An extended sentence is comprised of two parts : a ‘normal’ prison sentence, and an extended period of time on licence. It can only be imposed for certain, generally more serious, sentences.
An extended sentence can only be imposed if someone has been convicted of a ‘specified offence’ (one that is listed in Schedule 15 Criminal Justice Act 2003). These are offences that are relatively serious, and of a violent or sexual nature.
Before one can be imposed, a judge has to rule out a life sentence or IPP (if it could be imposed).
If a judge thinks that, due to the nature of the offence and the sort of person you are, you present a danger to the public (in that you present a significant risk of serious harm) and that the public needs extra protection, but an IPP is unnecessary, then an extended sentence can be imposed (but does not have to be).
But this can only be imposed if :
(a) You have been convicted previously of a Serious Specified Offence (an offence listed in Schedule 15A). These are the more serious offences, OR
(b) The Judge would impose a sentence of at least 4 years imprisonment.
If the maximum sentence available is a fixed term (ie, not life imprisonment), then the total sentence cannot exceed the maximum.
The extension period cannot be more than five years for a violent offence, or eight years for a sexual offence.
The minimum ‘normal’ part of the sentence is 12 months. If a judge imposes an Extended Sentence and would otherwise have given a ‘normal’ sentence of under 12 months, he has to give a 12-month sentence (plus the extension period). There is no minimum period of extension.
An important thing to note is that for someone serving an extended sentence, they have to go before the parole board and get their approval before being released.