The suit, filed in federal court, is the biggest pushback from city officials since President Donald Trump invoked a provision of the Home Rule Act — the 1970s law that allows for limited self-governance by D.C.’s government — which allows the president to request MPD’s services to address “special conditions of an emergency nature.”

Trump on Monday federalized the Washington, D.C., police department and ordered the deployment of National Guard troops in the capital city.

Washington’s police department chief says a Trump administration order installing a federal official as its head would upend command structure and be a “dangerous” threat to law and order.