Suppose your local police department decides to work with a masked man who routinely grabs people off the street and beats them up in the name of catching criminals. Would state law impose any restrictions on local law enforcement’s dealings with this vigilante group?

No, not Batman. ICE agent.

The Trump administration has deployed thousands of federal agents, including Immigration and Customs Enforcement (ICE) and Customs and Border Protection agents, to cities and states across the country. Whatever the benefits of this surge in enforcement, the costs are alarming. In Minneapolis, federal agents shot and killed Renee Good and Alex Preti. In Chicago, agents brutalized protesters, journalists, and bystanders alike, including local officials and religious leaders. Across the country, people caught up in immigration enforcement are being killed by federal agents or dying in federal custody.

But the surge in federal enforcement is only half the picture. Both ICE and the federal Border Patrol rely on cooperation with state and local law enforcement to detain immigrants, share data and resources, and suppress protests. In Tennessee, for example, State Highway Patrol troopers, along with ICE officers wielding shotguns, reportedly conducted racist traffic stops on pretext. In Massachusetts, local officials reportedly shared the identities and locations of immigrants in state custody with federal immigration authorities. Even in so-called sanctuary jurisdictions that prohibit or discourage cooperation, state and local police share information with ICE, resulting in the detention and deportation of residents. Additionally, over the past year, local governments have signed a record number of agreements under the 287(g) program that create formal partnerships between state and local police departments and ICE.

President Donald Trump has falsely suggested that states are obligated to provide this kind of assistance to federal immigration authorities. He accused the sanctuary jurisdiction of being “lawless.” He has issued several executive orders seeking to punish these sanctuary cities and states. And the Justice Department has filed a series of lawsuits against cities and states for refusing to assist federal immigration officials.

Trump is wrong. The 10th Amendment gives states the power to refuse to participate in federal programs, including immigration enforcement. Just as many states have chosen not to assist the federal government in enforcing federal prohibitions on marijuana possession (indeed, many states have explicitly decriminalized marijuana possession under state law), they can also choose not to assist the federal government in enforcing federal immigration laws. Some states and municipalities are doing just that.

But the abhorrent conduct of federal immigration officials in recent months, combined with the federal government’s apparent determination to continue that conduct, raises the possibility of more. allow States and cities can opt out of federal agents’ assistance in immigration enforcement, but state constitutions may actually allow them to do so. force It’s an opt-out.

State constitutions can go beyond the United States Constitution in protecting individual rights. For example, suppose a police officer stops a car because he suspects the passenger is an illegal immigrant, but claims the reason for the stop was a malfunctioning taillight. Even if that pretext stop were permissible under the Fourth Amendment, the officers’ actions could still violate the state’s constitutional rights against unreasonable searches and seizures. Similarly, a suspension based in part on a suspect’s language, race, ethnicity, or occupation, law professor Anil Kalhan called a “Kavanaugh suspension,” referring to Justice Brett Kavanaugh’s concurring opinion. Noem v. Vasquez Perdomo — Even if a federal court deems the summons permissible under the U.S. Constitution, it could violate the states’ equal protection guarantees.

Federal officials are unlikely to worry about increased state constitutional protections. Due to the Supremacy Clause of the U.S. Constitution, these agents generally do not have to follow the constitutions of the states in which they operate. (I feel like people don’t really care about the U.S. Constitution these days.)

State and local officials don’t have that luxury. The state constitution fully binds federal immigration officials, including when using state law enforcement powers to assist them. At a minimum, state and local officials must not directly engage in actions that violate the state constitution. But shouldn’t we also avoid encouraging such behavior by federal employees?

This question, of course, goes back to Batman. Suppose the fictional Commissioner Gordon believes that important evidence is in a person’s home or that only the bad guys know about it. But instead of requesting a search warrant or inviting the bad guy for questioning, he lights up the Bat-signal – perhaps anticipating that Batman might use physical force to extract evidence. Under what circumstances would the state constitution hold the commissioner accountable for Batman’s methods?

The state constitutional question of whether state actors are legally responsible for the actions of those they choose to cooperate with should not depend on whether you think Batman’s (or ICE’s) heart is in the right (or wrong) place. The answer may be found in the principles of state conduct. Applying this principle, courts have held that the acts of a third party are attributable to the state if there is a close relationship between the state and the third party.

For example, the California Supreme Court concluded that constitutional protection extends to illegal searches by civilians participating in police operations if the police officer “stood silently by” while the illegal searches were taking place. Similarly, the New Mexico Supreme Court held that state courts should exclude evidence collected by private security guards if they “routinely exceeded the bounds of a reasonable investigation” and “the officers knowingly condoned or participated in the conduct…or did not discourage it.”

Although these “attribution” cases typically involve third-party private actors, the logic applies more strongly when state and local officials are involved with third parties who are federal employees. Federal agents are government subjects, and state constitutions require that, at a minimum, they protect the rights of their citizens from government encroachment. In fact, some state courts interpret state constitutions to broadly protect rights, regardless of the status of those who violate them.

States also have strong incentives to ensure that state and local police officers do not negligently or intentionally collaborate with federal agents to engage in activities that harm their residents. For example, even in the absence of any wrongdoing by state officials, the New Mexico Supreme Court applied the exclusionary rule to evidence seized by federal agents in violation of the New Mexico Constitution. The court reasoned that the court “has the power, and indeed the duty, to insulate the court from evidence seized in violation of the state constitution.” Superior courts in Oregon and Washington have adopted similar rules. These decisions suggest that, for purposes of the state action doctrine, in determining when to refer federal actions to state and local officials, state courts should be wary of any conduct by state and local officials that risks encouraging anyone to violate the state constitution.

State officials should be on guard as well. When ICE and Customs and Border Protection act with clear disregard for the rights of state residents, the intertwining of local police and federal immigration enforcement poses a risk that goes beyond undermining trust with local communities. It could also effectively erode state constitutional guarantees. Therefore, not only do state and local officials have the option to support federal immigration enforcement under the U.S. Constitution, but they should also consider the possibility that their own constitutions may force them to decline assistance.

Matthew Segal is co-director of the American Civil Liberties Union’s (ACLU) State Supreme Court Initiative.

Liana Wang is a student at Harvard Law School.

Recommended Citation: Matthew Segal & Liana Wang, State constitution could bar state and local police from cooperating with ICESᴛᴀᴛᴇ Cᴏᴜʀᴛ Rᴇᴘᴏʀᴛ (March 11, 2026), https://statecourtreport.org/our-work/analysis-opinion/state-constitutions-could-bar-state-and-local-police-collaboration-ice