R (EXR) v Home Secretary: High Court rules reasonableness governs age assessments for UK-France Treaty removals

The High Court has ruled that the reasonableness standard of judicial review, not the correctness standard, applies to the Home Secretary's decision to treat an unaccompanied individual as an adult for the purposes of removal to France under the UK-France Treaty 2025 (UFT), in a judgement on a preliminary issue handed down on 25 June 2026 ([2026] EWHC 1568 (Admin)).

The case was brought by an anonymised asylum seeker, EXR, and identified as a test case to resolve a discrete question of law of wider significance to the UFT scheme. Under the UFT, persons arriving by small boat from France may be removed for readmission. The treaty expressly excludes unaccompanied children: France has no duty to readmit them, and the SSHD's own published guidance identifies unaccompanied asylum-seeking children as ineligible for the inadmissibility process. An unlawful decision to treat a child as an adult therefore renders the removal itself unlawful, a point the Secretary of State accepted.

The sole question before Fordham J was which standard of review applies to that age decision. The correctness standard, argued by Stephanie Harrison KC for the claimant, would require the court to determine for itself whether the individual is in fact a child, without any margin for error and with access to fresh evidence. The reasonableness standard, argued by Cathryn McGahey KC for the Secretary of State, would ask only whether the Home Office's decision fell within the range of reasonable responses, assessed by reference to the evidence available at the time of the decision.

Fordham J held that reasonableness applies. The correctness standard has been established in adjacent statutory contexts: in R (A) v Croydon LBC [2009] UKSC 8, the Supreme Court held that "child" within the Children Act 1989 attracts correctness when local authorities assess need, and in R (AA (Sudan)) v SSHD [2017] EWCA Civ 138, the Court of Appeal applied the same standard to a statutory restriction on detention of unaccompanied children introduced by Parliament in 2014. In both cases, the correctness standard flowed from the language and structure of primary legislation. No equivalent statutory restriction governs the inadmissibility declaration power in section 80B of the Nationality, Immigration and Asylum Act 2002 or the removal power in section 10 of the Immigration and Asylum Act 1999.

Fordham J rejected each of the seven grounds advanced in favour of a correctness standard. Home Office policy guidance, even where subject to the Lumba duty of adherence, cannot constitute the source of a correctness standard for questions of fact: the court's role is to determine the correct interpretation of the policy, while its application remains for the decision-maker subject to reasonableness review. The UFT, as an undomesticated international treaty without direct effect in domestic law, cannot supply a correctness standard either. Fordham J also declined to accept that knock-on unlawfulness operates in reverse: where detention for removal is unlawful because the individual is in fact a child, that does not automatically vitiate the removal decision. Finally, the practical coherence argument, that parallel challenges to detention and to local authority age assessments both attract correctness and so the removal challenge should too, was rejected; the same question may attract different standards when asked for legally distinct purposes.

The judgement leaves open for the next hearing, listed for 2 July 2026, a series of consequential questions about how the reasonableness standard operates in this context, including the appropriate closeness of scrutiny, the treatment of fresh evidence, and the approach to collateral challenges founded on whether local authority age assessments are Merton-compliant.

[2026] EWHC 1568 (Admin) | Administrative Court | Fordham J | Decided: 25 June 2026