Detainer

The act (or the juridical fact) of withholding from a lawfully entitled person the possession of land or goods, or the restraint of a person's personal liberty against his or her will; detention. The wrongful keeping of a person's goods is called an UNLAWFUL DETAINER although the original taking may have been lawful.

A request filed by a criminal justice agency with the institution in which a prisoner is incarcerated asking the institution either to hold the prisoner for the agency or to notify the agency when release of the prisoner is imminent.