Professional practice

C&P Top Ranked 2023Legal 500 Leading Silk 2023

Hugh Mercer KC is a highly regarded advocate practising in a broad range of areas with a particular emphasis on public and private international law, public and regulatory law, EU law (including Retained EU law & Brexit/NI Protocol issues), human rights and international investment law. He has extensive experience at appellate level in England and Wales, in the CJEU and has been instructed in relation to cases before the appellate courts of other countries (e.g. Supreme Courts of Switzerland and Cyprus) working alongside local counsel.

He is described by clients as “excellent and approachable” and “a super lawyer” and his reputation is as a “fine litigation strategist”. He chairs the Brexit Working Group of the Bar and the CCBE European Lawyers’ Committee.

He sits as a Deputy High Court Judge and as an arbitrator/mediator. He is a Master of the Bench of Middle Temple. He has excellent French, good German, Spanish and Italian. He is also a member of the Bar of Northern Ireland and, as an avocat, the Barreau du Brabant Wallon, Belgium.  He continues to have a right of audience in the CJEU for EU cases.


What Others Say

Chambers and Partners UK 2023

“Hugh Mercer KC is exceptional. He is a brilliant advocate and has an incredibly ability to distil complex legal arguments into pithy points.”

“He provides very good analysis and excellent advocacy.”

“He is always a very impressive advocate.”

“He provides very good analysis and excellent advocacy.”

“Hugh Mercer KC is exceptional. He is a brilliant advocate and has an incredibly ability to distil complex legal arguments into pithy points.”

Legal 500 2023

“He has the finest mind I have encountered on administrative law issues relating to food and agriculture and EU law generally.”

Legal 500 2022

“He has the finest mind I have encountered on administrative law issues relating to food and agriculture and EU law generally.”

“He has a very impressive ability to break down and present complex legal arguments in a readily understandable and persuasive way.”

Chambers and Partners UK 2022

“He is a creative thinker who brings new ideas and is constantly innovating rather than simply reproducing case law.”

“He is a unique and special advocate with unrivalled expertise in EU Agricultural law.”

“A terrific EU and English constitutional lawyer.”

Legal 500 2021

“A masterclass in terms of his ability to assimilate complex issues.”

“An excellent advocate able to distil complex legal arguments in a manner accessible to the court.”

“He is undoubtedly extremely strong on all relevant jurisdictional conflict issues.”

Chambers and Partners UK 2020

“He is masterful on his feet. His preparation is so immaculate and tells the story in such a way that it is easy to follow. It sort of spoils you because you can’t instruct him on everything.”

Legal 500 2020

“A leading light in agricultural and public law issues… He shows in-depth knowledge of EU civil procedure law and creativity to find out-of-box solutions.” A creative and industrious lawyer, his preparation is meticulous and well judged.”

Chambers and Partners UK 2019

“He has a very good way of building arguments in a straightforward and convincing way, an ability to look at questions from different angles and an enormous knowledge of EU law… Knows European law back to front and works very closely with us in ensuring that our client’s needs are met.”

Examples of notable cases

Eleanor Sharpston v. la Cour de Justice de l’Union Européenne C-684-5/20P (termination of Advocate General’s term of office; whether reviewable act in EU law)

Re Northern Irish Protocol (advice on interpretation and application of the Protocol to the food sector)

Re NI Troubles amnesty proposal (advice on legality of the proposed amnesty under ECHR)

Unwired Planet v. Huawei [2020] UK Supreme Court 37 (representing Apple Inc in a challenge on grounds of breach of international law to English court fixing royalty rate for US consumers on US patents in USA)

Re sale of shipping company, LMAA Arbitration (Greek debt crisis prevented payment of balance; whether seller’s action breached good faith under the applicable Greek/Italian law)

Bayer v. European Commission, CJEU, Case C-499/18P (whether European Commission prohibition of authorised pesticide infringed procedural protection under the terms of the authorisation)

Re EU & International law, Federal Court of Australia, 2020 (expert witness on EU and International law)

R (Newby Foods) v. Food Standards Agency [2019] UKSC 18 (interpretation of the EU law definition of meat in relation to innovative process to recover meat not removed from bone by initial butchery process)

Arbitration re expropriation of financial services provider, ICSID (whether alleged abuse of right by state in the application of Banking Recovery and Resolution directive breached the fair and equitable treatment clause of the relevant bilateral investment treaty)

AMT Futures Limited v. Marzillier [2017] UKSC 13 (challenge to English jurisdiction; derivatives trader sued German law firm in London for allegedly inducing German consumer investors to sue trader in German courts in breach of English jurisdiction clause; damage occurred on commencement of proceedings by consumers in Germany)

Moreno v. Motor Insurers Bureau [2016] UKSC 52 (law applicable to tort claims for accidents abroad involving uninsured drivers; claim against MIB in UK but law of place of tort, not English law, applied – overturning CA case law)

Re D [2016] UKSC 34 (jurisdiction of Supreme Court to entertain appeal; recognition of Romanian child custody order; Brussels II Regulation)

Lehman Brothers Finance AG v. Klaus Tschira Stiftung GmbH, Swiss Supreme Court (true interpretation of jurisdiction clause in ISDA Master Agreement; whether clause providing for exclusive or non-exclusive jurisdiction)

Cox v. Ergo Versicherung AG [2014] UKSC 22 (whether territorial limitation on English tort statute; whether applicable law was German law as place of accident)

Re legality of worldwide specialist shipping pool, LCIA Arbitration (whether rules and structure of a specialist shipping pool were anti-competitive and in restraint of trade)

Georgias v. European Council CJEU, C-545/14P (whether EU sanctions had been lawfully applied to the claimant and whether, if not, claimant was entitled to damages for breach of his fundamental rights)

Re energy infrastructure (Greek, English, Swiss law) ICC Arbitration (whether German engineering company contractually liable to Greek owners for design errors in design of infrastructure)

Mangouras v. Spain (The Prestige) ECHR Grand Chamber, 28 September 2010 (whether imprisonment of ship’s master following loss of his vessel without taking into account his personal circumstances breached Article 5(3) ECHR)

Mothers of Srebrenica ICTY (whether prosecutor of ICTY was in breach of duty under the UN Statute for ICTY through the handling and disposal of artefacts, belonging to victims of Srebrenica, removed from mass graves)

Microsoft v. European Commission EU General Court, T-167/08 (whether European Commission order to license software on fair, reasonable and non-discriminatory terms infringed legal certainty; whether infringement of right of effective remedy when no mechanism for determining whether relevant rate was FRAND)

R (Intertanko) v. Secretary of State for Transport, CJEU, C-308/06 (whether the EU Ship Source Pollution Directive breached the public international law obligations of the EU under the MARPOL Treaty)

Huawei v. Libya Investment Authority, District Court of Port Louis, Mauritius (whether EU Libya sanctions rendered the payment for services rendered unlawful; territorial scope under international law of EU sanctions)

R v. Ministry of Agriculture ex p Fisher, CJEU, C-369/98 (rights of defence; whether, where claimant for benefit did not have access to relevant information in hands of public body, public body entitled to penalise claimant for error in relation to that information)

Arbitration & related court applications

Experienced litigator and regularly acts as counsel in arbitral tribunals, often where EU, competition or foreign law issues arise – in appropriate circumstances also acts as expert witness.  Can litigate/arbitrate in French and with underlying documents in German, Spanish and Italian. Also sits as an arbitrator.

  • Arbitration arising out of share sale agreement between Greek and Italian shipping lines – Greek and Italian law
  • ICSID Arbitration in relation to compensation for expropriation of financial services provider
  • Arbitration on effect of EC competition law on specialist shipping pool
  • Arbitration Greek/German – under Greek, Swiss and English laws, ICC, Geneva
Banking & financial services

Particularly experienced in the application of EU Directives to the financial industry (e.g. seeking to sanction failure of Government to apply the Insurance Directives) including claims for:

  • Francovich damages (as group actions) but also covers the public/regulatory law aspects of financial services including hearings before the Regulatory Decisions Committee and the Upper Tribunal.
  • AMTF v. Marzillier UK Supreme Court
  • Adamson v. Gain Capital & others
  • Poole v. HM Treasury CA
Commercial dispute resolution

Has been involved in litigation involving multiple damages claims based on Francovich arising from the failure of Government to implement EU directives in the field of insurance, financial services, tax and also in both stand alone and follow-on actions for damages arising from cartels for example in the vitamins cartel and the air cargo cartel. Handles many cases with expert evidence of foreign law and where conflict of laws issues are uppermost.

  • Lehman Bros v. Klaus Tschira Stiftung GmbH Comm Ct & Swiss Supreme Court
  • BA v. SEPLA
  • National Iranian Oil Corporation v. IRI International Corp. CA
Conflict of laws & private international law

Is a recognised authority on the Brussels I Regulation in the light of his commentary (Layton & Mercer, European Civil Practice) on the Regulation. Frequently handles the specalist conflict of laws issues such as applicable law and jurisdiction at the outset of a case. Particularly experienced in cases where foreign law becomes an issue.

  • AMTF v. Marzillier Supreme Court
  • Moreno v. MIB Supreme Court
  • Re D Supreme Court
  • Cox v. Ergo Supreme Court
  • Olafsson v. Gissurarson CA
  • Nordea v. Unicredit
  • Henderson v. Jaouen CA
  • National Iranian Oil Corporation v. IRI International Corp. CA
  • Agnew v. Lansforsakringsbolagens House of Lords
  • Kitechnology v. Unicor CA
Energy & natural resources

Covers a range of environmental issues arising in farming and fisheries contexts such as the application of the precautionary principle to the ecosystem of the mid-Atlantic ridge but is also involved in judicial review of EU directives in the field of the environment.

Has had regular involvement with climate change issues, both under EU and UK law, including both the CRC Trading Scheme and the EU Emissions Trading System.

  • King v. Environment Agency
  • ATH v. Environment Agency
  • R (Mabanaft) v. Secretary of State for Energy and Climate Change
  • Poland v. European Commission CJEU
European law & competition

Very experienced advocate in the CJEU. Broad range of EU, competition and state aid experience across a very wide range of industries from telecoms, electronics and IT to vitamins; specialist chemicals and oil derivatives to materials for the construction industry; supermarkets to cigarettes & beer/alcoholic drinks.

Often covers interaction between national law and EU law and has been involved in several high profile claims for damages for breach of EU law as well as applications based on the Viking case to prevent industrial action.

  • Syngenta v. Commission CJEU
  • Bayer v. Commission CJEU
  • R (Newby Foods) v. Food Standards Agency CJEU
  • Repertoire Culinaire v. HMRC
  • Georgias v. Council CJEU
  • BA v. SEPLA
  • Microsoft v. Commission CJEU
  • Vtesse v. Commission CJEU
  • Emerald v. BA
  • Thai Airways v. BA
  • R (Fruition) v. RPA CJEU
  • R (Intertanko) v. Secretary of State for Transport CJEU
  • Região autónoma dos Açores v Council CJEU
  • Arkin v. Borchard Lines
  • R v. MAFF ex p Fisher CJEU
  • European Commission v. East Africa Conference Lines
Food, agriculture, fisheries & farming

Has been involved in most of the big regulatory issues between food and farming interests and public authorities over the last 15-20 years, often but not exclusively with an EU flavour. He has litigated many issues on definition of food products, pesticide authorisation and issues of Single Payment or Basic Payment Scheme including alleged cross-compliance breaches.

  • Syngenta v. European Commission CJEU
  • Bayer v. European Commission CJEU
  • Cranswick v. Food Standards Agency
  • R (Newby Foods) v. Food Standards Agency
  • R (Fairness for the Uplands) v. Welsh Ministers
  • R (Fruition) v. RPA CJEU
  • R (Humber Growers) v. RPA
  • R (Gwillim) v. Welsh Ministers
  • R (Mitchelmores) v. Marine Management Organisation
  • R (Bickford-Smith) v. Defra
  • R (Jaspers of Treburley) v. Food Standards Agency
  • Weightman v. Welsh Ministers
  • Bloomsbury v. Sea Fish Authority Supreme Court
  • R (Partridge) v. Defra CA
  • Região autónoma dos Açores v Council CJEU
  • Leidig v. IBAP CA
  • R v. MAFF ex p Fisher CJEU
  • R v. Secretary of State for Health ex p Eastside Cheese CA
Human rights & civil liberties

Has particular experience in the application of human rights within a diverse range of fields of civil law such as agriculture, environment, due process, competition and extending even to the impact of human rights on the conduct of inquests (acted as lead counsel for the coroner in the case of Middleton in the House of Lords). Represented the majority of the worldwide shipping industry in the case brought by Capt Mangouras against Spain on the breach of his right to bail and currently representing NGOs in Bosnia in relation to the conduct of the International Criminal Tribunal for the former Yugoslavia.

  • Mothers of Srebrenica ICTY
  • Mangouras v. Spain ECHR
  • Varley v. UK ECHR
  • R v. West Somerset Coroner ex p Middleton House of Lords
  • Taylor v. Lancs CC CA
Media, art, entertainment

Deals with various competition, regulatory and state aid issues arising out of telecoms liberalisation policies, related regulatory issues and extending to competition issues arising from satellite broadcasting, licensing of programmes and sport.

  • EU city re recovery of medieval panels
  • Bruce Baker v. Boxing Board of Control
  • Vtesse Networks CJEU
  • Three Tenors
  • Stevenage v. Football League
Public & administrative law

Has been a regular litigant for and against Government entities for over ten years, generally in cases which raise EU issues but also in cases with Human Rights or regulatory law. Very experienced in the application of public law applied to agriculture, fisheries, food, environmental issues and also in relation to a diverse range of regulatory panels and procedures.

  • R (Newby Foods) v. Food Standards Agency CA
  • Hemming v. Westminster Supreme Court
  • R (Jaspers of Treburley) v. Food Standards Agency
  • R (Friends of the Earth) v. Defra and NFU
  • Bloomsbury v. Sea Fish Authority Supreme Court
  • R (Mabanaft) v. Secretary of State for Energy and Climate Change
  • R (Castille) v. DTI
  • R (O’Connor) v. HM Coroner for Avon
  • R (Partridge) v. Defra CA
  • R v. DTI ex parte Isle of Wight
  • R v. Swale BC ex p Lidl
Public international law

Frequently covers the public international law arguments arising in relation to English or EU law such as the Law of the Sea or sanctions but also extends to independent PIL issues in fields such as WTO and sovereign debt issues. Litigated the impact of international law on EC law in the context of shipping pollution and advised on the legal issues arising from the eurozone crisis.

Involved in legal and regulatory challenges in several of the EU sanctions regimes, challenging the implementing regulation in the EU General court, claiming damages, bringing national court challenges, dealing with the impact of the EU blocking regulation against US sanctions (Reg 2271/96).

  • Mothers of Srebrenica ICTY/UN Security Council
  • Georgias v. Council CJEU
  • R (Intertanko) v. Secretary of State for Transport CJEU
  • Região autónoma dos Açores v Council CJEU
Regulatory law & investigations

Very experienced in the conduct of regulatory investigations in the utilities, food, agriculture and telecoms sectors both in the UK and the EU, in conjunction with any subsequent public law proceedings in the Administrative Court or the General Court of the EU.

  • King v. Environment Agency
  • R (Fruition) v. Food Standards Agency
  • Vtesse Networks v. Commission
  • Holleran v. Severn Trent Water Plc
  • R (Partridge) v. Defra
  • Sutton & East Surrey Water v. Ofwat
  • Leeds City Council v. Watkins
  • European Commission v. East Africa Conference
Revenue law (including VAT, IPT, duties & excise)

Deals with tax issues arising in an EU context such as differential taxation of subsidiaries based in another EU country and extending into state aid arguments arising out of differential business rates taxation. Has been involved in challenges to a wide range of levies, charges, excise duties, often in an EU context.

  • Hemming v. Westminster Supreme Court
  • Repertoire Culinaire v. HMRC CJEU
  • Vtesse v. Bradford
  • Bloomsbury v. Sea Fish Authority Supreme Court
  • R (Castille) v. DTI
  • Boake Allen v. HMRC House of Lords
  • Pirelli Cable v. HMRC House of Lords
Shipping & admiralty

Extensive experience of competition issues both before UK competition authorities and the EU Commission in relation to transport including liner conferences; bulk and tramp shipping; shipping pools; reefer trades; specialist shipping; port and airport pricing and discrimination arguments; differential pricing by monopoly operators on shipping routes.

  • Arbitration in relation to liabilities under share sale agreement of shipping line
  • Mangouras v. Spain (re Prestige) ECHR
  • R (Intertanko) v. Secretary of State for Transport CJEU
  • Arbitration re effect of EU competition law on specialist shipping pool
  • Arkin v. Borchard Lines
  • European Commission v. East Africa Conference
Travel Law

Has developed extensive experience, primarily at appellate level in test cases to determine the law applicable to causes of action litigated in the English courts. He brings to this field an in-depth knowledge of conflict of laws and EU law and works with juniors specialist in this area.

  • Moreno v. MIB Supreme Court
  • Wigley Foster v. MIB CA
  • Cox v. Ergo Supreme Court
  • Re A v. MOD CA
  • Henderson v. Jaouen CA

2022-date      Chair of International Committee, Bar Council

2021-date      Head of UK Delegation to CCBE, Brussels

2018 – date    Deputy High Court Judge assigned to the Queen’s Bench Division and the Administrative Court

2016 – 2021  Chair, Brexit Working Group, Bar Council

2016 – date   Chair, CCBE European Lawyers’ Committee

2016 – 2019  Leader, European Circuit

2015 – 2021  Vice Chair, International Committee of the Bar Council

2010 – 2016  Chair of the CCBE Permanent Delegation to the Court of Justice and General Court of the European Union

2007 – 2010  Head of UK Delegation to CCBE

2005 – 2008  Junior Counsel to the Crown (A Panel)


1986                 Licence spéciale en droit européen, Université Libre de Bruxelles

1981-1984       MA, Downing College, University of Cambridge

1972-1980       King Edward VI Grammar School, Stourbridge


1991    Commercial Debt in Europe, Guy & Mercer

2004   European Civil Practice, Layton & Mercer

2010 – date     EU law in Judicial Review, Supperstone, Goudie & Walker

March 2017     HL evidence for Brexit: Justice for Families, Individuals and Businesses