Militarized Enforcement and the Erosion of Civil Liberties

Ulysses Jaen

Director of the Law Library and Professor of Law | Legal Research, Administration

Published Jun 9, 2025

Introduction:

Recent events in mid-2025 have brought renewed attention to the longstanding tension between immigration enforcement and civil liberties in the United States. In Los Angeles, large-scale immigration raids provoked street protests and confrontations, prompting the unprecedented deployment of National Guard troops to the city’s streets. At the same time, federal authorities invoked an arcane 18th-century statute, the Alien Enemies Act, to summarily detain and deport certain noncitizens, a move swiftly challenged in court as unlawful. These developments underscore the central concern of this Article: the militarization of immigration enforcement and its erosion of constitutional rights. This Article revisits the core legal issues implicated by militarized enforcement, including Fourth and Fifth Amendment violations, the limits on deploying military forces under Title 10 of the U.S. Code, and the revival of dormant wartime powers such as the Alien Enemies Act. It offers a comparative historical perspective to illuminate how past episodes of aggressive enforcement inform the present moment. Finally, it assesses the constitutional and statutory constraints on such policies – drawing on recent court rulings and scholarly commentary, and argues for reinvigorating legal safeguards to prevent executive overreach. The analysis proceeds in four parts: a civil rights analysis of current practices; a comparative historical review of similar measures and their consequences; an examination of constitutional implications and legal checks; and a conclusion on the path forward.

I. Civil Rights Implications of Militarized Immigration Enforcement

A. Immigration Raids and the Fourth Amendment. The conduct of immigration raids in Los Angeles and elsewhere has raised serious Fourth Amendment concerns. The Fourth Amendment’s guarantee against unreasonable searches and seizures applies to “the people” in the United States, which includes noncitizens present in the country 1. Yet militarized enforcement tactics often test the boundaries of what is “reasonable” under the circumstances. In early June 2025, Immigration and Customs Enforcement (ICE) agents conducted sweeping raids of businesses and public spaces in Southern California, backed by heavily armed personnel and even deputized National Guard members 2. These raids sometimes involved cordoning off entire city blocks and questioning of anyone in the vicinity, echoing “dragnet” enforcement methods that courts have scrutinized in the past. For example, in INS v. Delgado, the Supreme Court reviewed factory-wide immigration “sweeps” and left troubling ambiguity about the line between a permissible questioning and a Fourth Amendment seizure of bystanders 3. In practice, large-scale raids create an atmosphere of coercion, blurring the line between targeted enforcement and general search. Reports from the Los Angeles raids indicate that protesters and even uninvolved residents felt the heavy presence of agents and soldiers “on high alert,” which one could argue resembles a de facto military occupation of civilian areas.

Moreover, the decision to deploy 2,000 National Guard troops to Los Angeles in response to civil protests represents an escalation of enforcement that is virtually unheard of in modern domestic policing. Governor Gavin Newsom condemned the deployment as “purposefully inflammatory” and likely to “escalate tensions,” emphasizing that local law enforcement was already managing the situation. The presence of federal troops in city streets, in battle gear, confronting protesters raises the question of posse comitatus limits – traditionally, the U.S. military is barred from civilian law enforcement activities 4. While National Guard units under state authority can assist in emergencies, their federalization under Title 10 to perform policing functions without state consent is extraordinarily rare and legally contentious. Erwin Chemerinsky, a leading constitutional scholar, described the federal takeover of California’s Guard to put down protests as “truly chilling,” highlighting how unusual and extreme such an action is. From a Fourth Amendment standpoint, using soldiers trained for combat in domestic arrest operations heightens the risk of excessive force and unreasonable searches, as military training and rules of engagement differ markedly from civilian policing standards. The American Civil Liberties Union (ACLU) warned that deploying federalized troops in response to protests “creates legal and ethical jeopardy for the troops” and undermines “our foundational democratic principle that the military should not police civilians”. These warnings echo the spirit of the Fourth Amendment: domestic peacekeeping should favor restraint and judicial oversight, not bayonets and battalions.

B. Due Process, Equal Protection, and the Fifth Amendment. Militarized immigration enforcement also implicates Fifth Amendment rights – most notably the guarantees of due process and equal protection (the latter via the Fifth Amendment’s Due Process Clause for federal actions). The use of the Alien Enemies Act of 1798 in 2025 provides a stark example. In March 2025, the President issued a proclamation invoking this centuries-old law to designate certain Venezuelan nationals as “alien enemies” on the premise that a Venezuelan criminal organization, Tren de Aragua (TdA), was perpetrating an “invasion” of the United States. On that basis, over 130 Venezuelan men in the U.S. were summarily detained, stripped of ongoing immigration proceedings (including asylum claims), and swiftly deported to a mega-prison in El Salvador, all without individualized hearings or judicial review. Such summary removal bypasses the basic due process requirement that persons on U.S. soil are entitled to a fair hearing before being deprived of liberty or deported5. Many of those expelled under the Act had no meaningful chance to contest the accusation that they were affiliated with the targeted group; indeed, reports show that officials relied on a crude “Alien Enemy Validation Guide” a point-based checklist of tattoos, clothing, and other tenuous indicators – to identify supposed gang members. In one illustrative case, an individual with a pending asylum application was deported under this program despite a lack of evidence beyond a claim that he fit a gang profile – a claim later shown to be unfounded. This kind of guilt by association and denial of a day in court is precisely what the Fifth Amendment forbids the government from doing to any “person,” citizen or not 6.

The equal protection component is also starkly implicated when enforcement targets individuals based on national origin or ethnicity. Invoking the Alien Enemies Act against Venezuelans (and only Venezuelans) is effectively a nationality-based classification. While Congress in wartime may authorize restrictions on enemy aliens, such measures are subject to constitutional limits. The Supreme Court’s notorious decision in Korematsu v. United States upholding the World War II internment of Japanese Americans on military orders – has since been repudiated as a shameful mistake 7. In Trump v. Hawaii (2018), the Court noted that Korematsu was “gravely wrong” and “overruled by history,” even as the Court majority in that case upheld a nationality-based entry ban on different grounds 8. The 2025 scenario, however, went further than an entry ban: it involved rounding up people who were already inside the United States, many seeking refuge, and expelling them under harsh conditions. It comes uncomfortably close to the logic of Korematsu, targeting a disfavored group without individual cause. Civil rights scholars and human rights organizations have strongly criticized this approach; Human Rights Watch condemned the March–April 2025 actions as “enforced disappearances” and arbitrary detentions, urging that the Alien Enemies Act be repealed as fundamentally incompatible with modern human rights standards. Indeed, bipartisan legislation dubbed the “Neighbors Not Enemies Act of 2025” has been introduced in Congress to repeal the Alien Enemies Act once and for all 9, reflecting a growing consensus that this relic of the 18th century has no place as a tool of immigration policy in the 21st.

The Fifth Amendment’s Due Process Clause also protects the right to protest and speak out without fear of disproportionate retaliation by the government. To the extent that federal forces in Los Angeles used aggressive tactics against demonstrators, those actions could raise First Amendment and due process issues as well. There are reports of confrontations where nonviolent protesters were met with batons and less-lethal munitions, and community leaders have argued that the federal response was intended to intimidate immigrant communities and chill dissent 10. Such a dynamic, where the government’s overwhelming show of force deters people from exercising their rights, can violate substantive due process if it “shocks the conscience,” or infringe on First Amendment freedoms to assemble and petition. While maintaining public order is a valid state interest, the means chosen must be carefully calibrated so as not to trample fundamental constitutional rights.

II. Historical Parallels and Comparative Perspectives

Today’s militarized approach to immigration enforcement did not emerge in a vacuum; it has notable historical precedents both in the United States and abroad. Understanding those episodes provides context for the current debate and cautionary lessons about the erosion of civil liberties in the name of security.

A. Domestic Precedents. The United States has at times turned to quasi-military campaigns in its efforts to control immigration or suppress internal “threats,” often with troubling results. A prime example frequently cited is Operation Wetback (1954), the largest mass deportation campaign in American history. Although the operation was carried out by civilian authorities (the INS and Border Patrol), it was militaristic in both name and execution. The campaign was headed in part by a retired general (Gen. Joseph Swing, then INS Commissioner) and “used military techniques and coordinated tactical operations” to sweep up Mexican immigrants on an enormous scale. Officers, armed and in battle dress, descended on Mexican-American neighborhoods and workplaces without warning. Tens of thousands of people were loaded onto buses, trains, even ships, often in squalid, dangerous conditions, and expelled to remote parts of Mexico. Reports from that time describe families separated and U.S. citizens of Mexican descent caught up in the dragnet due to the broad profiling of “Mexican-looking” individuals 11. Contemporary accounts likened the crowded deportation transports to “slave ships,” noting that some deportees died from heat exhaustion and neglect in custody. Operation Wetback stands as a stark reminder that mass enforcement drives can lead to brutal excesses and civil rights violations, especially when fueled by ethnic bias,1950s officials openly justified harsh treatment with racial stereotypes depicting Mexicans as inherently criminal or diseased. While Operation Wetback was not an official military deployment, its militarized ethos blurred the line between civil authority and warfare, much as current policies risk doing. Legal analysis in its aftermath criticized the lack of judicial process and the indiscriminate nature of the raids, foreshadowing the same criticisms leveled at today’s tactics.

Even earlier, during the Great Depression, the federal government undertook mass “repatriation” campaigns against Mexican immigrants, effectively deportations often carried out with the cooperation of local police and citizen vigilante groups. An estimated 1 to 1.8 million people of Mexican descent were forced out of the United States in the 1930s, up to 60% of whom were actually U.S. citizens by birth 12. Although not a military operation per se, this episode again saw the suspension of ordinary legal norms (e.g., little due process or regard for citizenship) under the guise of economic and social “security.” Such historical episodes underline a pattern: during times of national stress or heightened nativism, immigration enforcement can take on a wartime footing, and the usual protections for individuals, citizen and non-citizen alike, are at risk of being ignored.

Another infamous parallel is the World War II internment of Japanese Americans. While not an immigration enforcement action (most internees were U.S. citizens or long-term residents), it represents the extreme end of militarized violation of civil liberties on American soil. Pursuant to Executive Order 9066 and military proclamations, over 110,000 people of Japanese ancestry were forcibly removed from their homes and placed in camps under armed guard, without trial. In Korematsu, the Supreme Court upheld this sweeping action on the reasoning of military necessity, a decision now viewed as a profound injustice 7. The internment example is instructive for modern immigration policy because it shows how easily executive power, unchecked by courts, can trample individual rights in the name of national security. Notably, the government’s justification then, fear of an “internal enemy” during wartime, parallels the rhetoric of “invasion” used in 2025 to justify invoking the Alien Enemies Act against asylum-seekers from Venezuela. The eventual repudiation of Korematsu by all branches of government reinforces that extraordinary military-style measures directed at civilian populations are an anathema to constitutional values except perhaps in the most truly existential emergencies.

B. Limits on Military Involvement: Posse Comitatus and Insurrection Act History. The American legal tradition has generally been skeptical of using the military for domestic law enforcement. The Posse Comitatus Act of 1878 prohibits the use of the Army or Air Force to execute domestic laws except where expressly authorized by Congress 13. This post-Reconstruction statute enshrined the principle that soldiers should not act as cops on American streets, a reaction to federal troops’ role in the South after the Civil War. Over time, Congress also applied similar restrictions to the Navy and Marine Corps by Department of Defense regulation 14. Immigration enforcement has historically been a civilian agency responsibility, and direct Army or Marine involvement in rounding up immigrants would be plainly at odds with posse comitatus. Indeed, even when presidents have sent active-duty troops to the southern border (for example, Presidents Bush and Obama in limited support roles, or President Trump’s deployment of troops in 2018-2019), the military personnel were confined to logistical support and surveillance, not arrest authority, specifically to avoid violating the law 15. In 2025, however, the line appears to have been blurred. The Defense Secretary’s public musings about sending Marines from Camp Pendleton into Los Angeles to deal with civil unrest over immigration policy – an act Governor Newsom rightly called “deranged” suggest a willingness to edge toward a direct Insurrection Act invocation. The Insurrection Act of 1807, in its modern form, is one of the only avenues for a president to lawfully deploy federal troops domestically against civilians 16. It allows federalization of National Guard or use of the armed forces to suppress insurrection or civil disturbance when state authorities cannot or will not secure civil rights or enforce federal law 17. This law has been used sparingly, for instance, by President Eisenhower in 1957 to enforce school desegregation in Little Rock, Arkansas, when the state defied federal court orders. The contrast with the present situation is stark: Little Rock involved upholding constitutional rights (integration) against violent obstruction, whereas deploying troops to Los Angeles in 2025 would effectively suppress community protest and facilitate aggressive deportations. Legal scholars note that invoking the Insurrection Act in these circumstances stretches its intent to the breaking point 18. Chemerinsky observed that nationalizing a state’s Guard or calling in Marines should be “reserved for extreme circumstances” where no other alternative exists to maintain order, a threshold not met by isolated clashes at protests. The concern is that the administration sought to “send a message” of intimidation to dissenters, as Chemerinsky put it, rather than to respond to an actual insurrection. History counsels that once the military is drawn into domestic affairs, the risk of abuse and rights violations soars, which is why both law and tradition erect high walls against routine use of soldiers in policing roles.

C. Comparative International Perspectives. The United States is not alone in grappling with the militarization of immigration control. Other democracies have also flirted with deploying military forces for border security or migration management, often with contentious results. In the European Union, for example, the 2015 migrant crisis saw several countries send military units to reinforce their borders or aid in migrant interdiction in the Mediterranean Sea 19. While those efforts were framed as humanitarian or security assistance, human rights observers documented increased abuses wherever military tactics supplanted civilian asylum processes 20. Mexico provides a more direct parallel: in June 2019, under pressure from the Trump administration, Mexico dispatched 6,000 members of its newly created National Guard to its southern border to stop Central American migrants and asylum seekers 21. This militarized southern border strategy did reduce migration flows temporarily, but at the cost of pushing migrants into more dangerous routes and increasing reports of extortion and violence by authorities. It also raised legal questions under Mexico’s constitution about using military-organized forces for law enforcement, echoing the posse comitatus concerns in U.S. law.

The comparative lesson is that militarization tends to undermine the rule of law in immigration matters. Refugee and migration crises are fundamentally humanitarian issues requiring careful legal processing of asylum claims and coordinated international responses. When states respond as if facing a foreign enemy invasion, deploying troops, building prison camps, or invoking wartime national security powers, they often violate international legal norms. The United States, as a party to treaties like the 1967 Refugee Protocol and human rights conventions, is bound to ensure that its immigration enforcement (even against unauthorized migrants) upholds basic rights such as the right to seek asylum and protection from refoulement (return to persecution) 22. Heavy-handed tactics like those of early 2025 risk breaching these obligations. Indeed, a group of U.N. human rights experts expressed grave concern in April 2025 that the U.S.’s use of the Alien Enemies Act and militarized removals constituted arbitrary deportation and denial of asylum rights, calling for an immediate halt to such practices 23. The international backlash to U.S. policy in this period suggests that, beyond domestic constitutional issues, there are global ramifications when America’s immigration enforcement tilts toward militarism. It can erode U.S. moral authority on human rights and encourage other governments to also treat vulnerable migrant populations as security threats rather than as people with rights.

III. Constitutional and Legal Constraints on Militarized Enforcement

Having surveyed the current developments and their historical context, this Part turns to the constitutional and legal constraints that govern (and limit) militarized immigration enforcement. The events of 2025 have already prompted critical responses from the judiciary and from legislators, reinforcing that even in the face of executive assertions of extraordinary power, the rule of law is not absent.

A. Judicial Checks – The Courts Push Back. One of the most significant legal developments was the swift judicial response to the administration’s use of the Alien Enemies Act. In late April 2025, U.S. District Judge Fernando Rodriguez, Jr., in the Southern District of Texas, enjoined further deportations of Venezuelans under the Act and condemned the President’s proclamation as exceeding statutory authority. In his ruling, Judge Rodriguez emphasized that the Alien Enemies Act – by its text and historical context – requires a state of declared war or an actual “invasion or predatory incursion” by a foreign power 24. The judge noted that when Congress enacted the law in 1798, an “invasion” meant a military incursion by a nation-state’s forces, not merely criminal activity by a gang or non-state group. Accordingly, he found that the activities of Tren de Aragua, as alleged in the proclamation, did not meet the statute’s criteria: however dangerous that gang might be, its members’ crimes did not amount to an armed invasion by Venezuela. As a result, the President “does not possess the lawful authority under the [Alien Enemies Act]… to detain… or remove” the Venezuelan immigrants in question, and the invocation of that Act was ultra vires (beyond the law’s scope). Importantly, the court also rejected the notion that the President can unilaterally declare such an invasion to trigger emergency powers. As the ACLU’s attorney pointed out, “the court ruled the President can’t unilaterally declare an invasion… during peacetime” to justify using a wartime statute. This decision is a powerful reaffirmation of the principle that executive actions are subject to judicial review, even when national security is invoked. It draws a constitutional line: the President cannot simply circumvent Congress’s war-making authority or the normal immigration laws by rhetorically labeling a situation an “invasion.” The ruling thereby vindicates both the separation of powers (Congress did not authorize this use of the Act in the circumstances) and the due process rights of those individuals who would otherwise have been expelled without recourse.

Judicial oversight has also played a role in constraining harsh detention practices in immigration. Prior Supreme Court decisions, while deferential to Congress’s immigration power, have imposed some due process limits – for example, Zadvydas v. Davis held that indefinite detention of deportable aliens is impermissible absent a strong justification25. In the context of 2025, if the government were to detain alleged gang members for prolonged periods under military guard or transfer them abroad (as happened here, to El Salvador’s facilities), courts would likely scrutinize such actions under the Fifth Amendment’s prohibition on arbitrary detention. In fact, the reports of detainees being sent to El Salvador’s CECOT mega-prison (a facility notorious for harsh conditions) as part of a deal with that country have already sparked habeas corpus petitions 26. Federal judges have historically not looked kindly on executive attempts to move detainees beyond the reach of U.S. courts – as seen in cases like Boumediene v. Bush, where the Supreme Court rejected the idea that the government could evade habeas review by holding war-on-terror detainees at Guantánamo Bay 27. By analogy, shipping immigration detainees to a third country’s prison to avoid U.S. legal protections would raise serious constitutional red flags.

As for the use of military force in Los Angeles, any clash between federal troops and civilians could give rise to legal action as well. Injured protesters or state officials might seek injunctions or damages, arguing that the deployment violated the Posse Comitatus Act or constitutional rights. While courts traditionally hesitate to second-guess the Executive on matters of security, the overt domestic use of the military is exceptional enough that judges would likely demand clear legal justification. Notably, if the President invoked the Insurrection Act to justify the Guard or Marines in Los Angeles, that invocation itself can be reviewed on whether the statutory criteria were met (e.g., was there a rebellion or an inability of the state to protect rights?). The language of the Act requires an insurrection or obstruction of federal law that is beyond the power of normal law enforcement to handle 17. From the publicly known facts, California officials were not requesting federal troops – to the contrary, they opposed it – and the disturbances, while serious, were localized and temporary. This creates a credible argument that the deployment was unlawful. Some California officials have hinted at seeking a restraining order against further troop involvement, citing the lack of a bona fide insurrection 28. Although this precise legal showdown has not yet fully played out, the mere prospect has likely influenced federal decision-making; indeed, as of this writing, active-duty Marines have not been sent in, and the National Guard presence, while real, has been limited primarily to protective roles around federal buildings. The judicial branch thus stands as a crucial check, ready to enforce the constitutional boundaries if the political branches overreach.

B. Legislative Responses and Oversight. Congress, too, has been stirred into action by these developments. Even with partisan divisions, there are signs of legislative pushback. The introduction of the “Neighbors Not Enemies Act of 2025” by Rep. Ilhan Omar and Sen. Mazie Hirono – aiming to repeal the Alien Enemies Act – is one direct response. Although its prospects are uncertain (especially with Republican majorities in one or both chambers at the time of introduction) 29, the bill has served to focus debate on the antiquated nature of that law and the need to prevent future abuse. Congressional hearings have been proposed to investigate the March–April deportations, with particular attention to whether administration officials violated court orders or engaged in “enforced disappearances” by sending detainees abroad secretly. Even members of the President’s own party have expressed unease at the specter of wartime powers used in peacetime; there are reports that some senators are considering amendments to the annual defense authorization that would clarify limits on domestic military deployments for immigration enforcement 30.

Moreover, the situation in Los Angeles has drawn sharp scrutiny from California’s congressional delegation. Lawmakers have questioned under what authority the President moved Guard troops into the state without Governor Newsom’s consent, and whether Pentagon funds were improperly diverted to this mission. The House Homeland Security Committee and Senate Judiciary Committee have both signaled oversight hearings on “militarization of immigration enforcement and the impact on civil liberties” in the coming months. Such hearings are likely to call experts like constitutional scholar Erwin Chemerinsky and ACLU attorneys to testify, voices that have already been prominent in the public discourse. This legislative oversight serves an important constitutional function: it reinforces the separation of powers by signaling that the executive’s actions are not going unchecked. In the past, congressional pressure has sometimes reined in excessive enforcement tactics, for example, in the 1990s, public outrage and hearings about INS mistreatment of legal residents led to reforms in detention conditions and procedures 31. Here, the stakes are even higher, involving possible violations of core constitutional norms. If nothing else, the dialogue in Congress builds a record that could inform future legislation or even impeachment inquiries should unlawful conduct be confirmed.

Finally, it bears noting that state and local governments have a role in this dynamic as well. California, as a “sanctuary” jurisdiction, has its own laws limiting local cooperation with federal immigration enforcement. The clash in Los Angeles effectively pits state laws and community policing policies against the might of federal power. Legal challenges could arise under the Tenth Amendment (anti-commandeering principles) if the federal government attempts to compel state officers or resources to participate in the crackdowns. Already, Los Angeles officials have asserted that public safety has been undermined by the federal actions, citing residents’ fear of engaging with local police or accessing city services in the wake of the raids 32. These indirect effects on public trust and safety further bolster the argument that militarized immigration enforcement, far from making communities secure, actually erodes the rule of law at the local level. In the long run, a sustainable immigration policy will likely require cooperation and trust between federal authorities and local communities – something that heavy-handed tactics severely jeopardize.

Conclusion

The events of 2025, from the streets of Los Angeles to the courts of South Texas, have tested the limits of America’s tolerance for militarized immigration enforcement. This Article’s review of civil liberties implications, historical analogues, and legal constraints leads to several conclusions. First, the erosion of civil liberties in the face of militarized enforcement is not speculative; it is happening now, evident in warrantless raids, mass detentions, and the chilling sight of troops confronting civilians. Fundamental rights under the Fourth and Fifth Amendments are at risk when enforcement is pursued as if it were warfare. Second, history teaches that such approaches inflict lasting harm on our society’s fabric, whether the exemplar is Operation Wetback’s racial terror or the internment of Japanese Americans, the United States has repeatedly regretted policies that sacrificed civil rights out of fear or expediency. This time should be no different: the mix of a broad “enemy” label (Venezuelan migrants) with military-style responses is a red flag we ignore at our peril.

Third, there remain powerful constitutional and statutory checks on these excesses, if we choose to enforce them. The judiciary’s prompt intervention against the misuse of the Alien Enemies Act confirms that the courts can serve as a bulwark for the rule of law, even against a President’s claim of national security. Similarly, the legal norms codified in the Posse Comitatus Act and the Insurrection Act set boundaries that cannot be transgressed without consequence. A president determined to use soldiers as immigration police must confront not only these laws but the principles behind them: federalism, civilian supremacy, and individual rights. Thus far, the pushback from judges, legislators, and civil society suggests that American democracy still has the means to correct course. Indeed, by June 2025, the crisis was prompting a national conversation about how to reconcile immigration enforcement with constitutional values, a conversation that may yet yield reforms (such as repealing outdated authorities and clarifying the limits of executive power under immigration and emergency statutes).

In the end, the erosion of civil liberties is not an inevitable byproduct of enforcing immigration law; it is a choice. The United States can choose a different path, one that robustly secures the border and manages migration without resorting to military force or suspension of due process. This would involve recommitting to the idea that immigration is a civilian matter governed by law, courts, and careful policymaking, rather than a battlefield. It would also require confronting the climate of fear and xenophobia that often underlies calls for militarization. As the comparative analysis suggests, countries that have treated migrants as an invading enemy have neither solved the problem nor upheld their values. America, a nation built by immigrants and grounded in constitutional liberty, must do better. The summer of 2025 may well be remembered as a turning point – either as the moment when the nation drifted further into an era of “immigration exceptionalism” where normal rules don’t apply, or as the moment when legal and moral clarity prevailed to restore the primacy of civil liberties. For the sake of the Constitution and all who live under it, the latter outcome is not just preferable, but imperative.

Footnotes: