The Legality and Constitutionality of President Trump’s Military Deployments to Los Angeles
In June 2025, President Donald Trump authorized the deployment of federalized National Guard troops and active-duty Marines to Los Angeles, California, amidst protests against federal immigration enforcement raids and despite the strong objections of California Governor Gavin Newsom. The situation immediately raises profound questions about the scope of presidential authority, the principles of federalism, the specific statutes invoked, and the traditional American aversion to military intervention in civilian matters.
I. The General Rule: The Posse Comitatus Act (18 U.S.C. § 1385)
The starting point for any discussion of domestic military deployment is the Posse Comitatus Act (PCA). Enacted in 1878, this federal law generally prohibits the use of the U.S. Army, Navy, Marine Corps, Air Force, and Space Force for domestic civilian law enforcement purposes:
Whoever, except in cases and under circumstances expressly authorized by the Constitution or Act of Congress, willfully uses any part of the Army, the Navy, the Marine Corps, the Air Force, or the Space Force as a posse comitatus or otherwise to execute the laws shall be fined under this title or imprisoned not more than two years, or both.
18 U.S.C. § 1385. The PCA makes it a crime for federal military personnel to perform civilian law enforcement functions unless expressly authorized.
The inclusion of criminal penalties underscores the gravity with which Congress views the principle of separating military and civilian spheres. Any deviation requires explicit, affirmative legal authorization, placing the burden of demonstrating legality squarely on those advocating for military deployment.
The PCA applies to active-duty federal military personnel but does not generally apply to National Guard forces when they are operating under state authority at the command of a governor. However, the PCA does apply to National Guard forces once they are federalized and called into active federal service. This distinction is a direct consequence of federalism: states possess their own police powers and can utilize their militias (the National Guard in its state capacity) accordingly. A governor deploying the Guard is a state action. Conversely, the President federalizing the Guard or deploying active-duty troops is a federal action, directly implicating the PCA.
For the President to legally order or otherwise engage in those actions, therefore, he must rely on one of the PCA’s recognized exceptions. The most significant of these exceptions is the Insurrection Act.
II. The Major Exception: The Insurrection Act (10 U.S.C. § 251)
The Insurrection Act provides the primary “express statutory authorization” for the President to deploy federal military forces for domestic law enforcement, thereby creating an exception to the Posse Comitatus Act.
The Act comprises several key provisions that delineate the circumstances under which the President may act:
10 U.S.C. § 251: Federal aid for State governments. This section permits the President to deploy the militia (typically the National Guard) and armed forces to suppress an insurrection within a state against the state’s government; however, the state’s government must consent:
Whenever there is an insurrection in any State against its government, the President may, upon the request of its legislature or of its governor if the legislature cannot be convened, call into Federal service such of the militia of the other States, in the number requested by that State, and use such of the armed forces, as he considers necessary to suppress the insurrection.
10 U.S.C. § 252: Use of militia and armed forces to enforce Federal authority. This provision allows for unilateral presidential action if the purpose is to enforce federal law or to suppress a rebellion against federal authority, irrespective of state consent:
Whenever the President considers that unlawful obstructions, combinations, or assemblages, or rebellion against the authority of the United States, make it impracticable to enforce the laws of the United States in any State by the ordinary course of judicial proceedings, he may call into Federal service such of the militia of any State, and use such of the armed forces, as he considers necessary to enforce those laws or to suppress the rebellion.
10 U.S.C. § 253: Interference with State and Federal law. This section authorizes the President to use the militia, armed forces, or both to suppress an insurrection, domestic violence, unlawful combination, or conspiracy but only if certain conditions are met:
The President, by using the militia or the armed forces, or both, or by any other means, shall take such measures as he considers necessary to suppress, in a State, any insurrection, domestic violence, unlawful combination, or conspiracy, if it—
(1) so hinders the execution of the laws of that State, and of the United States within the State, that any part or class of its people is deprived of a right, privilege, immunity, or protection named in the Constitution and secured by law, and the constituted authorities of that State are unable, fail, or refuse to protect that right, privilege, or immunity, or to give that protection; or
(2) opposes or obstructs the execution of the laws of the United States or impedes the course of justice under those laws.
In any situation covered by clause (1), the State shall be considered to have denied the equal protection of the laws secured by the Constitution.
10 U.S.C. § 254: Proclamation to disperse. This section imposes a procedural requirement for formal public notice and an order to disperse before troops can be lawfully deployed under the Act.:
Whenever the President considers it necessary to use the militia or the armed forces under this chapter, he shall, by proclamation, immediately order the insurgents to disperse and retire peaceably to their abodes within a limited time.
III. “Federalizing” the National Guard: 10 U.S.C. § 12406
This statute provides the President with the authority to “federalize” the National Guard, effectively placing them under federal command. The statute outlines three specific conditions under which the President can exercise this power:
Whenever—
(1) the United States, or any of the Commonwealths or possessions, is invaded or is in danger of invasion by a foreign nation;
(2) there is a rebellion or danger of a rebellion against the authority of the Government of the United States; or
(3) the President is unable with the regular forces to execute the laws of the United States;
the President may call into Federal service members and units of the National Guard of any State in such numbers as he considers necessary to repel the invasion, suppress the rebellion, or execute those laws. Orders for these purposes shall be issued through the governors of the States or, in the case of the District of Columbia, through the commanding general of the National Guard of the District of Columbia.
Historically, § 12406 has been treated as a technical call-up authority accompanying the Insurrection Act’s substantive grant of power, with presidents typically invoking both together.
The following table summarizes the key provisions of the Insurrection Act and § 12406 pertinent to domestic troop deployment and the requirement of state consent:
| Section (10 U.S.C.) | Triggering Condition | State Consent Required? |
|---|---|---|
| § 251 | Insurrection within a state against its government. | Yes (from legislature/governor) |
| § 252 | Unlawful obstructions, combinations, or rebellion against U.S. authority, making federal law enforcement impracticable. | No |
| § 253(1) | Insurrection, domestic violence, conspiracy hindering state/federal laws AND depriving constitutional rights, AND state authorities unable/fail/refuse to protect. | No |
| § 253(2) | Insurrection, domestic violence, conspiracy opposing/obstructing federal laws or impeding the course of justice under those laws. | No |
| § 12406 | Invasion, danger of invasion, rebellion, danger of rebellion, or when the President is unable to execute the laws of the United States. | Debated (orders issued through governor) |
IV. Historical Precedents: Federal Intervention Over State Objections
The Insurrection Act has been invoked on numerous occasions throughout U.S. history, though its use, particularly over a governor’s objection, has become exceedingly rare since the civil rights era.
President Eisenhower and the Little Rock Crisis (1957): One of the most prominent instances of federal intervention against state opposition occurred during the desegregation of Little Rock Central High School. The Arkansas Governor mobilized the Arkansas National Guard to prevent nine African American students from enrolling, in defiance of a federal court order. President Eisenhower responded by federalizing the Arkansas National Guard and deploying paratroopers from the 101st Airborne Division to enforce the court’s desegregation order and protect the students. Eisenhower cited his authority under the Insurrection Act (specifically provisions analogous to the current 10 U.S.C. §§ 252 and 253), his duty to enforce federal court orders, and his to prevent the obstruction of justice.
President Kennedy and the University of Alabama (1963): A similar confrontation occurred when the Alabama Governor physically blocked the entrance to the University of Alabama to prevent the enrollment of two African American students, again in defiance of federal court orders. President John F. Kennedy federalized the Alabama National Guard to ensure the students could register. Kennedy acted under his constitutional authority to enforce federal law and court orders, effectively utilizing the principles underpinning the Insurrection Act.
These historical examples, primarily driven by the imperative to enforce federal desegregation mandates and protect civil rights against state resistance, highlight a pattern. The presence of federal court orders being actively defied by state officials provided a clear “obstruction of justice” and “hindrance of federal law,” strengthening the justification for presidential intervention.
Any modern invocation for different purposes, especially over state objection and without a direct federal court order being violated, would likely face intense scrutiny and comparison to these seminal cases. Indeed, the last widely acknowledged invocation of the Insurrection Act was in 1992 during the Los Angeles riots following the Rodney King verdict, but critically, that invocation involved a request from the state governor. The rarity of its use, especially against a state’s wishes, underscores the gravity of such presidential action and the general reluctance to deploy military force domestically due to the political ramifications and impact on federal-state comity.
V. The President’s Troop Deployment to Los Angeles in June 2025
Following protests over Immigration and Customs Enforcement (ICE) raids, President Trump authorized the deployment to Los Angeles, CA, of federalized National Guard soldiers and active-duty Marines. President Trump ordered that deployment against the wishes of California Governor Gavin Newsom, who, along with Los Angeles Mayor Karen Bass, disputed the President’s dire characterization of the situation in the city.
Notably, President Trump’s initial memorandum authorizing the deployment did not invoke the Insurrection Act. Instead, for the federalization and deployment of the National Guard, the administration cited 10 U.S.C. § 12406. The Trump administration’s apparent attempt to use § 12406 as a standalone authority, or possibly pairing it with claimed inherent constitutional powers, is novel. For the deployment of active-duty Marines, the administration appears to be relying solely on a claim of inherent constitutional power, as § 12406 could not authorize the deployment of active-duty forces.
President Trump has publicly stated he is open to invoking the Insurrection Act if he deems the situation an “insurrection.” His rhetoric, describing Los Angeles as a “trash heap” and protestors as “animals” and a “foreign enemy,” suggests an attempt to frame the situation in terms that might align with the Act’s criteria.
Because Governor Newsom objects to federal intervention, the President’s legal justification, if relying on the Insurrection Act, would necessarily rest on 10 U.S.C. §§ 252 or 253. As set forth above, these sections explicitly empower the President to deploy troops without a state’s request or even over a governor’s active opposition, but only if the enumerated prerequisites exist.
If, however, the administration relies primarily on 10 U.S.C. § 12406 for the National Guard deployment, the issue of gubernatorial consent becomes more complex. While the initial part of § 12406 appears to grant unilateral authority, a later amendment states that “[o]rders for these purposes shall be issued through the governors of the States,” suggesting a need for state cooperation.
To legally justify overriding a governor, the President should articulate a clear federal hook—that is, how the protests or riots specifically threaten federal authority, obstruct federal laws, or result in deprivations of federally protected constitutional rights that California is demonstrably failing to address. A mere disagreement with a governor’s approach to general public order, absent this distinct federal nexus, might not suffice under the Insurrection Act or a similarly constrained interpretation of § 12406.
VI. Judicial Review: Can the Courts Step In?
In the current Los Angeles deployment, legal challenges are already underway. California Attorney General Rob Bonta has filed a lawsuit over the use of National Guard troops. Additionally, Governor Newsom has filed a lawsuit alleging that the Department of Defense did not transmit the federalization orders through his office as potentially required by 10 U.S.C. § 12406.
These lawsuits will test the boundaries of presidential authority and the extent of judicial review in the context of the specific legal authorities cited by the Trump administration. The use of § 12406 as a primary authority, and the reliance on inherent powers for active-duty troops, presents novel questions that may lead courts to re-examine existing precedents, especially given heightened contemporary concerns about executive overreach and the protection of civil liberties.
VII. Conclusion: Navigating a Delicate Constitutional Balance in Real Time
The President of the United States does possess statutory authority, primarily under the Insurrection Act, to deploy federal military forces for domestic law enforcement purposes, even over a state governor’s objection. This authority, however, is intended for extraordinary circumstances. The ongoing situation in Los Angeles in June 2025, where President Trump has deployed federalized National Guard and active-duty Marines over Governor Newsom’s objections, brings these complex legal issues from the realm of theory into urgent practice.
The administration’s decision to initially rely on 10 U.S.C. § 12406 for National Guard deployment and asserted inherent constitutional powers for active-duty Marines, rather than an explicit invocation of the Insurrection Act, introduces new layers of legal complexity and controversy. This strategy sidesteps, at least for now, the more familiar and politically charged Insurrection Act but raises its own set of legal questions regarding the scope of § 12406 as a standalone authority and the limits of inherent presidential powers in domestic military deployment.
The Insurrection Act itself can be viewed as a “double-edged sword”: a potentially necessary instrument for addressing extreme national crises but also a power susceptible to abuse if not wielded with utmost restraint and clear, compelling justification. The recent troop deployment to a U.S. city fuels an ongoing debate about the Act’s proper scope and the potential for its misuse.
In sum, any decision to deploy military forces domestically demands the highest degree of prudence, a clear and demonstrable factual and legal basis showing that stringent statutory and constitutional conditions are unequivocally met, and a profound respect for the intricate constitutional framework that underpins American governance. Maintaining these powers as tools of last resort, subject to robust checks and balances, is crucial for preserving both liberty and the complex, often fragile, equilibrium of the federal system. The unfolding situation in Los Angeles serves as a stark reminder of these enduring principles.