Sanctuary cities and states have been a major focus of political conflict in the second Trump administration, perhaps even more than in the first. These jurisdictions refuse or severely limit assistance to federal efforts to detain and deport suspected illegal immigrants. Most only provide such assistance in cases involving undocumented migrants who have committed serious crimes. Regardless of the politics, the 10th Amendment protects sanctuary jurisdictions from compulsion by the federal government. And their policies are also well justified on moral and pragmatic grounds. This is particularly true at a time when many federal immigration enforcement efforts are cruel and illegal.

There are currently some 11 sanctuary states (the Trump administration claims there are 12) and numerous local governments that have sanctuary policies of their own. The 10th Amendment states that “powers not delegated to the United States by the Constitution, nor prohibited by it to the States, are reserved to the States respectively, or to the people.” In a series of decisions primarily supported by conservative justices, the Supreme Court has held that the 10th Amendment bars federal “commandeering” of state and local government personnel and resources, including forcing them to help enforce federal law against private parties.

The key rulings are New York v. United States (1992), which barred the federal government from forcing states to dispose of radioactive waste, and Printz v. United States (1997)—a decision written by conservative icon Justice Antonin Scalia, holding that the federal government may not commandeer state executive officials for law enforcement purposes. The anti-commandeering doctrine was extended in Murphy v. NCAA (2018), authored by Justice Samuel Alito, perhaps the most conservative member of the court today. It 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.

These decisions—particularly Murphy—were repeatedly invoked by both conservative and liberal federal judges to block President Donald Trump’s efforts to coerce sanctuary cities during his first term, and again during the first year of his second one. Numerous court decisions in both Trump terms have also ruled that the president cannot withhold federal funds from sanctuary jurisdictions in cases where doing so would be “coercive,” the immigration-enforcement conditions were not “related” to the purposes of the grants, or Congress had not authorized immigration-related conditions on recipients.

Critics argue that the court’s anti-commandeering jurisprudence has no basis in the text and original meaning of the Constitution. But the anti-commandeering rule does have textual support. Since the power to commandeer state and local officials is nowhere granted in the text of the Constitution, that suggests it is one of those “reserved” to the states. In addition, as originalist legal scholar Michael Rappaport showed in an important 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 abrogate by taking control over the state’s government apparatus. In Federalist 28, Alexander Hamilton emphasized that “It may safely be received as an axiom in our political system, that the State governments will, in all possible contingencies, afford complete security against invasions of the public liberty by the national authority.” States cannot assure such “complete security” against federal overreach if the federal government could seize control of their personnel anytime it wanted to.

The constitutional basis for protecting sanctuary jurisdictions against executive-created spending conditions is also strong. As numerous court decisions have held, the Constitution gives Congress, not the president, the power of the purse. Thus, the executive cannot attach its own conditions to federal grants to the states, as Trump has repeatedly tried to do. In addition, even Congress’ power to spend for the “general welfare” is not unlimited, and it cannot use this authority to completely gut state autonomy. The resulting anti-“coercion” rules are admittedly fuzzy. Elsewhere, I have argued it would be better to instead impose the narrower original meaning of what qualifies as the “general welfare.” The original meaning, as understood by James Madison, among others, only permitted spending to implement other enumerated federal powers, and—possibly—spending that really does benefit the entire country, as opposed to merely some region or subset of the population. Since the 1930s, however, the Supreme Court has said that the “general welfare” includes virtually any spending Congress deems beneficial. Unless and until that changes, the restrictions on coercion imposed by current doctrine are better than the alternative of giving the federal government a blank check in this field.

Some novel issues are raised by Trump’s recent efforts to coerce Minnesota state and local governments into giving up their sanctuary policies by sending thousands of armed federal agents to harass the population and disrupt state and local government operations. A federal district court recently refused to grant Minnesota a preliminary injunction blocking this operation, in large part because of uncertainty created by the “unprecedented” nature of the case. But, as I explained in articles for Lawfare and the Brennan Center’s State Court Report, there is still a 10th Amendment violation here. Trying to coerce states at the literal point of a gun is, if anything, even more egregious than doing so by passing a congressional statute or by imposing unauthorized conditions on federal grants. The illegality of many of the federal agents’ actions—including killing and injuring peaceful protesters, large-scale racial profiling, and more—makes this policy even more blatantly coercive.

Some try to discredit sanctuary policies by analogizing them to “nullification.” Nullification has a terrible reputation because of its association with state efforts to defend slavery and segregation. But there is a fundamental distinction between nullification and sanctuary policies. Nullificationists like John C. Calhoun claimed the federal laws they oppose are completely void and that states have the right to actively resist their enforcement. By contrast, sanctuary jurisdictions merely deny federal officials the aid of state employees and resources. The latter can significantly reduce the effectiveness of enforcement efforts, given that there are many more state and local law enforcement officers than federal ones. But it is not nullification. Refusing to help is not the same thing as active obstruction.

Conservatives tempted to jettison these constitutional rules in order to stick it to liberal immigration sanctuaries would do well to remember that the same principles also protect red-state “gun sanctuaries,” such as Missouri and Montana, which deny state assistance for enforcement of federal gun control laws. The two types of sanctuary jurisdictions stand or fall together. The seminal Printz case actually involved a federal law that commandeered state officials to carry out background checks on gun purchasers.

In addition to being constitutionally protected, sanctuary policies are also right and just. Sanctuary jurisdictions have rightly concluded that police resources are better used to combat violent and property crime instead of aiding in deportation efforts. As Minneapolis Mayor Jacob Frey put it last month, “The job of our police is to keep people safe, not enforce fed immigration laws. I want them preventing homicides, not hunting down a working dad who contributes to [Minneapolis] & is from Ecuador.” Undocumented migrants actually have much lower crime rates than native-born citizens, and most of those detained, especially in recent months, actually have no criminal records at all. Local and state participation in deportation efforts also makes it more difficult to combat crime by poisoning relations between law enforcement agencies and minority communities.

The cruel and illegal nature of much of the federal deportation effort provides additional justification for denying it state and local assistance. In more than 4,400 immigration cases over the last year, courts have ruled that the second Trump administration illegally detained people. The true number of illegal detentions is likely much greater, since many detainees lack the resources to fund legal challenges and cannot always get in touch with public interest lawyers willing to represent them pro bono (there is no right to government-funded counsel in deportation cases).

Meanwhile, federal immigration agents routinely engage in unconstitutional discrimination in the form of racial and ethnic profiling. The incredible extent of racial and ethnic profiling by federal immigration authorities is demonstrated by the fact that immigration arrests in Los Angeles County declined by 66 percent within just 16 days after a court order barred the use of such tactics (the ruling was later blocked by the Supreme Court, likely for procedural reasons). Conservatives and others who advocate color-blindness in government policy should support state governments’ refusal to facilitate such massive racial discrimination.

Federal immigration raids also often sweep up U.S. citizens. ProPublica found some 170 cases of illegal detention of citizens between Trump’s return to office in January and November 2025. And that figure is likely a severe underestimate, given that the federal government does not keep data on such cases and ProPublica could count only those they were able to track down.

Immigration and Customs Enforcement detention facilities routinely feature shockingly callous treatment of those imprisoned there, including overcrowding, inadequate food, denial of needed medical treatment, and child abuse, including hundreds of violations of a legal settlement barring detention of children for more than a 20-day period. State and local governments should not help imprison still more people in these horrific conditions.

In his General Orders to the Continental Army, issued on the occasion of the end of the Revolutionary War in 1783, George Washington wrote that the United States was founded to create “an Asylum for the poor and oppressed of all nations and religions.” Sanctuary jurisdictions help honor that promise by reducing the incidence of brutal treatment of migrants seeking freedom.

Sanctuary policies cannot address all the evils of our flawed immigration policies. But they make that system significantly less awful than it would be otherwise. The Constitution rightly protects states’ power to adopt them.