president's immigration policies.