Professional practice

Legal 500 Leading Silk

Hugh Mercer QC is a highly regarded advocate practising in a broad range of areas with a particular emphasis on public law, private international law, EU law and human rights. He has extensive experience at appellate level (Supreme Court and Court of Appeal), in the CJEU as well as in 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 is also Leader of the European Circuit.

He sits as a Deputy High Court Judge and is a Bencher of Middle Temple. He has excellent French, good German, Spanish and Italian. He is also an Avocat and member of the Belgian Bar.

Hugh does not currently accept direct access instructions.


What Others Say

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.”

Chambers and Partners UK 2018

“Mercer has a very good grasp of the law and is very good at identifying original arguments.”

Chambers and Partners UK 2017

“He is technically strong and also very pragmatic.”

Chambers and Partners UK 2015

“He’s first class and undoubtedly one of the top agriculture barristers in the country.” “A classy operator; he’s stunningly intellectual and a very experienced EU lawyer.”

“He’s so quick it’s terrifying.” “Excellent on his feet, he was really quite robust in a difficult case.”

“Excellent at getting what the client wants.”

Legal 500 2016

“Approachable and meticulous.”

Legal 500 2014

He is particularly noted as “a fine litigation strategist” who is “marvellous for EU law questions”.

Clients have described him in the legal guides as “very erudite and, frankly, brilliant”, “phenomenally clever and very likeable”, “excellent in all aspects” of his work, “excellent and approachable” and “a super lawyer”.

Examples of notable cases

Hugh specialises in innovative solutions to achieve the client’s objectives.

In a judicial review context, having obtained an injunction to permit a client to continue producing its product pending a final court decision, the client took the view that the European Commission had failed to abide by the injunction.  An application to court based on failure by the Commission to respect its duty of loyal cooperation had the desired effect. (Newby Foods).

Acting for the Motor Insurers’ Bureau in the Supreme Court, he overturned two unanimous Court of Appeal authorities to establish that the MIB’s liability in respect of uninsured drivers in accidents abroad was to be determined in accordance with the law of the place of the accident, not English law.

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


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


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


2019     Called to the Bar of Northern Ireland

2016     Chair, Brexit Working Group of the Bar Council

2016     Chair, CCBE European Lawyers’ Committee

2012     Bencher of Middle Temple

2010   Chairman of the CCBE Permanent Delegation to the Court of Justice and General Court of the European Union (liaison committee between all EU lawyers and the ECJ)

2008     Appointed Queen’s Counsel

2005-8 Junior Counsel to the Crown (A Panel)

1988-9 Tutor, London School of Economics

1985      Called at Middle Temple


1986    Licence spéciale en droit européen, Université Libre de Bruxelles

1984    MA, Downing College, University of Cambridge