Punishment of a criminal by imprisonment for the rest of his life. The only crime that carries a mandatory sentence of life imprisonment is murder, but there are many crimes (e.g. arson, manslaughter, wounding with intent, and rape) that carry a maximum penalty of life imprisonment, which is imposed in serious cases. An offender aged 21 or over who is convicted of murder must be sentenced to imprisonment for life under section 1(1) of the Murder (Abolition of the Death Penalty) Act 1965. For an offender aged under 21 the current sentence is custody for life; however, when the Criminal Justice and Court Services Act 2000 (s 61), comes into force the sentence of “custody for life” will be abolished with imprisonment for life being the sentence instead.
In practice the imprisonment may often not be for life (see parole). When imposing life imprisonment for murder, the judge may make a recommendation that the defendant should serve a minimum term (number of years). Under the Criminal Justice Act 2003 Sch 21, paras 4 to 11, there is a detailed scheme of general principles that act as guidelines in the determination of the minimum term to be served as part of the mandatory life sentence for murder. Following the decision in R (Anderson) v Secretary of State for the Home Department  1 AC 837, it was ruled that the Home Secretary's power to set a minimum term to be served for life imprisonment for murder was incompatible with article 6(1) of the European Convention on Human Rights, which gives the offender the right to have his sentence imposed by an independent tribunal.