Landmark Chambers

Home > Our people > Barristers > Gwion Lewis

Public law

Public law is at the heart of Gwion's practice. He is a member of the Attorney General's 'A' Panel of Junior Counsel, which means that he regularly acts for the UK Government in its most complex cases. He is also a member of the Welsh Government's ‘A’ Panel of Junior Counsel. Gwion's cross-border practice means that he appears frequently in administrative courts and tribunals across England and Wales. He was “the most active barrister” at the junior Bar in 2016, measured by case days in the English courts (The Lawyer Court Rankings, 2016).

Many of Gwion’s cases feature aspects of planning and/or environmental law, but his interest in public law and judicial review extends more broadly to issues arising in immigration, human trafficking, education, equality and discrimination law, detention, transport, standards and ethics, care standards and property-related public law.

Gwion also has particular interest in public law issues arising from the current devolution settlement for Wales. His regular clients in Wales include the Welsh Ministers, Natural Resources Wales and the Welsh Language Commissioner.

The legal directories have recognized Gwion as a leading junior in administrative and public law for several years. In Legal 500, he has been described as "a top-class advocate”for judicial review claims who is “impressive” and “quick on his feet”. His written pleadings for public law litigation are described as “extremely effective” (Chambers & Partners).

Examples of Gwion’s recent and ongoing public law work include:


  • ‘The Article 50 Challenge’ (ongoing) – acting for a campaign group that submits that no valid “decision to withdraw” from the European Union, as required by Art. 50(1) of the Lisbon Treaty, has been made in accordance with the UK’s constitutional requirements (with Hugh Mercer QC).


  • Calais ‘jungle’ camp and the Dubs scheme (ongoing) – acting for the Secretary of State for the Home Department (“SSHD”) responding to various claims and applications for interim relief by those who previously occupied the ‘jungle’ camp in northern France and who claim to be related to UK nationals;
  • R (AT) v SSHD (ongoing) – whether an application for indefinite leave to remain (“ILR”) as a victim of domestic violence incorporates, in principle, a human rights claim;
  • R (NO) v SSHD [2016] EWCA Civ 876 – whether the SSHD had wrongly denied humanitarian protection to an Afghan national with serious mental illness;
  • R (Rashid) v SSHD [2015] UKUT 190 (IAC) – successfully defended the SSHD’s decision to refuse a Bangladeshi national leave to remain as a student when he had terminated his studies;
  • R (Azizi) v SSHD [2014] EWHC 4021 (Admin) – whether the SSHD’s decision to grant a family 3 years’ discretionary leave rather than ILR was unlawful;
  • R (Al-Beri) v SSHD (2014, settled) – judicial review of the alleged failure of the SSHD to make adequate arrangements to process applications for family reunion by those affected by hostilities in Syria;
  • R (Capital Care Services UK Ltd) v SSHD [2012] EWCA Civ 1151 – challenge to the revocation of a licence to sponsor migrants under Tier 2 of the points-based system.

Human trafficking

  • R (EM) v SSHD (ongoing) – leading case on the SSHD’s obligations to those identified as potential victims of trafficking but whose detention is maintained on public order grounds (with James Eadie QC);
  • R (TDT) v SSHD [2016] EWHC 1912 (Admin) – successfully resisted the first claim brought in the UK alleging that the SSHD had breached her positive operational duty under Art. 4 ECHR by releasing from detention a Vietnamese national claimed to be at risk of re-trafficking.


  • RE v Governing Body of Ysgol Eifion Wyn, Porthmadog (ongoing) – acting for a young disabled boy who has Prader Willi syndrome in a claim before the Special Educational Needs Tribunal for Wales seeking a declaration that he has been discriminated against due to failures to make reasonable adjustments in relation to his education;
  • R (Jones) v Denbighshire County Council [2016] EWHC 2074 (Admin) – successfully challenged on behalf of a former pupil the decision to close a rural Welsh-medium primary school;
  • Advised the Royal Welsh College of Music and Drama on proposed changes to its funding model.

Equality and discrimination law

  • R (Welsh Language Commissioner) v National Savings and Investments [2014] EWHC 488 (Admin) – sole counsel for the Commissioner in her first judicial review, challenging successfully NS&I’s decision to revoke its Welsh language scheme and cease its Welsh language services;
  • R (St Clair Toussaint) v Secretary of State for the Home Department (Central London County Court, 2015) – claim that the SSHD breached her duty under the Equality Act 2010 to make reasonable adjustments when she transferred a disabled immigrant with no leave to remain in the UK from hospital to the detention estate;
  • R (MM) v Secretary of State for Work and Pensions [2013] EWCA Civ 1565 – landmark case under the Equality Act 2010 about the extent of the duty to make reasonable adjustments for those with mental health problems who apply for employment support allowance (with Martin Chamberlain QC);


  • R (Botan) v SSHD [2017] EWHC 550 (Admin) – whether the immigration detention of a Somali male who had committed a serious sexual assault was still lawful after almost 4 years;
  • R (WT) v SSHD [2016] EWHC 659 (Admin) – successfully resisted a challenge to the SSHD’s decision to maintain the detention of a national of Myanmar after he had issued a claim for judicial review;
  • R (AS (Afghanistan)) v SSHD [2014] EWHC 3478 (Admin) – whether the SSHD could lawfully maintain the detention of a person as an adult when the High Court had ruled that his claim to be a child was at least arguable pending a fact-finding hearing;
  • R (AA (Sudan)) v SSHD [2014] EWHC 2118 (Admin) – whether a father’s outstanding application for contact with his child in family law proceedings meant that he could no longer be lawfully detained;
  • Tsavdaris v Home Office [2014] EWHC 440 (QB) – effect of the transitional provisions of the Immigration (EEA) Regulations 2006 on the lawfulness of detention;
  • R (Kajuga) v SSHD [2014] EWHC 426 (Admin) – judicial review of the 2-year detention of a person claiming to be from Burundi, but unable to prove that.


  • HS2 (Select Committee hearings (2016)– acted for a coalition of 12 local authorities, led by Chiltern District Council, who were concerned about the noise impact of the project; also acted separately for Coventry City Council and the HS2 Action Alliance;
  • Crossrail (2007-2008) – one of the team of 5 Landmark Counsel who (i) advised the Department for Transport on the many public law issues arising in this £17 billion scheme; and (ii) appeared for the Department in Select Committee hearings in Parliament relating to the Crossrail Bill.

Standards and ethics

  • Heesom v Public Services Ombudsman for Wales [2014] EWHC 1504 (Admin) – intervened for the Welsh Ministers to make submissions about the compatibility of the Welsh ethical standards system for councillors with Article 10 ECHR.

Property-related public law

  • Wharton Park, Durham (2017) – acted for Durham County Council in a right of way inquiry: successfully persuaded the inspector to depart from her interim decision and conclude that public use of parkland held under the Public Health Act 1875 and Open Spaces Act 1906 was “by right”, not “as of right”.

Duty of candour

  • R (Khan) v SSHD [2016] EWCA Civ 416 – obtained an order setting aside a grant of permission to appeal to the Court of Appeal due to a failure to comply with the duty of candour.


  • Advised Ofwat on a series of appeals relating to the transfer of private sewers or pumping stations;
  • Advised various public bodies on the implications of the Wales Act 2017 for the devolution settlement;
  • Advised the National Accounts Classification Committee on the classification of trust ports.

For details about Gwion’s planning judicial review practice, please click here, and for details about his environmental judicial review practice, please click here.