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Produced by the Sentencing Academy

Measuring Sentence Inflation

A Review of Recent Research and Developments

Jose Pina-Sánchez, Julian V. Roberts and Jonathan Bild

Published: 27 Oct 2025 Last updated: Apr 2025

Executive summary

  • This research paper reports findings from the first comprehensive analysis of ‘sentence inflation’ in England and Wales. Unlike previous analyses, this one encompasses all years since 2005 and all offences.
  • In a previous research by the Sentencing Academy, Pina-Sánchez et al. (2023) documented a significant increase in sentence severity in England and Wales over the last two decades. However, the extent to which this increase in sentence severity is due to a genuine process of ‘sentence inflation’ was unclear. The changing nature of crime might have affected the offence mix processed through our criminal courts. It is possible that the cases sentenced by the courts have become more serious over the period in question. To the extent that this has occurred it would constitute ‘explainable’ or natural inflation. If the cases sentenced are more serious, sentence severity should reflect this changing pattern.
  • The analysis relates two indices. One – the Imprisonment Index – measures sentence severity by combining the custody rate and Average Custodial Sentence Length (ACSL). The second index measures the seriousness of cases appearing for sentencing.
  • The Sentencing Academy’s submission to the Sentencing Review reported new analyses comparing trends of sentence severity and crime seriousness for three offence groups: sexual offences, drug offences, and criminal damage offences. In this report, we expand that preliminary analysis to include all major offence groups. This enables us to estimate the overall increase in sentence severity independent of changes in the mix of offences sentenced.
  • We estimate that since 2005, sentence severity has increased by 62%, while the seriousness of crimes processed through courts has increased by only 8%. This means that 87% of the increased sentence severity over the period was due to changes in sentencing practice, or as we term it, ‘sentence inflation’. Put differently, we estimate that sentencing in England and Wales is today 54% more punitive than in 2005. This is the first analysis to provide an estimate of the overall degree of sentence inflation in this or any other jurisdiction.
  • Our analysis reveals that sentence inflation has been far from uniform. Whereas no discernible pattern can be detected for drug offences, or public order offences, sentence severity for offences involving violence or weapons related offences has doubled since 2005. Sentence severity for fraud offences has tripled.

1. Introduction

Sentencing in England and Wales has become more severe over recent decades (Pina-Sánchez et al., 2023). This is due to a simultaneous reduction of short sentences for summary offences and longer prison sentences for triable either way and indictable offences. Specifically, the Average Custodial Sentence Length (ACSL) was 60% longer in 2024 than in 2005. Several possible causes have been suggested, ranging from legislative changes such as the introduction of statutory starting points for minimum terms for murder, the introduction of sentencing guidelines (Allen, 2016; Isaac, 2021; Pina-Sánchez et al., 2019); and underinvestment in probation and other alternatives to prison (Gauke, 2025).

However, it is possible that the increase in sentence severity might also be driven – at least in part – by a change in the mix of offences processed through courts. Successive budget cuts have forced police forces, the Crown Prosecution Service and HM Courts and Tribunals Service to prioritise the processing of more serious crime types. If so, it is likely that the observed increase in sentence severity is not entirely due to a change in sentencing practice. For example, if some less serious offences of assault were resolved by way of out of court disposals, the cohort of all assault cases receiving a sentence in court would contain a higher proportion of the more serious assaults. This could explain a higher custody rate or longer average prison sentence for the category of assault convictions processed through the courts.

On the 20th of February 2025, following the publication of Part 1 of the Sentencing Review led by David Gauke, the Ministry of Justice (MoJ) published a study testing this hypothesis. The report found some evidence that the increase in sentence severity was partially due to a change in the offence mix, but only for a few offence groups and certain years. However, this study was limited in that it only reported whether trends in sentence severity and crime seriousness pointed in the same direction. It did not provide an estimate of the overall change of sentencing practice, nor did it help visualise changes over time.

In the Sentencing Academy response to the Sentencing Review (Roberts et al., 2025), submitted on the 9th of January 2025, we employed a different methodology to investigate this issue. We created indexes of sentence severity and crime seriousness and plotted them against each other to observe how they change over time. The Imprisonment Index is composed of the custody rate combined with the average custodial sentence length (ACSL). The Crime Seriousness Index drew upon the Office for National Statistics (ONS) Crime Severity Score.

Given the urgency to respond to the Sentencing Review, the analysis we presented in Roberts et al. (2025) was restricted to just three offence groups: drug offences, sexual offences and criminal damage.1 This new research expands our analysis by including all other major offence groups. By providing a comprehensive examination of the change in sentencing trends experienced in England and Wales, we provide the first estimate of the extent to which the increase in sentence severity corresponds to a true change in sentencing practice, or as we term it, ‘sentence inflation’.

2. Analytical Strategy

Our analytical strategy involved contrasting trends in sentence severity with trends in crime seriousness in England and Wales over the 20 years from 2005 to December 2024. The datasets we used were manually derived from the pivot tables in two criminal justice statistics reports from the MoJ. For the period covering 2010 to 2024 we used data from ‘Criminal Justice System statistics quarterly: June 2024’, and from 2004 to 2009 we used data from ‘Criminal justice system statistics quarterly: December 2014’. We could not go further back in time as earlier reports did not disaggregate sentence outcomes by offence type in a consistent manner.2

Measuring Sentence Severity and Offence Seriousness

To estimate differences in sentence severity across offence types and time we multiplied the custody rate observed for each offence type by their average custodial sentence length. This is the Imprisonment Index.3

To estimate the level of crime seriousness for each offence category and year we used the ONS Crime Severity Score (CSS). At the core of the CSS is a weighting system, based on sentencing data, designed to reflect the seriousness of each crime type (Bangs, 2016). The seriousness scale combines sentence ranges in the sentencing guidelines, actual sentencing outcomes from court data, and subjective expert judgements.4 For crimes resulting in prison sentences, the length of the sentence (measured in months) forms the basis of the weight.5 For crimes leading to community order and financial penalties, the length of time to complete the order and the size of the fine are converted into an equivalent harm measure. Crimes that rarely result in prosecution or sentencing are assigned weights based on expert judgment or analogous offences. The resulting weights are standardised to create a consistent scale, ensuring that crimes of greater harm (e.g., homicide or grievous bodily harm) have higher values than less serious offences (e.g., shoplifting or graffiti). A more detailed example of how crime seriousness weights are calculated for the case of shoplifting can be found here, and the full list of crime severity scores for each offence type here.6

3. Findings

When we compare trends in sentence severity and crime seriousness across all offences, a clear pattern of increasing divergence emerges over time (Figure 1). The only exception is the pandemic period, which caused a sharp decline in sentence severity, followed by an equally significant rebound the following year.

Specifically, we estimate that, in England and Wales, since 2005, sentence severity has increased by 62%, while the seriousness of crimes processed through courts has only increased by 8%. This means that 87% of the increased sentence severity was due to genuine sentence inflation. Put differently, we estimate that England and Wales has experienced an increase in sentence inflation of 54% since 2005.

Figure 1: Trends in Sentence Severity and Crime Seriousness (2005 as baseline)

Sentence Inflation Varies Across Offences

Figure 2 illustrates offence-specific trends and reveals that sentence inflation has been far from uniform.7 No discernible pattern of sentence inflation can be detected for drug offences and public order offences, at least until 2021. However, we observe significant sentence inflation affecting offences involving violence, weapons, and fraud. Specifically, we estimate that sentence outcomes for violent and weapons-related offences are now twice as severe as in 2005. Sentences for fraud offences have tripled in severity.

Figure 2: Trends in Sentence Severity and Crime Seriousness (2005 as baseline)

4. Conclusion

The increase in sentence severity observed in England and Wales over the last two decades cannot be attributed to changes in the offence mix processed through the courts. Using our Imprisonment Index and the ONS Crime Severity Score, we estimate that sentencing today is 54% more severe than it was in 2005.

Although our analyses were able to reflect relative changes in the offence types processed through court, some other factors relevant were not captured by the analysis. If the criminal histories of offenders appearing for sentencing had become more serious over the past 20 years, this would explain some of the increase in sentence severity. Similarly, if there had been an increase in the proportion of offenders pleading not guilty, this too would contribute to an increase in sentence severity. Offenders with more serious criminal histories generally attract more severe sentences, and offenders convicted following a trial (rather than having pled guilty) also receive more severe sentences. There is no evidence to suggest that the seriousness of criminal histories or guilty plea rates have changed significantly over the period covered by our analyses, however we do not know whether guilty pleas and previous convictions are now more or less present in the more severe offences, which could be biasing our findings to some extent. Future research could explore these possible explanations for changes in sentence severity by controlling for both guilty plea, previous convictions, and their interactions with offence severity.

In addition, future research should explore the relative impact of different contributors to sentence inflation. These could include: i) increases in statutory minima/maxima for specific offence types; ii) changes to the sentencing powers of the magistrates’ courts; iii) punitive populist views influencing sentencers; or v) the indirect effects of budget cuts in the criminal justice system, such as the increased proportion of ‘cracked’ trials, court backlogs, or the number of unrepresented defendants.

This paper is part of a series covering developments in sentencing research, policy, and practice in England & Wales. Other Research & Policy Papers can be found here.

For further information, contact Annalena Wolcke at a.wolcke@sentencingacademy.org.uk

References

  1. We found markedly different patterns: i) the increase in sentence severity was explained by a change in the offence mix; ii) for criminal damage and arson, offence seriousness closely followed changes in sentence severity, but they increasingly diverge across time; iii) sexual offences presented the clear case of sentence inflation since sentence severity grew steadily while crime seriousness remained stable throughout the last two decades. ↩︎
  2. The datasets derived from the MoJ criminal justice statistics and the R code used in our analysis are available here and here. ↩︎
  3. It can be expressed mathematically as: 𝑌𝑖,𝑡 = 𝐶𝑖,𝑡 ∙ 𝐿𝑖,𝑡, with 𝑌 referring to sentence severity, 𝐶 to custody rate, 𝐿 to average sentence length, with subindexes 𝑖 and 𝑡 used to distinguish across offence types and years. ↩︎
  4. For more information on the methodology, see ‘Crime Severity Score data tool’. ↩︎
  5. Both our measures sentence severity and crime seriousness include a component of sentence data. However, any ‘circularity bias’ is avoided by the fact that the estimation of weights for the ONS crime seriousness score relies on cross-sectional data, namely average sentence outcomes in England and Wales from 2011 to 2015. That is, we only use one weight for each specific offence type, rather than updating the weights across the window of observation of our analysis. ↩︎
  6. To estimate the changing levels of crime seriousness across time, which we denote as 𝑋𝑖,𝑡, we use an arithmetic mean for each of the ten offence groups that we explore, so: 𝑋𝑖,𝑡 = 𝛴(𝑊𝑖∙𝑛𝑖,𝑡) / 𝑁𝑡, where 𝑊𝑖 refers to the severity score allocated to a specific offence type, 𝑛𝑖,𝑡 denotes the number of sentences imposed of the specific offence type (e.g. indecent assault) within a year, and 𝑁𝑡 the number of offences sentenced within the broader category under analysis (e.g. sexual offences) in a year. ↩︎
  7. Changes in crime seriousness within Robbery offences could not be calculated as this offence group is composed of a single offence type. ↩︎