1. Introduction The world’s prison population has risen substantially in recent decades and now stands at well over 11 million. In much of the world, increases in prison populations have not been matched by additional built capacity or greater investment in staff and other resources. This has led to overcrowded and unhealthy environments, with cramped living spaces and reduced access to the basic minimum requirements for human health: natural light, fresh air, drinking water, sanitation, food, medicines and treatment. Well over 60 per cent of countries have overcrowded prison systems today.1 People in prison retain their fundamental right to enjoy good health. They are entitled to a standard of healthcare equivalent to that provided in the wider community. When the state deprives people of their liberty, it takes on a responsibility to look after their health, by ensuring safe, healthy living conditions and by meeting treatment needs. The reality, sadly, is very far from this. Prisoners often arrive in prison with pre-existing mental and physical health problems, including untreated (perhaps undiagnosed) medical conditions. Poor material conditions and lack of healthcare cause these problems to worsen and can give rise to new health problems, among staff as well as prisoners. The consequences of overcrowded, under-resourced prisons for public health are serious, particularly as regards communicable diseases, mental illness, substance misuse and increased risk of violence, self-harm and suicide. The risk of harm exists not only for the millions of people (staff and prisoners alike) who spend time in overcrowded prisons around the world in any given year, but also for their families and wider communities. Damage to prisoners’ health also undermines prospects for rehabilitation and desistance from offending. Yet despite their severity and impact, the health risks presented by the over-use of imprisonment and by overcrowded, under-resourced prisons rarely figure in public or political discourse. 1.1 Background This report aims to provoke fresh consideration of the health risks associated with the over-use of imprisonment and to explain why addressing them should be regarded as a policy priority. It draws on data collected for ICPR’s international, comparative project, Understanding and reducing the use of imprisonment in ten countries (‘the ten country project’), which was launched in 2017.2 The project examines the use of imprisonment in the following diverse group of countries spanning all five continents: • Kenya and South Africa in Africa • Brazil and the United States in the Americas • India and Thailand in Asia • England and Wales, Hungary and the Netherlands in Europe • Australia in Oceania 1 Data on prison populations and (where available) national prison systems’ official capacity are available on the World Prison Brief website, hosted and published by the Institute for Criminal Policy Research (ICPR): http://www.prisonstudies.org/. The extent of global prison overcrowding is described in section 3.2.2 below. 2 The project’s first report (Jacobson et al, 2017) presented brief accounts of the ten countries’ recent patterns of imprisonment. The report showed that of the ten countries, only one – the Netherlands – has achieved a significant reversal in the upward trend, with a sustained reduction in prisoner numbers, although steady falls have also been seen in American prisoner numbers since their peak in 2008. The report can be accessed here: http://www.prisonstudies.org/sites/default/files/resources/downloads/global_imprisonment_ web2c.pdf 1