detainer

A detainer is a notice or request from one governmental agency directing another agency to detain or hold a person in custody for a future action. Historically, the writ of detainer was a common-law instrument requiring a jailer to detain a prisoner until the appropriate court or sovereign could take action.

In modern practice, detainers appear in several contexts. In criminal justice, a detainer may be lodged with a jail or prison to keep an individual beyond the usual release time so that prosecutors or courts can pursue additional charges, arrange extradition, or complete sentencing. In immigration enforcement, an immigration detainer (often called a civil detainer) is a request by an immigration authority to a local or state facility to notify and hold a detainee who may be subject to removal proceedings. The detainer is a request, not a warrant or binding order, and compliance varies by jurisdiction.

Legal and policy considerations accompany detainers. They can raise due process and civil rights concerns when release is deferred without judicial oversight, probable cause, or accurate information. Some jurisdictions limit or do not honor detainers absent a warrant, a court order, or other lawful basis, while others implement safeguards such as clear duration limits, timely notice, or alignment with state law.

Impact and challenges often center on how detainers affect individuals and agencies. For individuals, detainers can extend custody, complicate bail decisions, or delay release. For agencies, detainers are tools for interagency cooperation but require adherence to constitutional rights and accurate information. Remedies may include legal challenges, policy reforms, or procedural safeguards to ensure proper oversight.