The potential for the President of the United States to “federalize” the National Guard has recently returned to the spotlight – arising out of ongoing domestic political tensions at the southern border and promises and plans made during a presidential campaign. It is accordingly important to understand the legal and policy framework governing this authority, as well as the history of its use.

The ongoing confrontation between state and federal officials over illegal migration in the border town of Eagle Pass, Texas escalated recently after state law enforcement and National Guard personnel placed razor wire and other obstacles in the middle of the Rio Grande River. After Texas officials refused a federal request to remove the barriers and a lower federal court enjoined federal officials from removing the razor wire, the Supreme Court dissolved the injunction, without explanation. 

Texas Governor Greg Abbott reacted with a statement claiming that the Constitution grants states a right to defend themselves against “invasion,” and that Texas authority “supersedes any federal statutes to the contrary.” In addition to expressing outrage at Abbot’s repudiation of federal authority over immigration and the border, some prominent Democrats urged President Joe Biden to federalize the Texas National Guard, a response that would presumably lead to those soldiers removing the state-installed razor wire but also would almost surely escalate the political conflict.

The impulse to deploy the military domestically is not limited by party. Candidate Donald Trump has indicated his intention if re-elected to use the military more aggressively both at the border and to enforce the law in cities such as Chicago and New York, which he has referred to as “crime dens.” 

The norm in our democracy has always been to entrust law enforcement to civilian police, or in circumstances when civilian law enforcement are overwhelmed to rely on citizen militias, today’s National Guard to quell disturbances. Yet Congress has exercised its authority in the Insurrection Act and a few other laws to allow the president to “federalize” the national guard in loosely defined circumstances, overcoming the presumption of state control of law enforcement. U.S. history includes a long list of examples where that power has been considered or actually used. However, the domestic use of federal troops should be weighed as a serious and potentially escalatory step with long-term consequences.

Background History and Legal Architecture for Domestic Use of the Military

Experience with the British Crown caused the Framers to be wary of the establishment of a standing army. They decided to rely primarily on the states’ militias for domestic security instead. The Constitution accordingly calls on Congress to “provide for calling forth the Militia to execute the Laws of the Union, suppress Insurrections and repel Invasions,” and to “provide for organizing, arming, and disciplining, the Militia, and for governing such Part of them as may be employed in the service of the United States.” The domestic use of troops has been a fact of life and a matter of controversy at least since President George Washington called out the militia to put down the Whiskey Rebellion in 1794. This history is analyzed in greater depth in , Soldiers on the Home Front: The Domestic Role of the American Military (2016) by William C. Banks & Stephen Dycus.

During the Vietnam War, the Supreme Court noted “a traditional and strong resistance of Americans to any military intrusion into civilian affairs.” Indeed, although the American public has long viewed with suspicion any sort of military involvement in domestic life, U.S. history shows that active-duty military forces and National Guard troops have long been used to help recover from natural disasters, curb civil unrest, secure the borders, and fight the “war on drugs.” The militias, now known as National Guards, consist of some 450,000 personnel, and the nearly 5,000 Army and Air National Guard units scattered across the country have essentially the same relevant training and equipment as active-duty military elements. 

National Guard troops can serve in three different capacities. In their default and usual role, State Active Duty (SAD) status, soldiers are exercising state functions at the request of the state government and are generally governed by state law. A second Title 32 status (a reference to that part of the U.S. Code that deals with the National Guard) permits the state National Guard troops to remain subject to state command and control but are used for federal missions authorized by Congress. From the states’ point of view Title 32 deployments are desirable because the personnel and other costs are borne by federal taxpayers. Finally, Title 10 status occurs when state National Guard units are “federalized” by the president of the United States pursuant to one of the statutory authorities for doing so. Once federalized, National Guard troops come under the full command and control of the secretary of defense. In essence, National Guard troops become part of the federal military until and unless they are returned to state status. 

The use of the militia to aid in law enforcement was never so extensive as the time following the Civil War. In the presidential election of 1876, President Ulysses S. Grant sent soldiers to polling places in three Southern states to assist federal marshals as posses comitatus (some say to influence the outcome of the election; others say to protect former slaves seeking to exercise their right to vote under the newly ratified Fifteenth Amendment). He was expressly authorized to do so by the 1870 Enforcement Act, and the Ku Klux Klan Act of 1871. When Rutherford B. Hayes defeated Samuel Tilden by one electoral vote (but lost the popular vote) in the 1876 election, aggrieved Democrats agreed not to contest the outcome if Hayes would withdraw all remaining federal forces from former Confederate states, ending Reconstruction. The next year, Southern Democrats in Congress forced passage of the Posse Comitatus Act (PCA), barring the use of troops for law enforcement “except in cases and under circumstances expressly authorized by the Constitution or Act of Congress.” The PCA thus enshrined in federal law the default that the military would not engage in law enforcement, a presumption that could be overcome only by express authorization from Congress or the Constitution. 

National Guard forces in their default state status are not subject to the limitations in the PCA. For this reason, National Guard troops often play critical law enforcement roles in the wake of natural disasters. National Guard personnel may also enforce the laws in Title 32 status — ordered by their respective governors to support “operations or missions undertaken by the member’s unit at the request of the President or Secretary of Defense.” The soldiers remain at least nominally under their governor’s control and are therefore not regarded as federal military personnel subject to the PCA, even though they may receive federal pay and benefits.

When National Guard troops are called into federal service, they immediately fall under the DOD chain of command and are thus subject to the PCA. However, federalized National Guard personnel may engage in law enforcement in the same circumstances as regular federal troops, for instance, if acting under the Insurrection Act, (10 U.S.C. 251-255) a pre-existing statutory exception to the PCA. 

The earliest versions of the Insurrection Act, in 1792, 1795, and 1807 authorized the president to federalize state militias to repel “an invasion” of the United States or, upon the request of a state, when there is “an insurrection in any state.” The same laws permitted the president to deploy the militia without a request from a state whenever “the laws of the United States shall be opposed, or the execution thereof obstructed … by combinations too powerful to be suppressed by the ordinary course of judicial proceedings, or by the powers vested in the [federal] marshals.” Although the terms of the Insurrection Act suggested that the militias would be federalized when civilian authorities were overwhelmed, in 1827 the Supreme Court indicated, in a case called Martin v. Mott, that the President had broad discretion in determining when to use these statutes in calling forth the militia, and that his determination was not subject to judicial review. 

The modern Insurrection Act confers even more sweeping authority to the President. If he finds it “impracticable to enforce the laws of the United States in any State by the ordinary course of judicial proceedings” he may federalize the Guard “or by any other means. .., take such measures as he considers necessary” to enforce the laws or quell domestic violence in any state. 

The Insurrection Act has been invoked for a variety of purposes, including the breaking of the Pullman Strike in 1894, to help integrate public schools and universities, to control racial unrest, and to enforce a variety of state and federal laws. It was last invoked by President George H.W. Bush in 1992 to send federalized California National Guard troops and active-duty soldiers to Los Angeles to help control rioting in the wake of the Rodney King trial verdict. 

There are several additional circumstances where the National Guard may be federalized. 

Civil Disturbances

After the murder of George Floyd by Minneapolis police officers on May 25, 2020, mostly peaceful protests broke out around the country. Scattered local violence was quickly contained by law enforcement authorities, sometimes aided by National Guard troops deployed by the states. Nevertheless, then-President Trump “strongly recommended” that every governor deploy the National Guard to establish an overwhelming law enforcement presence until the violence has been quelled. If any refused, Trump promised to “deploy the United States military and quickly solve the problem for them.” 

White House staff drafted a proclamation to invoke the Insurrection Act to enable the deployment of federal troops to quell protests in Washington, D.C. But upon the advice of the attorney general, defense secretary, and chairman of the Joint Chiefs of Staff, Trump reluctantly decided not to invoke the Act. Arguably, Trump could have relied on the Insurrection Act to justify deployment of active-duty military or federalized National Guard to quell protests in a state, even over the objection of its governor. 

The Trump administration also considered invoking the Insurrection Act in ways that directly threatened our democracy.. In the last days of the administration Trump’s advisers suggested using the Insurrection Act to federalize the Guard in response to unrest anticipated on January 6 to stop the certification of the election results.

Under a 19th century provision of the D.C. Code, the President is the commander in chief of the D.C. National Guard. As the equivalent of a state militia, the D.C. Guard is not subject to the PCA when deployed to quell disturbances or enforce the laws. Ironically, President Trump never gave an order to deploy the Guard to secure the Capitol on January 6 (January 6th select committee final report), and the  DC Guard finally arrived only after the violence subsided (final report, appendix 2).  

Border Security

Presidents George W. Bush and Barack Obama sent several thousand National Guard personnel to the U.S.-Mexico border in Title 32 status under the command of their respective governors to help curtail drug smuggling and illegal immigration. President Trump followed suit in 2018, with the deployment of some 4,000 National Guard personnel from 20 states, again in Title 32 status. 

Later in 2018, Trump expanded this use of military forces by sending nearly 5,800 active-duty service members to the border, authorizing them to perform “military protective activities,” including “a show or use of force (including lethal force, where necessary), crowd control, temporary detention, and cursory search” to protect border agents. If these troops were, in fact, used in ways that were “regulatory, proscriptive, or compulsory,” in the language of the Wounded Knee cases and DOD directives, such use would have violated the PCA, absent invocation of the Insurrection Act or some other statutory authority. But in spite of the bellicose language, these troops were used mainly for stringing concertina wire, transporting Immigration and Customs Enforcement personnel, conducting surveillance, and caring for Border Patrol horses. 

In February 2019, Trump declared a national emergency at the southern border, authorizing the call-up of military personnel and specifically relying on the somewhat peculiar authority of 10 U.S.C. §2808(a) for them to “undertake military construction projects.” 

Immediately upon taking office, Biden revoked Trump’s April 2018 order and 2019 emergency proclamation. But some 2,500 National Guard personnel continued to provide logistical support to Customs and Border Protection agents on the southern border in early 2024. One additional relevant statutory provision is 10 U.S.C. §284, which permits the use of armed forces to assist in drug interdiction and control transnational organized crime. Their use is limited, however, to maintenance or upgrade of equipment, transportation, establishment of operations or training bases, training of law enforcement personnel, and monitoring traffic within 25 miles of the border. They may also construct roads and fences, install lights along smuggling corridors, provide linguists, and conduct aerial and ground reconnaissance. 

Otherwise, the PCA may limit the activities of the deployed forces at the border unless a statutory exception provides the necessary authority. Of course, Title 32 Guard forces could and do perform tasks that active-duty federalized Guards could not. 

In the end, there are few legal limits to duties that could be assigned to troops at the border if the president invokes the Insurrection Act. Prudent judgment has so far prevented Biden from taking such a step. Trump and some of his close advisors have plans to use the military to effectuate mass deportations and migrant detention camps, according to recent reporting by the Washington Post.

Republican candidates for the 2024 presidential election suggested a more aggressive approach to combatting drug smuggling across the U.S.-Mexico border. Some advocated the use of lethal force against drug smugglers. Trump promised to use U.S. Special Operations troops “to kill or capture drug cartel members and destroy their labs and distribution centers” in Mexico. Such a use of force would violate international law as well as potentially U.S. law absent a congressional authorization for the use of military force.

Troops in Elections

Before the 2020 presidential election, there was widespread concern about possible acts of violence on election day aimed at disrupting voting. Many also worried that Trump might use threats or isolated acts of violence as a pretext for sending active-duty military or federalized National Guard troops to polling places in an effort to influence the election. These concerns prompted Gen. Mark Milley, chairman of the Joint Chiefs of Staff, to declare that “if there’s a disputed election, that’ll be handled by Congress and the courts. There’s no role for the U.S. military in determining the outcome of a U.S. election. Zero, there is no role there.” Fortunately, threats of violence did not materialize. 

Troops in a Pandemic

Early in the COVID-19 pandemic, when large numbers of cases threatened to overwhelm civilian health care systems, the Army Corps of Engineers constructed field hospitals in parking lots, stadiums, and convention centers around the country. The Navy deployed two hospital ships, the USNS Comfort to New York and the USNS Mercy to Los Angeles, to alleviate overcrowding in local hospitals. And hundreds of medical professionals from the Army, Navy, and Air Force deployed to bolster COVID-19-related health care efforts in Texas and California. In addition, roughly 46,000 National Guard members in Title 32 status joined in COVID-19 relief efforts in 2020. Later, soldiers helped administer COVID-19 vaccines at sites around the country. Unless troops were needed for law enforcement or to quell disturbances during a pandemic, in which case the authorities already discussed could support a federalized National Guard role, state-based National Guard personnel would perform the necessary tasks. 


The Texas border has provided the most recent setting for wrangling over the lawful and prudent role of the U.S. military on domestic soil. Despite the theatrics of a purported “invasion” by migrants, Biden has so far exercised caution in not federalizing the military presence in that powder keg environment. Particularly since the most extreme threats by former-President Trump to federalize the National Guard in the several circumstances sketched above, many have sought to persuade Congress to tighten the limits on presidential discretion in the Insurrection Act, the main lever for presidential initiative to deploy the military domestically. The efforts at reform are also ongoing, and whether the next president is Joe Biden, Donald Trump, or someone else, the reforms are desperately needed. 


Photo Credit: Texas National Guard soldiers stand guard on the banks of the Rio Grande river at Shelby Park on January 12, 2024 in Eagle Pass, Texas (Brandon Bell/Getty Images)