How do ICE detainers and judicial warrants differ, and when will local agencies comply?
Executive summary
ICE “detainers” are administrative requests from a federal immigration agency asking a jail to hold someone for transfer to ICE; they are not judicial warrants and carry no standalone legal authority to arrest or extend custody [1] [2]. By contrast, a judicial warrant is issued by a neutral judge based on probable cause and—unlike ICE’s administrative forms—authorizes arrest and, in many circumstances, limited entry into private spaces [3] [4].
1. What an ICE detainer actually is (and is not)
An ICE detainer is a written request that asks a state or local jail to hold an individual for a short period so federal immigration officers can assume custody, but the detainer itself “is a request” and “carries no legal force” authorizing a new arrest or seizure by local authorities [1] [5]. Detainers are typically administrative paperwork generated by ICE and often accompany ICE-issued administrative warrants (forms like the I‑200 or I‑205), yet neither the detainer nor the ICE administrative warrant is a judicially issued arrest warrant [2] [5].
2. Administrative (ICE) warrants versus judicial warrants
ICE and DHS may issue administrative removal or arrest warrants that permit ICE officers to detain named individuals for civil immigration purposes, but those documents are signed by ICE officials—not by a judge or magistrate—and do not equate to a judicial arrest/search warrant founded on probable cause [3] [6]. Judicial warrants, by contrast, require a detached magistrate’s finding of probable cause and carry constitutional weight for arrests and nonconsensual entries into private dwellings [3] [7].
3. What federal ICE guidance and internal memos say (and the controversy)
ICE publicly asserts it can make arrests without a judicial warrant and trains officers to use administrative warrants in routine enforcement [8] [3], and internal ICE memos disclosed in 2025 instruct officers that administrative I‑205 forms can be used to enter homes in some circumstances—an approach that has sparked litigation and judicial pushback [9] [10]. Courts and whistleblower materials have flagged that relying solely on administrative forms for warrantless home entry raises Fourth Amendment concerns [9] [7].
4. When local law enforcement will (and won’t) comply
Local agencies are not legally obligated to honor ICE detainers; multiple state and municipal policies—and federal court rulings—underscore that detainers do not automatically authorize continued custody beyond what state law permits, and jails that honor detainers risk liability if detention exceeds lawful limits or lacks probable cause [1] [5] [2]. Many jurisdictions decline to honor detainers except when ICE produces a judicial warrant, or when the local agency independently has probable cause or a criminal warrant authorizing continued detention; statutory local rules (e.g., TRUST‑type statutes) and local ordinances often codify that approach [11] [2].
5. Practical thresholds that trigger cooperation
In practice, local compliance commonly occurs in three narrow scenarios documented in guidance and case law: when an individual is already in custody on state criminal charges and the jail lawfully processes an ICE request without extending detention beyond lawful release times (sometimes up to ICE’s requested 48 hours), when ICE presents a judicial warrant, or when local authorities independently have probable cause or a criminal warrant to hold the person [11] [4] [5]. Outside those conditions, many legal advisers and civil‑rights organizations advise that compliance is discretionary and potentially unconstitutional [12] [4].
6. Competing narratives and institutional incentives
ICE and DHS emphasize operational flexibility—saying administrative warrants and detainers are valid tools to enforce civil immigration law—while state attorneys general and immigrant‑rights groups emphasize constitutional limits and local liability for warrantless holds [8] [2] [5]. Hidden agendas are evident: ICE’s operational memos aim to expand enforcement leeway, whereas local policies limiting cooperation often reflect public‑safety and community‑trust priorities as well as litigation risk management [9] [2].
7. Bottom line for when local agencies will comply
A detainer alone will not legally compel local compliance; compliance typically requires either a judicial warrant or independent probable cause under state law, explicit local policy permitting cooperation, or an operational arrangement where the jail lawfully retains custody for the limited ICE window without extending detention unlawfully—otherwise the local agency faces constitutional and civil‑liability risk [1] [5] [11]. Where ICE asserts broader authority—such as entering homes on administrative warrants—courts are actively testing those claims, so the legal boundary remains contested and fact‑specific [9] [10] [7].