Why do perpetrators of serious crimes get long sentences only for them to be cut drastically short?
It has more to do with the actual sentences passed and the laws behind them. In the Uk the aim of custodial sentences is punishment but also rehabilitation into the community. The sentence expiry date (the date on which the sentence ends) is calculated from the date sentence is passed. All custodial sentences, (apart from life sentences, which are governed by different rules) include time served in prison and time served in the community, so the person will not be in prison for the whole of the sentence. How much time will they spend in prison? This depends on a number of factors, including the length of the sentence and date of offence: If the sentence is less than 12 months, regardless of when the offence was committed, the prisoner will get Automatic unconditional release (ACR) at the half way point (eg after 3 months of a 6 month sentence), serving half of their sentence in prison. From release until the sentence expiry date, they are classified as “at risk”. This means that if, du