Secretary of State for Justice Shabana Mahmood is reportedly looking into a potential ‘national rollout of voluntary chemical castration for sex offenders’. The proposal is one of the recommendations outlined in the recently published Independent Sentencing Review led by former Lord Chancellor David Gauke, commissioned to investigate ‘the prison overcrowding crisis and to consider alternative punishments to custodial sentences’. According to the Review, ‘sexual offences accounted for 21% of adults serving immediate custodial sentences at the end of March 2025’. Mahmood has said that she is ‘not squeamish about taking these further measures’ to extend use of anti-libidinal interventions (ALIs)—medication that lowers recipients’ testosterone levels with the aim of reducing their recidivism risk—and that she ‘will make sure that that is what happens’. While the Gauke Review focuses on voluntary ALI use and emphasises that ‘valid, informed consent’ to interventions ‘is a key tenet of medical law in England and Wales’, Mahmood has, according to the BBC, told the House of Commons that she is ‘exploring whether mandating the approach is possible’.
Don Grubin, Emeritus Professor of Forensic Psychiatry at Newcastle University, has expressed doubts that the government would ‘get the mandatory element of it off the ground’, as well as concern that it would be unethical to do, and that doctors would be resistant. He is right that there are a number of important ethical considerations in the mix, especially—but not exclusively—if ALI use is to be made mandatory.
ALIs’ Purpose and Ethical and Legal Permissibility
One key question concerns the purpose for which ALIs are used. ALIs are an example of dual-purpose intervention, that is, an interventions that can be used either to benefit recipients, or for public protection purposes, or both.
We need to know an intervention’s purpose to measure its success. The success of therapeutic interventions in health care is measured in terms of the patient’s health and well-being. A public protective intervention’s success in contexts such as criminal justice (and—sometimes—public health and mental health) is measured against other indicators, such as the recipient’s risk to others or actual recidivism. Sometimes, interventions both benefit recipients and reduce their risk to others, but sometimes they do one and not the other. ALIs may reduce the risk of reoffending, but may not improve a sex offender’s well-being, and vice versa. Which goal are we aiming for in ALI use?
Some news reports mention the importance of potential recipients giving their valid consent to ALIs. But consent requirements are much less straightforward when an intervention is used solely for public protection, or for both therapy and the protection of others, than when the goal is solely therapeutic. It may well be ethically permissible to provide ALIs without recipient consent if public protection is one of the state’s goals. Consent requirements vary according to an intervention’s purpose; what an intervention’s purpose is has important implications for its ethical and legal permissibility, and how its permissibility should be evaluated. We don’t normally ask for recipient consent to, for example, incarceration or probation, nor for quarantine or isolation.
To determine the ethical permissibility of ALIs, it is important to clarify how benefit/harm to recipients should be understood, and how benefit/disbenefit interacts with consent. As Gauke notes in an interview with Sky News, some sex offenders may wish to have sexual desires which they themselves find problematic attenuated. But as Professor Grubin notes, ALIs may also have significant side effects. Therapeutic interventions are typically ethically permissible when they are expected to benefit recipients who give valid consent. Assuming that ALIs are indeed effective in reducing problematic sexual desires, it is plausible that some sex offenders may be benefited by such interventions, side-effects notwithstanding. But it is unclear exactly how ‘benefit’ should be understood: Is it beneficial for sex offenders to have their sexual desires attenuated? Can we be benefited by being prevented from acting in immoral ways that are consistent with our desires? Does the possible avoidance of future punishment due to further offending itself count as a benefit? Can it be beneficial also to offenders who do not consent to the intervention? And when, if ever, may it be ethically permissible to provide ALIs without benefit to the recipient? A more clearly articulated understanding of benefit is required to answer the question of permissible ALI use.
Other important questions concern legal justification. While the Independent Sentencing Review is right to note that recipient consent is central in general health law, it is less clear that this offers a complete answer to the question of ALIs’ lawfulness. My analysis of the legal framework in England and Wales shows that providing ALIs to sex offenders may be consistent with the obligations imposed on public authorities in the UK under the European Convention on Human Rights (via the Human Rights Act 1998), even when this is done without recipients’ consent. Here too, it is necessary to clarify how benefit/harm to recipients interacts with recipient consent in determining lawfulness when interventions are used for different purposes. Interventions that use medical means—as ALIs do—are usually lawful to offer to patients under English general health law because they are expected to benefit recipients. Even here, it is unclear what ‘benefit’ means—e.g. whether it is narrowly-construed clinical benefit, or some broader welfare benefit, an issue I have explored in previous work (open access). But the lawfulness of interventions whose purpose is public protection—potentially not benefitting recipients at all—is even less clear. Careful analysis is needed of how English law construes benefit for the purposes of legal justification, and whether public protective interventions are lawful on the same normative grounds as therapeutic interventions or require distinct justification. The fact that ALIs are potentially non-beneficial (depending on how we understand benefit) makes their legal status unclear (even when provided with recipient consent).
Professional Obligations
A rollout of ALIs to sex offenders—whether voluntary or mandatory—also requires careful consideration of how the ethical and legal considerations bear on the obligations of those involved in or directing provision of these interventions—both individuals and (in particular state) institutions. Professor Grubin has said that the administration of ALIs is ‘about doctors treating patients, rather than doctors doing a job for criminal justice agencies, but a side effect is that reoffending is likely to be reduced’. However, it is not clear that ALI use should always be understood primarily as ‘doctors treating patients’, in the same way as we would normally expect for therapeutic interventions. ALI use in sex offenders will often generate conflicting duties, which we must find ways to navigate. Can it be compatible with professional obligations to provide interventions that aren’t in recipients’ clinical interests if it benefits others? Do professional obligations vary according to an intervention’s purpose? How might conflicts between providers’ obligations to individual recipients and to others/society be resolved? ALIs expose tensions in the ethical and legal obligations individual and institutional providers owe to recipients and to society.
These are some of the questions I explore in a new research project investigating how we ought to understand, evaluate, and regulate interventions that can be used for either or both therapeutic and public protection purposes, including ALIs. They are questions that the government, and those involved in provision, will need to carefully consider, when deciding on whether to extend the use of ALIs with or for sex offenders.
A shorter version of this blog post is published in The Conversation.