Sanctuary and Anti-Sanctuary Laws: Federalism, Immigration Enforcement, and State Authority
Last updated on September 14, 2026
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Sanctuary and Anti-Sanctuary Laws: Federalism, Immigration Enforcement, and State Authority
Immigration enforcement in the United States is primarily a federal responsibility, but state and local governments regularly interact with federal immigration authorities. This relationship has produced one of the most important federalism debates in modern immigration law: sanctuary policies versus anti-sanctuary laws.
The terms are frequently used in political debate, but they do not describe one uniform legal system.
A so-called sanctuary jurisdiction generally refers to a state, county, or municipality that limits the circumstances in which its officials will cooperate with federal immigration enforcement. Depending on the jurisdiction, such policies may restrict the use of local resources for immigration enforcement, limit responses to federal requests concerning detained individuals, restrict access to local databases, or establish rules governing when local officers may communicate or cooperate with federal immigration authorities.
An anti-sanctuary law, by contrast, generally seeks to require or encourage state and local officials to cooperate with federal immigration enforcement or prohibits local governments from adopting policies that restrict such cooperation.
The constitutional question is not simply whether a jurisdiction supports or opposes federal immigration enforcement. The deeper question is how federal supremacy, state police powers, federal preemption, and the Tenth Amendment interact when state and local governments encounter federal immigration law.
The Supreme Court has repeatedly recognized the federal government’s dominant role in regulating immigration. At the same time, federal law does not automatically transform every state or local official into a federal immigration officer. The constitutional limits on federal commandeering of state officials are therefore an essential part of the analysis.
What Is a Sanctuary Jurisdiction?
“Sanctuary jurisdiction” is not a single legal classification with one universally applicable definition.
The term is generally used to describe a state or local government that has adopted laws, ordinances, policies, or practices limiting its cooperation with federal immigration enforcement.
The policies can take many forms.
A jurisdiction might, for example:
- limit when local officers may ask about immigration status;
- restrict the use of local personnel or resources for federal immigration enforcement;
- limit detention of a person beyond the period authorized by state or local law solely because federal immigration authorities have requested additional detention;
- establish procedures for responding to federal immigration requests;
- restrict participation in federal immigration-enforcement activities;
- protect access to local governmental services without regard to immigration status; or
- establish rules governing the transfer of individuals from local custody to federal immigration authorities.
These policies are not necessarily equivalent.
A city that prohibits its police officers from independently enforcing federal immigration law is legally different from a city that refuses to provide information that federal law expressly requires it to provide.
Consequently, the word sanctuary should not be treated as a substitute for examining the actual text of the state statute, municipal ordinance, executive order, or departmental policy.
Why Do Sanctuary Policies Exist?
Sanctuary policies have developed for several different reasons.
One recurring argument is that local police departments depend upon cooperation and trust between law enforcement and the communities they police. If residents fear that reporting a crime or cooperating with an investigation could expose themselves or family members to immigration enforcement, local authorities may be concerned that victims and witnesses will become less willing to contact the police.
Some jurisdictions therefore distinguish between local public-safety responsibilities and federal immigration enforcement.
Under such an approach, local police may investigate crimes, arrest individuals under state law, and cooperate with federal authorities where state law permits it, while declining to perform certain immigration-enforcement functions on behalf of the federal government.
Other jurisdictions take the opposite view. They argue that local governments should cooperate fully with federal immigration authorities because immigration violations affect public safety, border enforcement, detention, and the administration of federal law.
The resulting dispute is therefore partly a question of policy, but it also raises important constitutional questions about which government has authority to require whom to do what.
Federal Immigration Power
The starting point for understanding sanctuary laws is the federal government’s constitutional authority over immigration.
Congress possesses broad authority over naturalization and immigration-related matters, while the federal executive branch administers and enforces federal immigration laws through agencies including the Department of Homeland Security and the Department of Justice.
The Supreme Court’s decision in Arizona v. United States is one of the most important cases in this area.
Arizona had enacted S.B. 1070, a state law addressing unlawful immigration. The Supreme Court held that several provisions were preempted by federal law because they conflicted with the federal government’s authority and regulatory framework. The Court emphasized the federal government’s significant power over immigration and concluded that states cannot establish immigration policies that undermine federal law.
The decision does not mean that states have no authority whatsoever when immigration is involved.
States retain substantial authority over matters within their traditional police powers, including ordinary criminal law, public safety, licensing, employment regulation in areas not preempted by federal law, and administration of state and local government.
The difficulty arises when a state or local law attempts to regulate immigration itself or conflicts with federal immigration policy.
That is where federal preemption becomes central.
Federal Preemption and Sanctuary Laws
The Supremacy Clause establishes that valid federal law takes priority over conflicting state law.
In immigration cases, federal preemption can arise when:
- Congress expressly preempts state regulation;
- federal regulation occupies a field so extensively that state regulation is displaced; or
- state law conflicts with federal law or makes it impossible to accomplish federal objectives.
Arizona v. United States illustrates the importance of conflict and field preemption in immigration regulation. The Supreme Court concluded that several provisions of Arizona’s law could not operate alongside the federal immigration system.
But preemption analysis does not automatically answer every sanctuary-law dispute.
A sanctuary policy that merely determines how a state or local government allocates its own law-enforcement resources may raise different questions from a law that directly prohibits conduct federal law expressly requires.
The actual statutory language therefore matters.
The Anti-Commandeering Principle
The other side of the constitutional equation is the anti-commandeering doctrine.
The federal government generally cannot simply order state governments to enact or administer a federal regulatory program.
The Supreme Court established important principles in New York v. United States and Printz v. United States, and later reinforced them in Murphy v. NCAA.
The basic principle is that the federal government cannot command state legislatures or state executive officers to administer a federal regulatory program merely because Congress wants state officials to do so. Cornell’s U.S. Constitution Annotated describes this as the modern anti-commandeering doctrine arising from the Tenth Amendment and federalism principles.
Murphy v. NCAA is particularly important because the Supreme Court explained that the federal government cannot evade this principle simply by telling states that they may not enact or maintain certain state laws.
This doctrine creates an important limitation on the idea that the federal government can simply require every state and municipality to participate in immigration enforcement.
Federal immigration law may be supreme, but federal supremacy and federal commandeering are not the same thing.
Does Federal Immigration Law Require Local Police to Enforce Immigration Law?
Generally, federal immigration enforcement authority does not mean that every state or local police officer must become a federal immigration-enforcement officer.
The federal government has its own immigration enforcement agencies and personnel.
Congress can, however, create statutory rules affecting state and local governments. The constitutional question may then become whether a particular federal requirement validly regulates state activity, preempts conflicting state law, or impermissibly commandeers state officials.
This distinction is essential.
A state government may be unable to prohibit federal immigration officers from carrying out federal functions simply because the state disagrees with federal immigration policy.
But that does not automatically mean the federal government can require state police officers to perform every federal immigration task.
The Constitution draws a distinction between preempting conflicting state law and forcing state officials to administer federal law.
8 U.S.C. §1373 and Communication About Immigration Status
One federal statute frequently appears in sanctuary-jurisdiction disputes: 8 U.S.C. §1373.
Section 1373 addresses communication between federal, state, and local government entities concerning citizenship and immigration-status information.
The statute provides that state and local government entities generally may not prohibit or restrict government entities or officials from sending to or receiving from federal immigration authorities information concerning an individual’s citizenship or immigration status.
The statutory language is important because it concerns information sharing.
It should not automatically be read as requiring every local police department to perform federal immigration enforcement.
The distinction between:
- communicating information,
- responding to federal requests,
- holding a person in custody,
- transferring a person to federal authorities, and
- independently enforcing federal immigration law
is legally significant.
Each activity can involve different statutory and constitutional questions.
The full text of 8 U.S.C. §1373 is available through Cornell’s Legal Information Institute.
8 U.S.C. §1644
Another federal provision relevant to state and local immigration-related policies is 8 U.S.C. §1644.
Section 1644 similarly addresses restrictions on state and local governments communicating with federal immigration authorities concerning immigration status.
The provision states that state or local governments may not be prohibited or restricted from sending to or receiving from federal immigration authorities information regarding the immigration status of an alien.
Together, §§1373 and 1644 are important components of the federal statutory framework surrounding state and local communication with federal immigration authorities.
They do not, however, eliminate every federalism question surrounding sanctuary policies.
Sanctuary Policies and Federal Detainers
One of the most legally significant areas of disagreement concerns immigration detainers.
A federal immigration authority may request that a state or local law-enforcement agency maintain custody of an individual so that federal immigration authorities can take custody.
The legal question is not necessarily whether federal immigration authorities have immigration authority over the person.
The separate question is whether a state or local government may be required to continue holding that person under state or local authority solely because a federal immigration authority has requested additional detention.
This distinction has generated substantial litigation because state and local detention authority derives from state law, while federal immigration authority derives from federal law.
Some jurisdictions therefore restrict compliance with certain immigration detainers unless specified legal conditions are satisfied.
Others have adopted laws or policies requiring greater cooperation.
The constitutional and statutory analysis depends upon the precise wording of the federal request, the applicable state law, the circumstances of the detention, and the legal authority supporting continued custody.
Anti-Sanctuary Laws
An anti-sanctuary law generally attempts to prevent state or local governments from limiting cooperation with federal immigration enforcement.
These laws may:
- prohibit local governments from adopting sanctuary policies;
- require cooperation with federal immigration authorities;
- require local officials to honor certain federal requests;
- require information sharing;
- impose penalties on officials or governments that refuse to cooperate;
- authorize or require local officers to inquire into immigration status under specified circumstances; or
- condition certain state or local practices on cooperation with federal authorities.
The legal effect depends entirely upon the particular statute.
An anti-sanctuary law can itself raise constitutional questions if it attempts to regulate conduct outside the state’s authority or conflicts with federal law.
At the same time, a state generally has considerable authority to determine how its own governmental institutions operate.
Thus, an anti-sanctuary law may sometimes be understood not as the state “enforcing federal immigration law,” but as the state directing its own officials and agencies concerning the use of state resources.
That distinction can be decisive.
Texas and the Anti-Sanctuary Model
Texas provides an important example of state-level anti-sanctuary legislation.
Texas enacted legislation restricting local governmental policies that prohibit or discourage enforcement of immigration laws. Texas law also establishes requirements concerning cooperation and information relating to immigration enforcement.
The Texas Legislature’s statutory framework illustrates the difference between a state attempting to establish its own immigration offenses and a state regulating how its own local governments cooperate with federal immigration enforcement.
The latter was a central feature of Texas’s 2017 Senate Bill 4, which addressed local governmental policies concerning immigration enforcement and imposed duties on certain local officials. The legislation also addressed information sharing and cooperation with federal immigration officers.
Texas later enacted a separate and much broader 2023 S.B. 4 concerning state-created offenses for certain conduct involving unlawful entry or presence and mechanisms for state enforcement. That legislation raises a different set of federal-preemption questions from ordinary anti-sanctuary rules.
The distinction is important.
A law requiring a local police department to cooperate with federal authorities is not necessarily constitutionally equivalent to a law creating a new state criminal system for immigration violations.
The first primarily concerns intergovernmental cooperation; the second may directly implicate federal supremacy over immigration regulation.
California and the Sanctuary Model
California provides a prominent example of the opposite approach.
The California Values Act, commonly known as S.B. 54, establishes limits on the circumstances under which state and local law-enforcement agencies may participate in immigration enforcement.
The California Attorney General’s current guidance describes the law as establishing parameters for state and local law-enforcement agencies’ participation in immigration enforcement and imposing certain reporting requirements concerning interactions with federal immigration authorities.
The purpose and structure of such legislation are therefore quite different from Texas’s anti-sanctuary approach.
California does not purport to abolish federal immigration enforcement.
Rather, its laws regulate when and how California governmental agencies and officers may participate in immigration enforcement activities.
This distinction is central to understanding sanctuary federalism.
Sanctuary Does Not Mean Federal Immigration Law Does Not Apply
A common misunderstanding is that a sanctuary jurisdiction somehow becomes exempt from federal immigration law.
That is not what sanctuary policies generally do.
Federal immigration law continues to apply within sanctuary jurisdictions.
Federal agencies retain federal immigration authority.
A sanctuary policy generally concerns the conduct of the state or local government, not the validity of federal immigration law itself.
For example, a city may decide that its police officers will not use local resources to conduct immigration investigations except under specified circumstances. That does not make federal immigration law inapplicable within the city.
The federal government remains able to enforce federal immigration law through federal officers and agencies, subject to the Constitution, statutes, and judicial review.
Anti-Sanctuary Laws Do Not Eliminate Federalism
The opposite misunderstanding is equally important.
An anti-sanctuary law does not automatically give state or local officials unlimited authority to enforce federal immigration law.
States remain subject to the Supremacy Clause.
If a state law conflicts with valid federal immigration law, the federal law may preempt the state provision.
The Supreme Court’s decision in Arizona v. United States demonstrates the limits of state efforts to establish independent immigration-enforcement regimes. Several Arizona provisions were preempted because they interfered with the federal immigration system.
At the same time, the anti-commandeering doctrine limits the federal government’s ability to require state officials to administer federal programs.
The result is a constitutional structure in which neither side possesses unlimited authority.
The Difference Between Federal Preemption and Anti-Commandeering
These two doctrines are sometimes confused because they can appear to point in opposite directions.
Federal preemption
Federal preemption asks:
Can state or local law operate when it conflicts with federal law?
If federal law validly occupies the field or conflicts with state law, the state provision may be invalid.
Anti-commandeering
Anti-commandeering asks:
Can the federal government force state governments or their officers to administer a federal regulatory program?
Under the Supreme Court’s federalism cases, the answer is generally no when the federal government is directly commandeering state legislative or executive processes.
These principles can coexist.
A state may be prohibited from enacting a law that conflicts with federal immigration law while still being constitutionally protected from being forced to administer every aspect of the federal immigration system.
This is one of the most important concepts for understanding sanctuary-law disputes.
Can States Refuse to Cooperate With Federal Immigration Enforcement?
There is no single yes-or-no answer.
The answer depends on what type of cooperation is involved.
A state may have substantial authority over the use of its own personnel and resources. The anti-commandeering doctrine can limit the federal government’s ability to require state officials to administer federal programs.
But state and local governments remain subject to valid federal statutes.
For example, Congress has enacted specific provisions governing communication between state and federal authorities concerning immigration status. Sections 1373 and 1644 therefore have to be considered when evaluating policies restricting immigration-related information sharing.
Likewise, state governments cannot simply declare that federal immigration law is invalid within their borders.
The constitutional issue is therefore not whether a state “supports” or “opposes” federal immigration law.
It is whether the particular state or local action is:
- permitted by state law;
- consistent with federal statutes;
- preempted by federal law;
- protected by principles of federalism; or
- improperly requiring or prohibiting conduct that another level of government has constitutional authority to regulate.
The Role of Local Police
Local police departments occupy a particularly complicated position.
Their primary legal authority ordinarily comes from state and local law. Their officers may investigate state crimes, make arrests under state law, and perform other functions authorized by their jurisdiction.
Federal immigration officers, by contrast, operate under federal authority.
Cooperation between the two systems can be authorized in several ways, including agreements and other mechanisms established under federal immigration law.
But cooperation does not automatically transform a local officer into a federal immigration officer.
The distinction between cooperation and independent federal enforcement is therefore essential.
A local police department may cooperate with federal authorities in one context while declining to perform a particular federal immigration function in another.
That is why sanctuary policies must be analyzed provision by provision rather than through political labels.
Federal Funding and Sanctuary Jurisdictions
Federal funding has also become part of the sanctuary-jurisdiction debate.
The federal government may attempt to condition federal grants on compliance with federal requirements. But federal spending power is not unlimited.
The Supreme Court has recognized constitutional limits on conditions attached to federal funds, including concerns about coercion. The broader federalism framework discussed in cases such as NFIB v. Sebelius therefore matters when the federal government attempts to use funding as leverage over state policy.
The legality of a particular funding condition depends on the statute, the program involved, the precise condition imposed, and the constitutional basis for the federal government’s action.
It is therefore inaccurate to state categorically that the federal government may simply “defund” any jurisdiction that disagrees with federal immigration policy.
Congressional authorization, statutory authority, administrative law, and constitutional limitations all matter.
Federal Designations of Sanctuary Jurisdictions
The terminology surrounding sanctuary jurisdictions has also become part of federal executive policy.
In 2025, the U.S. Department of Justice published a list of jurisdictions it identified as sanctuary jurisdictions pursuant to Executive Order 14287. The Department stated that the designation was based on laws, policies, practices, or directives that it considered to materially impede enforcement of federal immigration laws.
Such a federal designation should not be confused with a new constitutional category of government.
The term remains descriptive of policies and practices identified by the federal government. The underlying laws and policies must still be evaluated under the Constitution, federal statutes, and applicable judicial decisions.
A federal executive determination that a jurisdiction is a “sanctuary jurisdiction” does not by itself resolve whether a particular state or local policy is legally valid.
That remains a question of law.
Sanctuary Policies and Individual Rights
Sanctuary-law debates also intersect with individual constitutional rights.
Immigration enforcement can involve searches, seizures, detention, due process, equal protection, privacy, and other constitutional concerns.
State and local officers cannot avoid constitutional restrictions simply because immigration is involved.
Likewise, federal immigration officers remain subject to constitutional and statutory limits.
The fact that an individual may be removable under federal immigration law does not mean that every governmental action taken against that person is automatically lawful.
The legality of an immigration enforcement action depends on the applicable federal statutes, constitutional protections, procedural requirements, and facts of the individual case.
Why Sanctuary Laws Are So Difficult to Analyze
Sanctuary disputes are difficult because several separate legal systems overlap.
Federal immigration law
Congress establishes the federal immigration framework, while federal agencies administer and enforce it.
State police powers
States retain broad authority over public safety, criminal law, licensing, and the operation of state government, subject to federal constitutional limitations.
Local government authority
Cities and counties exercise powers delegated to them by state law. Their authority can therefore vary substantially from state to state.
Federal preemption
State or local laws that conflict with federal immigration law may be invalid.
Anti-commandeering
The federal government generally cannot directly commandeer state legislatures or executive officials into administering a federal regulatory program.
Statutory cooperation requirements
Congress can enact specific statutes governing communication and cooperation between levels of government, such as 8 U.S.C. §§1373 and 1644.
The result is a legal landscape in which apparently similar sanctuary policies can produce very different constitutional questions.
Sanctuary and Anti-Sanctuary Laws in the Broader Federalism Debate
The sanctuary debate illustrates a broader question in American constitutional law:
How should governmental power be divided when federal and state governments have legitimate interests in the same subject?
Immigration is particularly difficult because federal authority is unusually strong.
The Supreme Court has repeatedly emphasized the federal government’s central role in immigration regulation. Arizona v. United States illustrates how federal supremacy can invalidate state immigration laws that interfere with federal policy.
But federal supremacy does not mean that the federal government can simply convert state and local governments into federal administrative agencies.
The anti-commandeering doctrine protects an important aspect of state sovereignty and preserves political accountability between different levels of government.
Sanctuary and anti-sanctuary laws therefore exist within a constitutional tension between federal supremacy and state autonomy.
Frequently Asked Questions
What is a sanctuary city?
A sanctuary city is generally a municipality that has adopted policies limiting some forms of local cooperation with federal immigration enforcement. There is no single nationwide legal definition covering every sanctuary jurisdiction.
Are sanctuary cities exempt from federal immigration law?
No. Sanctuary policies generally regulate the conduct of state or local governments. They do not invalidate federal immigration law or prevent federal immigration authorities from enforcing federal law.
Can a state refuse to enforce federal immigration law?
The answer depends on what “enforce” means. The anti-commandeering doctrine limits the federal government’s ability to compel state officials to administer federal programs, but states cannot enact laws that conflict with valid federal immigration law. The distinction between refusing to assist and affirmatively obstructing federal enforcement is therefore important.
Does federal law require local police to enforce immigration law?
Not simply because federal immigration law exists. Whether a particular federal statute requires state or local participation depends on the statute and constitutional framework. Federal law does impose specific requirements concerning certain immigration-status information, including under 8 U.S.C. §1373.
Can states create their own immigration laws?
States retain authority over many matters involving public safety and state criminal law, but immigration is an area of strong federal authority. State laws that conflict with or interfere with federal immigration regulation may be preempted.
What is an anti-sanctuary law?
An anti-sanctuary law generally restricts state or local governments from limiting cooperation with federal immigration enforcement or affirmatively requires certain forms of cooperation.
Is Arizona v. United States still important?
Yes. The Supreme Court’s 2012 decision remains a foundational case concerning federal preemption of state immigration laws and the federal government’s dominant role in immigration regulation.
Can the federal government withhold federal funds from sanctuary jurisdictions?
Potentially, but the legality of a particular funding condition depends on congressional authorization, the statute governing the funds, the condition imposed, and constitutional limitations on federal spending power.
Are sanctuary policies unconstitutional?
Not necessarily. The legality of a sanctuary policy depends on what the policy actually does, what federal law requires, and whether the policy conflicts with federal statutes or valid federal regulations.
Are anti-sanctuary laws always constitutional?
No. An anti-sanctuary law must itself comply with the Constitution and federal law. A state cannot use an anti-sanctuary statute as a basis for exercising immigration powers that federal law preempts.
Key Takeaways
Sanctuary and anti-sanctuary laws are best understood as federalism disputes within the larger field of U.S. immigration law.
The central principles are:
- Immigration is primarily governed by federal law.
- States and local governments nevertheless retain substantial authority over their own governmental operations and traditional police powers.
- Federal law can preempt state or local immigration laws that conflict with federal authority.
- The Supreme Court’s decision in Arizona v. United States remains a foundational preemption case.
- The anti-commandeering doctrine limits the federal government’s ability to force state and local officials to administer federal regulatory programs.
- 8 U.S.C. §1373 and §1644 specifically address certain communications between state, local, and federal authorities concerning immigration status.
- Sanctuary policies differ significantly from one jurisdiction to another.
- Anti-sanctuary laws likewise differ in their scope and legal mechanisms.
- Federal immigration enforcement authority does not automatically make every local officer a federal immigration officer.
- A sanctuary designation does not exempt a jurisdiction or its residents from federal immigration law.
- An anti-sanctuary statute does not give a state unlimited authority to regulate immigration.
- The actual text and operation of the challenged law or policy are more important than its political label.
The sanctuary debate is therefore not simply a conflict between jurisdictions that “support” immigration enforcement and those that oppose it. It is a constitutional and statutory question about federal supremacy, preemption, state sovereignty, local authority, and the limits of governmental power.
For students of American law, sanctuary jurisdictions provide a particularly useful example of how federalism operates when federal, state, and local governments have overlapping interests but different constitutional powers.
The information provided in this article ("Sanctuary and Anti-Sanctuary Laws: Federalism, Immigration Enforcement, and State Authority") is for general educational and informational purposes only and does not constitute formal legal advice. Reading this content does not create an attorney-client relationship. Laws vary by jurisdiction; consult a licensed attorney for specific legal matters.
Tsvety, LL.M., M.A.
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