After a relatively quick pit-stop to deal with some niggling ethical queries, the UK NHS’s heavily challenged Randomised Controlled Trial (RCT) into Puberty Blockers for gender dysphoric children is back on the road again. In the following article Peter Jenkins provides some in-depth critical analysis of this concerning development.
Background
Hilary Cass, a leading paediatrician, produced a landmark review of gender care, describing the evidence base for prescribing controversial puberty-blocking GnRHa drugs as ‘remarkably weak’ (2024: 13). In 2024, puberty blockers for children under 18 were subject to a UK-wide ban, covering both the National Health Service and private providers. This current RCT is apparently designed to test the efficacy of these powerful drugs under controlled conditions. According to Cass, “some of the hype about risks have been exaggerated in that we genuinely don’t know if there are harms. …the trial was ‘essential’ to answer the question about ‘whether these drugs are helpful or not’” (Kuenssberg, 2026).
The RCT has, however, kicked up a storm of controversy, surviving a hostile motion in Parliament, and now subject to a judicial review. Critics allege that the RCT re-opens the door to the use of a discredited drug regime, cannot produce definitive data because of its research design, and turns children and parents (wholly committed to the concept of medical transition) into guinea-pigs for pointless experimental medicine (Jenkins, 2026).
Cass as the voice of ‘the reasonable centre’
This puts Hilary Cass in an unenviable position. Formerly lauded as a heroine by gender critical supporters for closing down the notorious Tavistock Gender Identity Development Service, her star has increasingly lost most its lustre. Her prestige has taken a further knock with her insistence on the need for an RCT to fill in the missing research and evidence gaps for gender medicine. For many critics, her passionate defence of the RCT seems to directly contradict her former sustained criticisms of past research on gender interventions. Much of this research was linked to the World Professional Association for Transgender Health (WPATH) Standards of Care, version 8. For Cass, the WPATH guidelines were found to be woefully lacking in “developmental rigour and transparency” (BMJ, 2024: 385). Now attacked from both sides of the trans divide, Cass has carefully re-positioned herself as the voice of the ‘reasonable centre’. For Cass, children had been weaponised in a toxic debate, and “people at the extremes” had caused “quite a lot of distress for young people” (Kuenssberg, 2026). Some trans rights activists had proved to be strident, while people who had taken the view no-one should ever transition had “similarly made it difficult”.
Trajectory of Cass’s policy development
So, how did it all come to this? If we look closely enough at the trajectory of Cass’s policy development, the early warning signs were always there that she took a distinctive position on the nature and origins of gender dysphoria, now ideally to be confirmed by the RCT. She warned, in the opening pages of her landmark review, that this was indeed a toxic debate, and that children had been exceptionalised within this unusual process (Cass, 2024: 13). In one interview, she clearly signalled that research was needed to distinguish more precisely between the differing cohorts of young people:
“The challenge of the assessment process is that while it may direct a broader care plan, it does not give certainty about which young people will ultimately develop a long term trans identity and which will resolve their gender-related distress in other ways … The review has spoken to young adults who are happy and empowered by their decision to medically transition and to others who have regrets” (BMJ, 2024).
“Very tiny number of young people”
A year later, in the House of Lords in 2025, Cass referred directly to “the very tiny number of young people who clinicians believe will ultimately have a long-standing gender incongruence and will therefore be eligible for this trial” (Hansard, 2025: Col 859). So, for her, the real clinical problem and focus for research is how to differentiate between children with long-term gender distress and those likely to desist, detransition, or drop out of treatment. The reference to the ‘very tiny number’ exposed to puberty blockers (and later cross-sex hormones) might well be reassuring to some. However, it is already clear that the managers of the RCT have established that its target of 226 participants will not present a barrier to recruiting even higher numbers, if considered appropriate (LCE REC, 2025: 2).
Hilary Cass’s arguments in support of the contested RCT have taken on a distinct tone of concern about this issue. In the House of Lords, she explained: “… of the 75 children a month who are coming to the new services, about 20% are getting these medications and, worse, testosterone and estrogen from unlicensed and unregulated sources—and those are the ones we know about. In addition, referrals to the new services have dropped from 200 a month to only 30 a month, so we think that a large number of those young people are also being harmed through those mechanisms. We are concerned about this much broader harm; children are voting with their feet now. Does the Minister agree with me that, for the very tiny number of young people who clinicians believe will ultimately have a long-standing gender incongruence and will therefore be eligible for this trial, it is better that they get their medication under careful clinical supervision rather than on the dark web?” (Hansard, 2025: Col 859).
Language of harm reduction
This is the moralising language of harm reduction. However, it presents a doubtful case, resting on assertions and unproven assumptions. It would be alarming for any showcase medical system to have a sudden drop in demand, particularly given that the regional hubs were designed, at least in part, to deal with the massive backlog of cases at the Tavistock. However, this decline may well be due to other factors entirely, such as an absolute decline in numbers of young people identifying as trans or non-binary, and thus not seeking medical transition. The second factor, namely that a proportion of young people are apparently accessing puberty blockers illegally via unregulated providers or the Dark Web, is shoehorned into a handy harm reduction role for the RCT. This was never its primary, or even its secondary, purpose. If there is an issue concerning illegal access to puberty blockers, then there are other viable solutions, such as vital improvements in child safeguarding and more effective regulation of the illegal supply of unauthorised drugs.
Using the persuasive language of harm reduction, although without convincing evidence of how harm is actually being reduced, rather strangely puts Cass into territory uneasily shared with WPATH. Despite Cass’s well-founded criticisms of WPATH, both Cass and WPATH lean heavily on harm reduction as a common motif. In fact, harm reduction runs as a central theme throughout the WPATH Standards of Care version 8: “The SOC-8 supports …the value of harm reduction approaches” (Coleman et al, 2022: S6). Health practitioners should “commit to harm reduction approaches where appropriate” (S17, 21). In WPATH’s eager hands, harm reduction then becomes a blunt hammer, where every barrier to children and adults accessing medical transition now resembles a nail urgently needing straightening. Desirable harm reduction measures range from: providing information about gender affirming medicine (S22); avoiding treatment delay (S37, S65) or rigid assessments (S36); providing breast binding to avoid harm via misgendering (S54); and not withholding treatment from eunuchs (to reduce harm from self-surgery) (S90). The harm thus reduced does not need quantifying in any way, but for WPATH represents a self-evident moral good.
WPATH’s social activism model of medical transition
So, how can we understand this shared imperative of ‘harm reduction’, now seemingly held jointly by WPATH, but also by one of WPATH’s formerly fiercest critics, Hilary Cass? The answer perhaps lies in the considerable overlap between the two otherwise distinct models of gender medicine held by WPATH and by Cass.
WPATH itself is clearly a hybrid trans activist organisation, rather than one following the traditional form of a medical professional association (Jenkins, 2022). For WPATH, gender identity is “an internal identification and experience” (S31), with no known criteria, save self-declaration. It is a concept, a belief, which is the crucial foundation of a carefully articulated ideology. WPATH pursues a ‘Social activism model’ of Gender [PJ: Identity] Affirming Medicine (GAM). Briefly, in ethical terms, GAM supposedly provides beneficial individual and social outcomes (welfare); avoids/reduces negative outcomes (avoidance of harm); promotes patient choice for children and adults (autonomy); is consistent with achieving wider social goals of equity, non-discrimination (justice). Research is evaluated in strictly ideological terms, i.e. it is judged to be of value where it directly serves to achieve these goals, hence WPATH’s reliance on observational cohort studies, rather than on systematic reviews, or RCTs. Thus, WPATH avoided publication of adverse research by John Hopkins University on the grounds that it required such research only “for the benefit of advancing transgender health in a positive manner” (Kozlowska et al, 2025: 6). WPATH’s primary focus is on quantity, i.e. on increasing the numbers of patients undergoing transition, with limited regard for apparent collateral damage in the form of detransitioners and others.
Cass’s ‘Targeted/individual patient need model’
Cass, fortunately, takes a different view of research. Within paediatric medicine, best practice is determined by research evidence, and not by ideological considerations. Hence the standard paediatric advice that new infants should be left to sleep on their backs is based on extensive research (Moon et al, 2022). However, specifically in relation to gender medicine, Cass seemingly takes a position based more on belief, rather than on research evidence. This is the belief about the existence of the ‘tiny numbers’ of children with gender distress, who genuinely need medical transition in order to live their lives more comfortably in their preferred manner. There is simply no hard evidence to support Cass’s firm belief. It is a belief about a belief system based on gender identity, not a verifiable fact which is consistent with the tenets of medical science.
Cass’s approach is more of a ‘Targeted/individual patient need model’, in sharp contrast with WPATH’s indiscriminate social activism model. Hence, for Cass, GAM may cause harms to some or even a majority of patients, but positive outcomes can be justified in the case of a very small number of genuine cases of children with persistent Gender Dysphoria. The overriding ethical risk of harm here for Cass would be to abandon this special cohort to a non-treatment pathway. Here, individual patient choice is an important, but not decisive, factor, being heavily qualified by a rigorous assessment process. Hence, the new research trial is necessary to resolve the current uncertainty of outcomes and to achieve a more targeted focus on effective treatment for a small minority of long-term persistent cases of GD.
Ethical jeopardy facing Cass
However, there is a stark ethical dilemma here for Cass. The two models of gender medicine are both unviable. Cass is necessarily critical of WPATH’s social activism approach to research, which clashes with standard paediatric research practice, as seen above. However, for Cass, the perceived ethical jeopardy of adopting a moratorium on further research and/or GAM would mean: the potential denial of positive outcomes of treatment (welfare) to a deserving minority of ‘tiny numbers’ (avoidance of harm); it would also breach autonomy in individual cases; it also would breach justice in a much broader social sense. The resultant search for welfare and justice for a tiny minority of patients (‘true trans’) therefore provides her with the decisive ethical justification for continuing the current PB RCT, despite all its overwhelming methodological flaws.
The obvious problem here is that there are, at present, simply no reliable protocols for triage of patient demand into likely desisters/potential detransitioners/patients with co-occurring conditions, subject to diagnostic overshadowing/long-term persistent GD cases. Alternatively, a standard medical utilitarian approach (‘the greatest good of the greatest number’) would be to risk the abandonment of this speculative minority, in order to protect the vast majority of child patients from the known and well-documented harms of GAM. In a similar way, mass vaccination for Covid always carried a definite risk that this intervention might be harmful to a small minority of patients (CDC, 2025).
Cass and WPATH: trapped within a non-medical paradigm
There is an all-too evident irony at work here. Cass may have been the most persistent critic of WPATH in terms of its research methodology, and rightly so. However, Cass and WPATH are both trapped within the same non-medical paradigm of realising a child’s inner gender identity. In WPATH’s case, this is promoted via indiscriminate social activism, and in Cass’s case, through a more targeted individualised patient approach, but one still lacking any credible scientific justification. Having alerted others to the very real dangers of ‘exceptionalising’ this group of children in her game-changing Review, Cass has fallen into precisely the same error, in exceptionalising and prioritising the purported needs of ‘true trans’, albeit on a much smaller scale.
Many are called by the sirens of gender identity, so it seems, but few will actually be chosen for this particular research trial. And for those chosen for the RCT, it will undoubtedly be the case, to paraphrase Alice yet again, of not just harm to children yesterday, and harm again today, but definitely yet more harm to come tomorrow.
Non electronic references
Carroll, L. (n.d.) Through the looking glass and what Alice found there. London: Ward Lock.
By Peter Jenkins, counsellor, supervisor, trainer and researcher in the UK. He has been a member of both the BACP Professional Conduct Committee and the UKCP Ethics Committee. He has published a number of books on legal aspects of therapy, including Professional Practice in Counselling and Psychotherapy: Ethics and the Law (Sage, 2017). https://uk.sagepub.com/en-gb/eur/counselling-and-psychotherapy-professional-practice/book243292
Peter is also a member of Thoughtful Therapists. His critique of the Memorandum of Understanding on Conversion Therapy was described as ‘instrumental’ in persuading the UKCP Board of the case for leaving the MOU in 2024.
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