The U.S. Justice Department contends the city of Chicago and Cook County violated federal immigration laws when they were awarded public safety grants last year.
The Justice Department made the assertion in letters to Chicago police Superintendent Eddie Johnson and Cook County Board President Toni Preckwinkle.
Although the letters don't specify why the city and county are in violation of the law, the Justice Department gives them until Oct. 27 to prove otherwise.
The letters concern Edward Byrne Memorial Justice Assistance Grants, which have become ensnarled in controversy because of the Trump administration's immigration policies.
A federal judge last month granted Chicago Mayor Rahm Emanuel a preliminary injunction preventing the Justice Department from applying new rules to grant recipients. The rules would require recipients to cooperate with immigration agents.
Emanuel said Thursday he rejects the Trump administration's stance. A Preckwinkle spokesman says the county is in compliance with all applicable federal laws.