Texas National Guard members are seen at the Elwood Army Reserve Training Center in Elwood, Illinois, Oct. 7, 2025. (Photo by Scott Olson/Getty Images)
President Donald Trump has not yet met the requirements for sending National Guard troops to Chicago, the US Supreme Court ruled on Tuesday afternoon – a earnest setback for the president.
The court’s majority rejected the Trump administration’s request to stay or stop a lower court order banning the federalization of National Guard troops to assist federal immigration agents in Chicago.
The president has the authority to federalize National Guard units only if the troops enforce laws that regular military forces are legally permitted to enforce, the court said in a ruling from its emergency filing that will stand while the merits of the case are heard.
The Posse County ActThe law, passed in 1878, fundamentally prevents the military from participating in civilian law enforcement.
The Decision On the eve of a five-day holiday weekend for the federal government, it appeared to be 6-3, with three conservative justices, Samuel Alito, Clarence Thomas and Neil Gorsuch, dissenting. The ruling marked the first time the Supreme Court weighed in on Trump’s deployment of the Guard in multiple cities, although other legal battles continue.
The government failed to explain why the situation in Chicago, where residents protested aggressive immigration enforcement, should constitute an exception to the law, the court majority said.
“At this preliminary stage, the government has failed to identify a source of authority that would enable the military to implement the laws in Illinois,” the majority opinion states.
In an emailed statement, White House spokeswoman Abigail Jackson said the ruling would not affect Trump’s “core agenda.”
“The President has promised the American people that he will work tirelessly to enforce our immigration laws and protect federal personnel from violent rioters,” Jackson wrote. “He activated the National Guard to protect federal law enforcement officers and ensure that rioters do not destroy federal buildings and properties.”
Protection of Federal Officials
In a concurring opinion, Judge Brett Kavanaugh, whom Trump appointed during his first term, wrote that he agreed with the decision to deny the stay request but did so for narrower reasons.
The majority opinion is too restrictive and would prevent the president from using National Guard forces to protect federal property and personnel, Kavanaugh said.
Alito wrote in a dissent joined by Thomas that her interpretation of the majority’s order could have far-reaching consequences that undermine the time-honored role of the watchdog.
It would give National Guard members the freedom to enforce immigration law, but not to provide protection to Immigration and Customs Enforcement officers assigned that task, Alito wrote.
“Whatever one may think about the current administration’s enforcement of immigration laws or the way ICE has conducted its operations, protecting federal officers from potentially deadly attacks should not be thwarted,” Alito wrote. “So I respectfully disagree.”
Impact on other cities
The ruling applies only to the duration of the litigation in which Illinois is challenging the government’s operate there.
But it represents a rebuke, including from a Trump appointee, of the administration’s strategy of deploying National Guard troops to assist with aggressive immigration enforcement.
Trump has ordered troops to Los Angeles, Washington DC, Memphis, Tennessee and Portland, Oregon, either to combat crime there generally or to support federal immigration authorities. Governors of Democratic-led states have pushed back vigorously against these missions. Republican attorneys general have argued that their states are being harmed by protests in Chicago and other cities that are preventing federal ICE officers from doing their jobs.
Illinois Gov. JB Pritzer praised the ruling in a statement. “Today is a great victory for Illinois and American democracy,” he said. “I am pleased that the Supreme Court has ruled that Donald Trump did not have the authority to deploy the federal Guard in Illinois. This is an important step in curbing the Trump administration’s consistent abuse of power and slowing Trump’s march toward authoritarianism.”
