On December 23, 2025, the U.S. Supreme Court issued a 6-3 ruling that denied President Donald Trump's request to deploy National Guard troops in Chicago. The court's unsigned order emphasized that the Trump administration failed to demonstrate adequate legal authority for federalizing the National Guard to protect Immigration and Customs Enforcement (ICE) agents in the area.

The ruling upheld a lower court's decision that blocked the deployment, stating that the administration did not meet the statutory requirements necessary to justify such action. The court clarified that the term 'regular forces' in the relevant federal law refers specifically to the U.S. military, not civilian law enforcement, which is significantly restricted under the Posse Comitatus Act. This act limits military involvement in domestic law enforcement, allowing such actions only under specific constitutional or congressional authorizations.

Illinois Attorney General Kwame Raoul, who initiated the lawsuit against the Trump administration, expressed satisfaction with the ruling, noting that the conditions for deploying federal troops over state objections were not met in Illinois. Raoul highlighted that the decision would keep armed National Guard members off the streets of Illinois while legal proceedings continue.

The dissenting opinions from Justices Samuel Alito, Clarence Thomas, and Neil Gorsuch indicated a division within the court regarding the use of military force in domestic matters. Alito criticized the majority's conclusions and the handling of the application, suggesting that the protection of federal officers should not be compromised, regardless of differing views on immigration enforcement.

Legal analysts viewed the ruling as a significant affirmation of the rule of law, suggesting it reflects a decline in attempts by the Trump administration to exert unchecked power. The decision may also have implications for similar legal challenges in other jurisdictions where the administration has sought to deploy National Guard troops, including Washington, D.C., Los Angeles, and Portland, Oregon. The ongoing legal scrutiny of such deployments raises concerns about the balance of power between federal and state authorities, particularly regarding the militarization of domestic law enforcement.