The UK’s High Court has rejected a challenge to the regulatory approval for a clinical trial that is investigating puberty blockers in teenagers with gender incongruence.
The PATHWAYS trial (ISRCTN12491684), which has created a great deal of controversy since its unveiling late last year, is a programme of research aiming to help find out how the NHS can better support children and young people with gender incongruence.
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During the initial review of the trial application in November 2025, a legal challenge was brought by a campaign group and two people challenging the decision to approve the trial. This legal challenge was updated to reflect the changes made to the trial as part of an approved modification in June 2026. The legal challenge sought permission to stop the trial and apply for a judicial review.
A hearing took place on 27 and 28 July to hear evidence and consider the application from the claimants. On 31 July, Mr Justice Chamberlain refused the legal challenge. The High Court judge’s ruling means there will be no judicial review and the trial can start.
Chamberlain determined that “none of the grounds of challenge” had a realistic prospect of success. He stated that patients in the trial will be children with persistent gender incongruence who are receiving treatment from specialist gender services.
As a result, patients will have received months of treatment by specialist doctors and the treating team will have had enough time to have formed the opinion that the child has a reasonable prospect of receiving a clinical benefit from the treatment.
Dr Matt Westmore, chief executive of the Health Research Authority (HRA), said: “The checks that we carry out, alongside the independent ethics review process, ensure the interests of participants are put first, and that the research is safe and ethical. High-profile studies like this will always attract extra scrutiny, and we welcome the opportunity to assure the public of the safeguards put in place to protect research participants. We are grateful to the Court for its careful consideration of this case, and its recognition that Research Ethics Committees (REC) have the right expertise to review complex studies like the PATHWAYS Trial.”
The study, which will look into young people’s physical, social and emotional wellbeing when on the medication, received a favourable opinion in November 2025.
In February 2026, the MHRA raised some concerns about the trial and began a scientific dialogue with the trial sponsor, King’s College London (KCL).
The scientific dialogue between KCL and the MHRA resulted in the sponsor proposing changes to the previously approved study protocol and associated documents for the trial.
A modification to the trial was reviewed in May 2026, with another favourable opinion being provided in June 2026.
The modified protocol includes strengthened safeguards, including the introduction of minimum ages of entry to the trial, which will be 11 for birth-registered females and 12 for birth-registered males. There is also a more clearly defined discontinuation measure around safety for bone health, cognition, and vaginal bleeding, as well as more detailed information for participants on fertility preservation.
In the UK, puberty blockers for people under-18 were banned in 2024 after the Cass Review. The Commission on Human Medicines (CHM) provided an independent report on the continued prescribing of puberty blockers in children to the government, concluding there is “currently an unacceptable safety risk”.
