A British citizen deprived of citizenship for alleged ISIL alignment challenged SIAC’s approach to national security assessments. The Supreme Court held SIAC reviews the rationality of the Secretary of State’s risk assessment using administrative law principles, not by making its own factual findings on the balance of probabilities. Appeal dismissed.
Background
The appellant, designated U3, was a British citizen who lived with her husband (designated O) and three children in ISIL-controlled territory in Syria between August 2014 and October or November 2017. On 18 April 2017, the Secretary of State for the Home Department gave notice of a decision to deprive U3 of her British citizenship under section 40(2) of the British Nationality Act 1981, on the ground that deprivation was conducive to the public good. The notice stated that U3 was assessed to be a dual British/Moroccan national who had travelled to Syria and was aligned with ISIL, and that her return to the UK would present a risk to national security. A national security certificate was issued directing that any appeal would lie to the Special Immigration Appeals Commission (SIAC) rather than the First-tier Tribunal. The deprivation order was made on 22 April 2017.
U3’s three children were repatriated to the UK in 2019 and cared for by family members. U3 remained in Syria. On 11 August 2020 she applied for entry clearance to the UK, which was refused on 18 December 2020. She appealed both decisions to SIAC: the deprivation decision under section 2B of the Special Immigration Appeals Commission Act 1997, and the entry clearance refusal under section 2 on the ground that it violated the right to respect for family life under Article 8 ECHR.
U3’s case was that she posed no risk to national security. She argued that her travel to Syria was in the context of an abusive, coercive and controlling relationship with O, that she was not ideologically aligned with ISIL, and that she had not become radicalised. However, she had accepted tweeting or retweeting messages with extremist content and remaining in contact with individuals she described as “Dawlah fanatics”.
The Issue(s)
The central issue was the proper approach SIAC should take when reviewing the Secretary of State’s assessment that a person poses a risk to national security, in the context of appeals against deprivation of citizenship and refusal of entry clearance. Specifically:
Should SIAC make its own findings of fact on the balance of probabilities?
The appellant argued that SIAC should reach its own findings of fact on the central “building blocks” of the Secretary of State’s national security assessment, including whether she was aligned with ISIL, and that if a different assessment was possible on SIAC’s findings, the appeal should be allowed and remitted.
Was SIAC’s approach compatible with Convention rights?
It was argued that the approach adopted by SIAC and the Court of Appeal, following R (Begum) v Special Immigration Appeals Commission [2021] UKSC 7, was incompatible with ECHR requirements, particularly Article 8, where Convention rights were engaged.
The Court’s Reasoning
The nature of SIAC’s jurisdiction
Lord Reed, delivering the unanimous judgment, clarified that an appeal to SIAC under sections 2 or 2B of the 1997 Act is a genuine appeal and not merely equivalent to judicial review. Different issues arising in an appeal require different approaches. SIAC can admit evidence not before the Secretary of State, can consider material post-dating the original decision, and can make findings of fact. However, not every issue can be determined by fact-finding on the balance of probabilities.
Risk assessment differs from fact-finding
The Court drew a fundamental distinction between issues that require fact-finding on the balance of probabilities (such as whether a deprivation order would render a person stateless) and issues involving the evaluation of risk to national security. Lord Reed stated:
“A decision of the former kind is based on an evaluative judgement or assessment that an unacceptable risk exists, not on the existence of a particular fact or the occurrence of a particular event.”
Drawing on the reasoning of Lord Hoffmann in Rehman [2001] UKHL 47, Lord Reed explained that risk assessments depend on a cumulative evaluation of evidence, much of which may be individually inconclusive:
“… it was wrong to treat the Home Secretary’s reasons as counts in an indictment and to ask whether each had been established to an appropriate standard of proof. The question was not simply what the appellant had done but whether the Home Secretary was entitled to consider, on the basis of the case against him as a whole, that his presence in the United Kingdom was a danger to national security.”
Lord Reed further explained that the standard of proof is inapt for risk evaluation:
“A risk is a possibility. The existence of a risk can therefore arise from evidence which is sufficient to establish a possibility but falls short of proof on a balance of probabilities.”
Institutional and constitutional deference
The Court identified two reasons for attaching very considerable weight to the Secretary of State’s evaluation. Institutionally, the Secretary of State acts on expert advice from the Security Service, possessing expertise that judges cannot match. Constitutionally, Lord Reed endorsed Lord Hoffmann’s observation in Rehman:
“such decisions, with serious potential results for the community, require a legitimacy which can be conferred only by entrusting them to persons responsible to the community through the democratic process”
The correct approach for SIAC
Lord Reed confirmed that SIAC’s role is to review the Secretary of State’s exercise of discretion based on evaluative judgement, applying principles of administrative law. An appeal can be allowed on grounds including irrationality, reliance on evidence incapable of supporting the assessment, a plainly untenable factual basis, misunderstanding of an established and relevant fact, or perverse inferences. However, SIAC cannot substitute its own evaluation merely because it would have reached a different view.
Critically, Lord Reed rejected the Court of Appeal’s distinction between “pivotal” and “non-pivotal” facts:
“SIAC cannot, by making findings of fact on the balance of probabilities, allow an appeal on the basis that there is ‘a pivotal finding, such as that the appellant travelled or stayed somewhere, which SIAC is in a position to contradict’. The relevant question is not whether SIAC considers, on a balance of probabilities, that the appellant travelled or stayed somewhere, but whether the evidence as a whole provides a rational basis for the Secretary of State’s decision.”
He illustrated the point: even if SIAC considered there was a greater than 50% probability that the appellant had not been in Syria, the appeal would not automatically succeed. The question would remain whether the evidence as a whole provided a rational basis for the decision. Only if there was no real possibility that the appellant had been in Syria would the factual basis fall away.
The updating process
Lord Reed emphasised the distinctive procedure before SIAC whereby the Secretary of State’s national security assessment is kept under review throughout the appeal, updated in light of the appellant’s evidence and submissions. This means new evidence is taken into account without requiring the decision to be set aside and remade.
SIAC’s minor error
Lord Reed identified one error: SIAC had confined itself to assessing the rationality of the deprivation decision as at the date it was made, without considering post-decision evidence in relation to that appeal. However, since SIAC considered that evidence in relation to the entry clearance appeal and found the Secretary of State’s assessment was not flawed, the error had no effect on the outcome.
Convention compatibility
The Court rejected the argument that SIAC’s procedures failed to meet ECHR standards. Lord Reed reviewed the Strasbourg case law, including IR v United Kingdom (2014) 58 EHRR SE14, where the European Court of Human Rights had found SIAC’s procedures compliant with Convention requirements. He concluded:
“appeals under sections 2 and 2B of the 1997 Act are adversarial proceedings before an independent body competent to review the reasons for the decision and relevant evidence, in which the appellant can challenge in an effective manner the allegations that he or she represents a danger to national security, and in which SIAC can react in cases where the assessment has no reasonable basis in the facts or is otherwise unlawful or arbitrary.”
Practical Significance
This judgment is of considerable importance in clarifying the scope of SIAC’s appellate jurisdiction in national security cases following Begum. It confirms that SIAC applies administrative law principles when reviewing the Secretary of State’s risk assessments, rather than substituting its own factual findings on the balance of probabilities. It rejects the Court of Appeal’s attempt to create a category of “pivotal” facts on which SIAC could override the Secretary of State. The decision reinforces the deference owed to the executive on national security matters, grounded in both institutional expertise and democratic legitimacy, while clarifying that SIAC nonetheless conducts rigorous scrutiny of the evidential basis of such decisions. The judgment also confirms that this approach is compatible with ECHR requirements, including in cases engaging Article 8 rights of affected children.
Verdict: The appeal was 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. Both the deprivation of citizenship decision and the refusal of entry clearance were upheld.
Source: U3 v Secretary of State for the Home Department [2025] UKSC 19
