Analysis of prison population levels: FOI release

Information requested

Scottish Government analysis underpinning the claim that Scottish Conservative Justice policy would result in 3000 additional prisoner places being required across the prison estate.

Response

The figures are based on analysis which was undertaken in 2016 to assess the potential impact of the Scottish Conservative Party’s election manifesto proposals on automatic early release from custodial sentences.

The analysis used the most recent data available then on prison population and release patterns, to estimate how the prison population might change under various scenarios of how revised release criteria might affect the proportions of the prison population being released. The revised criteria  applied in the analysis were based on prior amendments lodged by Conservative MSPs to the Criminal Justice (Scotland) Act 2016 when it was being considered by Parliament in 2015.

The estimated additional places alluded to, were derived from comparing prison population levels under prevailing release practices at the time with what might happen if these were changed in line with the amendments lodged. So if all prisoners were released at the end rather than the halfway point of their sentence, one might expect the prison population to double in the long term, all other things being equal. 

The results of the analysis referred to in your request are shown in the following table, along with the assumptions which underpinned it.

Impact of changing early release practice

   Additional prison places for population at equilibrium

Sentences under 4 years	Sentences of 4 years or more (excluding life)
2,400	700

Source: Scottish Government Justice Analytical Services

Notes:
Figures have been rounded to nearest 100
Base population as at 31 March 2012 (3,600 short term, 1,600 long term).
Impact assessed in relation to prevailing release practices in 2016.

Assumptions
Currently all short termers are released at halfway point.
If discretionary release implemented, unlikely to involve intermediate review process due to timescales. Assume all released at 5/6 point

Currently about 35% of long-termers get parole licence (release at halfway point) (Parole Board figures and criminal proceedings data), the rest are automatically released at 2/3 stage on non-parole licence. Assume 80% released at 5/6 point and 20% at the end point, 

Method
Extra places assessed by multiplying the existing population by an estimate of what proportion of extra prison places would be required if the release process was changed (population at equilibrium, all else being equal).

For the short termers, the population would increase by two thirds (100% released at 5/6 point divided by 100% released at 1/2 point), which for a population of 3,600 gives 2,400 extra places.

For the long term population, the increase would be about 40% (80% released at 5/6 stage and 20% released at end of term divided by 35% released at 1/2 point and 65% released at 2/3 point).

 

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