Yes. In many circumstances, state and local police can decline to participate in federal immigration enforcement, even though Immigration and Customs Enforcement (ICE) has authority to enforce federal immigration law. The US Constitution’s anti-commandeering doctrine generally prevents the federal government from forcing state and local governments to administer or enforce a federal regulatory programme. That principle does not, however, give local officials permission to obstruct lawful federal operations or disregard independently applicable legal obligations.
The key distinction is between refusing voluntary assistance and violating a legal duty. Local police may generally decline to hold someone beyond an otherwise lawful release time solely because ICE requests it, unless a separate legal basis authorises the continued detention. But state and local agencies must still comply with applicable laws, valid court orders and their own binding legal obligations. Whether a particular policy is lawful depends on what it requires, the jurisdiction involved and the specific circumstances.
Why Federal Authority Does Not Automatically Control Local Police
Immigration enforcement is primarily a federal responsibility. ICE investigates immigration violations, arrests people under its statutory authority, manages detention and carries out removals under federal law.
Local police, meanwhile, are generally responsible for enforcing state and local criminal laws, responding to emergencies and maintaining public safety. They may cooperate with federal agencies, but their ordinary law-enforcement responsibilities do not automatically make them federal immigration officers.
The constitutional boundary is known as the anti-commandeering doctrine. Under decisions including New York v. United States (1992), Printz v. United States (1997) and Murphy v. NCAA (2018), Congress generally cannot directly command state governments or their officers to administer a federal regulatory programme.
This principle protects the division of authority between federal and state governments. It also preserves political accountability: the federal government must take responsibility for administering federal programmes rather than automatically transferring the work and costs to local authorities.
The doctrine does not mean federal law is optional. Federal law remains supreme within its constitutional scope, and local officials cannot use state or city policies to invalidate lawful federal authority. The distinction is between requiring local officers to enforce federal law and preventing them from violating valid federal law themselves.
What Local Police Must Do—and What They Can Decline to Do
The legal position becomes clearer when different forms of cooperation are considered separately. A request from ICE, a formal agreement to perform immigration duties and a binding legal obligation are not interchangeable.
| Type of cooperation | General legal position | What determines the outcome |
|---|---|---|
| Enforcing federal civil immigration law | Local officers generally cannot be compelled by the federal government to administer a federal enforcement programme | Constitutional limits, state law and any applicable agreement |
| Honouring an ICE detainer | Generally a request, not a command requiring a local jail to extend custody | State law, local policy, independent legal authority and constitutional detention requirements |
| Sharing immigration-status information | Subject to specific federal statutes and applicable state and local rules | The information requested, the relevant law and controlling court decisions |
| Participating in a formal 287(g) programme | Participation is voluntary under federal law | State law may require or prohibit local participation, and the agreement defines delegated duties |
| Obstructing a lawful federal operation | Local officials cannot assume they are free to obstruct federal officers | Applicable criminal law, constitutional protections and the specific conduct involved |
The table describes general principles, not a substitute for checking the law in a particular state. The Congressional Research Service’s September 2025 legal overview and the Brennan Center for Justice’s August 2026 analysis explain the distinction between voluntary assistance and mandatory legal duties.
ICE detainers: Requests to extend custody
An ICE detainer generally asks a state or local law-enforcement agency to notify federal authorities before releasing someone and, where requested, to maintain custody for up to 48 hours beyond the time the person would otherwise be released.
ICE describes detainers as requests. They do not independently require a local jail to hold someone, and compliance can raise Fourth Amendment concerns if it results in detention without adequate legal authority.
Consider a person who has completed a sentence and is otherwise entitled to release. If ICE asks a local jail to keep that person for additional time, the jail must consider the applicable state law and whether an independent legal basis authorises continued detention. An immigration detainer alone should not automatically be treated as equivalent to a judicial arrest warrant.
Some states restrict compliance with detainers, while others require or permit cooperation in specified circumstances. As a result, the answer may differ even between neighbouring jurisdictions.
Section 1373: What federal law says about information sharing
Section 1373 of Title 8 of the US Code addresses restrictions on government policies concerning the exchange of information about immigration or citizenship status with federal immigration authorities.
The statute is narrower than a general requirement to cooperate with ICE. It does not, by itself, require local police to investigate immigration violations, participate in arrests or maintain custody solely at ICE’s request. Its constitutional status and application have also been disputed in litigation.
It is therefore important to distinguish a restriction on government policies limiting certain information exchanges from an affirmative obligation to provide every type of information or assistance requested by federal authorities.
A local government considering an information-sharing policy should obtain advice on the exact statutory language, applicable state law and relevant court rulings rather than assume that either unrestricted sharing or a complete prohibition is legally required.
What Is a 287(g) Agreement?
Section 287(g) of the Immigration and Nationality Act, codified at 8 U.S.C. § 1357(g), allows the federal government to enter into written agreements with state or local governments under which designated officers may perform specified immigration-enforcement functions.
Under these agreements, participating officers receive authorisation and training to carry out designated duties. The extent of their authority depends on the agreement and the programme model.
The distinction is important: local police do not automatically acquire federal immigration-enforcement powers simply because they are police officers. Their authority to carry out delegated immigration functions must come from an applicable legal framework and, where required, a formal agreement.
Federal law expressly provides that a state or local government is not required to enter into a 287(g) agreement. However, a state may have its own legislation requiring local agencies to participate, while other states restrict or prohibit participation. Whether such a state requirement applies to a particular local agency is a separate question.
Participation can also change the practical relationship between local policing and immigration enforcement. Officers may take on additional immigration-related duties, while local governments must consider training, supervision, resources, liability and the effects on their other responsibilities.
Can the Federal Government Punish Sanctuary Jurisdictions?
Federal officials have pursued several approaches to encourage greater local cooperation, including litigation, executive directives and efforts to restrict funding.
In August 2025, the Department of Justice published a list of jurisdictions it identified as having policies that impeded federal immigration enforcement. The administration argued that those policies conflicted with federal law. Such designations represent the federal government’s position; they do not, by themselves, establish that every policy adopted by a listed jurisdiction is unlawful.
The constitutional dispute centres on two principles that must be considered together:
- Federal supremacy: Valid federal law takes precedence over conflicting state or local law within the scope of federal authority.
- Anti-commandeering: The federal government generally cannot force state and local governments to administer federal regulatory programmes.
Funding disputes introduce another layer. Congress may attach lawful conditions to federal grants, but the federal government cannot necessarily withhold funding simply because a jurisdiction declines to provide assistance it has no legal duty to provide. The validity of a particular funding condition depends on the statutory authority, the terms of the grant and constitutional restrictions.
Courts have reached different conclusions in some disputes involving immigration-related information sharing, funding and state restrictions. The status of litigation can change, so a claim that a particular city is violating federal law should be checked against the relevant statute and the latest court orders.
Why Local Cooperation Matters for Public Safety
The policy debate is not solely about whether local police support federal immigration enforcement. It also concerns how local departments allocate resources and maintain relationships with the communities they serve.
Supporters of cooperation argue that information sharing and coordinated custody transfers can help federal authorities identify people subject to removal and reduce the need for separate arrests in the community.
Critics argue that extensive involvement in civil immigration enforcement can divert local officers from criminal investigations, discourage victims and witnesses from reporting crimes, and weaken trust between police and immigrant communities.
Both the legal framework and the practical consequences matter. A local department may choose to assist ICE in some circumstances while declining to carry out other functions. For example, it may respond to a violent crime involving an immigrant, cooperate with a criminal investigation and still decline to extend someone’s detention solely on the basis of an immigration detainer.
That distinction helps explain why sanctuary policies do not necessarily mean that a city refuses all cooperation with federal authorities. Policies vary in their treatment of criminal investigations, immigration-status information, detention requests and formal enforcement agreements. The term sanctuary jurisdiction has no single, universally accepted legal definition.
What Residents Should Check in Their Own State
For anyone seeking to understand what local police can or must do in a particular city, four sources are especially useful:
- State law: Check whether the state requires, permits or restricts local participation in immigration enforcement.
- Local policy: Review police department rules on information sharing, detainers, jail transfers and cooperation with ICE.
- Federal agreements: Determine whether the agency participates in a 287(g) programme or another formal arrangement.
- Current court decisions: Check whether a relevant policy has been challenged, blocked, upheld or modified by a court.
A mayor’s public statement or a police chief’s announcement may describe policy, but neither necessarily answers every legal question. The precise wording of the governing law and the authority under which officers act are what matter.
The Constitutional Boundary Between Cooperation and Compulsion
The central legal question is not whether local police agree with federal immigration policy. It is whether the federal government is asking for voluntary assistance, invoking a valid legal obligation or attempting to compel state and local officials to administer federal law.
Under the anti-commandeering doctrine, local police generally cannot be forced by the federal government to become its immigration-enforcement workforce. Yet local governments cannot use that principle as a blanket exemption from valid federal law, and their own state laws may impose obligations that federal law alone would not.
For residents, the most useful distinction is between a refusal to provide voluntary assistance and an act that independently violates the law. Understanding that difference makes it easier to evaluate claims about sanctuary policies, ICE detainers and local police cooperation without assuming that either federal demands or local refusals are automatically lawful.