Prisoners are released in accordance with the statutory provisions laid down by Parliament, either by the Secretary of State or by the independent Parole Board, depending on the type of sentence the courts have imposed. Determinate sentences – that is, those of a fixed length – have an automatic release date at which point the Secretary of State has a statutory duty to release the prisoner. In some cases, there is a discretion for the Secretary of State to release before the automatic release date, for example, under the Home Detention Curfew (HDC) scheme, where the decision to release (on a tag) is taken on behalf of the Secretary of State by prison governors.
Indeterminate sentences – that is, life imprisonment or Imprisonment for Public Protection (IPP) – have a minimum period (the tariff) imposed by the court that the offender must spend in custody, after which the decision on whether to release can only be taken by the Parole Board. Some forms of determinate sentence also have a period of discretionary release by the Board, for example, extended sentences for serious sexual or violent offenders where release before the end point is for the Board to decide. For prisoners subject to Parole Board release, there is a statutory release test which requires the Board to be satisfied that detention is no longer necessary for the protection of the public.
Rule 7 of the Prison Rules 1999 governs categorisation. Prisoners are categorised by Her Majesty’s Prison and Probation Service (HMPPS) in accordance with the Secretary of State’s published policy. Decisions to categorise a prisoner as Category A are taken centrally by HMPPS while other categorisation decisions are taken at prison level. When assessing indeterminate sentence prisoners for open conditions, the advice of the Parole Board is sought, other than in exceptional circumstances.