Border Militarization Blurs the Distinction Between ‘Policing’ Immigration and ‘Combating’ Immigrants

Imagine the following hypothetical: From a guard tower adjacent to the border wall at 2:00 a.m., a U.S. Army private observes through her night vision goggles three men cutting through the razor wire with small knives several hundred meters away, on the Mexican side of the border, attempting to enter the newly designated “military installation” that exists on a strip of land extending into U.S. territory to a distance of 60 meters. They do not appear to have firearms. The soldier shines a spotlight and yells in Spanish to halt and move back away from the fence. The three men notice the soldier but persist in cutting the wire and the first man enters. The soldier fires several nonlethal rubber bullets in their vicinity but causes no injuries, and soon the second man crosses over. The soldier, prohibited from firing warning shots with live rounds, calls for backup and continues to fire her rubber bullets. The third man crosses over the breached razor wire fence. All three men, whom the soldier believes to be foreign nationals, are now inside military property having disabled or destroyed part of the fence line. The soldier sees the men stoop down and quickly smash a ground sensor and thermal imaging device, drop their knives and proceed on foot further into U.S. territory and away from the guard tower. The soldier gives chase, carrying her M-4 rifle loaded with live rounds. Can she shoot these men, using lethal force to stop their incursion and further destruction of what her orders call “assets vital to national security”? Or was it simply an unlawful trespass, for which nonlethal force is permitted so long as it is “reasonable”? What if it wasn’t three men, but three dozen? 

Sealing the Southern Border With a New “Military Installation”

On April 11, President Trump issued National Security Presidential Memorandum 4 (NSPM-4), otherwise known as “Military Mission for Sealing the Southern Border of the United States and Repelling Invasions.” The order blends traditional law enforcement rationales and authorities with traditional military use-of-force rationales and authorities in a way that obscures the fine-grained limits that ought to clearly and unambiguously regulate lethal force. Mark Nevitt has argued that this blurring confounds the well-established “military purpose doctrine.” Such a move has concerning implications for the extent to which lethal force would be permitted against illegal aliens identified just inside the U.S. side of the southern border.

Critically, 10 U.S.C. § 2672, entitled “Protection of buildings, grounds, property, and persons,” does not envision the limited use of force in a law enforcement capacity within a “military installation” according to the “rules for the use of force prescribed by the Secretary of Defense.” Rather, the statute permits the military to act as law enforcement within its own property and states expressly that those law enforcement powers “shall be exercised in accordance with guidelines approved by the Attorney General.” And notwithstanding Defense Department Directive 5525.21, a directive signed during the first Trump administration that gives guidance on the implementation of § 2672, nowhere in NSPM-4 does the president direct the defense secretary to work through the Department of Justice to write, promulgate, train, and enforce any such attorney general guidelines.

The Executive Order 14167 “Missions”

NSPM-4 supplements Trump’s Executive Order 14167. That Inauguration Day executive order is the clearest indicator that the administration foresees a militarized response at, and possibly south of, the border to combat illegal immigration and the illicit cartels that fuel and profit from human and drug trafficking into the United States. The executive order assigned U.S. Northern Command (USNORTHCOM) a new mission: “to seal the borders ... by repelling forms of invasion including unlawful mass migration, narcotics trafficking, human smuggling and trafficking, and other criminal activities.” He further directed USNORTHCOM to develop a “Level 3” plan for accomplishing this mission and directed the headquarters to plan a “campaign” of “steady-state southern border security” to “seal the border, and maintain the sovereignty, territorial integrity, and security of the United States.” “Level 3” planning refers to the development of a contingency “concept plan” (CONPLAN) “in anticipation of a potential crisis.”

Tying the new military installation plan in NSPM-4 to the specific military direction in Executive Order 14167 may suggest that Trump doesn’t intend to skirt the Posse Comitatus Act (PCA) after all, as some have reasonably argued he intends to do. This order suggests instead that the administration doesn’t view NSPM-4 as an exercise of law enforcement but rather as a wartime footing for the defense of national borders from an external attack, something that is arguably within the president’s exclusive Article II powers as commander in chief. Border defense against invasion is a traditional military responsibility, one for which Trump says the U.S. armed forces have “played a long and well-established role.” That Trump invoked the Alien Enemies Act under the pretense that the United States is suffering an “invasion” or “predatory incursion” by a transnational gang operating as a “hybrid criminal state” lends weight to that view. That Trump is using authorities for what appears to be law enforcement in the NSPM-4 in the context of these combat-preparatory and planning “missions” assigned in the earlier executive order is a harbinger of the confusion that comes from blurring two very different strategies.

“Protection of buildings, grounds, property, and persons”

The NSPM-4’s new authorities, drawn from 10 U.S.C. § 2672, granted to the military operating along the southern border are not authorities the public conventionally associates with the armed forces. Section 2672(c) expressly permits the military to:

(1) enforce Federal laws and regulations for the protection of persons and property; (2) carry firearms; (3) make arrests (A) without a warrant for any offense against the United States committed in the presence of the officer or agent; or (B) for any felony cognizable under the laws of the United States if the officer or agent has reasonable grounds to believe that the person to be arrested has committed or is committing a felony; (4) serve warrants and subpoenas issued under the authority of the United States; and (5) conduct investigations, on and off the property in question, of offenses that may have been committed against property under the jurisdiction, custody, or control of the Department of Defense or persons on such property. 

Outside the context of § 2672, employing the military in this way would likely violate the long-standing PCA. Dating back to 1878, this law bars the “willful” use of the active-duty military “as a posse comitatus or otherwise to execute the laws” unless “expressly authorized” by the Constitution or by an act of Congress. But as the text of § 2672 illustrates, the PCA is easily overcome by its vagueness, permitted exceptions, and “loopholes,” as this Brennan Center report argues.

The primary exception to the PCA—the one that poses most risk for widespread deployment of the military untrained to police American communities and territory—is the Insurrection Act, encoded principally at 10 U.S.C. §§ 251, 252, and 253. But these exceptional authorities may be invoked properly by the president only under exceptional circumstances: when certain enumerated factual preconditions are satisfied. For example, use of § 252 is permissible only when “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.”

These preconditions may be frustrating impediments to an administration that wishes to use the armed forces in a brawnier manner domestically to manage threats that are not traditional military threats from another nation or non-state armed group, like—for example—a so-called “invasion” of illegal immigrants or narcotics cartels. Therefore, designating the geographic locus of this supposed “invasion” threat as a “military installation” allows the president and defense secretary to overcome the PCA prohibition and simply ignore the Insurrection Act and its factual preconditions. Militarization of the border is hardly surprising given the administration’s use of the wartime Alien Enemies Act and designating transnational gangs and cartels as international terrorist organizations.

Nevertheless, arguing this territory is within the jurisdiction of the Defense Department as a military installation has the ironic consequence that the military should actually be more restrained in the use of force than what the president likely expects if the express terms of § 2672 are followed. 

Department of Justice Guidelines, Standing Rules for the Use of Force (SRUF), or Both?

According to § 2672(i), which the NSPM-4 incorporates, the law enforcement powers of arrest and investigation are to be addressed by “guidelines” from the U.S. attorney general. But according to NSPM-4, those powers will be executed according to the terms of the defense secretary’s “rules for the use of force.” In the absence of any news to the contrary, we should work from the assumption that this means the “Standing Rules for the Use of Force” (SRUF) already promulgated through the Office of the Chairman of the Joint Chiefs of Staff.

The distinction between the SRUF and the attorney general’s guidelines matters. For example, the extent to which constitutional protections from excessive use of force depends on which body of regulations will govern the armed forces while they execute their “protective” missions within (or from) this newly designated military installation. 

Perhaps unsurprisingly, I could find no published unclassified policy or directive from any office within the Department of Justice that serves as Department of Defense “guidelines” under § 2672(i) in the context of the Pentagon’s border mission. Of course, Attorney General Pam Bondi could simply “approve” the SRUF or some yet-to-be-published RUF as the applicable guidelines. But until that happens, we can make reasonable guesses as to what those guidelines should include. Generally, all federal agencies with law enforcement responsibilities—including Immigration and Customs Enforcement (ICE) and Customs and Border Protection (CPB)—must ensure that their personnel performing police functions are properly trained and certified to do so by Federal Law Enforcement Training Centers (FLETCs), whose curricula includes compliance with Fourth, Fifth, and Sixth Amendment rights. Additionally, 10 U.S.C. § 1585a requires “special agents” of the Department of Defense’s Criminal Investigative Service (and separate statutes for each of the Service-specific CISs, like the Navy CIS and the Army’s Criminal Investigative Division) to exercise their law enforcement authorities “in accordance with guidelines prescribed by the Inspector General of the Department of Defense and approved by the Attorney General and any other applicable guidelines prescribed by the Secretary of Defense or the Attorney General.” That’s encouraging news if we are limited to only worrying about civilian Department of Defense law enforcement officers. But what about military service members performing law enforcement functions on an uninhabited swath of desert along the border? 

Service members assigned to roles as military police (MPs) or security forces (SF) specialties carry badges and firearms and perform routine traditional law enforcement roles within ordinary military installations (for example, Fort Bragg’s Law Enforcement Center in North Carolina). MPs perform traffic law enforcement, interdiction of illicit substances or other contraband, gate access control, safety patrols, investigation of criminal misdemeanors and felonies (under Title 18 of the U.S. code) that are committed within the confines of the military installation—whether the suspect is civilian or military—in those routine settings. The Defense Department says it complies with the attorney general guideline requirement in § 2672(i) by mandating that “a prerequisite for the Service to be granted such authorities is for all entry-level training of Defense Department law enforcement personnel to be certified by FLETA [the Federal Law Enforcement Training Accreditation] and Defense Department POST [Department of Defense Peace Officer Standards and Training Commission] standards in entry-level training.” Per Department of Defense Instruction (DoDI) 5525.15 (“Law Enforcement (LE) Standards and Training in the Defense Department”), all Defense Department training centers instructing entry-level uniformed law enforcement personnel must meet accreditation standards overseen by FLETA, and this DoDI also establishes that such training will comply with the Defense Department POST Commission’s “Guidelines.”

A survey of these relatively recent POST guidelines (published in April 2023) is reassuring. The mandatory instruction includes training on compliance with federal constitutional law, including “protecting individual rights, human dignity, and upholding the human rights of all persons.” Other elements of the training curriculum cover “cultural diversity/discrimination,” the legal foundation for the authority to use force on a suspect, Miranda rights, the PCA, interrogation of suspects, the difference between “reasonable suspicion” and “probable cause,” elements of various common federal offenses, firearm safety, medical aid, the “proper collection, preservation, processing, storage, and chain of custody procedures of evidentiary items,” and scores of other tasks the public commonly expects of police forces.

However, DoDI 5210.56 (“Arming and the Use of Force”) also purports to implement § 2672. Without referencing the attorney general or any Department of Justice guidelines, this instruction lists the various circumstances in which deadly force is authorized. In brief, that list includes an authority to use lethal force to protect certain categories of defense property—albeit “vital” and “critical” property that extends past what is conventionally understood to be the basis for deadly force. This list matches almost verbatim to the SRUF’s list, described below.

Fourth Amendment Use of Force 

It is worth emphasizing that military service members performing law enforcement functions (even if not MPs) on military installations comply with federal constitutional law, in addition to various federal agency regulations and—in some instances—state criminal law. The Supreme Court and lower circuit courts of appeal have long addressed the Fourth Amendment “seizure” implications of law enforcement personnel using physical force on individual persons, whether to “stop and frisk” or in employing deadly force with a firearm or other instrument (like a patrol car to run the fleeing suspect off the road in a car chase): The powers of the police officer “necessarily include” the power to use “at least some degree of physical coercion or threat thereof;” this degree of force is judged by an objective “reasonableness” standard (a reasonable officer at the scene at the time), in light of the totality of the circumstances in a given case. Lethal force is not unconstitutional, according to the Court, when “the officer has probable cause to believe that the suspect poses a threat of serious physical harm, either to the officer or to others[.]” The Court has also approved of the use of deadly force in the context of attempts to arrest a person suspected of committing a serious “violent” felony and to prevent a prisoner from escaping custody.

The Justice Department’s internal policies and procedures reflect these constitutional limits. According to the Justice Manual, section 9-16.200, deadly force may be used “only when necessary, that is, when the officer has a reasonable belief that the subject of such force poses an imminent danger of death or serious physical injury to the officer or to another person.” But lethal force is explicitly not authorized to prevent an escape of a “fleeing suspect.”

Concerns over the extent to which force—including deadly force—could be used to physically detain or stop such persons are heightened if only the SRUF regulates law enforcement-type conduct at the border. 

A Twilight Zone Between Law Enforcement and Combat Rules of Engagement

According to the Domestic Operational Handbook published by the U.S. Army JAG Corps, “[t]he domestic use of force authority is ingrained in the constitutional role of the Executive branch, and are tempered by the Bill of Rights.” As for guarding military real property and the activities that occur there, the handbook notes that “[a]s Commander-in-Chief, the President has the authority to ... order installation force protection.” The handbook also emphasizes to military lawyers that the constitutional law standard relevant to the use of force, in the installation force protection mode or any other, is the Fourth Amendment’s fundamental demand for “reasonableness.” In other words, the RUF is intended to be consistent with the “appropriate constitutional law standards as interpreted by the courts and the executive branch.” This makes DoDI 5210.56’s authority to use deadly force to protect certain property a bit perplexing; to the extent that this authority maps to those in the SRUF, the potential for confusion is only perpetuated.

The SRUF’s authorities for the use of deadly force unquestionably surpass ordinary domestic law enforcement authorities. By its terms, the SRUF applies to “land homeland defense missions occurring within U.S. territory and to Defense Department forces, civilians and contractors performing law enforcement and security duties at all Defense Department installations ... unless otherwise directed by the SecDef.” Paragraph 5.c. lists the circumstances in which “deadly force is authorized,” provided “all lesser means have failed or cannot reasonably be employed.” These include the “inherent” right of unit self-defense, which can be employed at the discretion of the relevant commander (who may limit it), when the commander “reasonably believes that a person poses an imminent threat of death or serious bodily harm to Defense Department forces.”

Deadly force is further authorized in three additional circumstances in the context of protecting persons. These three permissive circumstances fit within the Supreme Court’s current interpretation of reasonable force under the Fourth Amendment.

But this is not where deadly force authorization under the SRUF stops. Shooting to kill is also authorized in three contexts in which property is endangered. First, when it “reasonably appears to be necessary to prevent the theft or sabotage of assets vital to national security[.]” An earlier section of the SRUF defines such assets broadly, to include “designated restricted areas containing strategic operational assets” where “the actual theft of sabotage of which the President determines would seriously jeopardize the fulfillment of a national defense mission and would create an imminent threat of death or serious bodily harm.”

Deadly force is also permissible when it “reasonably appears to be necessary to prevent the theft or sabotage of inherently dangerous property[.]” On-scene commanders are authorized to designate property, including but not limited to, arms and ammunition, explosives, and chemical agents, as “inherently dangerous.”

And deadly force is permissible when it “reasonably appears to be necessary to prevent the sabotage of national critical infrastructure[.]” Such “critical infrastructure” is defined as “President-designated public utilities, or similar critical infrastructure, vital to public health or safety, the damage to which the President determines would create an imminent threat of death or serious bodily harm.” An earlier section of the SRUF partly defines “imminent” as “not necessarily mean[ing] immediate or instantaneous.” 

But perhaps the SRUF’s most permissive authority to use deadly force is this: “in defense of non-DOD persons in the vicinity, when directly related to the assigned mission” (emphasis added). This authority does not appear in DoDI 5210.56, nor come with the standard caveats attached to the other lethal force authorities: “reasonably appears necessary to” and to prevent “imminent threat of death or serious bodily harm.” This authority is wide enough to, as they say, fly a Chinook helicopter through. Consider the missions assigned to the Defense Department in Executive Order 14167: “to seal the borders ... by repelling forms of invasion including unlawful mass migration, narcotics trafficking, human smuggling and trafficking, and other criminal activities.” Unless it is further limited by the secretary, the SRUF would permit a soldier sitting in a guard tower inside the Roosevelt Reservation to use lethal force against a group of unarmed “trespassing” teenagers who—having illegally crossed the border—find themselves already inside a military installation, the purpose of which is to “seal the border” and “repel an invasion” if the soldier believes that less-than-lethal force would be ineffective. Moreover, that soldier could use deadly force even before those teenagers enter the military installation if he sees them breaking through a fence or wall on grounds that it is “sabotage of assets vital to national security.” Given Trump’s rhetoric and implications of his executive orders, it is difficult to imagine Trump not claiming any part of the wall or fence to be an asset vital to national security. If that soldier’s act was the basis for a Fourth Amendment civil lawsuit, it is not clear to me whether the fact-finder would condemn it as objectively “unreasonable” given that the soldier was not trained and certified in law enforcement and was following authorities provided by the SRUF. 

It is only fair to note, though, that the SRUF is, in some ways, more restrictive on the use of force than what the courts say the Fourth Amendment requires of “seizures.” Where objective reasonableness under the circumstances is the standard by which excessive force is measured for ordinary civilian law enforcement, the SRUF goes further by directing attempts to “de-escalate” when time and circumstances permit, that nonlethal force used must be the “minimum necessary,” and as a “last resort.”

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By regulating the military’s use of force to prevent “trespassing” on this property according to the RUF rather than guidelines approved by the attorney general according to 10 U.S.C. § 2672(i)—the president has militarized the border in ways that reflect his political view that illegal immigration constitutes a national security threat and does it in a way that circumvents the Posse Comitatus Act without having to invoke the Insurrection Act. The SRUF is not law, even if it attempts in good faith to be consistent with the Fourth Amendment; § 2672 is—along with the protections for Fourth Amendment rights that bind law enforcement use of force all over this country. The NSPM-4’s juxtaposition of § 2672(i) and the RUF obscures whether soldiers and Defense Department civilians engaged in “law enforcement” on this new military installation are to use force as de facto CBP officers, as ordinary military police on an ordinary military installation, or more permissibly under the SRUF. But legally, the line is critical for distinguishing the amount of armed force that may be used without violating constitutional rights and statutory prohibitions. As a general rule, no provision for the use of force by government agents should be handicapped by preventable ambiguity.