An IPP (Imprisonment for Public Protection) sentence is a form of indeterminate sentence that was introduced in England and Wales by the Criminal Justice Act 2003. IPP sentences are given to serious offenders who pose a significant risk of harm to the public. Unlike fixed-term sentences, IPP sentences have a minimum term that must be served in custody, sometimes called a tariff. After completing their tariff, offenders can apply to the Parole Board for release. However, the Parole Board will only release an offender if it is satisfied that it is no longer necessary for the protection of the public for the offender to be confined. If offenders are given parole, they will be on supervised license for at least 10 years. Although there is no limit to how long prisoners can be detained under IPPs, and some may never be released, they may be released on review; an IPP sentence is not a sentence of life imprisonment with a whole-life tariff. IPPs have been criticized for being difficult to understand and leading to inconsistent sentencing. IPP sentences for new cases were abolished by the Legal Aid, Sentencing and Punishment of Offenders Act 2012, enacted under the coalition government. However, thousands of people remain in prison, held not for what they have done, but for what they might do. Current IPP prisoners will continue to serve their sentences, and will not be affected by the changes.