There is no universally accepted definition of prison overcrowding. What is it, exactly? The Council of Europe describes it as a situation in which “demand for space in prisons exceeds the overall capacity of prison places in a given member state or in a particular prison of that state.” Simply put, when there are more incarcerated individuals than available places, the occupancy rate exceeds 100% and the facility is considered overcrowded.

It is more complicated to identify what exactly is meant by one prison place. The European Committee for the Prevention of Torture (CPT) recommends a minimum of 6 m2 per person in single-occupancy cells and 4 m2 for multiple-occupancy cells – not including sanitary facilities. Each country is free to decide whether or not to follow these recommendations. In the Netherlands, the minimum standard is set at 10 m2 per person. It is 3 m2 in Italy and Poland. Clearly, each country defines the living space that it considers to be one place. As such, calculations for prison occupancy levels and overcrowding differ from one country to the next.

National averages also conceal local disparities, which are often rather significant. Some areas experience more pronounced prison overcrowding, in line with local contexts or policies. This is the case for the French overseas departments and territories, where occupancy rates greatly exceed those in mainland France. In December 2024 in Mayotte, 650 people were incarcerated at Majicavo prison, which was built for 278 places. This represents an occupancy rate of 240% at this facility, while the national occupancy rate was 129.5% on the same date.

Some types of facilities tend towards overcrowding more than others. In Poland and France, remand prisons, where people are held while awaiting sentencing or while serving short sentences, are more overcrowded than facilities holding convicted individuals. In Romania, overcrowding is concentrated in prisons with closed detention regimes and in remand detention centres.

National prison occupancy rates therefore represent an incomplete and sometimes misleading piece of data. Taken individually, they cannot give a clear picture of the reality of a country’s prisons and are even less helpful in understanding carceral issues. This figure must be viewed as an indicator for various carceral policies: do we incarcerate more or less than before? Who is imprisoned, on what grounds and for how long?

Europe’s prison population has risen nearly 12% over the last 25 years. This figure is trending upwards – and with it, overcrowding is spreading and getting worse. What could explain this saturation? To understand it, one must navigate through the criminal justice system to its origins and observe through the peephole what came before incarceration. Overcrowding is merely the consequence of deeper causes.

The growing reliance on incarceration is the primary driver of overcrowding: the more people we lock up, the fuller facilities become. This process is measured by the rate of incarceration – the number of people incarcerated per 100,000 inhabitants – which, in Europe, is on the rise. Among countries studied by the Council of Europe, the median prison population rose from 101.8 incarcerated people per 100,000 inhabitants in 2021 to 106.5 in 2023. The increase was particularly significant between 2020 and 2023 in Hungary, where the rate rose from 180 to 211; in France, from 93 to 106; and in Denmark from 67 to 71. Similar trends have been observed in Italy and Portugal.

What is behind increased incarceration? Contrary to popular belief, it is not a rise in delinquency or criminality. That was the conclusion drawn in a recent study carried out in the cantons of Geneva and Vaud, in Switzerland. The results, published in July 2025, are unquestionable: “the significant rise in the number of incarcerated individuals in the cantons of Geneva and Vaud took place specifically during a general period of low criminality in Switzerland, in particular from 2011 to 2018, in which a clear decrease was observed in most of the offences that supposedly contribute to incarceration, notably theft, burglary, robbery, and drug trafficking”. The authors thus concluded: “The idea that prisons are full because criminality is higher in Geneva and Vaud compared to other cantons, or even because criminality is constantly rising over time, relates more to belief than scientific evidence.” Criminality is not the cause of prison overcrowding: an increase in behaviours criminalised by law is. The number of behaviours considered to be offences, infractions or serious criminal offences is rising.

 In France, nearly 3,600 new offences were created in eleven years, ranging from very minor offences to serious criminal offences. Passive soliciting, occupying a site during a meeting or a building entrance or even driving without a license now constitute misconduct.

Inevitably, widening the carceral net necessarily leads to higher numbers of people being convicted and subsequently incarcerated. The growing recourse to prison sentences drives up the numbers, even when the sentences are short. In Switzerland, 66% of the incarcerated people released in 2022 had spent less than three months in detention. The same year in England and Wales, nearly two in five prison sentences were for six months or less.

The use of preventive detention is also increasing in numerous European countries. Between 2023 and 2024, the number of people locked up while awaiting judgment in France increased by around 19%; in Norway, by over 45%; and in Portugal by nearly 9.5%.

Procedures to ensure expeditious trials, such as immediate appearances in France, accelerate the timeline for processing cases but often lead to more severe sentences, further filling up prisons.

The lengthening of sentences in certain countries has a serious impact on prison overcrowding. This is the case in England and Wales, where the average duration of detention is much longer than it was 25 years ago.

Overcrowding is the result of a combination of prison policies that increase reliance on incarceration. As long as the root causes are not resolved, the problem will crop back up time and again. Could building new prisons help curb this phenomenon? Several European countries are counting on an expansion of their prison estates to check overcrowding. The true impact of these additional places still remains to be measured.

The United Kingdom has already earmarked around 2.3 billion pounds sterling for the construction of 6,400 additional places. By the end of 2025, the government plans to spend 12 million pounds on 10,000 new places. Belgium has invested in “masterplans” such as Haren Prison: one billion euros for the construction of this massive prison complex, which opened in 2022 with a capacity of 1,400 incarcerated people. The number of prison places in Belgium continues to grow – 6,574 in 2021, 9,567 in 2022, 9,712 in 2023 – while overcrowding follows the same trend – rising from 108% in 2021 to 114.6% in 2022 and 115.3% a year later. In France, the number of prison places has remained stable – 60,583 in 2021, then 60,662 in 2023 – while overcrowding has climbed unrelentingly, rising from 103.5% to 119.2% over the same two-year period. While the debt incurred for the construction of new prisons has reached nearly 5.4 billion euros in 2025, even the French prison service observes that “if the number of incarcerated people continues to rise, [new] places [in prisons] will not help control occupancy levels in remand prison districts¹ across the country.”

In addition, the construction of new facilities raises various issues. Choosing a location is often controversial because few communities are interested in welcoming a prison into their local area. On top of that, worksite delays lengthen the period between the announcement of the intention to build and the prison’s effective opening.

 Another major challenge presents itself: how can prison services ensure operations at these new facilities while existing prisons are already facing staff shortages? In the Netherlands, the shortage of prison staff is such that in September 2024, the Ministry of Justice suggested that incarcerated individuals could serve their sentences in Estonian prisons.

In contrast, some countries have succeeded in decreasing the occupancy levels of their prisons without increasing the number of places. This is the case in Greece, whose prison density shrunk from 107.6% to 102.9% between 2022 and 2023, i.e. nearly 78,000 fewer incarcerated people, with the same number of places.

The numbers speak for themselves: building new prisons only adds more bricks in the wall, without any impact on prison overcrowding.

Overcrowding is the tree that prevents us from seeing the forest. Behind it, we catch glimpses of an increase in the number of criminalised behaviours, the growing reliance on preventive detention, the lengthening of sentences, and all the penal policies causing a steady increase in the number of incarcerated people. It does not have to be this way. Other paths are possible, such as reducing the use of prisons. This is the choice made by several countries – especially in Scandinavia – which have adopted a resolutely reductionist approach. They have managed to reduce the use of prisons and continue to maintain some of the lowest incarceration rates in Europe.

In the Netherlands, the rate of incarceration was divided by 2.3 between 2006 and 2018, dropping from 125 incarcerated individuals per 100,000 inhabitants to 54. This downward trend is the result of a drop in recidivism, budget cuts and increased use of non-custodial sentences. And it has only continued: over the past ten years, the size of the prison population has remained relatively stable, with 9,334 people incarcerated in January 2023, despite a slight increase more recently. In Norway, the number of incarcerated individuals fell from 3,850 in 2016 to 3,044 in 2025.

Researcher Julie de Dardel demonstrates how policies of decriminalisation, sentence reductions, limiting remand detention and promoting alternative sentences enabled Finland to halve its incarceration rate between the end of World War II and 1980, then by another half by 2018. It has continued to maintain this rate, with 52 incarcerated individuals per 100,000 inhabitants.

In addition, the penitentiary systems in these countries are often touted as “carceral models”, featuring open facilities, small-scale structures, a low reliance on prison and reinforced reintegration systems. The prison conditions there are reportedly more respectful overall of human rights. Although this might be the case regarding material conditions, such as accommodation and hygiene, can the same be said of other aspects of detention? In Norway, the evaluations of the Prison Life Index highlight frequent violations of the physical and psychological integrity of incarcerated people in 2024. The excessive use of solitary confinement, in particular for those with mental disorders, is a recurring issue. Can these really be called “models”? These countries definitely incarcerate less, but does that necessarily mean rights are respected? This is the very question that Prison Insider asks in the next article in this series.