The World Prison Brief is 20! Roy Walmsley, its Founder and Director, reflects on the journey so far, in conversation with Catherine Heard.

28 Sep 2020

Since its launch in September 2000, the World Prison Brief (hosted and published by the Institute for Crime & Justice Policy Research, at Birkbeck) has become a gem of a resource – a completely unique database, giving open access to a wealth of information on prison systems worldwide. It now provides data on almost every country in the world. With a website visited over a million times a year and data relied on by policy makers, journalists, researchers, international agencies, NGOs and activists across the world, the Brief has gone from strength to strength.

CH: Roy, congratulations on this incredible milestone! I feel very lucky to have such a solid foundation for our World Prison Research Programme. You must be proud to have spotted the need and conceived the idea for the Brief?

RW: I’m not sure about pride, but I’m very pleased that it has proved useful. That was my goal – to fill a gap in knowledge and thereby enable better dialogue about comparative prison population levels.

CH: Let’s go back to the start. Before the launch of the database in 2000 there were a couple of years of hard graft, tracing and analysing prison populations data from various sources. How did you become interested? And what was that early work like?

RW: After university I worked as a probation officer. Then I moved into criminal justice research at the Home Office. I became deputy head of the Home Office research department, and was part of the UK delegation at the annual meetings of the United Nations Commission on Crime and Criminal Justice. Later, I was seconded to the UN as a consultant on the improvement of prison standards. This international work convinced me of the need for worldwide data on prison population levels and I decided I’d try to put this together.

CH: What challenges did you encounter at the start?

RW: Obviously I needed to present the data in a consistent way. So it was important, for example, to ascertain that the figures I traced covered the whole prison population, not just the sentenced population, and that they were the total at a specific date (or a daily average), not the total number of people who had passed through the prison system over a given year. That in itself proved challenging given the variable approaches taken by prison administrations to collecting and publishing their own figures.

CH: The result of that initial tracing work was the first ever World Prison Population List. What did that contain?

RW: Yes, by the end of 1998 I had put together a List which contained, for a total of 180 countries, the prison population totals, and the rates per 100,000 of the national populations, which I called the ‘prison population rates’. It was published in early 1999 and has been updated periodically since – the 12th edition came out in November 2018.

CH: And how did the World Prison Brief website come about?

RW: I wanted to show more details about the prison population in each country – for example, information about the number of pre-trial prisoners, the number of women, of children and of foreign prisoners. I also wanted to provide an indication of overcrowding by showing the occupancy levels in the prisons. In 2000 Professor Andrew Coyle, Director of the International Centre for Prison Studies (ICPS) gave me the opportunity to do exactly this. And at 5pm on Thursday 28 September 2000, the World Prison Brief was launched on the ICPS website by Professor Nils Christie of the University of Oslo, the world-renowned criminologist and sociologist. Data was presented on 200 countries.

CH: Since 2000, the website has gone from strength to strength. Can you tell us about the main developments in terms of its scope and functionality?

RW: The key developments have been:

  • The steady addition of more countries. The Brief now provides prison population numbers for all the world’s independent countries, except for Eritrea and North Korea (which never produce figures), and Somalia, where figures are not available for all parts of the country. It also provides data for all dependent territories apart from those with very small populations.
  • The introduction of the ‘Highest to Lowest’ lists showing where each country comes in terms of prison population and occupancy levels and the proportions of pre-trial, women and foreign national prisoners.
  • The introduction of information about trends in prison population levels and in pre-trial/remand imprisonment and female imprisonment.
  • And two further lists have been introduced - the World Female Imprisonment List (since 2006 - fourth edition 2017) and the World Pre-trial/Remand Imprisonment List (since 2008 - fourth edition 2020).

CH: One of the worst effects of the steady rise in prisoner numbers that the Brief has been charting since 2000 is overcrowding and the terrible living conditions it produces. What are your reflections on prison overcrowding and how occupancy data should be interpreted?

RW: The World Prison Brief provides an indication of overcrowding by showing the official capacity as stated by each administration and the occupancy level. This is only an indication of overcrowding because many countries set their official capacity at a level which allows so little space per prisoner that, according to international standards, anything close to 100% occupancy in such countries should be regarded as serious overcrowding. But it’s generally accepted that if a country’s prisons hold more prisoners than the official capacity that the country has set for its prison system (in other words the prison system has an occupancy above 100%), this is a clear sign that there is indeed overcrowding in the system. And that is what can be ascertained from the World Prison Brief.

CH: Obviously the data on the Brief and in its publications are only as good as the official sources they are drawn from.

RW: That’s right, of course. The more accurate and timely the national data, the better the Brief and its prison population lists will be. There are some notable gaps. China does not publish the total held in pre-trial detention and in the other forms of detention that are under the Ministry of Public Security. And in some countries pre-trial detainees who are held in police facilities are not included in official prison population figures. I’ve already mentioned the absence of data for Eritrea, North Korea and parts of Somalia. The publication of figures for some countries are published after a long interval and many countries in Africa and Western Asia (the Middle East) do not release figures on any regular basis.

CH: If the official sources are wrong or late, this is a limitation on the accuracy of the database. How can we tackle this?

RW: Our colleague, Helen Fair, does a huge amount of work to track down additional figures for countries that don’t regularly publish data, scouring news reports of speeches by government ministers and discovering numerous other published documents. We also invite researchers, NGOs and other national experts to draw our attention to additional data and to point out any official statistics that they consider unreliable.

CH: Do the Brief’s comparative and trend data operate as a spur to countries to reduce their prisoner numbers?

RW: I think so, yes. One example is the explicit policy of Kazakhstan to reduce the prison population such that its prison population rate no longer places the country in the 50 countries the Brief shows to have the highest levels.

CH: And Barack Obama, when he left office, wrote an article for the Harvard Law Review on the President’s role in advancing criminal justice reform, citing data from the Brief to show what an outlier America had become in its prison population rate.

RW: Yes. A number of American experts have made the same point but perhaps the voice of such a high-profile figure will be making some impact.

CH: As the Brief was officially launched in 2000 some people might assume its data only go back as far as 2000. But, in fact, it’s a treasure trove for penal historians isn’t it, more so now than ever before?

RW: Although the Brief was launched in 2000 it includes trend data going back further than that. The country pages show prison population data at two-year intervals back to 2000 (where that has been traced) and the ‘further information’ tab reveals pre-2000 data, where available, going back further at approximately five-year intervals. Also added to the site since its launch, and available via the ‘further information’ tabs, is trend information on pre-trial/remand imprisonment and female imprisonment. What’s more, new data has recently been traced for over 30 countries, showing prison population levels pre-1950. The data can now be accessed via the Brief.

CH: What would you hope for the Brief in years to come? Are there other categories of information you’d like it to cover?

RW: It would be good to provide additional information on those detained in the world’s prisons. Useful topics would be:

  • length of time spent in pre-trial detention;
  • length of sentences being served by convicted prisoners;
  • numbers of older prisoners;
  • numbers of deaths in prison and the causes.

Information on some of these topics is available, for example, for European countries through the Council of Europe’s Annual Penal Statistics (SPACE), but only a small number of countries elsewhere record and publicise data of this kind on a regular basis. To go beyond that small number would require extensive research which would be difficult to replicate on a routine basis.

CH: Looking back, what, for you, has been the Brief’s main contribution so far?

RW: It is in the interests of every country to be familiar with the basic statistics on its prison population. Only then can it make appropriate policy decisions. An important consideration, in making these decisions, can be to compare its prison population level with those in other countries. They can now do so via the Brief – which many do, as we see from the inclusion of international comparisons in their annual reports, citing the Brief as their source.

I think it’s fair to say that the World Prison Brief has contributed to the discourse on the use of imprisonment around the world. It is quoted widely by Governments, by prison administrations, by NGOs, in academic articles and journals, in regional and international conferences and in the media.

CH: Thank you, Roy, for the immense contribution you’ve made to improving understanding of the use of imprisonment around the world.




ICPR’s prisons research team:

Catherine Heard is a Senior Research Fellow at the Institute for Crime & Justice Policy Research, based at Birkbeck, University of London. Catherine directs ICPR’s World Prison Research Programme, incorporating the World Prison Brief. For more information on ICPR, go to:

Roy Walmsley is Director and Founder of the World Prison Brief, hosted and published by ICPR. For more information on the Brief and to access its data and publications, go to:

The prisons research team at ICPR also includes Professor Jessica Jacobson, Director of ICPR and Reader in Criminal Justice, and Helen Fair, Research Fellow and World Prison Brief researcher.

Note: The World Prison Brief was originally based at the NGO, the International Centre for Prison Studies, then moved to ICPR in 2014 following the merger of the two organisations.