U3 v Secretary of State for the Home Department [2025] UKSC 19 (12 May 2025)

A British citizen who travelled to ISIL-controlled Syria with her husband had her citizenship revoked on national security grounds. She appealed against both the deprivation decision and refusal of entry clearance to rejoin her children in the UK. The Supreme Court clarified SIAC's role in reviewing national security assessments, holding it applies administrative law principles rather than making independent factual determinations on risk.

Facts

The appellant, a British/Moroccan dual national designated U3, lived in ISIL-controlled territory in Syria between August 2014 and October/November 2017 with her then husband O and their children. On 18 April 2017, the Secretary of State gave notice of intention to deprive her of British citizenship under section 40(2) of the British Nationality Act 1981, on grounds that deprivation was conducive to the public good, based on an assessment that she was aligned with ISIL and her return would present a risk to UK national security. The deprivation order was made on 22 April 2017. Her children were repatriated to the UK in 2019 and cared for by family members. Her subsequent application for entry clearance was refused on 18 December 2020. She appealed both decisions to SIAC.

The Appellant’s Case

The appellant contended she was not ideologically aligned with ISIL, that she had travelled to Syria whilst in a coercive and abusive relationship with O, and that she posed no risk to national security. She argued SIAC should make its own findings of fact on the balance of probabilities regarding the ‘building blocks’ of the Secretary of State’s assessment.

Issues

The central issue was the proper approach SIAC should take when reviewing the Secretary of State’s national security assessment in appeals under sections 2 and 2B of the Special Immigration Appeals Commission Act 1997. Specifically, whether SIAC should determine disputed facts on the balance of probabilities and substitute its own assessment for that of the Secretary of State.

Judgment

The Supreme Court unanimously dismissed the appeal. Lord Reed, delivering the judgment, clarified that appeals to SIAC are genuine appeals, not equivalent to judicial review applications, and SIAC can consider evidence not before the Secretary of State when the decision was made. However, the nature of the issue determines SIAC’s approach.

National Security Assessments

Where the appeal concerns national security risk assessment, SIAC’s role differs from ordinary fact-finding. Risk assessment is evaluative and predictive, based on possibilities rather than facts proven on the balance of probabilities. Lord Reed explained that assessing risk appropriately requires considering information that may fall short of proof on a balance of probabilities but nonetheless establishes a possibility of danger.

The Court emphasised that the Secretary of State exercises discretionary power based on expert advice from the Security Service. Both institutional factors (the expertise of intelligence services) and constitutional factors (democratic accountability) require SIAC to attach considerable weight to the Secretary of State’s evaluation rather than substituting its own.

SIAC’s Proper Function

SIAC reviews the Secretary of State’s assessment applying administrative law principles. It can allow an appeal if the assessment has no reasonable basis in the facts, is based on evidence that could not reasonably support it, is irrational, or reveals other public law errors. However, SIAC cannot substitute its own view merely because it would have assessed matters differently.

Human Rights Compliance

The Court held that SIAC’s procedures comply with Convention requirements, noting European Court of Human Rights jurisprudence accepts that administrative law review can provide adequate procedural protection, particularly where decisions involve specialised knowledge and democratic accountability.

Implications

This judgment authoritatively clarifies SIAC’s role in national security cases following the earlier decision in Begum. It confirms that while SIAC conducts genuine appeals with power to receive evidence and make factual findings on appropriate issues, its review of national security assessments is conducted through administrative law principles rather than de novo determination. The decision reinforces the significant deference accorded to the executive in matters of national security, whilst maintaining meaningful judicial oversight. It also confirms that this approach complies with European Convention on Human Rights requirements for procedural fairness.

Verdict: Appeal dismissed. SIAC was entitled to reach the conclusions it did, and the Court of Appeal was correct to dismiss the appeals against SIAC's decisions. The deprivation of citizenship and refusal of entry clearance were upheld.

Source: U3 v Secretary of State for the Home Department [2025] UKSC 19 (12 May 2025)