BF (Eritrea), R (on the application of) v Secretary of State for the Home Department

Factual and Procedural Background

Respondent, an Eritrean national, entered The State clandestinely in 2014 and claimed asylum as an unaccompanied child, stating he was 16. Immigration officers, applying “criterion C” of the Secretary of State’s detention policy, judged him to be an adult and detained him pending removal to Italy under the Dublin III Regulation. Subsequent Merton-style social-work assessments produced conflicting conclusions about his age, and removal was stayed while judicial review proceedings were commenced.

The Respondent sought to quash criterion C on the basis that visual age-assessment is unreliable and risks unlawful detention of children. The Upper Tribunal dismissed the claim, but the Court of Appeal (majority) allowed it, holding that the guidance was unlawful unless officers treated claimants as adults only when they appeared about 23–25 years old. The Secretary of State appealed to the Supreme Court; the Respondent cross-supported the Court of Appeal’s reasoning.

Legal Issues Presented

1. Whether the Court of Appeal applied the correct legal test when assessing the lawfulness of administrative policy, in particular by asking if the guidance created “a real risk of more than a minimal number of children being detained.”
2. Whether criterion C of the Secretary of State’s age-assessment guidance, in any of its versions, is unlawful because it allegedly permits or encourages immigration officers to act contrary to statutory duties and Article 5 ECHR.

Arguments of the Parties

Appellant’s Arguments (Secretary of State)

• The correct benchmark is the Gillick test: policy is unlawful only if it directs officers to act contrary to law; criterion C does not.
• The Court of Appeal’s “real risk” formulation wrongly conflates distinct jurisprudence on systemic unfairness and access to justice (UNISON).
• Section 55 of the 2009 Act is satisfied: the policy already builds in a generous “benefit-of-doubt” safeguard and a mandatory second-officer review.
• No common-law or Convention obligation requires replacing the statutory 18-year threshold with a 23/25-year proxy.

Respondent’s Arguments (BF)

• Applying Gillick and UNISON, the guidance is unlawful because it fails to eliminate the risk that children will be detained as adults, thereby “permitting or encouraging” unlawful conduct.
• The empirical unreliability of visual age assessment (Royal College of Paediatrics material) means a five-year margin of error is necessary; criterion C therefore needs re-formulation.
• Article 5 ECHR and the Secretary of State’s section 55 duties require a policy that removes the risk of child detention.

Table of Precedents Cited

Court's Reasoning and Analysis

The Supreme Court held that the central “Gillick obligation” is narrowly focused: policy must not direct officials to act unlawfully. Criterion C instructs officers to treat claimants as adults only when appearance and demeanour “very strongly” suggest they are “significantly over 18,” and requires independent confirmation by a second senior officer. Far from encouraging illegality, the policy builds in a protective margin and aligns with section 55’s welfare duty.

The majority view in the Court of Appeal incorrectly substituted a broader test—whether the guidance created a “real risk” of child detention—and, by doing so, conflated jurisprudence on systemic unfairness and access to justice. The Supreme Court clarified that:

• There is no common-law or statutory duty to issue guidance eliminating all risk of error; mistakes are addressed via individual legal remedies, not by rewriting the statutory line at 18.
• Requiring officers to treat apparent 18-22-year-olds as children would undermine Parliament’s objective of effective immigration control and risk unlawful deprivation of liberty to adults.
• Convention rights (Articles 3 and 5) do not impose additional obligations beyond the existing safeguards incorporated in criterion C.

Holding and Implications

APPEAL ALLOWED; CRITERION C DECLARED LAWFUL.

Immediate effect: the Secretary of State’s pre-existing versions of criterion C remain valid; the post-Court-of-Appeal amendment raising the threshold to 25 is not legally required. Broader implication: the decision re-affirms that policy guidance is unlawful only if it positively directs non-compliance with legal duties, narrowing the circumstances in which courts may compel executive revision of guidance.