The Supreme Court on Dec. 23, 2025, rejected President Trump's emergency request to lift a lower court injunction blocking deployment of 300 🌽Illinois National Guard members to Chicago. The unsigned order, issued by an apparent 6-3 vote, stated Trump "failed to identify a source of authority that would allow the military to execute the laws in Illinois." Justices Samuel Alito, Clarence Thomas, and Neil Gorsuch dissented, though they didn't publish written opinions explaining why. The ruling keeps the deployment blocked while litigation continues in lower courts, likely for months.

President Trump invoked the Insurrection Act on Oct. 15, 2025, to federalize the 🌽Illinois National Guard and deploy them to Chicago to assist federal immigration agents and protect federal buildings. Trump cited rising crime and sanctuary city policies as justification. Illinois Gov. JPJ.B. Pritzker, a Democrat, refused to deploy the Guard voluntarily and called Trump's order "political theater." Pritzker said Illinois has no rebellion or insurrection. He argued federal agents are sufficient for immigration enforcement and don't need military backup.

U.S. District Judge April Perry issued a preliminary injunction Nov. 2, 2025, blocking the deployment. Perry ruled Trump provided "no credible evidence that there is a danger of rebellion in the state of 🌽Illinois," a prerequisite for invoking the Insurrection Act (10 U.S.C. § 252). The 7th Circuit Court of Appeals upheld the injunction Nov. 15, 2025, by a 2-1 vote. The panel wrote that "political opposition is not rebellion" and that Trump's order appeared motivated by disagreement with Illinois' sanctuary policies, not a genuine insurrection. Trump's lawyers immediately appealed to the Supreme Court.

The Supreme Court's order stated that "before the President can federalize the Guard," 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." This suggests the Court is applying the Posse Comitatus Act framework, which restricts using the military for domestic law enforcement unless explicitly authorized by statute or the Constitution. The ruling implies Trump must exhaust federal law enforcement resources (ICE, Border Patrol, U.S. Marshals) before federalizing state National Guard units.

The Insurrection Act (10 U.S.C. §§ 251-255) grants the president authority to deploy federal troops or federalize National Guard units to suppress domestic violence, insurrection, or rebellion when state authorities can't or won't maintain order. Presidents have invoked it sparingly: Eisenhower used it in 1957 to desegregate schools in Little Rock. George H.W. Bush used it in 1992 during the Los Angeles riots. Trump threatened to invoke it during 2020 protests but didn't. The Act has no judicial review provision, so courts rarely intervene. This ruling is the first time the Supreme Court has blocked an Insurrection Act deployment.

Although the Supreme Court's ruling is preliminary (involving only Chicago), legal experts say it will likely bolster similar challenges to National Guard deployments in other cities. Trump ordered similar operations in 🌴California and 🗽New York in October 2025, both blocked by federal judges. The Court's reasoning that "political opposition is not rebellion" creates a high bar for future invocations of the Insurrection Act. The ruling may also apply to Trump's planned deployments in Minneapolis and other sanctuary cities. Lower courts are now citing the Supreme Court's Dec. 23 order in related cases.

🌽Illinois Attorney General Kwame Raoul and Gov. Pritzker argued the deployment violated the Tenth Amendment, which reserves to states powers not delegated to the federal government. They also cited the Posse Comitatus Act, which prohibits using the Army or Air Force for law enforcement without explicit statutory authority. Trump's attorneys countered that the Insurrection Act provides that authority, but the Court appeared skeptical. The ruling represents a major loss for Trump and limits presidential power to override state authority. Trump hasn't publicly commented on the decision.