Sentencing of dangerous offenders

The Prison Reform Trust and the Institute for Criminal Policy Research at King’s College London have called for an urgent review of the social and financial costs and benefits of the controversial indeterminate sentence of imprisonment for public protection (IPP). 

The IPP sentence was created by the Criminal Justice Act 2003 (CJA). The sentence enables the courts to imprison for an indefinite period those convicted of violent and sexual offences who are deemed to be dangerous, but whose offending is not so serious that they qualify for a life sentence.

Around 6,000 people have received the sentence since it was implemented in April 2005; about 2,500 of these are currently being held in custody beyond expiry of their minimum term in custody, or ‘tariff’.

Professor Mike Hough at the Institute for Criminal Policy Research led an investigation into the IPP sentence and its implementation. His research was funded by the Nuffield Foundation and concluded:

Main findings

  • The IPP was poorly planned and implemented. 
  • Projections about levels of use of the IPP were inadequate and, as a consequence, the resources required to implement the sentence were far too limited. 
  • The ability to predict the risk posed by those convicted of violent and sexual offences was over-estimated. 

Based on these findings Professor Hough identified three main policy options: 

  • To abolish the IPP sentence, and revert to the use of the discretionary life sentence to deal with those who genuinely pose a grave risk to society. 
  • To retain the IPP sentence but further narrow its criteria, to ensure that it is used less often, and targeted more carefully on those representing a real risk of serious reoffending. 
  • To leave the current arrangements in place, but locate sufficient resources to enable the Prison Service and Parole Board to operate release from the sentence in an effective, humane and fair way. 
Project details



Professor Mike Hough, Institute for Criminal Policy Research

Funding programme

Open Door

Grant amount and duration


May 2007 - June 2009



Unjust deserts: Imprisonment for public protection, by Jessica Jacobson and Mike Hough, Prison Reform Trust, July 2010

Download Report (PDF)