In England and Wales, life imprisonment is a sentence that lasts until the death of the prisoner, although in most cases the prisoner will be eligible for early release after a minimum term set by the judge. In exceptional cases, however, a judge may impose a "whole life order", meaning that the offender is never considered for parole, although they may still be released on compassionate grounds at the discretion of the Home Secretary. Whole life orders are usually imposed for aggravated murder, and can only be imposed where the offender was at least 21 years old at the time of the offence being committed.