The United States Supreme Court has delivered a decisive ruling against former President Donald Trump’s initiative to deploy 300 Illinois National Guardsmen to Chicago, a sanctuary city, with the aim of bolstering the protection for Immigration and Customs Enforcement (ICE) agents amidst violent protests.

Back in October, Trump proposed the mobilization of the National Guard to support ICE operations. However, a federal judge, who was appointed by former President Joe Biden, intervened with a temporary restraining order, effectively blocking the plan.

Seeking to overturn this decision, the Trump administration appealed to the U.S. Court of Appeals for the Seventh Circuit, hoping for a reprieve. Nevertheless, the panel of judges upheld the initial ruling, refusing to grant the administration’s request.

Subsequently, the Trump administration escalated the matter to the Supreme Court, seeking a stay on the federal judge’s order to facilitate the deployment of National Guardsmen to Chicago.

In a landmark 6-3 decision made on Tuesday, the Supreme Court found that the Trump administration “has failed to identify a source of authority that would allow the military to execute the laws in Illinois.” Consequently, the request for a stay was denied, marking a significant legal setback for the administration.

At this preliminary stage, the Government has failed to identify a source of authority that would allow the military to execute the laws in Illinois. The President has not invoked a statute that provides an exception to the Posse Comitatus Act. Instead, he relies on inherent constitutional authority that, according to the Government, allows him to use the military to protect federal personnel and property. But the Government also claims—consistent with the longstanding view of the Executive Branch—that performing such protective functions does not constitute “execut[ing] the laws” within the meaning of the Posse Comitatus Act. If that is correct, it is hard to see how performing those functions could constitute “execut[ing] the laws” under §12406(3). (“This Court does not lightly assume that Congress silently attaches different meanings to the same term in the same or related statutes”). Thus, at least in this posture, the Government has not carried its burden to show that §12406(3) permits the President to federalize the Guard in the exercise of inherent authority to protect federal personnel and property in Illinois. We need not and do not address the reviewability of findings made by the President under §12406(3) or any other statute. The application for stay is denied. [Emphasis added]

Justices John Roberts, Sonia Sotomayor, Elena Kagan, Amy Coney Barrett, and Ketanji Brown Jackson seemingly backed the unsigned order while Justice Brett Kavanaugh wrote a concurring opinion.