On 12 May 2025, the UK Supreme Court (UKSC) delivered its decision in the case U3 (AP) (Appellant) v Secretary of State for the Home Department (Respondent) [2025] UKSC 19, concerning an appeal against the decision taken by the Special Immigration Appeals Commission (SIAC) relating to deprivation of citizenship and refusal of entry clearance.

SIAC is an independent tribunal established by the Special Immigration Appeals Commission Act 1997. Its jurisdiction is to hear appeals against certain decisions taken by the Secretary of State for the Home Department (SSHD) on national security grounds.

In its ruling, the Supreme Court upheld SIAC’s decision to dismiss the appellant’s appeals against the deprivation of citizenship and refusal of entry clearance. It concluded that SIAC had assessed the issues adequately and was entitled to reach the conclusions it did.

Facts of the case

The appellant, a dual citizen (British and Moroccan), was deprived of her British nationality and refused entry clearance. Between August 2014 and October or November 2017, the appellant, her children and her husband lived in ISIL-controlled territory in Syria.

On 18 April 2017, the UK government deprived the appellant of her British nationality. The UK government further indicated that “[the] decision was taken partly in reliance on information which […] should not be made public in the interests of national security and in the public interest”. On 11 August 2020, the appellant unsuccessfully applied to enter the UK. She appealed to SIAC, which dismissed her appeal. The Court of Appeal subsequently upheld SIAC’s decision.

UK Supreme Court judgement

The Supreme Court indicated that a key issue in the appeals concerned SIAC’s role in assessing the SSHD’s assessment of the risk posed by the appellant to national security. The Court also clarified that an appeal to SIAC differs from an application for judicial review.

Fresh evidence

The Court indicated that contrary to typical judicial review proceedings, SIAC can consider evidence that postdates the SSHD’s decision. The Court further explained that the SSHD can update the national security assessment during the appellate process, and that it will be this updated assessment that will be considered by SIAC. In this case, the SSHD reviewed and updated the national security assessment, meaning SIAC was adjudicating a re-considered decision.

Balance of probabilities vs. reasonable basis

SIAC must not apply Judicial Review principles in respect of findings of fact; instead, it determines matters of fact on a civil standard of the balance of probabilities.  However, the UK government retains a very high threshold of discretion in relation to matters of national security. When assessing risks in the context of national security, there is a lot of evidence considered that may give rise to reasonable grounds that, for example, the person is aligned with terrorists. As the Court further explained at paras 61 and 87:

“Those possibilities do not have to be proved to have occurred on a balance of probabilities (…) Rather, the central question is whether the evidence, viewed as a whole, provides a rational basis for the Secretary of State’s decision (…)”

This standard is lower than that of the balance of probabilities.  

This decision highlights the wide margin given to the SSHD’s discretion when it assesses the risk to national security. It also emphasizes the crucial role of experienced legal representation in navigating appeals to SIAC.

How Gherson can assist

At Gherson, our team has a renowned track record in succeeding in some of the most complex immigration cases ever dealt with by the Home Office or the Courts. Gherson also has expertise in appeals against the removal of citizenships.

Gherson has extensive experience advising on complex asylum matters and is highly experienced in advising on UK visa matters. If you have any questions arising from this blog, please do not hesitate to contact us for advice, send us an e-mail, or, alternatively, follow us on Twitter, Facebook, Instagram, or LinkedIn to stay-up-to-date.

Updated: 22 May 2025

The information in this blog is for general information purposes only and does not purport to be comprehensive or to provide legal advice. Whilst every effort is made to ensure the information and law is current as of the date of publication it should be stressed that, due to the passage of time, this does not necessarily reflect the present legal position. Gherson accepts no responsibility for loss which may arise from accessing or reliance on information contained in this blog. For formal advice on the current law please do not hesitate to contact Gherson. Legal advice is only provided pursuant to a written agreement, identified as such, and signed by the client and by or on behalf of Gherson.

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