Blog: Tackling Prison Overcrowding – Lessons from International NPMs
In November 2025, Sam Gluckstein, outgoing Head of the UK NPM, attended one of the quarterly European NPM Forum workshops in Strasbourg: “Tackling Overcrowding in European Prisons: Strengthening NPMs’ Role in Safeguarding Rights and Ensuring Effective Oversight.” The event gathered experts from 38 countries to support NPMs in scrutinising one of the most persistent human rights challenges in Europe—prison overcrowding.
Overcrowding poses a systemic risk to detainees’ rights and dignity, heightening the likelihood of ill-treatment, undermining rehabilitation, and creating conditions where monitoring becomes more complex. Understanding the drivers, consequences, and solutions to overcrowding is essential for effective intervention by inspectors and monitors.
Key Insights
At the workshop, several key insights were highlighted by distinguished speakers, including from international NPMs, the Committee for the Prevention of Torture (CPT), international and civil society organisations and academics:
1. Building more prisons Is not the answer
Experts stressed that expanding prison infrastructure is not a sustainable solution. Instead, reforms should focus on reducing reliance on incarceration through alternatives such as probation, community sanctions, and restorative justice. Evidence from the Netherlands, Spain, and Estonia shows that sentencing reform and non-custodial measures are far more effective in reducing prison populations.
2. Recognise the human impact
Overcrowding compromises access to healthcare, education, and rehabilitation, disproportionately affecting vulnerable groups. Inspectors and monitors should focus on these areas during visits and highlight systemic risks in reports.
While focussing on these immediate issues of prison overcrowding, the workshop made clear that tackling them requires more than emergency fixes—it demands systemic reform, cultural change, and robust oversight. For NPMs, this means moving beyond observation to active advocacy, leveraging OPCAT powers, and ensuring that monitoring translates into meaningful policy impact:
3. Leverage OPCAT powers
Article 19 of OPCAT gives NPMs a mandate to influence legislation, which is often underutilised. The workshop urged NPMs to move beyond monitoring to actively shape sentencing policies and pre-trial detention practices.
4. Document conditions with precision
Guidance from UK NPM former Chair John Wadham on NPM reporting emphasised concise, evidence-based reports. Clear, high-quality documentation is critical for influencing decision-makers and ensuring compliance with standards.
5. Data transparency is essential
Without accurate capacity and occupancy data, oversight is ineffective. NPMs should advocate for open data policies and integrate comparative analysis into their monitoring frameworks.
6. Digital tools and AI – opportunities and risks
AI can support resource allocation and risk assessment, but ethical safeguards and human oversight are essential. The Council of Europe’s new treaty on AI sets clear principles: transparency, accountability, and compliance with human rights standards.
Digital literacy is now a critical component of effective scrutiny, particularly as the use of AI tools increases in detention settings. To drive this forward, the UK NPM has established an AI in Scrutiny Task & Finish Group, focused on building capacity, setting standards, and responsibly integrating technology into scrutiny practices. By combining traditional monitoring with innovative approaches, the UK NPM can continue to strengthen its ability to prevent torture and ill treatment in places where people are deprived of their liberty.
This blog was created with support from Microsoft Copilot Generative AI, guided and reviewed by the NPM Central Team, in line with UK Government AI policy. If you are interested to learn more about any of the topics discussed in this blog, please contact the UK NPM team.