On September 2, 2025, federal judge Charles Breyer ruled that President Trump’s deployment of approximately 4,000 National Guard troops and 700 Marines to Los Angeles to mitigate mass protests against ICE earlier this summer violated federal law. Newsom filed a formal lawsuit on the basis of primarily two violations: the Posse Comitatus Act and the 10th Amendment.
Was California’s Reasoning to Sue Valid?
The Posse Comitatus Act of 1878 (PCA) is a federal law that prohibits the use of the federal military to enforce state laws. This law came into effect to ensure that the federal military would not be used to intervene in the establishment of Jim Crow in the former Confederacy. Despite the negative history behind the creation of the law, the broader principle is that the military should not be allowed to interfere in the affairs of civilian government, and Newsom argued that the administration’s actions were a breach of said principle.
The 10th Amendment reserves to the states (or the people) any powers the Constitution does not explicitly grant to the federal government. This could include items such as marriage licenses, professional license distribution, and other relevant documents. California claimed Trump violated this by infringing on California’s sovereign right to control its own militia and not gaining Newsom’s confirmation to send the National Guard beforehand.
The Trump Administration’s Argument
President Trump’s administration claimed that the PCA was not violated because the military was deployed to protect federal personnel and property, not to perform traditional law enforcement tasks. That, they argued, was within the president’s constitutional authority, and therefore revokes California’s right to sue.
On the Tenth Amendment, the administration pointed to a federal statute, 10 U.S.C. § 252, which allows presidents to federalize state Guards, meaning they have been ordered to active duty by the President, if they are “executing the laws of the United States.” Once federalized, they said, the Guard was no longer bound by state laws, and Newsom’s argument was void.
The Ruling & What to Expect
Judge Breyer ruled that Trump’s deployment did violate the PCA because troops were being used in ways that clearly resembled local Californian law enforcement, such as when they attempted to control the protesting crowds, which goes against the Trump administration’s claims. Breyer blocked further military involvement in arrests, searches, and similar law-enforcement tasks, ruling that those actions essentially created a “national police force” under the president, which is not allowed and limits state independence. The ruling complicates the administration’s desire to handle immigration law and carry out deportations in California and other states. Reporters expect the Trump Administration to appeal this ruling in the near future.
Why This Case Matters to Youth
This lawsuit isn’t just a public clash between a governor and a president, but rather a test of the limits of executive power. The decision by Judge Breyer to determine the administration’s actions as illegal demonstrates the importance of upholding the democracy Americans fought for. Today, areas in Kansas face ICE raids and unfair political that border what we classify as constitutional and place vulnerable and protesting people in danger of military personnel acting like state police to overpower citizens. That alone matters to everyone, but especially young people, who are often the ones participating in protests or civic movements, such as the walkout Mill Valley recently had. This stands as a reminder that constitutional debates covered in AP U.S. History or AP European History aren’t boring concepts of the past. They’re still happening now, and they shape how people are governed, what we’ll one day vote on, and the outcome of your and your peers’ future.
