This guide is written for solicitors, trainees and law students in England and Wales.
IPP sentences, imprisonment for public protection, were indeterminate sentences imposed in England and Wales between 2005 and 2012 that set a minimum term but no release date. The sentence was abolished in 2012, yet the abolition was not retrospective, and 2,271 people remain in prison on IPPs today. This explainer covers how the sentence worked, why it persists, and why a UN ruling has put it back at the centre of legal news.
What was an IPP sentence and how did it work?
Created by section 225 of the Criminal Justice Act 2003 and in force from April 2005, the IPP was designed for offenders considered dangerous but whose offences did not merit a life sentence. The court set a tariff, the minimum term reflecting punishment, after which the prisoner could be released only if the Parole Board was satisfied that detention was no longer necessary for public protection. The burden effectively fell on the prisoner to prove reduced risk, typically through offending behaviour courses that many prisons could not provide, and release on licence remained revocable for years afterwards, so recall to custody has been a constant feature of the regime. Around 8,000 IPP sentences were imposed before abolition, far more than the legislation’s sponsors predicted, and some carried tariffs measured in months.
Why are thousands still in prison if the sentence was abolished?
Abolition in 2012, by the Legal Aid, Sentencing and Punishment of Offenders Act, was prospective only: it stopped new IPPs but left every existing one in place. The consequence is a shrinking but stubborn population of prisoners held years or decades beyond tariff, whose route out still runs through the Parole Board, alongside a second population serving the sentence in the community under licence and liable to recall. Successive reforms have trimmed the edges, notably changes to licence termination, and parliamentary committees have recommended a full resentencing exercise, which governments have so far declined. The Sentencing Act 2026 did not resolve the position either, as we reported when its release changes were paused, and the new progression model in our Sentencing Act tracker does not apply to IPP prisoners.
What did the UN Working Group decide in 2026?
In Opinion No. 16/2026, its first on the IPP, the UN Working Group on Arbitrary Detention upheld all three grounds argued for five IPP prisoners: their continued post-tariff detention has no legal basis in international law, the government had not shown their risk could not be managed by alternative measures, and the parole system fails as an effective mechanism for challenging the lawfulness of detention. The five had served almost 87 years between them, and one, Josh McRae, died in custody in 2025 aged 34. The opinion is not binding on the United Kingdom, but their lawyers are preparing a habeas corpus challenge to the High Court, and the prime minister, Andy Burnham, has said he intends to resolve the issue, developments analysed in our report on the opinion and the coming challenge.
Talking about IPP in interviews: the angles that land
- Retrospectivity and the rule of law: abolishing a sentence prospectively while leaving thousands serving it is the tension every discussion circles.
- Institutional design: a release test that depends on courses the system cannot deliver shows how policy fails in implementation rather than intention.
- International law in domestic litigation: a non-binding UN opinion deployed to support a habeas corpus application illustrates persuasive authority in action.
- Separation of powers: courts have held the sentences lawful as imposed, so change requires Parliament, which explains why campaigning targets ministers rather than judges.
- The cost dimension: holding people beyond tariff occupies prison places during an overcrowding crisis, which is why the issue now surfaces in capacity debates.
Common mistakes
Candidates conflate IPP with life sentences, when the defining feature was its use for offences below the life threshold. They say the sentence was “ruled unlawful”, which no domestic court has done; the European Court of Human Rights in James, Wells and Lee found a violation only in the period when rehabilitation courses were unavailable. They assume abolition freed existing prisoners, missing the retrospectivity point on which the whole controversy rests. And they overlook the licence population, which is larger than the custodial one and where recall keeps the sentence alive long after release.
IPP is the rare topic that connects sentencing policy, human rights, prison capacity and constitutional principle in one story, and the UNWGAD opinion plus a live habeas corpus challenge make it current rather than historical. For students it is a ready-made commercial awareness answer; for the profession it is a caseload, since every over-tariff prisoner has parole representations to make.
Official sources
The sentence was created by section 225 of the Criminal Justice Act 2003, and the Working Group’s opinion is published on the OHCHR website.
Date last updated: 14 August 2026.