Max Planck Institute for Foreign and International Criminal Law

Imprisonment is the most serious penal sanction that is frequently imposed in the modern state. Three kinds of questions arise in relation to a society’s use of imprisonment: the first is the general justification of the use of imprisonment as a criminal sanction, which addresses whether prisons should be used as a criminal sanction; the second is the justification of the use of imprisonment in particular cases, which concerns whether particular offenders should be sent to prison in the first place; the third is the separate question of the scale of the use of prisons as a penal method, which involves the size of a society’s prison system in relation to other criminal sanctions and to the general population.

How many prisoners? How many prisons? What criteria should govern decisions about how large a prison system should be, or how it should be constructed and maintained? The problem of imprisonment rates is distinctive and important. Although concerns have been intermittently raised about prison overcrowding throughout the 20th century, little attention has been paid to the factors which determine the extent to which imprisonment is used. Discussion of the purposes of punishment in general, and of imprisonment in particular, have taken precedence over questions concerning how far the use of imprisonment is responsive to social factors and what factors determine the amount of imprisonment imposed.

As prison populations have risen over the past few decades, interest in the scale of imprisonment has attracted increased attention in the field of criminal justice. In contemporary discussions on punishment it is customary though not without limitation, to use imprisonment rates per 100,000 as a measure of both the severity of penal policies in a jurisdiction and of changes over time. While the institution of the prison is a universal characteristic of modern nations, the scale of imprisonment varies substantially from place to place and over time. Since the early 1970s, the United States and the Netherlands have experienced steadily rising imprisonment rates so that they were roughly four times higher, per capita, at the beginning of the twenty-first century compared with early 1970s. Imprisonment rates in England and Wales were broadly stable from 1970 to the early 1990s after which they nearly doubled, rising to the highest level in the Western world after the United States. Similarly, over the past three decades, China has also experienced a dramatic increase in its imprisonment rate. China now maintains the second largest prison system in the world, second only to the US. It is estimated that since 1978 the Chinese imprisonment rate has increased between three and fourfold. At present the Chinese imprisonment rate is about 250 per 100,000. At the other end of the scale, the imprisonment rate of Finland declined steadily from 1970 to 2000. Between these extremes, patterns varied widely. Imprisonment rates in the Scandinavian countries other than Finland remained stable, varying between 50 and 70 per 100,000 throughout the period. Imprisonment rates in France and Italy oscillated, moving up rapidly, falling abruptly, moving up rapidly again, and so on. German imprisonment rates fell somewhat by the early 1970s from their average level during the 1960s and were broadly stable during the 1970s, 80s, 90s and the first decade of twenty-first century.

What are the factors which account for these variations? In other words, what has determined the different imprisonment policies in different countries? Five major theoretical models have attempted to answer this question: Durheim’s (1900) social control model, the Rusche-Kirchheimer (1939) economic model and the conflict theories that emerged from this perspective, Liska’s (1992) social threat model, integrated or multiple causal models proposed by Savelsberg (1994), Caplow and Simon (1999), Inverarity (1992) and Tonry (1999), and Black’s (1976, 1989) sociological theory of law. Inspired by these traditional theoretical models, numerous empirical studies have been undertaken in the US and Europe. However, these studies have been proved to be partially or completely unsatisfactory in terms of providing a general plausible explanation of the variations of imprisonment rates in these countries.

It should be noted that over the past three decades, political theories of imprisonment rates have also accumulated. Zimring and Hawkins (1991) have argued the possibility and necessity of the political economy of imprisonment. Jacobs and Helms (1996), Jacobs and Carmichael (2001), Tonry (2004, 2009), Zimring (2005), Cavadino and Dignan (2006), Lacey (2008) and Barker (2009) analyzed the politics of imprisonment in the US. Some European criminologists have related penal policies to the imprisonment rates in European countries such as England and Wales, Belgium, the Netherlands and Germany. However, generally speaking, these studies have been fragmental and parochial, and unable to provide a general explanation between politics and imprisonment. To a large extent, the issue of the variations of imprisonment rates remains unresolved.

As Tonry (2004, 2009) pointed out, a comprehensive comparative study of imprisonment rates is still seriously inadequate. It should however be recognized that this type of comparative research is undoubtedly necessary in the sense of providing a scientific foundation for decision makers. As such, the objective of this project is to explore the relationship between governmental structures as well as corresponding penal policy-making processes and the realities of imprisonment rates in specific country by analyzing the penal dynamics over the past three decades in the US, China and selected European countries which represent the five main patterns of imprisonment rates in the contemporary world. Based on these comparative, cross-sectional and longitudinal studies, this project will develop a general theory of the politics of imprisonment rates and make some suggestions for future penal reform. It is intended that the researchers involved in the project will produce a series of articles or a monograph. In addition, a collection of conference papers will also be published.

In this project, qualitative methodology and quantitative methodology as well as comparative methodology and longitudinal analysis methods will be combined. On the one hand, this project will critically review the theories available to explain variations in imprisonment rates: a new imprisonment rate theory will also be proposed in the final part of this project. On the other hand, empirical data and findings that relate to imprisonment rates in the US, selected European countries and China from the past three decades will be collected and analyzed. In addition, the researchers will conduct interviews with relevant experts and criminal justice professionals in China and selected European countries.