U3 v Secretary of State for the Home Department

On a statutory appeal concerning a discretionary national security decision, SIAC must scrutinise the evidence as a whole and decide whether it provides a rational basis for the Secretary of State’s assessment. It must not resolve each component of a predictive risk assessment as a binary fact on the balance of probabilities.

SIAC may consider new and subsequent evidence because the assessment is kept under review during the appeal. It may make factual findings where the nature of an issue requires them, including for statelessness and human-rights questions. In reviewing national security risk, however, it must give very considerable weight to the Secretary of State’s evaluation and cannot substitute its own merely because it would have reached a different view.

The Secretary of State deprived U3 of British citizenship after assessing that she had aligned with ISIL and that her return from Syria would threaten national security. The Secretary of State later refused her entry clearance. U3 appealed both decisions to SIAC, challenging the national security assessment and relying, in the entry-clearance appeal, on her children’s rights under article 8 of the Convention.

SIAC dismissed both appeals. The Court of Appeal dismissed further appeals in [2023] EWCA Civ 811; [2024] KB 433, while holding that SIAC could contradict certain pivotal factual findings made by the Secretary of State.

The central issue before the Supreme Court was whether SIAC had to determine the factual building blocks of a national security assessment on the balance of probabilities, or instead review the assessment under administrative-law principles.

1. The appeals were dismissed unanimously. Lord Reed gave the judgment, with which Lord Hodge, Lord Lloyd-Jones, Lord Sales and Lord Stephens agreed. SIAC was entitled to uphold both the deprivation of citizenship and the refusal of entry clearance.

2. An appeal under sections 2 or 2B of the Special Immigration Appeals Commission Act 1997 is an appeal in substance and is not equivalent to judicial review. SIAC may receive new evidence and make findings of fact on the balance of probabilities. The approach required nevertheless depends on the nature of each issue. Statelessness and the factual effects of a decision upon Convention rights ordinarily require SIAC’s own findings and assessment.

3. A national security risk assessment is different. Risk concerns possibilities and prediction. Information which is individually inconclusive, or which does not prove a past event on the balance of probabilities, may cumulatively provide a reasonable basis for apprehending future harm. The assessment must consider the degree of risk, the means available to address it and the gravity of the consequences if it materialises.

4. Parliament entrusted the relevant discretionary decisions to the Secretary of State. SIAC therefore reviews a national security assessment under administrative-law principles. It must scrutinise the evidence as a whole and may intervene for legal error, irrationality, bad faith, an untenable factual basis, absence of supporting evidence, misunderstanding of an established relevant fact or a perverse inference. It cannot substitute its own evaluation merely because it would have assessed the risk differently. Institutional expertise and democratic accountability require very considerable weight to be given to the Secretary of State’s evaluation.

5. The Secretary of State’s assessment is kept under review during the appeal and may lawfully be reviewed by departmental officials under the Carltona principle. SIAC may consider evidence arising after the original decision and determine whether the maintained decision remains rationally sustainable. SIAC erred by treating the deprivation appeal as confined to the rationality of the decision when originally made, but the error was immaterial because it considered the later evidence in the entry-clearance appeal and found no administrative-law defect.

6. The Court of Appeal’s suggested distinction between pivotal and non-pivotal facts was incorrect. Even a finding that an alleged event was less likely than not would not necessarily invalidate a risk assessment. The operative question remained whether the whole body of evidence afforded a rational basis for the maintained decision.

7. This form of scrutiny complied with the Convention. SIAC independently determined the impact on the children, treated their best interests as a primary consideration and conducted the proportionality assessment. It was entitled to conclude that the national security interest outweighed the interference with their article 8 rights.

1. United Kingdom Supreme Court: Dismissed the appeals and upheld the Court of Appeal’s disposition: [2025] UKSC 19 .
2. Court of Appeal: Dismissed U3’s appeals from SIAC, while identifying an immaterial error in SIAC’s understanding of its fact-finding power: [2023] EWCA Civ 811 ; [2024] KB 433 .
3. Special Immigration Appeals Commission: Dismissed the deprivation-of-citizenship and entry-clearance appeals on 4 March 2022.