There’s growing concern that President Donald Trump might invoke the Insurrection Act to bring National Guard troops under federal control and deploy them within the U.S. This speculation may be partly because one of President Trump’s Inauguration Day executive orders, which declared a national emergency at the southern border set an April 20 deadline for the Departments of Defense and Homeland Security to recommend whether to use the Insurrection Act. That date is approaching quickly.

Make no mistake: If Trump invokes the Insurrection Act to activate federalized troops for mass deportation—whether at the border or somewhere else in the country—it would be unprecedented, unnecessary, and wrong. But the president has already been increasing domestic military use. As recently as April 11th, he issued a new memorandum with yet another chill-inducing title: "Military Mission for Sealing the Southern Border of the United States and Repelling Invasions.” It’s worth repeating that there is no invasion of America, and if President Trump doubts that, he could consult himself. Last month he declared on Truth Social that the (fictional) “Invasion of our Country is OVER.” Yet under his new directive, the Defense Department is claiming new and potentially expansive powers over large swaths of federal land—including where US citizens and other border residents live. .

Let’s step back a bit first and recall the military’s proper, limited role on U.S. soil, and the dangerous steps President Trump is already taking in service of his cruel anti-immigrant, anti-American agenda.

When the Founders drafted the Constitution, they were concerned about constraining a rogue executive, preventing a standing (i.e. large and permanent) army, ensuring civilian government and a nonpartisan military, and safeguarding civil rights and civil liberties. From then until now, we know that a core component of liberty and democracy is the strong presumption against military enforcement of civil law—put simply, the military should not be policing civilians.

For these reasons, even when the Founders and Congress have given the president war and emergency powers, it is with constraints. For example, the Posse Comitatus Act of 1878 makes it a crime to use federal military forces “to execute the law,” except when “expressly authorized” under the Constitution or by an act of Congress. In practice, this means that the Defense Department generally forbids federal troops from carrying out direct civilian law enforcement activities on U.S. soil such as surveillance of individuals, questioning and interrogations, arrests, searches, and seizures, among other things.

Another key principle is civilian control over the military, which means that military troops must follow a president’s lawful orders. Troops don’t get to pick and choose which lawful civilian orders they follow and which they don’t. But for this system to work, presidents and military leaders must be careful to ensure that the orders they give are unambiguously lawful. Otherwise, they put troops at legal and ethical risk, weaken military cohesion, and undermine the constitutional design, which prevents direct military involvement in civilian life, except in the limited circumstance of genuine crises.

Nor should the military act—or appear to act—in service of a partisan political agenda. Domestic deployment of the federal military is rare and has historically been reserved for genuine emergencies, like the extreme situation of an actual war, an armed rebellion, or to enforce federal laws if civilian agencies and courts aren’t functioning. One clear example comes from 1958, when President Dwight D. Eisenhower invoked the Insurrection Act (which is an exception to the Posse Comitatus Act) and deployed federal troops to Arkansas to enforce the Supreme Court’s Brown v. Board decision and guard the Little Rock Nine against a racist and violent mob. President Eisenhower acted after then- Governor Orval Faubus had deployed the state National Guard to support segregationists in defiance of the Supreme Court’s decision.

The Constitution also allocates power between the federal government and the states, generally imposing on the federal government the duty to enforce federal law and defend against truly extreme crises and emergencies, while reserving police powers to the states. Normally, National Guard troops are maintained by states, under the command of their governors, as explained below. States have a critically important role to play in ensuring lawful and appropriate use of police powers within their state while safeguarding individual civil liberties and rights.

Applying these principles, here are the key things to know about how domestic military deployment normally works:

States’ National Guard Deployment

• The National Guard’s normal, default role is under the control of the governor of each state or territory (or, for Washington, D.C., the commanding general of the D.C. National Guard). Governors may activate their National Guard within the state, at state expense, for purposes authorized by state laws and regulations. When National Guard troops are activated, their conduct—including use of force—is also governed by state law. The federal Posse Comitatus Act’s prohibition against troops carrying out civilian law enforcement functions does not apply to National Guard units in state status, but governors, National Guard commanding officers, and troops themselves must always abide by the limits and protections in their state constitution and the U.S. Constitution.

Federal Role in National Guard Deployment

Congress has enacted laws governing both federal military and National Guard deployment and conduct in Titles 10 and 32 of the U.S. Code.

• Title 32 duty. Under Title 32, National Guard troops can be deployed into active duty to provide support for federal or joint state-federal operations or missions that are authorized by Congress or carried out at the request of the president or secretary of defense. Historically, these federally-supported purposes include things like a large-scale humanitarian or natural disaster response, or drug interdiction. In this status, the troops are federally funded and trained but remain under the command and control of their state governor.
  As a matter of federal law and practice, the president or secretary of defense can request state National Guard deployment in Title 32 status. State governors can decline such a request. If National Guard troops in Title 32 status are deployed across a state’s borders to another state, it is generally with the authorization of both the requesting and “receiving” states. Like with state active-duty troops, the conduct of National Guard troops in Title 32 status is governed—and limited—by state rules and law, as well as the Constitution and other relevant federal laws.

• Title 10 duty. In Title 10 of the U.S. Code, Congress has legislated the roles of the federal armed forces and the Department of Defense. Title 10 federal duty for National Guard troops has historically been rare. The National Guard may be deployed into active duty by the president under Title 10 for a federal purpose, with command and control resting solely with the president and the secretary of defense. National Guard troops deployed under Title 10 are federally funded and are often referred to as “federalized” National Guard.
  Congress has prohibited troops—federal and federalized National Guard—deployed under Title 10 from providing “direct assistance” to civilian law enforcement—under both the Posse Comitatus Act and a separate provision of Title 10. The Posse Comitatus Act applies to all current Title 10 deployments on U.S. soil, and troops deployed under it to the southern border are prohibited from carrying out arrests, searches, and seizures. The Insurrection Act is generally understood as the primary exception to the Posse Comitatus Act’s prohibitions.

On Inauguration Day, Trump declared a national emergency at the southern border, falsely claiming an invasion, and authorized a dramatic increase in the number of federalized National Guard troops deployed to the border under Title 10. Since then, he’s also sent combat vehicles to our border communities. So far, Trump’s domestic troop deployment has been limited to support for border operations. Troops have been supporting border wall construction and materials transportation, monitoring and detection assistance, and providing logistical assistance for civilian agencies like Immigration and Customs Enforcement (ICE) and Customs and Border Protection (CBP).

But his actions are worsening the conditions under which civilian border communities live. Our southern border is home to approximately 19 million people, in addition to the regular business and trade commuters who come across the border every day. In recent years, U.S. citizens and other border residents have been exposed to intrusive civilian law enforcement surveillance, aggressive federal policing, border patrol checkpoints they must pass through for medical care and daily activities, and environmental degradation from border wall construction. Border patrol agents have engaged in deadly vehicular pursuits and excessive use of force against border residents, and in one of his initial executive orders, President Trump revoked the 2023 Customs and Border Protection policy to limit these deadly chases.

On April 11, Trump issued a memorandum giving the Defense Department use and jurisdiction over public civilian lands along the border—including the Roosevelt Reservation in New Mexico and excluding Federal Indian Reservations—for military activities. Trump’s directive allows the secretary of defense to identify “military activities that are reasonably necessary and appropriate” including actions to “protect and maintain the security of military installations” and exclude people from newly designated “national defense areas.” In other words, Trump is opening the door to an expanding military role that goes beyond logistical support—and potentially beyond the identified zone.

The new policy has serious implications for border residents living under this expanded militarized zone, which includes cities like San Diego, CA; Nogales, Arizona; El Paso, Texas and other heavily populated, thriving communities. People in these areas could now face federal prosecution for trespassing if they unintentionally walk or drive onto a designated “national defense area.”

Given the numerous documented cases of excessive use of force by border patrol agents, we are deeply concerned about the potentially dangerous consequences of adding more armed troops to border communities, in an environment that military personnel may not be trained for. Trump’s new memorandum states that “members of the Armed Forces will follow rules for the use of force prescribed by the Secretary of Defense,” but these rules may be completely inappropriate for densely populated, civilian areas.

President Trump has not invoked the Insurrection Act—yet. But his administration continues to invest in the theatre of war, like wrongly invoking wartime authorities such as the Alien Enemies Act, and threatening drone strikes against drug cartels in Mexico. None of this makes us safer, and this latest move to hand over public land to the military forces our civilian communities to live in fear.

Right now, we are calling on members of Congress to insist on oversight for these expanded actions—in particular, any changes to rules governing use of force—and to call for safeguards and transparency to protect border residents from escalating military control over their daily lives.

These developments are bad enough. Invocation of the Insurrection Act is both unnecessary and would make them worse.

This post was originally posted on March 14, 2017 and updated on March 21, 2025.

The government has long claimed that Fourth Amendment protections prohibiting warrantless searches don’t apply at the border. The American Civil Liberties Union takes issue with this position generally, especially when it comes to electronic devices like smartphones and laptops. Our smartphones store detailed accounts of our conversations, professional lives, whereabouts, and web-browsing habits. They paint a far more detailed picture of our private lives than, say, a piece of luggage.

The Supreme Court recognized this reality when it ruled in 2014 that the Constitution requires the police to obtain a warrant to search the smartphone of someone under arrest. As the ACLU has argued in various court filings, there’s no reason the Constitution’s safeguards against unwarranted searches shouldn’t also apply when we travel internationally given the ubiquity of these devices, and their ever-growing capacity to track the minutiae of our private lives.

Unfortunately, the government doesn’t agree, and the law on the matter is far from settled. Because of the high-stakes implications of these kinds of searches, and amidst evidence suggesting they’re on the rise, it’s important to understand the landscape so that you can make decisions that are right for you ahead of your travels.

The government claims the authority to search all electronic devices at the border, no matter your legal status in the country or whether they have any reason to suspect that you’ve committed a crime. You can state that you don’t consent to such a search, but unfortunately this likely won’t prevent Customs and Border Protection (CBP) from taking your phone.

If you’ve given CBP agents the password to your device (or if you don’t have one), they might conduct what’s often called a “basic search” on the spot. They might also download the full contents of your device and save a copy of your data. Since 2018, they are not required to return your device before you leave the airport or other port of entry, and they might choose to send it off for a more thorough “advanced” or “forensic” search. Barring “extenuating circumstances,” they claim the authority to hold onto your device for five days — though “extenuating circumstances” is an undefined term in this context, and this period can be extended by seven-day increments. We’ve received reports of phones being held for weeks or even months.

As a result of this policy, even the most universally recognized private information — like communications with your lawyers — are insufficiently protected at the border. If you possess information that is protected by attorney-client privilege, you should tell the CBP agent you’re interacting with. Although CBP policy imposes some limitations, it still permits government employees to search the phone.

Journalists carrying sensitive information about their work or sources are also insufficiently protected. The CBP directive states that “work related information carried by journalists shall be handled in accordance with any applicable federal law and CBP policy” — but it’s unclear what this means. Journalists who feel their rights have been violated at the border should let us know, and those who have upcoming travel should consult with their organizations’ general counsel offices or press associations.

If you leave the airport or other border checkpoint without your device, make sure you get a receipt, which should include information about your device and contact information allowing you to follow up. If, after the forensic search is conducted, there is no probable cause to believe the device contains evidence of a crime, the government says it will destroy any information it copied within 21 days. Yet there’s a caveat here, too. CBP might retain the notes it took during the search of your device or any questioning while you were at the border.

Your legal status in the country may inform what you decide to do if you’re asked for a password to unlock your device.

If you’re a citizen, you can’t be denied entry into the country if you refuse to comply with a request to unlock your device or to provide a password. But you might be detained for longer or have your device seized and not returned to you for weeks or months. The same should be true for those who have previously been admitted to the United States as lawful permanent residents and have maintained their status — their green cards can’t be revoked without a hearing before an immigration judge. If you are not a citizen and are concerned about having your devices searched, you should consult with an immigration lawyer about your particular circumstances before traveling.

Visa holders and tourists from visa waiver countries, however, run the risk of being denied entry if they refuse to provide a password, and they should consider that risk before deciding how to proceed.

Whether you’re a citizen or not, though, we always recommend that you enter the password yourself rather than divulging it to a CBP agent. They still might demand that you share it, but it’s a precaution worth trying to take. If you do hand over your password, it’s likely to end up in a government database, so change it as soon as you have the chance and make sure you no longer use that password for any other account.

Here are a few precautions you can take in preparation for your trip to ensure things go as smoothly as possible:

• Travel with as little data and as few devices as possible. The less you’re carrying, the less there is to search. Consider using a travel-only smartphone or laptop that doesn’t contain private or sensitive information. You could also ship your devices to yourself in advance. (Be aware that CBP claims the authority to search international packages so it is best to encrypt any devices that you ship.) Keep in mind that a forensic search of your device will unearth deleted items, metadata, and other files.
• Encrypt devices with strong and unique passwords and shut them down when crossing the border. A good resource on how to do so can be found here.
• Store sensitive data in end-to-end encrypted cloud-storage account and remove any sensitive data from your device. Disable any apps that connect to cloud-based accounts where you store sensitive communications or files, and don’t keep a copy of cloud-stored data in your physical possession. In July 2017, CBP publicly stated it is against policy for border agents to search cloud-stored data on electronic devices. This means that any search of an electronic device at the border should not extend to data that is only accessible via the internet — such as email or social media messages and posts that are stored on remote servers. Keep in mind that if there are copies of cloud-stored data cached on the device (for example, recent emails), border agents will be able to see that information.
• Upload sensitive photos on your camera to your password-protected laptop or a cloud-storage account. Digital cameras don’t offer encrypted storage, so you should consider backing up your photos and deleting them from your camera and reformatting the camera's memory card.
• Keep devices off. If you must turn them on, ensure that they are in airplane mode, with both wifi and bluetooth disabled, before crossing a border checkpoint. CBP stated in July 2017 that its policy does not permit searches of cloud-stored data that is accessible from electronic devices through the internet. Keeping your devices in airplane mode will help ensure compliance with this policy.
• Let officers know if you have privileged material on your device. The 2018 CBP Directive on border device searches requires certain procedures to be followed before border officers can search attorney-client or attorney work product materials. If you have any privileged or sensitive material on your device, tell the border officers before they begin any search.

Until the Supreme Court weighs in on the constitutional limits of the government’s powers at the border, questions about the government’s authority to conduct these kinds of searches aren’t likely to be settled. Lower courts have issued conflicting rulings on whether individualized suspicion should be a condition for such a search. The Ninth Circuit, which covers several western states, for example, requires at least reasonable suspicion that the device contains digital contraband for a “forensic” search of a seized device, but has not imposed an individualized suspicion requirement for “cursory” on-the-spot searches. The Fourth Circuit, which covers several mid-Atlantic states, requires reasonable suspicion that the phone contains evidence of a border-related offense for a forensic search. The Eleventh Circuit, which covers three southeastern states, imposes no limits at all.

It is crucial that more courts weigh in, given that device searches at the border seem to be on the rise. CBP reports that in 2023, more than 41,000 electronic devices were searched, a huge jump from the 8,503 devices that were searched in 2015. With border officials increasingly exercising authorities that haven’t been sufficiently considered by the courts, the urgency for clear protections mounts. In the meantime, travelers should take the precautions they feel are right for them.

This resource offers a basic snapshot of possible scenarios relating specifically to electronic device searches. For a fuller picture of the many other civil liberties issues that often arise at the border, click here.