UK High Court Clears PATHWAYS Puberty-Blocker Trial to Begin Recruitment

The UK High Court has dismissed a legal challenge against the Pathways clinical trial of puberty blockers, clearing the way for researchers at King's College London to begin recruiting over 220 children aged 11 to 16 on August 1, 2026. Commissioned by NHS England following the 2024 Cass Review, the trial aims to evaluate the long-term physical and psychological effects of the drugs. Campaigners, including Keira Bell and the Bayswater Support Group, argued the trial lacks adequate safeguards, while the court ruled that safety assessments are properly the domain of specialist regulators.

High Court trial challenge rejection

• ▪Mr Justice Chamberlain refused the application for a judicial review, ruling that none of the campaigners' claims had a realistic chance of success.
• ▪The High Court rejected a legal challenge against the Pathways clinical trial of puberty blockers, allowing the study to proceed.
• ▪The Pathways trial, run by researchers at King's College London, is scheduled to begin recruiting more than 220 children aged 11 to 16 starting August 1, 2026.

Cass Review trial rationale

• ▪The Pathways trial was commissioned by NHS England in response to the April 2024 Cass Review, which found the evidence for treating young people with puberty blockers was remarkably weak.
• ▪Following the Cass Review, the UK government banned the prescription of puberty-blocking drugs for children's gender care across the UK, allowing new prescriptions only within controlled clinical trials.
• ▪The Pathways trial will study the effects of puberty blockers on bone density, brain development, fertility, and mental wellbeing.

Claimant safety ethics concerns

• ▪The Pathways trial was originally scheduled to begin in January 2026 but was paused due to the legal action.
• ▪Campaigners argued that the trial's safeguards were inadequate and raised concerns about long-term physical and psychological damage, including infertility.
• ▪The legal challenge was brought by the Bayswater Support Group, psychotherapist James Esses, and Keira Bell, who detransitioned after taking puberty blockers at age 16.

Regulatory approval legal arguments

• ▪Lawyers for the Health Research Authority and King's College London argued that participants must be assessed over many months by specialist doctors who determine they have a reasonable prospect of clinical benefit.
• ▪In February 2026, the Medicines and Healthcare products Regulatory Agency raised safety concerns and suggested a minimum participant age of 14, which was later lowered to age 11 for girls and age 12 for boys after discussions with researchers.
• ▪The trial design splits the approximately 220 participants into two groups, where half will receive the puberty-suppressing medication immediately and the other half will start treatment one year later.

Campaigner researcher reactions

• ▪Claimants Keira Bell and James Esses expressed deep disappointment with the ruling, with Esses stating he is consulting with lawyers regarding a potential appeal.
• ▪King's College London and the Health Research Authority welcomed the High Court decision, stating that the trial has strict eligibility requirements and that participant safety remains their highest priority.
• ▪Helen Joyce, director of advocacy at the charity Sex Matters, called the High Court's decision devastating and inexplicable, describing the trial as ethically monstrous.