The government is weighing up whether chemical castration should be made mandatory for some of the most serious sex offenders, as part of a wider set of reforms aimed at tackling prison overcrowding. Justice Secretary Shabana Mahmood has announced plans to expand a voluntary pilot scheme to 20 prisons across England and Wales. She has also confirmed that the possibility of making the treatment compulsory in certain cases is under review.
The treatment involves a combination of medication and psychological therapy. The drugs work to reduce libido and limit compulsive sexual thoughts, while therapy addresses underlying causes of sexual offending, such as power, control and coercion. Currently, the programme is voluntary. Offenders can choose to take part if they meet the criteria and give informed consent.
The idea of making this treatment mandatory has drawn attention for a number of reasons. Supporters say it could help reduce reoffending, particularly among a small group of offenders who remain a high risk to the public. But others, including medical professionals, have raised questions about what compulsory treatment would mean for patient consent and medical ethics. Professor Don Grubin, a leading expert in forensic psychiatry, told the BBC he doubts a mandatory scheme would be accepted by doctors, describing it as “very unethical”.
Shabana Mahmood has said she is “not squeamish” about taking stronger measures to prevent further harm, but stressed that any national rollout would need a solid evidence base. A small pilot in the south-west of England has been running since 2022 and is set to continue into next year. Results from earlier schemes suggest a reduction in reoffending among participants, but the data is limited and researchers say more time is needed to properly understand the long-term impact.
Former justice secretary David Gauke, who led an independent review of sentencing and prison policy, recommended continuing the voluntary pilot and building a stronger evidence base. His report also highlighted examples from other European countries. In Germany and Denmark, similar treatments are used on a voluntary basis. Poland is the only country in the EU where chemical suppression has been made mandatory in certain cases.
The drugs used – typically SSRIs and anti-androgens – are already prescribed in the NHS for a range of conditions, including depression and hormone-related disorders. When used in this context, they can help reduce sexual preoccupation and arousal in individuals where these patterns have played a role in serious offending. The treatment is not considered suitable for every case, and the review makes clear it should never be used as a substitute for wider rehabilitative work.
Within feminist and survivor advocacy spaces, the idea of chemical castration often divides opinion. Some see it as a necessary step to prevent repeat harm and improve community safety, particularly when the criminal justice system has historically failed to protect women and marginalised groups from sexual violence. Others warn that focusing too heavily on medical intervention risks simplifying a complex problem. Sexual offending is rarely just about desire – it’s also about power, entitlement and lack of accountability, and experts have consistently argued that meaningful change requires addressing those drivers too.
Gauke’s review, commissioned in response to the growing crisis in prison capacity, made a series of recommendations aimed at reducing reliance on short-term sentences and investing more in probation services. Alongside proposals like increasing the use of electronic tagging and specialist domestic abuse courts, the report called for greater flexibility in sentencing and a clearer emphasis on victim protection. It also warned that without increased funding, reforms may fall short of their aims.
Mahmood is expected to outline which recommendations the government will accept in the coming weeks. While her support for expanding the chemical castration pilot marks one of the more high-profile aspects of the review, it sits within a much larger package of changes aimed at rethinking how the justice system handles risk, rehabilitation and public safety.
For now, the treatment remains voluntary and relatively limited in scope. But its future and its use will depend on decisions made in the coming months. Those decisions will shape how the justice system defines consent, protection and accountability in the long term.
