INTRODUCTION

An unprecedented expansion of penal control has occurred in recent decades in different parts of the world. Since the mid-1970s, North American imprisonment rates have increased nearly fivefold. Many other countries followed from the 1980s onwards, in Africa, Asia, Europe, South America and Oceania. This has resulted to high imprisonment rates and severe overcrowding. In 2016, more than two out of three countries have an occupancy rate of over 100%. In the worst cases, the number of prisoners exceeds the number of prison places by three to one.

This text gives an overview of major trends in the use of imprisonment across the world. Trends and differences in imprisonment rates are examined both cross-sectionally and over time.

Imprisonment rates. In the following, the use of imprisonment is examined mainly in terms of imprisonment rates / 100,000 population. Imprisonment rates indicate how many of its residents the state keeps in prison on any given day (Stock-statistics). The main data-source is the World Prison Brief database (WPB). The database is hosted by the Institute for Criminal Policy Research (ICPR), at Birkbeck University of London. The WPB holds statistics for 223 independent countries and dependent territories. For most countries, there is also data on specific categories of prisoners, including juveniles, persons detained in pre-trial or prior to sentencing, female prisoners and foreigners. Other sources include the Council of Europe data from the SPACE I project. It allows more exact comparisons between European countries by providing standardized (adjusted) figures through the use of identical counting methods. The third source of information includes national time-series, dating back to the early 1960s or early 1980s.

Besides stock-based imprisonment rates, the use of imprisonment can also be measured by the number of people admitted to prison (flow-statistics), or by the length of served prison terms. Both measures provide complementary information about a country's prison profile. On the other hand, imprisonment rates (as stock-statistics) are a function of the number of entries and the duration of stay. It thus tells more than either of these two options alone and is the most complete basic indicator for the use of imprisonment.