State Constitutions Could Bar State and Local Police Collaboration with ICE 

Suppose your local police department decided to collaborate with a masked man who, under the guise of catching criminals, was routinely grabbing people off the street and beating them. Would state law impose any limits on local law enforcement’s arrangement with this vigilante?

No, not Batman. An ICE agent.

In cities and states nationwide, the Trump administration has deployed thousands of federal officers, including agents from Immigration and Customs Enforcement (ICE) and Customs and Border Protection. Whatever the purported benefits of this enforcement surge, its toll has been alarming. In Minneapolis, federal agents shot and killed Renee Good and Alex Pretti. In Chicago, agents brutalized protesters, journalists, and bystanders alike, including local officials and religious leaders. Across the country, people caught in the immigration crackdown have been killed by federal officers or died in federal custody. 

But the federal enforcement surge is only half the picture. Both ICE and federal border patrol rely on collaboration with state and local law enforcement to detain immigrants, share data and resources, and control protests. In Tennessee, for example, state highway patrol officers reportedly conducted pretextual, racially discriminatory traffic stops with ICE agents riding shotgun. In Massachusetts, local officers have 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 collaboration, state and local police have nevertheless shared information with ICE, resulting in the detention and deportation of residents. In addition, over the past year, municipalities have signed record numbers of agreements under the 287(g) program, which creates formal partnerships between state and local police departments and ICE.

President Donald Trump has suggested, incorrectly, that states are duty-bound to provide this kind of assistance to federal immigration authorities. He has denounced sanctuary jurisdictions as “lawless.” He has issued multiple executive orders seeking to punish these sanctuary cities and states. And the Department of Justice has launched a series of lawsuits against cities and states for refusing to assist federal immigration officers.

Trump is wrong. The 10th Amendment gives states the authority to refuse to participate in federal programs, including immigration enforcement. Just as many states have chosen not to assist in enforcement of the federal prohibition on marijuana possession — indeed, many have expressly decriminalized marijuana possession under state law — they can choose not to assist the federal government in enforcing federal immigration law. Some states or municipalities have done precisely that.

But the abhorrent behavior of federal immigration agents in recent months, combined with the federal government’s apparent determination to continue that behavior, raises an additional possibility: While the U.S. Constitution permits states and cities to opt out of assisting federal officers with immigration enforcement, state constitutions may actually compel that opt-out.

State constitutions can go beyond the U.S. Constitution in protecting individual rights. For example, suppose an officer pulls over a vehicle because he suspects the passengers are undocumented immigrants, but claims the reason for the stop is a broken taillight. Even if that pretextual stop is permissible under the U.S. Constitution’s Fourth Amendment, the officer’s actions might still violate a state constitutional right against unreasonable searches and seizures. Similarly, making a stop partly based on a suspect’s language, race, ethnicity, or occupation — what law professor Anil Kalhan termed a “Kavanaugh stop,” in reference to Justice Brett Kavanaugh’s concurring opinion in Noem v. Vasquez Perdomo — could violate a state’s equal protection guarantee even if federal courts deem it to pass muster under the U.S. Constitution.

Federal agents are unlikely to worry about the heightened protections of state constitutional law. By virtue of the U.S. Constitution’s Supremacy Clause, those agents typically don’t have to follow the constitutions for the states in which they operate. (Heck, these days it feels like they scarcely worry about the U.S. Constitution.)

State and local officers don’t have that luxury. State constitutions fully bind those officers, including when exercising state law enforcement authority to assist federal immigration agents. At a minimum, state and local officers must not directly undertake conduct that violates the state constitution. But shouldn’t they also avoid facilitating such conduct by federal agents?

That question brings us, naturally, back to Batman. Suppose the fictional Commissioner Gordon thinks vital evidence is inside a private home or is known only to a bad guy. But instead of seeking a search warrant, or inviting the bad guy for questioning, he lights up the Bat Signal — perhaps anticipating Batman might use physical force to extract the evidence. Under what circumstances would the state constitution hold the commissioner responsible for Batman’s methods?

That state constitutional question — that is, whether state actors are legally responsible for the actions of someone with whom they’ve chosen to collaborate — shouldn’t hinge on whether you think Batman’s heart (or ICE’s) is in the right (or wrong) place. The answer might be found in the state action doctrine. Applying that doctrine, courts have attributed third-party conduct to the state when there is a close nexus between the state and the third party.

For example, the California Supreme Court has concluded that constitutional protections extend to illegal searches by private citizens who participated in a police operation, if police officers “stood silently by” while the illegal search took place. Similarly, the New Mexico Supreme Court has held that state courts should exclude evidence gathered by private security guards if those guards “routinely exceeded” the bounds of a reasonable search, and “police officers knew of that practice and condoned or participated . . . or even failed to discourage it.”

Although these “attribution” cases typically involved third-party private actors, their logic applies more forcefully when state and local officers associate with third parties who are federal agents. Federal agents are government actors, and state constitutions seek, at a minimum, to protect their residents’ rights against government infringement. Indeed, some state courts have interpreted state constitutions to protect rights broadly without regard to the status of the person violating those rights.

States also have strong incentives to ensure state and local police officers do not negligently, or even willfully, undertake joint activities with federal officers that harm their own residents. Even in the absence of wrongdoing by state officials, for example, the New Mexico Supreme Court has applied the exclusionary rule to evidence seized by a federal agent who violated the New Mexico Constitution. The court reasoned that it had “the authority — and indeed the duty — to insulate our courts from evidence seized in contravention of our state’s constitution.” High courts in Oregon and Washington have adopted similar rules. These decisions suggest that, in deciding when to attribute federal action to state and local officers for purposes of the state action doctrine, state courts should be wary of any conduct by state and local officials that risks facilitating behavior — by anyone — that contravenes the state constitution.

State officials should be just as wary. If ICE and Customs and Border Protection act without apparent regard for the rights of state residents, local police entanglement with federal immigration enforcement risks more than the erosion of trust with local communities. It may also, in effect, erode the guarantees of their state constitutions. State and local officials should therefore consider the possibility that not only does the U.S. Constitution give them a choice about whether to assist federal immigration enforcement, their own state constitutions might compel them to decline.

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

Liana Wang is a student at Harvard Law School.

Suggested Citation: Matthew Segal & Liana Wang, State Constitutions Could Bar State and Local Police Collaboration with ICE, Sᴛᴀᴛᴇ Cᴏᴜʀᴛ Rᴇᴘᴏʀᴛ (Mar. 11, 2026), https://statecourtreport.org/our-work/analysis-opinion/state-constitutions-could-bar-state-and-local-police-collaboration-ice