Public and Administrative

National Security

National security law covers all aspects of the law relating to the security and defence of the nation, including its citizens, economy and institutions. Threats may be from state or non-state actors, and include espionage, terrorism, cyber-crime and economic warfare. These cases give rise to some of the most cutting-edge and sensitive issues in Public Law litigation today.


Landmark Chambers is recognised as a leader in the field of national security law. Its barristers are regularly instructed in the leading cases in this area. Members of chambers appear on behalf of the Government, claimants and appellants, interveners and as Special Advocates. They have experience in acting at all courts where national security issues arise, including in cases in the international courts.

Members have experience of proceedings before specialist bodies such as the Special Immigration Appeals Commission (SIAC), the Proscribed Organisations Appeals Commission (POAC) and the Investigatory Powers Tribunal (IPT). These include the use of closed material procedures. They are also regularly instructed in national security proceedings in the ordinary civil courts, for example in the context of judicial review work or civil damages actions, including where closed material procedures under the Justice and Security Act 2013 are engaged.  Members have also been appointed as Counsel to the IPT.

Particular areas of expertise in the national security field include national security related immigration cases (such as deportations, deportations with assurances, exclusion orders, temporary exclusion orders, cancellation of leave, control orders, terrorism prevention and investigation measures). In the nationality field, members are regularly involved in deprivation of citizenship cases and challenges to the refusal of naturalisation. Members are instructed in cases under the National Security and Investments Act 2021, involving responses to state threats. Landmark barristers have considerable experience in sanctions work and are acting in some of the first challenges by individuals designated as a result of the war in Ukraine.  Members have also acted in Parole Board proceedings and challenges to refusals under the ARAP scheme raising national security issues.

Prominent cases in which Landmark barristers have appeared in recent years include the following:

R (Begum) v. Special Immigration Appeals Commission (Supreme Court, SIAC) – challenge to Shamima Begum’s deprivation of British citizenship.

Al-Nashiri v. Security Service and others (IPT) – IPT complaint by Guantanamo Bay detainee alleging complicity by UK intelligence agencies with his alleged rendition, detention and ill-treatment.

Abu Zubaydah v. Foreign and Commonwealth Office and others (Supreme Court) – civil damages claim from long-standing Guantanamo Bay detainee based on allegations of UK complicity with his alleged detention and ill-treatment in CIA black sites.

R (Nexperia BV) v. Secretary of State for Business, Energy and Industrial Strategy (High Court) – one of the first challenges under the National Security and Investment Act 2021.

R (LetterOne) v. Secretary of State for Business, Energy and Industrial Strategy (High Court) – one of the first challenges under the National Security and Investment Act 2021.

Khan v. Secretary of State for Foreign, Commonwealth Development Affairs (High Court) – challenge to designation under the Russian sanctions regime.

Secretary of State for the Home Department v. P3 (Court of Appeal) – application of the Begum approach to the assessment of national security interests in human rights appeals.

R (XH and AI) v. Secretary of State for the Home Department (Court of Appeal) – leading case on the use of the Royal Prerogative to cancel and refuse passports based on national security grounds.

ALO v Secretary of State for the Home Department (High Court) – dealing with refusal of visa under the ARAP scheme on national security grounds.

Case C-573/14 Lounani (CJEU, Grand Chamber) – leading case in the CJEU on exclusion from refugee status on grounds of involvement in “acts contrary to the purposes and principles of the United Nations”.

Practice Managers

Contact our friendly and helpful Practice Managers for more information about our barristers and services or to make an enquiry.

Ben Connor

Practice Director

020 7421 2483

Ben Connor

Zoe Bluck

Practice Manager

020 7421 1301

Zoe Bluck new

Jamie Lal

Assistant Practice Manager

020 7421 1309

Jamie Lal new

Richard Bolton

Senior Practice Manager

020 7421 1392

Richard Bolton new

Charlotte Hockney

Assistant Practice Manager

020 7421 1303

Charlotte Hockney new

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