One who commits, as a principal or accessory, certain violent or sexual offences specified in the Criminal Justice Act 2003 (sch 15) where the court is of the opinion that there is a significant risk to members of the public of serious harm occasioned by the commission by him of further specified offences. Under a sentencing scheme introduced by the 2003 Act, dangerous offenders will be given an extended sentence of imprisonment, which is a determinate sentence of which the defendant must serve at least half. The defendant may be released during the second half of the sentence, providing he receives a positive recommendation from the Parole Board. In addition to the extended sentence provisions under the Act, dangerous offenders must also receive extended supervision periods of up to five years for nonviolent offenders and up to eight years for violent offenders. The dangerous-offender sentencing scheme under the 2003 Act replaces the custodial sentencing schemes in the Powers of Criminal Courts (Sentencing) Act 2000, under which offenders convicted of a violent or sexual offence were subjected to “longer than commensurate” sentencing when this was deemed necessary to protect the public from serious harm, and where offenders convicted of a second serious offence received automatic life sentences.