Reading Bell v Tavistock https://www.judiciary.uk/judgments/r-on-the-application-of-quincy-bell-and-a-v-tavistock-and-portman-nhs-trust-and-others/ and five basic legal points strike me 1) capacity testing for minors (and under the Mental Capacity Act) is decision-specific because capacity is functional, not status or age-based, and may vary from decision to decision.
In deciding that minors need to understand a future possible/likely treatment (cross-sex hormones) in order to consent to a current treatment option (puberty blockers), the court has strayed from a decision-specific approach to capacity. 2) Capacity testing is person-specific.
In stating that individual children belonging to an age-based group of patients i.e. under 15s are unlikely to be able to consent to a particular treatment, the court is moving from the person-specific functional approach associated with Gillick competence (and the MCA).
3 Although the court ultimately says (para 130), rightly imo, that the higher Montgomery informed consent standard is not the appropriate legal standard for assessing the question of a minor's competence to give a valid/real consent, there is an unhelpful and confusing conflation
of two different legal standards for consent in the judgment. This is because it refers to both 'informed consent' and 'valid consent' without distinguishing fully between them, sometimes using the phrase 'informed consent' (paras 6-7) when minor's 'valid consent' is at stake.
The legal question here is what standard of 'understanding' has to be shown in order for children to be capable of 'valid consent', or authorising a treatment so that it is not a trespass to the person. Usually the civil legal norms of battery require basic info & understanding
see Chatterton v Gerson 1981 for authority and Cave here for an explanation of the distinction https://jme.bmj.com/content/early/2020/06/23/medethics-2020-106287.full
A higher standard of information - risks, options, alternatives, patient-responsive info - is required to avoid a negligence and failure in the standard of care. Because negligence means the patient has suffered an actionable harm as a result of the procedure when they might
not have gone ahead with it, if they had been informed differently. But Bell is not making a claim of negligence here in relation to her treatment. She is retrospectively challenging the lawfulness of her consent (as a then minor) being the means of the treatment's legal validity
4. The characterisation of the puberty blockers as 'experimental' seemed weak to me. If the treatment is being used routinely, then monitoring its use continues to be appropriate, but it's hardly 'experimental'? see further https://www.tandfonline.com/doi/full/10.1080/26895269.2020.1747768
The treatment in Simms 2002 https://www.bailii.org/ew/cases/EWHC/Fam/2002/2734.html was experimental and unapproved, but still in the minors' best interests given they were dying of vCJD and no alternative treatment. Which brings me to 5) there is no explicit reference to the 'best interests' test under s1
of the Children Act 1989 as the legal standard to which parental responsibility is held to account, if a decision is to be made about treating the child without relying solely on the child's consent. So even if Bell is right in law and her consent was not enough, by itself, to
authorise her treatment with puberty blockers, the legal test which applies then is one where the treatment has to be found to be in her 'best interests'. Her wishes count as part of her interests and a best interests decision could justify proceeding with puberty blockers.
There is more to say about this case, not least the way that cis gender experience is normalised and trans gender pathologised, as @Sandra_NiD has said. But the gap betw the judgment and some key objectives & distinctions in the law authorising medical treatment, merits comment.