Polls show a majority of Americans disapprove of how Immigration and Customs Enforcement (ICE) is doing its job, with outrage stoked by a surge in immigration arrests across the country and multiple killings by federal immigration officials. In many places, residents are against their state and local officials cooperating with immigration authorities. And many local law enforcement leaders argue that cooperating with federal immigration enforcement operations undermines public safety by taking resources away from local priorities and eroding communities’ trust in law enforcement.
Trump administration officials have repeatedly argued that states and localities are legally obligated to cooperate with federal immigration enforcement efforts. They have also warned that state and local laws limiting cooperation with ICE will be met with harsh crackdowns.
But by and large, states and localities have the authority to decide whether and how their officials cooperate with federal immigration enforcement. The legal questions around these decisions are explored below.
Does federal law require states and localities to cooperate with ICE?
No federal law requires states and localities to cooperate with ICE. Instead, state law often governs the extent of cooperation.
But where state law is silent, state and local officials have discretion to manage law enforcement operations to meet their communities’ needs. That means they may decide whether to collect information about immigration status; how much information, if any, to share with ICE; and whether to comply with ICE requests to hold detained people until federal agents can transfer them into federal custody. Any jurisdictions that wish to cooperate can enter into agreements authorizing their officers to carry out all manner of immigration enforcement activities.
Can the federal government force states and localities to adopt immigration cooperation policies?
No. In our federal system, federal and state governments each have independent sources of authority and their own power to make and enforce laws within their spheres. The Constitution’s Supremacy Clause says that valid federal law is supreme over conflicting state law. But the federal government’s power is limited: The 10th Amendment confirms that the states (and the people) hold all powers the Constitution does not explicitly grant to the federal government. This reservation of power has been interpreted as banning federal “commandeering” of state policymaking. In other words, the federal government “can’t tell a state what its policy on a particular topic will be,” Georgetown University Law Professor Steve Vladeck has explained. It also “can’t require local or state law enforcement officers to enforce federal law.”
This means that, like everyone else, state and local officials may not violate federal law, and there are some general federal laws that may be applied to state and local actions in the immigration context. For example, federal law prohibits obstructing federal proceedings. A Wisconsin judge was recently convicted of obstruction after instructing the target of an ICE search to exit through a restricted courthouse door. But no federal law requires state or local cooperation with ICE or other federal officials. Any such law would almost certainly violate the 10th Amendment.
One immigration-specific federal law purports to govern state and local policymaking: Section 1373 of Title 8 of the U.S. Code prohibits states and localities from enacting laws that limit their employees from sharing immigration status with the Department of Homeland Security (DHS), which houses ICE. But Section 1373’s scope is very narrow; its restriction on laws that would limit sharing one type of information imposes no requirement that states or localities share information or otherwise cooperate with immigration enforcement.
How have courts ruled in disputes over local cooperation with federal immigration enforcement?
Long cited by conservatives in support of arguments to limit the power of the federal government, the U.S. Supreme Court has relied on the 10th Amendment to strike down federal environmental and gun control laws. The U.S. Supreme Court has yet to definitely decide how the 10th Amendment applies in the debate over state and local cooperation with federal immigration enforcement.
Several federal lower courts have held that Section 1373, the statute barring state and local laws that limit sharing immigration statuses with ICE, violates the 10th Amendment. Section 1373 “regulate[s] state and local governmental entities and officials, which is fatal to [its] constitutionality,” a federal judge in Pennsylvania said in 2018.
While the constitutionality of Section 1373 has not definitively been resolved, almost all federal appellate courts agree on one point: The federal government may not condition federal funds on compliance with Section 1373. President Trump’s executive order doing just that during his first administration was struck down by four of the five circuit courts that considered the issue. The administration lacked the statutory authority to impose immigration-related conditions on the grants in question, the courts said. Only the U.S. Court of Appeals for the Second Circuit read the grant-making statute to authorize that constraint.
The federal government has also filed numerous lawsuits challenging state and local laws limiting cooperation with federal immigration enforcement. These cases are ongoing, but most initial rulings have sided with the state and local governments invoking the 10th Amendment to justify their policies. Last month, a federal judge rejected the administration’s challenge to Minnesota’s “sanctuary” policies, confirming that “refusing to help” ICE is a state’s prerogative.
States and localities are also making claims under the 10th Amendment in affirmative litigation challenging federal immigration enforcement measures. After ICE agents in Minneapolis killed Renee Good and Alexander Pretti and gravely injured Alberto Castañeda Mondragón, Minnesota and the cities of Minneapolis and St. Paul filed a lawsuit arguing that the administration’s enforcement surge was an attempt to coerce them into adopting federal policy priorities that would commandeer state and local law enforcement resources. Citing the unprecedented nature of the claims raised in the case, a federal judge declined to temporarily block the ICE deployment, though she emphasized that her order did not signal the federal government would ultimately prevail in that lawsuit.
How much information must states and localities share with ICE?
Beyond Section 1373’s narrow limitation, states and localities have considerable flexibility to formulate their own policies around law enforcement cooperation with ICE, including information collecting and sharing. Some jurisdictions, such as Oregon and Illinois, have adopted laws that prevent law enforcement agencies from asking about or collecting information about immigration status. Supporters say the laws build community trust necessary for public safety and allow local police to use their resources to stop violent crime rather than to enforce federal immigration law.
States and localities can also decide when and whether to share information with federal agencies. As a general practice, local police routinely share basic information with the federal government when anyone, regardless of citizenship status, is arrested, even though they are not legally required to do so. This information can be accessed by DHS for use in immigration enforcement.
This information-sharing practice began after the September 11 attacks through Secure Communities, a program devised to prioritize the removal of individuals already in the custody of criminal law enforcement agencies. While the program no longer exists by that name, the basic structure remains: State and local law enforcement agencies, which lack comprehensive biometric databases, send fingerprints to the FBI, which checks them against its extensive Next Generation Information system for identity and criminal history.
In a process that does not involve localities, the FBI passes those fingerprints and additional identifying information to DHS. The FBI-to-DHS system, known as interoperability, provides ICE with a wealth of information about immigrants — including dates and places of birth, photographs, and immigration status — even in so-called sanctuary jurisdictions. Other federal–state cooperation structures, like fusion centers, have also given DHS access to troves of state and local law enforcement data.
Are states and localities required to comply with ICE requests related to people in their custody?
No. States and localities have broad latitude to decide whether to comply with requests from ICE to notify the agency before releasing someone from state or local custody or to hold the person for up to two additional days so that federal officials can take custody. These requests are known as immigration detainers. Historically, most people detained by ICE have been taken directly from local jails, often through the use of immigration detainers. But prison or jail officials who decline to honor detainer requests have not violated federal law.
Federal and state courts have repeatedly ruled that local law enforcement need not follow detainer requests absent a state law requiring them to do so. For example, in Galarza v. Szalczyk, the U.S. Court of Appeals for the Third Circuit held that “immigration detainers do not and cannot compel a state or local law enforcement agency to detain suspected aliens subject to removal.” This conclusion, the court said, was based on “settled constitutional law,” including the 10th Amendment’s anticommandeering principles. “Essentially, the federal government cannot command the government agencies of the states to imprison persons of interest to federal officials,” the court explained.
Immigration detainers also raise concerns under the Fourth Amendment, which guarantees “the right of the people to be secure in their persons, houses, papers, and effects, against unreasonable searches and seizures.” Holding people in custody beyond the terms of their sentences amounts to a new seizure, which generally requires a warrant based on probable cause, issued by a neutral adjudicator. In 2013, U.S. citizen Gerardo Gonzalez, representing a class of individuals subject to immigration detainers, sued ICE for Fourth Amendment violations after he was held by the Los Angeles Sheriff’s Department pursuant to an immigration detainer issued on the faulty premise that he had entered the country illegally. In 2024, DHS agreed to a settlement requiring a neutral probable cause review for all detainers, performed by federal personnel “housed within DHS,” “with a strong preference” that reviewers have relevant legal experience, “preferably as an immigration judge, appellate immigration judge, or administrative law judge.”
Still, due in part to continued concerns over the constitutionality of the practice, some states — including California, Colorado, Connecticut, Illinois, and Oregon — have adopted laws forbidding unconditional compliance with ICE detainers. State courts in Massachusetts and New York, meanwhile, have barred local law enforcement from complying with detainers, interpreting state law to prohibit such cooperation. Many of these statutes include exceptions for individuals convicted of serious or violent crimes. California, for example, bars keeping immigrants in custody beyond the term of their sentence on a civil detainer request from ICE, but it requires corrections facilities to work with DHS to transfer custody of undocumented immigrants convicted of felonies. Indeed, a recent New York Times analysis found that even states that have bans on cooperation with ICE regularly turn over people convicted of serious crimes to the agency.
On the other hand, some states — including Arkansas, Florida, Georgia, Louisiana, North Carolina, Tennessee, and Texas — have enacted laws requiring local law enforcement to comply with ICE detainer requests. Where state law does not explicitly speak to compliance with immigration detainers, local jurisdictions may decide whether they will cooperate.
What is a 287(g) agreement?
State and local governments can decide to enter into 287(g) agreements — named for the section of the federal immigration law that authorizes them — to delegate various immigration enforcement duties to state and local officials. Federal law is clear, however, that no state or local jurisdiction is required to enter such an agreement.
Some states, including Georgia and Tennessee, have passed laws requiring localities to enter into 287(g) agreements. Other states, such as Illinois and New York, have passed laws forbidding them. Where state law is silent, the decision about whether to enter into a 287(g) agreement rests with local officials.
There are three kinds of 287(g) agreements, categorized based on the level of support a locality provides. The warrant service officer model provides the lowest level of support, giving local police only the authority to issue administrative warrants to noncitizens while they are still in local jails, eliminating the need for DHS to issue detainers. The jail enforcement model authorizes state and local police to perform the full range of immigration enforcement actions, such as interrogating people to determine their immigration status or facilitating their transfer to ICE custody, but only while they are working in their local jails. Finally, nearly 60 percent of 287(g) agreements follow the task force model, fully deputizing local law enforcement to take on all federal immigration officers’ duties, including making arrests, conducting warrantless searches in public places, and issuing detainers.
In 2025, Congress authorized unprecedented reimbursements to local law enforcement agencies that enter task force model 287(g) agreements. Not only does the federal government pay the salaries, benefits, and overtime of state and local 287(g) officers; it also promises “quarterly monetary performance awards” to locate undocumented immigrants, although the exact bases for the bonuses are not specified. Florida’s highway patrol, for example, received $13.6 million last year.
Empirical evidence suggests that these incentives lead to increased racial profiling and civil rights violations. A recent ACLU report described hundreds of incidents of local officers pulling over and arresting people they thought were undocumented, apparently based on appearance, many of which were likely efforts to fulfill the terms of their 287(g) agreements. In May 2025, for example, Florida highway patrol and federal border patrol agents stopped a car carrying people who appeared Latino, and a video shows the officers dragging a passenger by the neck, tasing him, arresting a teenage citizen, and laughing about a $30,000 bonus, presumably referring to federal incentives.
The incentives have also increased the number of 287(g) agreements in place across the country: There are now 2,315, up from 45 in 2019 during Trump’s first term. Each 287(g) agreement adds personnel to supplement ICE’s roughly 20,000 officials, making the program a significant force multiplier for the agency. Even so, with more than 17,000 local law enforcement agencies in the country, the vast majority of jurisdictions have not entered into one.
Kathrina Szymborski Wolfkot is the managing editor of State Court Report and a senior counsel and manager in the Judiciary Program at the Brennan Center for Justice.
Margy O’Herron is a senior fellow in the Brennan Center’s Liberty and National Security Program.
Samson Tu is a student at NYU Law School. He previously participated in the Brennan Center’s Public Policy Advocacy Clinic.
