On December 24, 2025, the U.S. Supreme Court delivered a landmark decision, handing President Donald Trump a rare defeat in his ongoing efforts to deploy National Guard troops in Illinois as a means to protect Immigration and Customs Enforcement (ICE) agents engaged in mass deportations. The ruling, which came via the court’s so-called "shadow docket," not only upheld a lower court’s temporary restraining order but also set significant new limits on presidential power over the National Guard—a move that legal experts say could have ripple effects across the country.
According to AP and NBC News, the case originated in early October when U.S. District Judge April M. Perry, a Biden appointee, issued a temporary restraining order that barred the Trump administration from federalizing and deploying the National Guard in Illinois. The administration, seeking to override local objections, quickly appealed the decision, first to the U.S. Court of Appeals for the 7th Circuit and then to the Supreme Court after receiving only partial relief from the appellate panel. The high court’s unsigned order, a common feature of its emergency docket, ultimately rejected the Trump administration’s emergency request, stating that the president’s authority in this area was more limited than previously interpreted.
At the heart of the dispute was a legal debate over the meaning of "regular forces" as referenced in 10 U.S.C. §12406—a statute that allows the president to federalize National Guard troops if he is "unable with the regular forces to execute the laws of the United States." For years, the definition of "regular forces" had gone largely unchallenged, but this case forced both sides to clarify their positions. The government argued that the term referred to the civilian law enforcement agencies that regularly enforce the laws, such as the FBI and DEA, while the state of Illinois contended that it meant the standing, professional military.
Justice Amy Coney Barrett, writing for the majority, zeroed in on this definitional dispute. The opinion, which appeared to split the six conservative justices evenly (with the three liberals joining the majority), concluded that "the term 'regular forces' likely refers to the regular forces of the United States military." This interpretation, the court explained, means the president cannot federalize the Guard unless he is first unable to execute the laws with the regular military—a much higher bar than the administration had argued for.
"Because the statute requires an assessment of the military's ability to execute the laws, it likely applies only where the military could legally execute the laws. Such circumstances are exceptional," the unsigned opinion stated, as reported by Mediaite. The majority further noted that under the Posse Comitatus Act, the military is generally prohibited from enforcing domestic laws unless specifically authorized by Congress or the Constitution. "So before the President can federalize the Guard under §12406(3), he likely must have statutory or constitutional authority to execute the laws with the regular military and must be 'unable' with those forces to perform that function," the opinion continued.
In practical terms, the court’s ruling means that the president would need clear statutory or constitutional authority to use the regular military for domestic law enforcement—and only if those forces were insufficient could he then call up the National Guard. The government, according to the court, had failed to identify any such authority in this case, relying instead on what it described as "inherent constitutional authority" to protect federal personnel and property. But as the opinion pointed out, the executive branch has long maintained that such protective functions do not constitute "executing the laws" under the Posse Comitatus Act, undermining the administration's own argument.
The decision was immediately hailed by opponents of the deployment as a victory for states’ rights and a check on executive power. Local officials in Illinois, who had strenuously objected to the federalization plan, saw the ruling as a vindication of their stance. According to NBC News, the decision is expected to bolster similar legal challenges in other cities where the administration has sought to deploy the National Guard for immigration enforcement purposes.
But not everyone was pleased. In a sharply worded dissent, Justice Samuel Alito, joined by Justices Clarence Thomas and Neil Gorsuch, accused the majority of overstepping its bounds and departing from standard judicial practice. "In this case, the Court has unnecessarily and unwisely departed from standard practice," Alito wrote. He argued that the parties had previously agreed the term "regular forces" referred to civilian law enforcement officers, not the military, and that the majority was effectively rewriting the law. "There is no basis for rejecting the President's determination that he was unable to execute the federal immigration laws using the civilian law enforcement resources at his command," Alito insisted, stressing that local police had provided "insufficient assistance" and warning that "the protection of federal officers from potentially lethal attacks should not be thwarted."
Justice Gorsuch, while joining the dissent, penned a separate opinion stating that he would have ruled in the government’s favor based on the earlier, agreed-upon definition of "regular forces," but "would hazard no opinion beyond that."
The ruling marks a rare setback for the Trump administration at a Supreme Court that has otherwise delivered a string of high-profile victories for the president in 2025, as noted by NBC News. The 6-3 conservative majority split down the middle, with three conservatives siding with the liberals in the majority and the other three conservatives dissenting. The decision, while technically preliminary and specific to Illinois, sets a precedent that could influence future disputes over National Guard deployments and presidential authority.
Legal scholars say the outcome underscores the growing importance of the Supreme Court’s shadow docket—its mechanism for issuing rapid, often unsigned decisions without full briefing or oral argument. While these rulings are not always considered binding precedent, they increasingly shape the boundaries of executive power in real time, especially in politically charged contexts like immigration enforcement.
Beyond the immediate legal ramifications, the case has also highlighted the intense political pressures faced by federal judges who rule against the Trump administration. As reported by NBC News, judges who have blocked or criticized administration policies have often found themselves targets of harassment and threats, prompting increased security measures and a heightened sense of caution within the judiciary.
For now, the Supreme Court’s decision stands as a reminder that even in an era of robust executive action, there are still legal guardrails—and that the meaning of a single phrase in federal law can have far-reaching consequences for the balance of power between Washington and the states.
