Clíodhna accepts instructions in all areas of public law and is regularly instructed in judicial review proceedings, both as sole and junior counsel.

Recent instructions include:

• R (O’Connor) v National Institute for Clinical Excellence: acting for the claimant in a judicial review of NICE’s decision to reject trastuzumab deruxtecan (Enhertu) for use in the NHS in England. This arose from NICE’s new policy of assigning greater weight to treatments for “severe” conditions over those for terminal illnesses when determining whether a treatment should be funded within the NHS.
• R (BHO) v Secretary of State for Health and Social Care: acting for the IMA in its intervention in this claim, which concerns the lawfulness of the SSHSC’s policy of levying charges for NHS care to “late beneficiaries” of the UK-EU Withdrawal Agreement.
• R (WZ) v Secretary of State for Defence: acting for WZ, a former interpreter for British and US forces in Afghanistan in his challenge to the Secretary of State’s decision that he was not eligible for relocation to the UK under the Afghan Relocation and Assistance Programme on the basis that he was dismissed from service for a “non-minor” reason.
• R (IMA) v Secretary of State for the Home Department [2023] 1 WLR 817: acting for the Independent Monitoring Authority for the Citizens’ Rights Agreements in its successful challenge of the lawfulness of the European Union Settlement Scheme (with Robert Palmer KC).
• R (Good Law Project Limited) v Secretary of State for Health and Social Care v Abingdon Health Plc: acting for the interested party, the manufacturer of antibody lateral flow tests in response to a judicial review of the award of contracts during the COVID-19 pandemic. The challenge failed on all grounds.

Prior to joining the bar, Clíodhna worked as a legal fellow in the public affairs department of the British Pregnancy Advisory Service (BPAS), a charity which provides and advocates for reproductive healthcare. She regularly publishes on the topic of abortion and reproductive healthcare.

She is a trustee of Feed UK, a charity which advocates for the food needs of infants and of their families.

Cases

Clíodhna specialises in cases spanning all aspects of housing and social care law. Recent instructions include:

• Fertre v Vale of White Horse [2025] EWCA Civ 1057: Clíodhna acted for the AIRE Centre in its intervention in the Court of Appeal. The Court of Appeal determined that those with pre-settled status granted under the EU Settlement Scheme, but without a directly effective right to reside in the UK under the Withdrawal Agreement are not protected by the non-discrimination provisions of Article 23 WA. As such, the Appellant was not the subject of unlawful discrimination under the WA when she was refused homelessness assistance under Part 7 of the Housing Act 1996.
• R (EM) v LB Havering [2024] EWHC 3016 (Admin): Clíodhna acted for the successful claimant, a survivor of serious domestic abuse, in a challenge to the defendant’s decision to exclude her from its social housing register on the basis that she did not meet its residence requirement. EM argued that she qualified for a number of exceptions to the scheme, failing which the scheme discriminated unlawfully against her as a victim of domestic violence.
• R (SK) v Royal Borough of Windsor and Maidenhead [2024] HLR 23: Clíodhna acted for the successful claimant, the mother of two disabled children, in her challenge to the defendant’s failure to lawfully assess the family’s housing needs and to comply with the obligation to accommodate them in suitable accommodation. The defendant’s failure to accommodate the family had contributed to a year-long stay in hospital by the claimant’s 14 year old daughter, who could not be safely discharged to the family’s previous accommodation.
• Acting for the claimants in a challenge to a local authority’s failure to reaccommodate a family, where the existing accommodation posed a risk to life, involving claims under the Housing Act 1996 and Article 2 ECHR;
• Acting for the claimant in a challenge to the lawfulness of a decision by a local authority to withdraw accommodation from a “former relevant child”, involving claims under the Housing Act 1996 and Children Act 1989 (as sole counsel);
• Acting for the claimant in judicial review proceedings concerning the lawfulness of a local authority’s housing allocation scheme involving claims under the Housing Act 1996 and gender discrimination under the Equality Act 2010 (as sole counsel);
• Acting for the claimant in a challenge to a local authority and CCG’s compliance with its duties under the MHA 1983;
• Acting for the claimants in a challenge to an Integrated Care Board’s decision refusal to fund a “continuing care” package of healthcare services for a disabled child with healthcare needs;
• Acting for claimants in various challenges to the discharge of local authority homelessness duties, including:
  • A JR challenge to a local authority’s interpretation of the review duties in section 202 HA96;
  • A challenge to a local authority’s failure to comply with section 193 HA96;
  • A challenge to a local authority’s use of B&B accommodation in purported discharge of section 193 HA96.

Cases

Clíodhna acts across the spectrum of Chambers’ competition litigation work including bringing and defending damages actions and collective proceedings.

Cases

Recent instructions include:

• Tesco Stores Limited v Cermaq Group AS and ors: acting for Tesco in its damages claim against eight Norwegian and Scottish salmon producers, alleging anti-competitive conduct in relation to sales of Atlantic salmon farmed in Norway.
• Roadget / Shein v Whaleco: acting for Whaleco (a UK subsidiary of Temu) in its defence and competition law counterclaim against Shein in connection with the operation of each party’s online shopping platform.
• Google Shopping: acting for Google in its defence of claims by Kelkoo, Foundem and others arising from Commission Decision AT.39740 “Google Search (Shopping)”
• Euronet v Visa and Mastercard: acted for Euronet, a provider of payment services, in its standalone damages claim against Visa and Mastercard under Article 101 and/or relevant provisions of Czech, Polish and Greek law.
• Royal Mail and BT v DAF Trucks Limited: acted for Royal Mail and BT in its damages claim against DAF arising from the European Commission’s 2016 “Trucks” settlement decision. Clíodhna also acted for Dawsongroup and Tesco in their respective follow-on claims.
• Justin Gutmann v London & South Eastern Railway Limited: acting for a defendant in the  standalone “Boundary Fares” claims brought by Mr Justin Gutmann against the operators of the South Eastern and Southwestern rail franchises.
• Boyle v Govia Thameslink Railway Limited, the Go-Ahead Group Plc and Keolis (UK) Ltd: acting for the defendant in a standalone collective action against the operators of the London-Brighton mainline in the fares set for the Southern, Thameslink and Gatwick Express brands.

Clíodhna regularly advises on questions of interpretation of European law and of retained EU law across the breadth of her practice. Clíodhna is called to the Bar of Ireland and has a primary degree in Irish law.

Cases

• Clíodhna has advised widely on the interpretation of the UK-EU Withdrawal Agreement (“WA”) and the European law that underlies it, including in relation to the lawfulness of the EUSS as originally enacted (R(IMA) v Secretary of State for the Home Department), the availability of homelessness assistance to those with PSS-only (Fertre v Vale of White Horse DC), the entitlement of late beneficiaries of the WA to free NHS treatment (R (BHO) v Secretary of State for Health and Social Care) the compatibility of deportation decisions with the “conduct” provisions of the WA; the effect of the non-discrimination provisions; the proper calculation of time periods under the WA; the extent of the right of permanent residence conferred under the WA; rights of appeal, and restrictions on the rights of residence and entry conferred by the WA.
• Clíodhna regularly provides advice on UK-EU relations law.
• Testbiotech eV v EU Commission: acting for Testbiotech in European judicial review proceedings under the Aarhus Regulation to the European Commission’s decision to grant market authorisation to Monsanto to import genetically engineered maize and soybeans into the internal market (with Kassie Smith KC and Will Perry).

Clíodhna is regularly instructed in matters under the DPA, GDPR, PECR, EIR and FOIA:

• Colourcoat Limited v IC: Clíodhna successfully defended the imposition of an MPN in the amount of £130,000 in respect of the making of unsolicited direct marketing calls in breach of the PECR (as sole counsel).
• Department for Education v IC: Clíodhna successfully defended the Commissioner’s determination that details of decision-making by the appellant concerning faith schools could not lawfully be withheld on the basis of section 36 FOIA (prejudice to the effective conduct of public affairs).
• Shiel v IC: Clíodhna successfully defended the Commissioner’s decision that information sought by the appellant could be lawfully withheld on the basis that it did not constitute “environmental information” within the meaning of EIR
• Clíodhna has acted for appellants and for the Commissioner in a range of challenges against and to Decision Notices, including challenges to reliance on the exemptions in sections 31, 36, 40, 42, and 43 FOIA.

Clíodhna regularly advises public authorities on compliance with obligations under FOIA and EIR.

Clíodhna has been instructed in a number of high-profile procurement and State aid matters by economic operators and contracting authorities, including:

• R (Good Law Project) v Secretary of State for Health and Social Care and Abingdon Health Ltd: Clíodhna acted for the interested party in a procurement and State aid challenge to the grant of contracts for lateral flow antibody tests during the Covid-19 pandemic (with Ligia Osepciu).
• IGT v the Gambling Commission: acting for the claimant to a challenge to the award of the Fourth National Lottery licence.

Clíodhna regularly advises economic operators and contracting authorities on procurement matters. Recent advisory work includes:

• Advising claimants and defendants on the merits of proposed scoring challenges to concluded procurement exercises;
• Advising on compliance with the procurement rules;
• Advising on post-Brexit arrangements and the effect of the EU-UK TCA for contracting authorities.

Cases

Clíodhna speaks Irish (bilingual) and German (conversational).