When may the U.S. armed forces lawfully operate on home soil, and where does the legal boundary lie between civilian law enforcement and military force? Historically, domestic military deployments in the United States have spanned from disaster relief and humanitarian assistance to enforcing federal court orders and quelling severe domestic disturbances. Yet as recent executive actions under the current administration have highlighted, the invocation of military power within national borders touches upon fundamental constitutional questions regarding executive authority encroaching on American civil liberties.  

TCFR members were invited to the webinar hosted by American Bar Association (ABA), the featuring an expert panel to examine the constitutional and statutory frameworks governing domestic military deployments. The panel was moderated by TCFR board member, Professor William Banks, Professor Emeritus at Syracuse University College of Law. Co-author of Soldiers on the Home Front: The Domestic Role of the American Military, Prof. Banks provides a robust perspective of civilian law enforcement. He was joined by Commander Mark Nevitt (USN Ret.), Associate Professor of Law at Emory University School of Law and a 20-year U.S. Navy tactical jet aviator and JAG Corps officer, and Professor Laura Dickinson from Lyle T. Alverson Professor of Law at George Washington University Law School and former Special Counsel to the General Counsel of the Department of Defense. She also authored Outsourcing War and Peace. Together, the panelists dissected the constitutional origins of civilian military subordination, the statutory "number soup" governing domestic activations, operational risks, recent Supreme Court litigation, and pressing proposals for legislative reform.

Constitutional Foundations of the Primacy of Civilian Control

To understand modern debate surrounding domestic military troop deployments, Prof. Banks framed the discussion through America's revolutionary heritage. The drafters of the Declaration of Independence explicitly cited King George III’s practice of rendering the British military "independent of and superior to the civil power" as a primary catalyst for separation. In response, the Framers embedded two foundational traditions into the U.S. Constitution: the absolute subordination of the armed forces to civilian authority, and a preference for localism, ensuring that decisions regarding domestic public safety remain under state and local leadership whenever possible. 

As Prof. Banks explained, Article IV, Section 4 of the Constitution obligates the federal government to guarantee a republican form of government, protect states against foreign invasion, and safeguard against domestic violence when triggering protections only upon request from a state legislature or governor. Furthermore, Article I, Section 8 (the Calling Forth Clause) explicitly empowers Congress rather than the executive branch unilaterally to provide for calling forth the militia to execute Union laws, suppress insurrections, and repel invasions. Notably, "domestic violence" is omitted from Article I as a direct trigger for federal deployment; a reflection of the Framers' intent that federal military force be reserved solely for extreme existential threats to the republic.

Statutory Mechanics and the "Number Soup" of Domestic Operations

Moving from constitutional principles to statutory implementation, Cdr. Mark Nevitt outlined the primary legal mechanisms that govern military actions on home soil. The baseline statutory constraint is the Posse Comitatus Act of 1878 (18 U.S.C. § 1385), which strictly prohibits federal Title 10 military forces, which include the Army, Navy, Air Force, Marine Corps, and Space Force, from executing civilian laws unless expressly authorized by the Constitution or an Act of Congress. To navigate around Posse Comitatus limitations, executive administrations have increasingly relied upon what Cdr. Nevitt described as a "number soup" of statutory provisions found in the United States Code or a foundational Act of Congress. 

First, Title 10 U.S.C. § 12406. Enacted in 1904, this provision permits the President to federalize State National Guard units under Title 10 command in cases of foreign invasion, rebellion, or when the President is "unable with the regular forces to execute the laws".

Title 32 U.S.C. § 502(f) grants an "accounting authority" that allows National Guard units to remain under state command and governor control while receiving federal funding to perform operational support or "other duty" requested by the Secretary of Defense or President. While vital during public health emergencies like COVID-19, its undefined scope has raised constitutional concerns when guardsmen operate across state lines without host governor consent. It's a shift away from maintaining power in the republic and toward unchecked executive authority. 

Section 287(g) (Immigration and Nationality Act) authorizes the Department of Homeland Security to enter into Memoranda of Understanding (MOUs) with state and local entities to perform federal immigration enforcement. Cdr. Nevitt revealed that 287(g) agreements have exploded from roughly 35 to 100 historical agreements to nearly 2,600 active MOUs- including agreements with National Guard units in Arkansas, Texas, Florida, and West Virginia, creating a "supercharged immigration enforcement force". 

The 1033 Program (NDAA) permits the Department of Defense to transfer surplus military hardware, armored vehicles, and weaponry to domestic police departments. Cdr. Nevitt noted that this blurring of military equipment and civilian law enforcement was illustrated when a Government Accountability Office (GAO) investigation successfully created a fictitious law enforcement agency and obtained nearly $1 million in military gear.

Operational Hazards, Military Culture, and the Insurrection Act

The primary statutory exception to the Posse Comitatus Act is the Insurrection Act (10 U.S.C. §§ 251–253), first enacted in 1792. As Prof. Laura Dickinson detailed, the Act grants the President authority to deploy Title 10 armed forces or federalize National Guards to suppress insurrections (§ 251), enforce federal law when ordinary judicial proceedings become impracticable (§ 252), or protect constitutional rights against unlawful conspiracies (§ 253). Although historically vital for breaking up post-Civil War KKK violence and enforcing school desegregation during the Civil Rights movement, presidents across the political spectrum have utilized the Insurrection Act only approximately 30 times in 250 years, treating it strictly as a measure of last resort.

Cdr. Nevitt emphasized the severe operational risks of deploying combat-trained forces to civilian streets, sharing a chilling incident from the 1992 Los Angeles riots when the Insurrection Act was last invoked. When an LAPD officer asked accompanying Marines to "cover me" before approaching a door- a law enforcement term meaning to draw weapons and stand ready- the Marines responded according to their combat Rules of Engagement (ROE), firing 200 rounds into the apartment building. While no one was injured, the vignette underscores the dangerous tactical mismatch between warfighting and domestic policing. Prof. Dickinson added that placing troops in volatile domestic law enforcement roles threatens to demoralize service members and erode the rare bipartisan public trust that the military holds.

Litigation Watershed

The panel evaluated recent federal litigation arising from the troop deployments to California, Oregon, and Illinois. A major legal turning point occurred in late 2025 with Trump v. Illinois, which reached the Supreme Court after 300 members of the Illinois National Guard were federalized under 10 U.S.C. § 12406 to protect federal property in Chicago on October 4th of that year. The administration argued that civilian federal law enforcement agencies (such as ICE and the Federal Protective Service) constituted the "regular forces" that were overwhelmed. However, the Supreme Court upheld a stay against the deployment, accepting the historical argument that when Congress enacted § 12406 in 1904, "regular forces" meant the active-duty U.S. Army. Because the multi-hundred-thousand-strong active military was not unable to execute the law, the statutory predicate was not met. Cdr. Nevitt observed that this ruling effectively closed § 12406 as an executive "workaround" to bypass the political and statutory hurdles of the Insurrection Act. Parallel litigation in California (Newsom v. Trump) and Oregon similarly affirmed that statutory deployment triggers are subject to Article III judicial review rather than absolute presidential discretion.

Reforming Domestic Military Powers: A Bipartisan Imperative

Cdr. Nevitt and Prof. Dickinson highlighted what legislative and state-level avenues can be utilized for modernizing domestic military law. Cdr. Nevitt advocated for establishing stringent congressional notification and consultation while simultaneously creating a 60-day sunset requirement for domestic military deployments similar to the War Powers Resolution. Prof. Dickinson urged Congress to define antiquated statutory terms such as "insurrection" and "unlawful assemblage”; not strictly defining the thresholds for these terms open them up for too much interpretation. She also calls for the explicit prohibition of the federalization of private militias, and to statutorily clarify that § 12406 is not a loophole around Posse Comitatus.

On 287(g) immigration MOUs, states such as New York, Maryland, Maine, and New Mexico have recently enacted state laws prohibiting state entities and National Guards from entering into these enforcement agreements.

Enduring institutions that are vital for the safety and protection of civil liberties for the American people cannot fall prey to corruptive legislative loopholes. Prof. Dickinson and Prof. Banks emphasized that maintaining a strict boundary between civilian law enforcement and military force is not merely an abstract legal debate, but a cornerstone of American democracy designed to keep the military insulated from partisan conflict and ready to defend the nation when truly needed.