WASHINGTON — The nation’s capital sued to block President Donald Trump’s takeover of its police department in court on Friday, hours after his administration escalated its intervention into the city’s law enforcement by naming a federal official as the new emergency head of the department.

President Trump has given homeless people in Washington, D.C., an ultimatum, sparking concern among human rights advocates: Accept shelter treatment or go to jail. Donald Whitehead, executive director of the National Coalition for the Homeless,