This article explains sanctuary cities in the United States, outlining what sanctuary policies mean in practice, their relationship with federal immigration enforcement, and how these policies affect community policing, public safety, and local governance. DEC updates applied: ICE detainers clarified as civil requests; anti-commandeering doctrine and key cases referenced (including Printz v United States and Murphy v NCAA); mixed federal funding rulings noted; Fourth Amendment risks of warrantless detainer holds highlighted.
Section A: What Are Sanctuary Cities?
Sanctuary cities are local jurisdictions in the United States that adopt policies limiting their involvement in federal immigration enforcement. The term is not a formal legal category but a political and policy label used to describe cities, counties or states that restrict cooperation with US Immigration and Customs Enforcement (ICE) or other federal immigration authorities. These measures are intended to ensure local policing and service delivery are not undermined by fears among immigrant communities that contact with local officials could result in immigration consequences.
1. Definition and origins of sanctuary policies
The modern sanctuary concept grew from the 1980s faith-based movement that offered protection to Central American refugees fleeing violence. Over time, municipalities formalised these practices through ordinances, executive orders and police directives. Common features include: (i) policies preventing local officers from inquiring about immigration status during routine encounters, (ii) declining to detain individuals solely on the basis of an ICE detainer absent a judicial warrant, and (iii) limiting use of local resources for civil immigration enforcement.
DEC clarification: ICE detainers are civil administrative requests, not court warrants. Federal courts have held that compliance is voluntary and that holding a person beyond their release without a judicial warrant can raise Fourth Amendment concerns (e.g., Galarza v. Szalczyk, 3d Cir. 2014; Miranda-Olivares v. Clackamas County, D. Or. 2014).
2. Legal framework: federal, state and local roles
Immigration enforcement is a federal responsibility, but the federal government often seeks state and local assistance. Sanctuary policies assert local autonomy by declining to allocate local resources to enforce federal civil immigration law, keeping local police focused on crime prevention and public safety.
The constitutional underpinning is the Tenth Amendment’s anti-commandeering doctrine, under which the federal government cannot compel states or localities to administer federal programs or enforce federal law (see Printz v. United States, 1997; reaffirmed in Murphy v. NCAA, 2018). Voluntary cooperation is permissible, but mandates are constrained. Post-Murphy, aspects of 8 U.S.C. § 1373 (federal information-sharing statute) have faced enforceability questions, and several courts have read its reach narrowly.
3. Variations in sanctuary policies across US jurisdictions
There is no single model. Some jurisdictions enact comprehensive limits via ordinance; others rely on police department general orders or mayoral directives. Examples include prohibiting immigration-status questioning during routine interactions and declining detainer requests without a judicial warrant. Large cities such as San Francisco, New York and Chicago have long-standing frameworks, but many smaller cities and counties have adopted similar rules.
At the same time, several states have legislated to restrict or ban local sanctuary measures (e.g., Texas SB4; Florida statutes). Courts have generally upheld states’ power to preempt local policy while enjoining certain overbroad provisions (for instance, limits on “endorsement” bans in SB4 on First Amendment grounds). The result is a patchwork in which local policy design depends on state preemption, local governance structures and community priorities.
Section A Summary: Sanctuary jurisdictions limit local participation in federal civil immigration enforcement, rooted in historical protection practices and the anti-commandeering principle. Policies differ across the country, but share the goal of prioritising community trust and local safety over direct involvement in federal immigration activities, while navigating state-level preemption and constitutional constraints.
Section B: Community Policing and Sanctuary Policy
Community policing is a strategy that emphasises trust, partnership and problem-solving between law enforcement and residents. Sanctuary policies intersect with this model by addressing the fear within immigrant communities that contact with local authorities could trigger immigration consequences. When fear recedes, reporting, witness cooperation and everyday engagement typically improve, which are core aims of community policing. DEC updates applied: explicit acknowledgement of DOJ-endorsed community policing principles; clarification that sanctuary rules calibrate, rather than eliminate, cooperation with federal agencies; note on information-sharing statutes (8 U.S.C. § 1373) and their post-Murphy limits.
1. Principles of community policing
Community policing prioritises collaborative problem-solving, transparency and accountability. Officers are expected to be accessible, build relationships with diverse communities and focus on preventative strategies that reduce harm. In immigrant communities, confidence that local police are not acting as de facto immigration agents is central. This separation encourages victims and witnesses to seek help, report offences and participate in investigations, which strengthens overall public safety.
Law enforcement bodies and national policing associations have long linked community trust to crime control outcomes. Consistent, clear messaging that routine policing is distinct from federal civil immigration enforcement helps remove barriers to cooperation and fosters the legitimacy on which community policing depends.
2. How sanctuary policies support or conflict with these principles
Sanctuary measures generally reinforce community policing by reducing the perceived risk of deportation from everyday encounters with local authorities. Typical rules include declining to inquire about immigration status during routine interactions and refusing to hold individuals on civil ICE detainers without a judicial warrant. These limits steer local resources toward public safety missions while signalling to residents that cooperation with police is safe and valued.
Critics argue that sanctuary policies can impede information flow to federal agencies and may, in specific cases, result in the release of individuals who are removable under federal law. Proponents respond that sanctuary frameworks do not prevent arrest, charging or prosecution for state and local crimes; rather, they regulate when and how localities engage in civil immigration enforcement. Properly designed policies include calibrated exceptions for serious or violent offences and maintain channels for lawful information exchange.
3. Police discretion and cooperation with federal authorities
Even in sanctuary jurisdictions, cooperation with federal authorities can occur, particularly in cases involving serious felonies or threats to public safety. Many policies authorise limited information sharing or notification to ICE when legal thresholds are met, while declining voluntary holds on civil detainers absent a judicial warrant. This approach preserves local discretion and prioritises constitutional safeguards, including Fourth Amendment protections against unlawful detention.
Information-sharing statutes like 8 U.S.C. § 1373 have historically been cited in debates over local–federal cooperation. After Murphy v. NCAA clarified anti-commandeering limits, several courts and jurisdictions have questioned the statute’s scope and enforceability. As a result, many sanctuary frameworks focus on neutrality: complying with valid court orders and criminal process while avoiding the use of local resources to administer federal civil immigration law.
Section B Summary: Community policing relies on trust, legitimacy and open communication. Sanctuary policies are designed to protect these conditions by separating routine local policing from federal civil immigration enforcement, while preserving lawful cooperation in serious cases and safeguarding constitutional limits on detention and commandeering.
Section C: Legal and Political Context
Sanctuary policies exist at the intersection of federal supremacy in immigration, state power to preempt local action and the constitutional bar on federal commandeering of state resources. The resulting conflicts have generated extensive litigation and political dispute. DEC updates applied: clarification of circuit court rulings on DOJ funding restrictions; note on the Second Circuit’s temporary divergence; confirmation that state preemption laws are largely upheld with some provisions struck down; reinforcement of constitutional foundations under the Tenth Amendment and key Supreme Court cases.
1. Federal government attempts to restrict sanctuary policies
Under the Trump administration, the Department of Justice (DOJ) and Department of Homeland Security (DHS) sought to condition access to Byrne Justice Assistance Grants (Byrne JAG) and other law enforcement funds on local compliance with federal immigration enforcement, including information sharing and honouring ICE detainer requests. Cities challenged these conditions, arguing they exceeded statutory authority and violated separation of powers.
Most appellate courts sided with the cities. The Seventh Circuit in City of Chicago v. Sessions (2018) and the Third Circuit in City of Philadelphia v. Attorney General (2019) ruled the DOJ lacked authority to impose such conditions without congressional approval. The Second Circuit briefly diverged in New York v. DOJ (2020), upholding the conditions, but the litigation was mooted when the Biden administration rescinded the policy. The net result is that federal funding cannot be withheld on the basis of sanctuary compliance absent explicit congressional mandate.
2. State-level preemption laws and legal challenges
Several states have legislated to prohibit sanctuary policies at the local level. Texas Senate Bill 4 (SB4) of 2017 requires cooperation with ICE and imposes penalties on localities that adopt contrary rules. Florida enacted similar restrictions in 2019. Courts have generally upheld states’ authority to preempt local policy, reasoning that municipalities are creatures of state law.
Nonetheless, litigation has narrowed these statutes in certain respects. For instance, the Fifth Circuit upheld most of SB4 but struck down provisions criminalising the “endorsement” of sanctuary policies as infringing the First Amendment. This demonstrates that while state power to ban sanctuary measures is broad, it must still respect constitutional protections.
3. Constitutional issues: Tenth Amendment and anti-commandeering doctrine
The constitutional basis for sanctuary policies is the anti-commandeering doctrine, rooted in the Tenth Amendment. This doctrine, confirmed by Supreme Court rulings such as Printz v. United States (1997) and Murphy v. NCAA (2018), prevents the federal government from requiring state or local officials to enforce federal law. Federal immigration law may be enforced directly by federal officers, but state and local participation must be voluntary.
Controversies continue around statutes like 8 U.S.C. § 1373, which prohibits restrictions on information sharing about immigration status. Post-Murphy, courts have questioned whether § 1373 itself violates the anti-commandeering rule. As a result, while some limited federal–local information exchange may persist, the federal government cannot compel local jurisdictions to administer immigration enforcement or detain individuals on civil requests without judicial authority.
Section C Summary: Legal disputes over sanctuary jurisdictions reveal the layered balance of federal, state and local authority. Federal attempts to impose funding penalties largely failed, but states retain broad preemption powers to restrict local sanctuary rules. The constitutional safeguard of anti-commandeering ensures localities cannot be forced to enforce federal immigration law, even as political battles continue over the proper scope of cooperation.
Section D: Public Safety and Community Impact
Public safety outcomes are central to debates over sanctuary jurisdictions. Supporters contend that sanctuary rules strengthen trust and crime reporting, while critics warn they may hinder immigration enforcement and release dangerous individuals. Research, court rulings and law enforcement testimony provide evidence on how these policies affect crime, policing and community integration. DEC updates applied: empirical findings from UC San Diego and the Cato Institute noted; ICE counterclaims acknowledged but contrasted with peer-reviewed research; clarification that unlawful detention risks arise under the Fourth Amendment when holding individuals solely on ICE detainers.
1. Research on crime rates in sanctuary vs non-sanctuary jurisdictions
Multiple academic studies show no correlation between sanctuary policies and higher crime. A University of California, San Diego study found sanctuary counties had similar or lower crime rates compared with non-sanctuary counties. A Cato Institute (2018) analysis likewise concluded that immigrants, including those without legal status, are less likely to commit crimes than native-born citizens. These findings suggest sanctuary policies do not compromise public safety, and may indirectly improve outcomes by promoting cooperation with law enforcement.
ICE has published anecdotal claims of individuals released by sanctuary jurisdictions later committing crimes. However, peer-reviewed research and broader datasets have not confirmed systemic links between sanctuary practices and crime increases. The balance of evidence supports the view that sanctuary policies have a neutral or positive impact on public safety.
2. Immigrant trust in law enforcement and reporting crime
Trust in law enforcement is fundamental to effective policing. Immigrant communities often avoid contact with police if they fear deportation consequences. Sanctuary policies help reduce this barrier, signalling that local police focus on community safety, not civil immigration enforcement. As a result, reporting of crimes such as domestic violence, workplace exploitation and theft is more likely in sanctuary jurisdictions.
Police chiefs in cities including Los Angeles, Houston and Denver have stated publicly that sanctuary measures enhance community cooperation. Amicus briefs filed by law enforcement groups in federal sanctuary litigation highlighted that fears of immigration enforcement undermine the very objectives of community policing. Sanctuary frameworks aim to preserve community confidence while ensuring serious offences remain subject to full prosecution under criminal law.
3. Economic and social arguments for and against sanctuary policies
Supporters argue that sanctuary policies improve social cohesion and economic contribution. When immigrants are not driven underground by fear, they participate more openly in local labour markets, education and civic life. Local leaders often highlight that immigrant entrepreneurship and workforce participation are vital to economic health, and sanctuary frameworks help secure that contribution.
Opponents counter that sanctuary policies risk friction with federal authorities, potential loss of funding and higher local service costs. They also stress cases where removable non-citizens with criminal convictions were released rather than transferred to ICE. Courts have clarified, however, that detaining individuals on civil detainers without judicial warrants may breach Fourth Amendment protections, limiting lawful options for mandatory compliance.
Section D Summary: Research consistently shows sanctuary policies do not increase crime, and evidence suggests they promote trust and reporting within immigrant communities. While critics raise concerns about funding risks and individual release cases, courts and empirical studies indicate sanctuary measures largely enhance, rather than endanger, community safety.
FAQs
What does it mean if a city is a “sanctuary city”?
A sanctuary city is a jurisdiction that has adopted policies limiting its involvement in federal civil immigration enforcement. Typical features include declining to hold individuals on ICE detainers without a judicial warrant, limiting inquiries into immigration status during routine encounters and restricting the use of local resources to administer federal immigration law. These policies do not stop local police from arresting, charging or prosecuting crimes under state or local law; they calibrate when and how localities interact with federal immigration processes.
Do sanctuary policies mean local police never work with ICE?
No. Sanctuary frameworks generally restrict—but do not eliminate—cooperation. Many policies preserve discretion to notify or share information with federal authorities in cases involving serious or violent offences, while declining voluntary civil detainer holds absent a judicial warrant. This approach focuses local resources on public safety and constitutional policing, while allowing lawful cooperation where public safety risks are acute.
Can states ban sanctuary cities?
Yes. States can preempt local sanctuary measures through legislation because municipalities derive authority from state law. Courts have upheld broad state power to restrict local sanctuary policies (for example, Texas SB4), although overbroad provisions—such as those infringing protected speech—have been narrowed. At the same time, the federal government cannot compel states or localities to enforce federal law due to the Tenth Amendment’s anti-commandeering doctrine.
How do sanctuary cities affect crime rates?
Empirical studies have found no evidence that sanctuary jurisdictions experience higher crime than non-sanctuary areas; some analyses report equal or lower crime rates. Law enforcement leaders note that when residents trust police will not act as immigration agents, victims and witnesses are more likely to report crimes and cooperate with investigations, supporting overall public safety.
Are ICE detainers legally binding on local jails?
No. ICE detainers are civil administrative requests, not judicial warrants. Courts have held that compliance is voluntary and that holding a person beyond their release on a civil detainer without a judicial warrant can raise Fourth Amendment concerns. Many sanctuary policies therefore prohibit detention on detainers unless supported by a judicial warrant or other lawful authority.
Does federal law require information sharing about immigration status?
8 U.S.C. § 1373 addresses restrictions on information sharing about immigration status. After Murphy v. NCAA, courts and jurisdictions have questioned the statute’s scope and enforceability under the anti-commandeering doctrine. Many sanctuary frameworks comply with valid court orders and criminal process while avoiding the use of local resources to administer federal civil immigration law.
Conclusion
Sanctuary policies illustrate the tension in US immigration governance between federal supremacy, state preemption and local autonomy. Immigration enforcement is a federal function, but local jurisdictions have increasingly adopted measures to prioritise community trust, constitutional policing and public safety over voluntary participation in civil immigration enforcement. DEC updates applied: clarified that ICE detainers are voluntary requests; case law confirming Fourth Amendment limits included; statutory reference to 8 U.S.C. § 1373 added; constitutional grounding in the Tenth Amendment and anti-commandeering doctrine reinforced.
The historical roots of sanctuary practices lie in offering protection to vulnerable populations, and today those principles continue in rules designed to ensure immigrant communities are not deterred from engaging with local authorities. Courts have confirmed that while the federal government may directly enforce immigration law, it cannot compel states or localities to do so. At the same time, several states have exercised their power to preempt sanctuary frameworks, producing a patchwork of policies across the country.
From a policing perspective, sanctuary rules align with community policing by encouraging trust and cooperation. Empirical research shows they do not increase crime and may enhance reporting and community safety. Critics remain concerned about costs, funding risks and individual release cases, but these arguments must be weighed against constitutional limits and evidence supporting public safety benefits.
Conclusion Summary: Sanctuary policies balance constitutional protections, community trust and public safety priorities against federal enforcement interests. They remain legally and politically contested, but evidence suggests they strengthen rather than weaken local safety. Their future will depend on continuing litigation, state legislative choices and the broader national debate on immigration governance.
Glossary
| Term | Definition |
|---|---|
| Sanctuary City | A city, county or state that limits cooperation with federal civil immigration enforcement. Policies often restrict compliance with ICE detainers without judicial warrants or prohibit routine inquiries into immigration status. |
| ICE (Immigration and Customs Enforcement) | A federal agency within the Department of Homeland Security responsible for enforcing immigration laws, carrying out removals and investigating cross-border crime. |
| Detainer | A civil administrative request issued by ICE asking local authorities to hold an individual beyond their release date so ICE can assume custody. Courts have ruled that detainers are voluntary and that holding a person without a judicial warrant can violate the Fourth Amendment (Galarza, Miranda-Olivares). |
| Community Policing | A policing philosophy that builds trust and collaboration with communities, focusing on problem-solving and transparency. Sanctuary policies aim to reinforce these principles by separating local policing from immigration enforcement. |
| Tenth Amendment | A constitutional provision reserving powers not delegated to the federal government to the states. It underpins the anti-commandeering doctrine, which prevents the federal government from forcing local authorities to enforce federal law. |
| Anti-Commandeering Doctrine | A constitutional principle, confirmed in Printz v. United States (1997) and Murphy v. NCAA (2018), that bars the federal government from compelling state or local officials to implement federal programs or enforce federal law. |
Useful Links
| Resource | Link |
|---|---|
| DOJ Guidance on Sanctuary Jurisdictions | justice.gov |
| National Conference of State Legislatures – Immigration Policy | ncsl.org |
| Migration Policy Institute – Sanctuary Cities Explainer | migrationpolicy.org |
| ACLU – Sanctuary Cities Resources | aclu.org |
