What you need to know
While immigration policy is set at the federal level, enforcement in many cases involves local agencies. Undocumented immigrants generally come into contact with state and local authorities first, including local police or social services agencies. This makes cooperation between different levels of government necessary for implementing immigration enforcement. In recent years, “sanctuary cities” have become central to political and policy debates.
- What constitutes a sanctuary city?
- What are Immigration and Customs Enforcement (ICE) ‘detainer requests’?
- Is there any variation across local compliance with federal immigration enforcement?
What Is a Sanctuary City?
“Sanctuary city” is not a legal term, but a label for jurisdictions that limit cooperation with federal immigration authorities. These limits may include prohibiting local authorities from inquiring about immigration status, failure to notify ICE upon the identification of an undocumented person, or refusing detainer requests (an ICE request to hold individuals past their release time until proper arrangements for their transfer or custody by ICE are made).
While the federal government has jurisdiction over immigration policy, there is no legal requirement for state and local governments to comply with ICE policies regarding detainer requests.
Where are the Sanctuary Communities?
A 2025 Justice Department press release identified 13 states, four counties, and 18 cities as having “policies, laws, or regulations that impede the enforcement of federal immigration laws.” The state mentions focus primarily on state police and prison systems, the county mentions involve local sheriff's departments that run county jails, and the cities cite mostly city policy departments.
- States: California, Colorado, Connecticut, Delaware, District of Columbia, Illinois, Minnesota, Nevada, New York, Oregon, Rhode Island, Vermont, and Washington
- Counties: Baltimore County (MD), Cook County (IL), San Diego County (CA), and San Francisco County (CA)
- Cities: Albuquerque (NM), Berkeley (CA), Boston (MA), Chicago (IL), Denver (CO), East Lansing (MI), Hoboken (NJ), Jersey City (NJ), Los Angeles (CA), New Orleans (LA), New York City (NY), Newark (NJ), Paterson (NJ), Philadelphia (PA), Portland (OR), Rochester (NY), and Seattle (WA)
The states and communities listed in the press release are often the focus of public attention regarding immigration policy. However, these communities are a fraction of the total number of communities that do not fully comply with ICE.
A 2025 ICE report identified 551 state or local agencies that either refuse detainer requests entirely or comply under limited conditions. This includes agreeing to hold individuals for 24 hours rather than 48 hours, or notifying ICE only if an individual has prior felony convictions or confirmed gang affiliations. Analysis by Everything Policy reveals that approximately a quarter of these agencies are situated outside the localities mentioned in the Justice Department press release, including many rural counties across the Midwest and Mountain West.
Why do communities refuse detainer requests?
Many jurisdictions refuse to honor detainer requests because state or local laws prohibit compliance. Others opt out for practical, philosophical or legal reasons, including:
- Limited resources: Small, rural jails may not have the staff, resources, or space to hold individuals beyond their release dates.
- Legal risk: Holding someone without a judicial warrant can expose jurisdictions to lawsuits for unlawful detention.
- Court rulings: Federal courts have questioned the constitutionality of detaining individuals solely based on ICE requests.
- Subjective decisions: Not necessarily legally-driven, but refusal based on philosophical differences with Federal mandates.
The Takeaway
Although immigration enforcement is federally directed, its implementation depends heavily on voluntary cooperation from state and local governments.
The label “sanctuary city” does not capture the full complexity of local decisions regarding undocumented individuals.
Thousands of jurisdictions cooperate fully with ICE, hundreds do not, and a smaller number operate in between.
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Further reading
U.S. Department of Justice. (2025). Justice Department publishes list of sanctuary jurisdictions. https://tinyurl.com/53dtcxaw, accessed 7/8/25.
U.S. Immigration and Customs Enforcement. (2025). Immigration detainers. https://tinyurl.com/5xy46mfz, accessed 7/8/25.
Sources
Office of the Inspector General. (2016). Department of Justice Referral of Allegations of Potential Violations of 8 U.S.C. § 1373 by Grant Recipients. https://tinyurl.com/ss5cnztk, accessed 7/8/25.
U.S. Department of Justice. (2025). Justice Department publishes list of sanctuary jurisdictions. https://tinyurl.com/53dtcxaw, accessed 7/8/25.
Worker & Immigrant Rights Advocacy Clinic. (2019). Courting ICE: The role of judges in the deportation pipeline. Yale Law School. https://tinyurl.com/4rvkeyn2, accessed 7/8/25.
U.S. Immigration and Customs Enforcement. (2025). Immigration detainers. https://tinyurl.com/5xy46mfz, accessed 7/8/25.
Contributors
Lindsey Cormack (Content Lead) is an Associate Professor of Political Science at Stevens Institute of Technology and the Director of the Diplomacy Lab. She received her PhD from New York University. Her research explores congressional communication, civic education, and electoral systems. Lindsey is the creator of DCInbox, a comprehensive digital archive of Congress-to-constituent e-newsletters, and the author of How to Raise a Citizen (And Why It’s Up to You to Do It) and Congress and U.S. Veterans: From the GI Bill to the VA Crisis. Her work has been featured in The New York Times, The Washington Post, Bloomberg Businessweek, Big Think, and more. With a drive for connecting academic insights to real-world challenges, she collaborates with schools, communities, and parent groups to enhance civic participation and understanding.
William Bianco (Research Director) is Professor of Political Science at Indiana University and Founding Director of the Indiana Political Analytics Workshop. He received his PhD from the University of Rochester. His teaching focuses on first-year students and the Introduction to American Government class, emphasizing quantitative literacy. He is the co-author of American Politics Today, an introductory textbook published by W. W. Norton, now in its 8th edition, and authored a second textbook, American Politics: Strategy and Choice. His research program is on American politics, including Trust: Representatives and Constituents and numerous articles. He was also the PI or Co-PI for seven National Science Foundation grants and a current grant from the Russell Sage Foundation on the sources of inequalities in federal COVID assistance programs. His op-eds have been published in The Washington Post, Indianapolis Star, Newsday, and other venues.
