In an amicus brief filed October 20, nine former high-ranking military officials—including former Army and Navy secretaries and retired four-star admirals and generals—urged the Supreme Court to uphold lower court rulings blocking the deployment of federalized National Guard troops to Illinois.
The brief centers on Trump’s October 2025 order federalizing up to 300 Illinois National Guard members and 400 Texas Guard troops for deployment to the Chicago area, ostensibly to protect federal immigration enforcement operations. Both a federal district judge and the U.S. Court of Appeals for the Seventh Circuit blocked the deployment, ruling that the administration failed to meet the legal requirements under 10 U.S.C. § 12406, which permits federalization only in cases of rebellion or when the president cannot execute federal laws with regular forces.
The courts found no credible evidence of rebellion in Illinois. As the Seventh Circuit stated, “The spirited, sustained, and occasionally violent actions of demonstrators in protest of the federal government’s immigration policies and actions, without more, does not give rise to a danger of rebellion against the government’s authority.” The district court noted that while there have been “acts of vandalism, civil disobedience, and even assaults on federal agents,” the situation did not justify military intervention.
The Illinois case represents the latest in a series of controversial National Guard deployments by the Trump administration in 2025. The pattern began in June when Trump federalized California’s National Guard to Los Angeles—marking the first time in U.S. history a president invoked Section 12406 over a governor’s objections. A federal court subsequently ruled that deployment violated the Posse Comitatus Act, which prohibits the military from acting as domestic law enforcement absent express congressional authorization.
Since then, the administration has deployed Guard troops to Washington D.C., Memphis, Portland, and now Chicago—all over local officials’ objections. Trump has publicly threatened similar deployments to Baltimore, New Orleans, and St. Louis.
The amicus brief, signed by officials who served under presidents from John F. Kennedy to Barack Obama, presents three principal arguments against the deployments:
Diversion from Core Mission: The brief argues that domestic law enforcement deployments divert Guard members from their primary duties of national security and disaster response. When California troops were federalized for Los Angeles operations, they were pulled from wildfire protection, leaving specialized fire units at 40% strength during peak wildfire season. Similarly, South Carolina sent Guard members out of state during hurricane season for the D.C. deployment.
Lack of Proper Training: The military leaders emphasized that Guard personnel receive minimal training in domestic law enforcement techniques such as de-escalation, use of non-lethal force, and constitutional protections for civilians. As one federal court noted, “Members of the National Guard generally do not receive training to perform local law enforcement tasks.”
Risk of Politicization: Perhaps most significantly, the brief argues that deploying troops for domestic political purposes threatens the military’s apolitical tradition and public trust. The officials cited instances where Trump has publicly attacked political opponents while addressing troops in uniform and warned that protests at a military parade would “be met with very big force.”
“Over the centuries, American political and military leaders ingrained in the U.S. military a nonpartisan commitment to support and defend not any person or party but the Constitution itself,” the brief states. Politicization risks harming recruitment, retention, morale, and the military’s ability to maintain broad public support.
National Guard documents from the D.C. deployment revealed “mentions of fatigue, confusion, and demoralization” among troops, with concerns about an “unclear mission” and driving a “wedge between citizens and the military.”
Central to the legal arguments is the Posse Comitatus Act of 1878, which codified the longstanding American tradition against using the military for domestic law enforcement. The Act prohibits using federal military forces to “execute the laws” except when “expressly authorized by the Constitution or Act of Congress”.
The law permits exceptions for extraordinary circumstances, such as when a president lawfully invokes the Insurrection Act to address civil unrest—as President George H.W. Bush did during the 1992 Los Angeles riots at the governor’s request. However, Trump has not invoked the Insurrection Act for these deployments.
When Guard troops are federalized, they become legally equivalent to active-duty forces and are therefore subject to Posse Comitatus restrictions.
As of October 21, 2025, the Supreme Court has not acted on the stay request, though Justice Amy Coney Barrett directed an unusually fast briefing schedule—requiring Illinois’s response by Monday, October 20 at 5 p.m.. Once the Trump administration submitted its reply to those filings, the Court indicated it could act “at any time.”
