US President Donald Trump's administration has asked the Supreme Court to lift lower court rulings blocking his deployment of the National Guard in Chicago.
Mr Trump has ordered hundreds of National Guard troops to Chicago, claiming they are needed to combat crime and to protect immigration agents and facilities in America's third-largest city.
A district court judge blocked the deployment, and the halt was upheld by an appeals court on Thursday, leading to the emergency appeal by the Trump Justice Department to the conservative-dominated Supreme Court.
The three-judge appeals panel said the administration had not demonstrated that conditions on the ground in the Democratic-ruled Illinois city justify the deployment of troops.
"Even after affording great deference to the president's evaluation of the circumstances, we see insufficient evidence of a rebellion or danger of rebellion in Illinois," the court said.
"The spirited, sustained, and occasionally violent actions of demonstrators in protest of the federal government's immigration policies and actions, without more, does not give rise to a danger of rebellion against the government's authority."
In his filing with the Supreme Court, Solicitor General John Sauer claimed that federal agents in Chicago are being "forced to operate under the constant threat of mob violence."
The court order blocking deployment of the National Guard "improperly impinges on the president's authority and needlessly endangers federal personnel and property," Mr Sauer added.
Illinois and the city of Chicago filed suit to block the deployment; a move also taken by the authorities in the western state of Oregon to prevent the sending of National Guard troops to Portland.
Illinois and Oregon are not the first states to file legal challenges against the Trump administration's extraordinary domestic use of the National Guard.
Democratic-ruled California filed suit after the Republican president sent troops to Los Angeles earlier this year to quell demonstrations sparked by a federal crackdown on undocumented migrants.
A district court judge ruled it unlawful, but an appeals court panel allowed the Los Angeles deployment to proceed.
The appeal by the Justice Department of the Illinois ruling is the first time it is asking the Supreme Court, where conservatives hold a 6-3 majority, to weigh in on the issue.
