How have U.S. cities legally structured noncooperation policies with ICE since 2020 and what court challenges have they faced?
Executive summary
Since 2020 U.S. cities have layered a patchwork of formal ordinances, administrative directives and practical limits designed to blunt local cooperation with ICE — banning warrantless detainer holds, restricting data-sharing and formalizing “do not assist” guidance — even as state governments and the federal administration push back with funding conditions, deputization programs and lawsuits; that tug-of-war has produced a steady stream of court battles that have both reinforced limits on detainers and kept broader noncooperation measures legally unsettled [1] [2] [3]. The result is a splintered legal map where protections for immigrants vary by city and state, and where litigation remains the primary mechanism for resolving federal-local conflicts [4] [5].
1. How cities have legally structured noncooperation since 2020: ordinances, policies and statutory patchwork
Municipal responses since 2020 have included formal sanctuary ordinances and administrative policies that decline to honor ICE civil detainer requests without a judicial warrant, bar ICE arrests at courthouses, limit access to DMV and other municipal records, and instruct local agencies not to use local funds or personnel for federal immigration enforcement; New York’s “Protect Our Courts” measures and state Greenlight privacy rules exemplify this approach by explicitly shielding courthouses and DMV data from ICE [1] [4]. Many city policies are operationalized through internal police directives and immigrant affairs offices that issue “know your rights” guidance and set rules for information-sharing and access to municipal facilities, turning administrative practice into de facto legal limitation in the absence of a single federal rule [4] [6].
2. The legal tools cities rely on: detainer refusals, data limits, and oversight
Cities rely primarily on refusing to honor ICE detainers — a practice curtailed in many jurisdictions after courts found warrantless detainers unlawful — and on limiting information flows that facilitate federal enforcement, including revoking surveillance contracts and restricting DMV access; courts have already forced widespread changes to detainer compliance, prompting many jurisdictions to adopt clear written policies to avoid Fourth Amendment liability [2] [7] [8]. Municipalities also emphasize monitoring ICE activity and preparing civil remedies for misconduct, effectively creating oversight mechanisms intended to deter aggressive federal operations [6].
3. State and federal countermeasures: deputization, grant conditions and anti‑sanctuary laws
At the same time, several states and the federal government have sought to roll back or bypass local noncooperation: some states have required local officers to deputize for ICE under 287(g) agreements and passed anti‑sanctuary laws that limit municipal autonomy, while federal administrations have tried to condition grants on cooperation — tactics critics say are designed to pressure cities into compliance [2] [5] [9]. Governors and federal officials have also proposed targeting state grants to curb local noncooperation rather than outlawing it directly, a strategy that shifts leverage to funding rather than criminal or civil mandates [2] [3].
4. Major court fights and precedents shaping the landscape
Courts have been pivotal: a string of rulings beginning before 2020 invalidated warrantless ICE detainers and constrained detention without judicial process, prompting many cities to stop honoring detainers to avoid liability [2] [10] [7]. Conversely, the federal government has sued to block state and local limits — for example challenging California measures and seeking injunctions — citing agent safety and national enforcement priorities; those federal suits have put newer local laws on temporary hold and created active multi‑district litigation [6]. States and cities have also sued DHS — as Minnesota did in January 2026 seeking a temporary restraining order over a surge of federal agents — framing some federal deployments as unconstitutional intrusions on state sovereignty [11].
5. Outcomes, uneven enforcement and the political stakes
The collision of municipal protections and federal pressure has produced uneven outcomes: some jurisdictions have successfully insulated residents and reduced ICE arrests, while others — especially in states that mandate cooperation — have seen increased deputization and arrests [5]. High‑cost litigation and settlements, such as Los Angeles County’s $14 million class‑action payout tied to detainer practices, have also deterred some local cooperation and encouraged written noncooperation policies to manage liability [10]. Both sides wield plausible public‑safety and civil‑rights rationales; critics of sanctuary policies call them obstacles to federal law enforcement and seek funding penalties, while advocates argue that cooperation erodes trust and triggers constitutional harms, leaving courts to adjudicate competing institutional claims [3] [9].
6. Bottom line — a legal landscape in flux governed by litigation and politics
Since 2020 cities have used administrative rules, ordinances and careful limits on detainers and data-sharing to structure noncooperation with ICE, but the enduring question of how far local autonomy can go is unresolved and litigated; courts have curtailed warrantless detainers and provided some protection for municipal policies, yet federal suits and state-level mandates continue to challenge and reshape that framework, ensuring that the legal map will evolve with each new lawsuit and political shift [2] [6] [11].