Sanctuary Policies in a Federal System 

This article is part of a series about the relationship between state and federal law.

President Donald Trump’s new administration has made a high priority of pursuing mass deportation of undocumented immigrants. It has also stripped hundreds of thousands of legal migrants of status, thus making them eligible for deportation.

If fully implemented, the administration’s deportation agenda may consign hundreds of thousands of migrants to poverty, oppression, and sometimes even death in their countries of origin, such as Cubans and Venezuelans fleeing brutal authoritarian socialist regimes. It could also gravely damage the U.S. economy by deporting a large part of its labor force.

Over the last decade, “sanctuary” jurisdictions have become a focus of political and legal controversy. Sanctuary policies are adopted by state and local governments that refuse to aid federal officials in enforcing particular types of federal laws, including immigration restrictions and gun control regulations.

Sanctuary policies have their flaws and limitations, and the Trump administration may be able to use various means to at least partly get around them. But sanctuaries also have strong constitutional grounding and can help mitigate the harmful effects of his immigration policies.

What Are Sanctuary Policies?

Sanctuary policies are laws and regulations adopted by state and local governments that deny or restrict assistance to federal officials seeking to enforce particular federal laws. The most widespread type of sanctuary policies are left-leaning immigration sanctuaries. Over the last 20 years, numerous “sanctuary cities” and “sanctuary states” have adopted policies barring their law enforcement agencies from assisting in the deportation of many categories of undocumented immigrants — usually those not convicted of serious crimes.

The Center for Immigration Studies, a think tank favoring severe immigration restrictions, counts 12 states and several dozen local governments as sanctuary jurisdictions. Global Refuge, a pro-immigrant organization, lists only 11 sanctuary states. (Global Refuge excludes Utah from its count, which the Center for Immigration Studies counts as a sanctuary jurisdiction for dubious reasons.)

In recent years, left-wing immigration sanctuaries have been imitated by conservative gun sanctuaries, beginning with Montana. Gun sanctuary laws, or “Second Amendment Protection Acts,” as advocates call them, deny cooperation with enforcement of a variety of federal gun control laws. Three states — Idaho, Missouri, and Wyoming — now have full-blown gun sanctuary laws, thereby earning a “gold” rating from pro-gun rights advocacy group Gun Owners of America. Seven other red states have more limited legislation, earning a “silver” rating from the organization..

Sanctuary laws are sometimes analogized to “nullification” — the idea that states can render federal laws null and void within their territory. Nullification, of course, has a terrible reputation, because of its association with southern states’ defense of slavery and segregation. But there is an important distinction between sanctuary laws and nullification.

Nullificationists argue that the federal laws in question are completely void and that states have the right to actively impede their enforcement on their territory. By contrast, sanctuary jurisdictions do not necessarily claim the laws in question are void, and they do not assert any right to actively impede their enforcement by federal officials. They merely deny federal agents the assistance of state and local governments, particularly law enforcement agencies. For example, they refuse to help enforce the relevant laws themselves or to provide information to federal law enforcement agencies engaged in enforcement efforts. But the feds remain free to try to enforce these laws in sanctuary jurisdictions using only their own resources and personnel.

In this respect, sanctuary jurisdictions are not actually complete sanctuaries. Undocumented immigrants protected by immigration sanctuaries may still be caught and deported by Immigration and Customs Enforcement or other federal agencies. Gun owners protected by gun sanctuaries may, similarly, be apprehended by federal law enforcement agencies, such as the Bureau of Alcohol, Tobacco, and Firearms. Federal prosecutors remain free to charge violators of these laws in federal court, and defendants may be assessed criminal penalties if convicted.

Nonetheless, sanctuary jurisdictions’ denial of state and local assistance to federal law enforcement makes a big difference. In the federal system, some 90 percent of law enforcement personnel are state and local government employees; only about 10 percent work for the federal government. This is very different from many other democracies, including some federal systems, with more centralized law enforcement apparatuses.

Because of this imbalance, federal law enforcement agencies are heavily dependent on state and local cooperation to effectuate enforcement of most federal laws. When states and localities deny such assistance, it becomes extremely difficult for federal law enforcement to catch more than a small fraction of violators. This is particularly true of laws where the number of violators is very large — including immigration laws. There are some 11 million undocumented immigrants in the country.

For these reasons, sanctuary policies significantly reduce the enforcement of federal laws they target, even if they cannot eliminate such enforcement entirely. Such resource limitations are a key reason why the Trump administration has so far failed to reach its deportation targets. Indeed, it has not even been able to deport migrants as fast as the Biden administration did in its final year.

The Constitutional Basis for Sanctuary Laws

Constitutional protection for sanctuary jurisdictions rests on a series of Supreme Court decisions holding that the 10th Amendment — which states that “powers not delegated to the United States by the Constitution, nor prohibited by it to the States, are reserved to the States . . . or to the people” — bans federal “commandeering” of state governments. The leading decisions to that effect are New York v. United States (1992) and Printz v. United States (1997). They hold, among other things, that state and local governments cannot be compelled to help enforce federal law. The anti-commandeering doctrine was further extended in Murphy v. NCAA (2018), which held that the federal government cannot issue orders to state legislatures and thereby force states to enact legislation or to refrain from repealing state laws.

Critics often claim that the Supreme Court’s anti-commandeering jurisprudence has no basis in the text and original meaning of the Constitution. But the 10th Amendment provides at least some textual support. Since the power to commandeer state and local governments is nowhere explicitly granted, the inference is that power is one of those “reserved” to the states. In addition, as legal scholar Michael Rappaport showed in a 1999 article, the anti-commandeering decisions have a basis in the founding-era understanding of the word “state,” which implied a sovereign authority that the federal government could not undercut by seizing control over the state’s government apparatus.

Printz and New York were decided by mostly conservative Supreme Court justices over vociferous dissents by the Court’s liberals. Murphy was a 7–2 decision authored by conservative Justice Samuel Alito, with two liberal justices in dissent.

Like the anti-commandeering rule, precedents limiting the use of the federal spending power had been pioneered by conservative justices and opposed by many liberals (though not as uniformly). For example, in NFIB v. Sebelius (2012), a narrow 5–4 conservative majority struck down a law requiring states to massively expand Medicaid benefits on pain of losing federal Medicaid subsidies on the ground that this imposition was unconstitutionally “coercive.” Since states depended on federal Medicaid funding for some 10–20 percent of their total spending, Chief Justice John Roberts concluded the threat of withdrawal was analogous to a “gun to the head.”

Ironically, these conservative decisions were most extensively used by blue state immigration sanctuaries to successfully fend off efforts to force them to aid in deportation of undocumented migrants during Trump’s first term. Liberal states and migrant-rights activists learned to love — or at least make use of — conservative federalism precedents they had previously reviled. They are going to have to rely on them again now.

During Trump’s first term in office, his administration sought to undermine immigration sanctuaries — but was often thwarted by anti-commandeering rules. Among other things, the doctrine led courts to largely reject a Trump administration lawsuit seeking to overturn California’s “sanctuary state” law.

The extension of the doctrine in Murphy prevented the administration from making effective use of 8 U.S.C. Section 1373, a federal law barring state and local governments from instructing their employees to refuse to share information on undocumented immigrants with federal law enforcement agencies. Multiple lower court decisions ruled that Murphy either required the invalidation of Section 1373 or compelled judges to interpret it very narrowly, rendering the law essentially ineffective. While Murphy struck down a federal law restricting states’ abilities to legalize sports gambling, its biggest practical impact was to aid immigration sanction sanctuaries.

The first Trump administration also tried to pressure sanctuary cities by threatening to cut off federal grants. A 2017 executive order tried to cut off nearly all federal funds to states and localities that refused to obey Section 1373. Later, the Justice Department tried to deny certain law enforcement grants to jurisdictions that refused to meet several immigration-enforcement-related conditions.

Both policies were struck down by federal courts because they violated Supreme Court precedent limiting the use of the spending power to coerce state and local governments. The Court had previously held that grant conditions must be clearly spelled out in the relevant statute, must be related to the purpose of the grant, and could not be so sweeping as to be “coercive.” The policies violated the requirement of clarity; indeed, they sought to usurp Congress’s power over federal spending by imposing new conditions created by the executive branch. Courts also ruled that the executive order also violated the anti-coercion rule, because it covered such a vast range of grants. Some court decisions further concluded that the conditions violated the relatedness requirement.

Later, during the Biden administration, the Justice Department filed a lawsuit challenging the Missouri gun sanctuary law that was, in many ways, similar to the earlier lawsuits against immigration sanctuaries. The dubious arguments advanced by the administration mirrored those put forward by Trump against the California sanctuary state law. In March 2023, a federal district court issued a badly flawed decision ruling against the Missouri law. The judge recognized that the federal government cannot force Missouri to aid in the enforcement of federal gun laws but wrongly concluded that the state law went beyond merely withholding assistance. Instead, the court said, the state actually “regulate[d] federal law enforcement” and “interfere[d] with its operations.” (In reality, the Missouri law does no such thing.)

An appellate court later struck down the law in a poorly reasoned ruling that nonetheless left room for sanctuary laws to function — so long as they avoid Missouri’s mistake of openly stating that the federal laws the state seeks to avoid helping enforce are not binding at all.

While sanctuary policies enable states to deny assistance to federal efforts to enforce laws against private parties, it is important to recognize that they do not empower states to violate federal laws themselves. States cannot use such policies to prevent the federal government from, for example, suing them for violating citizens’ constitutional rights.

The Value of Sanctuary Policies

Politicians’ and activists’ positions on sanctuary laws often reek of “fair weather federalism.” Their stances depend on whose ox is being gored. Supporters of immigration sanctuaries oppose gun sanctuaries and vice versa, even though the constitutional issues in the two situations are very similar.

I am one of the relatively few people who support both left-wing immigration sanctuaries and conservative gun sanctuaries. Such consistency is easy for me, because I support both a presumption of open borders immigration and broad gun rights. Immigration sanctuaries are particularly valuable because they protect large numbers of people who have fled horrible tyranny and oppression, make valuable contributions to our economy and society, and should not be deported back to repressive regimes such as those of Cuba and Venezuela.

But there are good reasons to support state and local rights to adopt sanctuary policies that go beyond the merits of specific policy issues. One is the danger of excessive concentration of power in the hands of the federal government generally, and the executive in particular.

If the federal government has broad power to force states to do its bidding, that power could easily be abused — especially in an era where there is severe ideological polarization and many on both sides of the political spectrum are eager to coerce their adversaries.

The danger is heightened by the ways in which such power is likely to be concentrated in the hands of the executive. If the president can use vaguely worded laws to attach new conditions to federal grants, he could easily use that to consolidate power and impose his own preferences on unwilling states and localities.

The case for sanctuary policies is even stronger if you fear that Trump — or some potential future president — has authoritarian tendencies. Sanctuary jurisdictions can make authoritarian aspirations harder to realize by giving refuge to the would-be dictator’s opponents.

Even when there is no authoritarian threat looming, sanctuary policies play a valuable role in preserving diversity in our federal system. In a highly diverse nation like the United States, federally imposed uniformity would deny millions of people the opportunity to live under policies they prefer. Sanctuary jurisdictions help protect diversity, allowing both red and blue states to pursue divergent policies.

Sanctuary policies also help empower people to “vote with their feet” for policies they prefer. People who dislike their home state’s policies on immigration, guns, or some other issue, have the opportunity to move to a more congenial jurisdiction. Where decision-making autonomy devolves to local governments, foot-voting opportunities are even greater, as it is often cheaper and easier to move between localities than between states.

Thus, immigration sanctuaries provide valuable refuge to undocumented immigrants, their families, and those who seek to engage in various economic and social transactions with them. Gun-rights sanctuaries do the same for those who place a high value on the right to bear arms.

Both economic theory and empirical evidence indicate that foot voters generally make better-informed decisions than ballot-box voters do. In addition, the former can exercise greater freedom of choice than the latter, because their decisions are far more likely to decisively determine what laws they live under. In most elections, a ballot-box voter has only an infinitesimally small chance of decisively affecting the outcome (about 1 in 60 million in a presidential election, for example). Foot voters, by contrast, have much greater leverage. When they decide which state or local government they wish to live under, that decision has a very high probability of actually affecting the policies they will be subject to. The outcome is dependent on their choices alone, not on those of thousands or millions other voters.

Sanctuary policies do have the downside that they could potentially be used to weaken enforcement of valuable federal laws. But this danger is readily outweighed by the benefits of checking federal power, preserving diversity, and empowering people to vote with their feet.

How Trump Could Potentially Get Around Sanctuary Laws

While sanctuary laws have great value, they also have significant limitations. The most obvious is that, while they constrain deportation efforts, they cannot block the president from gutting legal migration, as the Trump administration has begun to do on a large scale — both by denying legal entry and by stripping legal status from hundreds of thousands of people already in the country, such as Cubans, Haitians, and Venezuelans who have “temporary protected status” or “parole.” Even if they can avoid deportation, loss of legal status severely curbs job and educational opportunities for these migrants — and thereby also damages the U.S. economy.

As in Trump’s first term, the Justice Department has filed lawsuits against sanctuary jurisdictions and tried to cut federal grants to them unless they give in — a policy which has been challenged in court by affected jurisdictions. The present administration’s efforts are likely to fail in court, as did similar actions by the first Trump administration. But it’s possible that congressional Republicans will enact new grant conditions that put such coercion on a stronger legal footing (though this might be hard to do, given their narrow majorities). Even then, immigration-related conditions might run afoul of other constitutional constraints, such as requirements that conditions not be “coercive” and that they must be related to the purposes of the grants.

The administration is also in the process of trying to use non-traditional federal law enforcement resources to help in deportation, such as the Drug Enforcement Administration and Bureau of Alcohol, Tobacco, Firearms and Explosives. But these agencies are not well suited for immigration enforcement, and they too have significant resource constraints, given the small size of federal law enforcement.

More menacingly, the administration is considering using the military for immigration enforcement, perhaps even beyond areas near the southern border. This effort might run into legal constraints. Even if it does not, the military is — to put it mildly — not well structured and trained for the task of immigration enforcement. Troops are trained for combat, not finding and detaining undocumented migrants embedded in a large civilian population. Still, the use of the military for immigration enforcement could potentially cause grave harm by leading to violent confrontations between troops and civilians and diverting military resources away from genuine national security threats.

Finally, the administration is working to involve state and local law enforcement in immigration enforcement through agreements that deputize them to detain and help deport migrants. This could potentially be an important “force multiplier” for federal deportation efforts. Many red state jurisdictions are likely to go along, as some have already. However, blue sanctuary jurisdictions will continue to refuse, giving migrants a degree of safety there. And even many red jurisdictions might not be willing to accept large-scale diversion of their law enforcement personnel away from their regular duties. Doing so would predictably result in more violent and property crimes, as officers tasked with fighting it would instead be diverted to focus on undocumented migrants, whose crime rates are actually much lower than those of native-born Americans.

In sum, the administration may be able to at least partly get around sanctuary laws. But doing so will be difficult and is unlikely to come close to fully negating their impact.

• • •

Though sanctuary laws are far from a panacea for the harm likely to be caused by the Trump administration’s draconian immigration policies, they can be a valuable tool in mitigating the policies’ effects.

Gun sanctuaries are likely to be less significant over the next four years. But they can potentially play a more important role if a future president makes federal gun control a higher priority.

Ilya Somin is Professor of Law at George Mason University, B. Kenneth Simon Chair in Constitutional Studies at the Cato Institute, and author of Free to Move: Foot Voting, Migration and Political Freedom. Parts of this article are adapted from an earlier one published by the UnPopulist.

Suggested Citation: Ilya Somin, Sanctuary Policies in a Federal System, Sᴛᴀᴛᴇ Cᴏᴜʀᴛ Rᴇᴘᴏʀᴛ (Apr. 4, 2025), https://statecourtreport.org/our-work/analysis-opinion/sanctuary-policies-federal-system