A clinical trial examining the potential benefits and risks of puberty blockers for young people with gender incongruence has been cleared to proceed after the High Court rejected a legal challenge from campaigners.
Mr Justice Chamberlain refused both an application for permission to seek judicial review and a request for an interim order suspending the PATHWAYS trial on Friday, 31 July.
The decision followed a two-day hearing involving more than 13,000 pages of documentation, 31 witness statements and detailed submissions from the parties. Because permission was refused, the case will not proceed to a full substantive judicial review unless a successful appeal is brought.
Court Did Not Decide the Medical Debate
The ruling does not establish that puberty blockers are safe, effective or appropriate for every young person.
Instead, the court considered whether decisions by the Medicines and Healthcare products Regulatory Agency and Health Research Authority to approve the study were arguably unlawful.
Mr Justice Chamberlain said courts should be cautious about substituting their own conclusions for those reached by specialist scientific and regulatory bodies.
“The Court’s function is not to say whether it agrees with the decision under challenge, but rather to examine whether the defendants have exercised their functions contrary to the legislative scheme or otherwise unlawfully,” the court’s summary said.
The judge concluded that none of the claimants’ five grounds had a realistic prospect of success. He also said that even if permission had been granted, the potential harm to the public interest and prospective participants from delaying the research outweighed the possible harm of allowing it to begin.
Who Brought the Challenge?
The case was brought by the Bayswater Support Group, Keira Bell and psychotherapist James Esses.
Bayswater says it provides advice and support to approximately 800 parents and guardians of children and young adults who identify as transgender or non-binary. Bell previously received treatment for gender dysphoria before detransitioning, while Esses founded the organisations Thoughtful Therapists and Just Therapy.
The claimants challenged regulatory approvals granted in November 2025 and again in June 2026, after the study’s protocol had been modified.
They argued that the trial was unlawful and that regulators had not adequately addressed concerns about its design, ethics, potential harms and the treatment participants might receive after leaving the study.
Why PATHWAYS Was Created
PATHWAYS was commissioned following the Cass Review of NHS gender-identity services for children and young people.
The review concluded that evidence concerning the use of puberty-suppressing hormones for gender incongruence was weak and recommended that their benefits and risks be investigated through carefully controlled NHS research.
PATHWAYS is led by King’s College London and co-sponsored by the university and South London and Maudsley NHS Foundation Trust.
The study is expected to involve 226 participants under the age of 16 who are already receiving care through specialist NHS gender services and have been assessed as potentially eligible for puberty suppression.
Participants will be randomly assigned to begin treatment either immediately or after a 12-month delay. Researchers will compare the groups over two years, examining quality of life, mental health, physical development, cognitive function and gender-related distress. Follow-up may continue for a further two-and-a-half years.
Court Highlights Trial Safeguards
In explaining its decision, the court said the trial had been designed with “conspicuous care” and reviewed by specialist bodies.
Each potential participant will have experienced persistent gender incongruence and undergone assessment over several months. Their treating clinicians must believe there is a reasonable prospect that they could receive a clinical benefit from puberty suppression.
The young person must provide informed assent, while a parent or legal guardian must consent. A national multidisciplinary team of paediatric and other specialists will provide a second opinion on whether participation is clinically appropriate.
The MHRA initially approved the trial in November 2025 but reconsidered it after clinicians raised concerns and NHS England paused new prescriptions of masculinising and feminising hormones for young people.
A modified protocol was approved in June. Changes included minimum entry ages, clearer criteria for stopping treatment over concerns involving bone health, cognition or vaginal bleeding, and more detailed information about fertility preservation.
Independent groups will monitor the research, including a Data Monitoring Committee responsible for identifying concerns about participants’ safety or wellbeing.
Research Team Welcomes Decision
The PATHWAYS researchers welcomed the High Court outcome.
“We welcome the Court’s decision. The safety and welfare of young people will remain our highest priority in carrying out this research,” the team said.
“PATHWAYS Trial is a carefully designed study to give much needed evidence about the potential benefits and risks of puberty suppression to improve NHS care.”
The researchers said only a small proportion of young people attending NHS gender services would be eligible.
“A small number of young people with long-term gender incongruence, who have already received comprehensive psychological and social support through NHS Gender Services, will be eligible.”
They added that prospective participants would undergo physical and mental-health checks, independent multidisciplinary assessment and a detailed consent process.
“The design of PATHWAYS Trial has been carefully reviewed by independent researchers and has been approved by the UK’s health research regulators, the HRA and MHRA,” the team said.
Recruitment had been scheduled to begin on 1 August following the conclusion of the legal proceedings.
Campaigners Consider an Appeal
Esses condemned the ruling and said he would discuss a possible appeal with his legal team.
“Vulnerable children should never be used as guinea pigs in medical experimentation that may lead them down a path towards irreversible physiological and emotional damage, including infertility,” he said.
“This trial is the antithesis of child safeguarding and I will now be consulting with my lawyers regarding the possibility of an appeal.”
Bell described the decision as a “tragedy”.
“It’s a tragedy that the court has refused permission for this challenge to proceed. The medical profession and morality do not always walk hand in hand. If they did, this trial would be out of the question,” she said.
Bayswater maintained that the trial did not meet what it considered the necessary legal and ethical standards for research involving children.
Cass Defends the Need for Research
Baroness Hilary Cass has defended the trial as necessary to resolve uncertainty around puberty suppression.
She said in June that she was “absolutely convinced that more children will be harmed if we don’t do the trial than if we do”.
Supporters of the research argue that without reliable evidence, clinicians, young people and families will remain unable to make properly informed decisions about the treatment. Opponents contend that the existing uncertainties make it unethical to expose young participants to its possible risks.
Puberty Blockers Remain Restricted Outside Research
Puberty blockers are not routinely available to new patients aged under 18 through NHS gender services.
The government also restricts their private sale and supply for gender incongruence or gender dysphoria, subject to narrow exceptions, including for some young people whose treatment began before June 2024.
They remain available for unrelated medical uses, such as the treatment of precocious puberty. Approved clinical research such as PATHWAYS is therefore the principal route through which new younger patients can receive puberty suppression for gender incongruence in the UK.
The High Court ruling removes the immediate legal barrier facing the study. However, an appeal remains possible, and the clinical, ethical and political debate surrounding PATHWAYS is unlikely to end with the court’s decision.
