Last updated: 16 January 2026
ISP
Indeterminate Sentence Prisoner - a prisoner serving a sentence with no fixed end date, including life sentences and the now-abolished IPP sentences. Release depends on demonstrating reduced risk and is decided by the Parole Board.
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IPP (Indeterminate Public Protection)
A type of indeterminate sentence introduced in 2005 and abolished in 2012. Many IPP prisoners remain in custody past their tariff date due to difficulties proving they are safe to release.