Under federal immigration law, an ICE detainer (Form I-247A) is an administrative request from the Department of Homeland Security asking a state or local law enforcement agency (LEA) to maintain custody of an alien for up to 48 hours beyond the time they would otherwise be released on state bail or sentence completion.

Multiple federal circuit courts—including the Third Circuit in Galarza v. Szalczyk (2014) and the First Circuit in Morales v. Chadbourne (2015)—have held that detainers are voluntary requests, not mandatory federal commands. Because administrative detainers are signed by immigration enforcement officers rather than neutral Article III judges, holding an individual solely on an administrative detainer constitutes a new civil arrest under the Fourth Amendment, subjecting local county sheriffs to personal Section 1983 liability and false imprisonment tort damages if probable cause is lacking.

In New York City, Administrative Code § 14-154 and § 9-131 (enacted in 2014) bar the NYPD and Department of Correction from honoring ICE civil detainers or notifying federal authorities unless two strict conditions are met simultaneously:

• ICE presents an Article III judicial arrest warrant signed by a federal judge; and
• The individual has been convicted of a violent or serious crime within the past five years (or is identified on a federal terrorist screening database).

During congressional debates (such as in New York's 17th Congressional District between Rep. Mike Lawler and Cait Conley), critics argue that this framework prevents ICE from taking custody of individuals charged with serious crimes before they are released into the community. Proponents contend the statute prevents unconstitutional warrantless detention and encourages immigrant victims and witnesses to cooperate with local police.