What happened

IPP sentences were introduced in 2005. The idea was to deal with offenders considered dangerous but whose offence did not justify a conventional life sentence.



The crucial feature was that the prisoner received a minimum tariff, but no fixed release date. Once the tariff had expired, they could remain in prison until the Parole Board decided they were safe to release.



The system was used far more extensively than originally intended. People received IPPs for offences that, viewed in isolation, could attract relatively short sentences - including theft, robbery and other non-homicide offences. ([The Guardian][1])



The IPP system was abolished in 2012 because of its serious problems. But - and this is the extraordinary part - abolishing it did not cancel the sentences that had already been imposed.



So people sentenced under a system that Parliament subsequently decided was unacceptable were left serving those sentences.

The numbers are staggering

At its height, more than 6,000 people were still in prison under IPP sentences. Even in 2024, nearly 3,000 remained in prison, many years beyond the tariff originally imposed for their offence. ([The Guardian][1])



There are cases of people who received tariffs of less than two years but who subsequently spent 10, 15 or even 20 years in prison. ([Academy of Ideas][2])



One particularly striking example involved someone imprisoned for stealing a flower pot, who ultimately spent 16 years in prison. ([The Guardian][1])



And there are cases involving people imprisoned for mobile-phone theft who have spent extraordinarily long periods behind bars. ([The Independent][3])

And there is a second problem

Even when an IPP prisoner is eventually released, the sentence doesn't simply disappear.



They are released on an IPP licence, and the licence can potentially last for 99 years. Breaching the licence conditions can result in being 'recalled to prison', potentially indefinitely.



That means someone who committed an offence decades ago can find themselves back in prison because of a comparatively minor breach of their licence. ([The Guardian][4])



This is why you'll sometimes hear IPP prisoners described as having received life sentences by the back door.

Why weren't they simply released?

This is the really interesting legal question.



There is a legitimate argument behind the system: some people who received IPPs were genuinely dangerous, and simply releasing everyone automatically could create a public-safety problem.



But the fundamental injustice is that the punishment became disconnected from the original offence.



Imagine:

• Person A commits an offence in 2006.
• The court determines that the appropriate minimum punishment is 18 months.
• Person A serves 18 months.
• But because they cannot satisfy the requirements of the post-sentence risk system, they remain imprisoned for another 10 years.

At that point, the question becomes:



Are we still punishing the person for the crime, or are we imprisoning them for what we think they might do in the future?



That's precisely why IPP became so controversial.



There has also been criticism that prisoners can find it extremely difficult to demonstrate their rehabilitation because access to appropriate courses and rehabilitation programmes has itself been inadequate.

And I think the couple of thousand you remembered is particularly significant: you're very likely remembering the roughly 2,500-3,000 IPP prisoners still incarcerated, rather than people who were simply given unusually long conventional sentences. As recently as 2025, reports were still putting the number above '2,500'. ([The Independent][3])



If you want, I can take this further and show you 'the actual history of the IPP scandal - who introduced it, why it was introduced, why it was abolished, why Parliament didn't make the abolition retrospective, and why successive governments have still failed to resolve the remaining cases.' That story is quite remarkable.




[1]: 'Sixteen years for stealing a flower pot: the film about the IPP jail sentence 'designed to bury you alive' | Movies | The Guardian'

[2]: Why won't ministers undo this 'stain on the justice system'?

[3]: 'Indefinite jail sentences: Senior judge Sir John Saunders says he would apologise to IPP prisoners he jailed | The Independent'

[4]: Marc Conway risked his life to stop the London Bridge terror attack. Why did he fear being sent to prison for it?