Patrick Leonard SC

Member of the Inner Bar

  • Junior Counsel: 1997
  • Senior Counsel: 2013

B.A. Hons, Dip. Business Studies, Diploma in International Arbitration, Certificat de Francais Juridíque.

Areas of Practice:
  • Arbitration
  • Commercial/Chancery
Patrick Leonard SC
Bar of England & Wales
Other Memberships:
Arbitration Ireland
Chartered Institute of Arbitrators
Construction Bar Association
EU Bar Association
Professional Regulatory and Disciplinary Bar Association
Other Languages:
French (Working)
Direct Professional Access:

Patrick Leonard is a senior counsel practising in Commercial and Public Law. He has appeared as leading counsel before the Supreme Court, the Court of Appeal, the High Court, the European Court of Justice, and in both international and domestic arbitrations. He has particular expertise in Financial, Construction, Insurance Coverage and Wind Energy Disputes, and a specialist interest in Professional Regulatory Law. He acts regularly in medical misconduct and medical negligence cases. He has acted for a number of Environmental NGOs, particularly in relation to the right to access information on the environment.

He was called to the Bar in 1997 and became an SC in 2013. He was called to the Bar of England and Wales in 2000.

Patrick is currently a member of the ICC Commission on Arbitration, and the ICC Taskforce on Addressing Issues of Corruption in International Arbitration. He is a member of the Irish Government’s Implementation Group for Ireland for Law and has spoken extensively about the impact of Brexit on legal services in Europe. Patrick is a member of the ICSID Panel of Arbitrators, the EU Panel of Arbitrators for bilateral trade disputes and a former elected member of the Bar Council of Ireland.


Ossory Road Enterprise Limited v Rogers and others [2022] IEHC 556 (Injunction – Commercial Property – Validity of lease – position of sub-tenants)

James Street Hotel Ltd. v Mullins and others [2022] IEHC 549 (Commercial Court – Security for Costs – Multiple Defendants – Phased Security)

CQMC CLG v Dublin City Council and others [2021] IEHC 811 (Commercial Court – Liability for Fire and Construction Defects in Multi Unit Development – General Conditions of Sale – Implied Terms)

Kelly and Others v v Clarion Quay Management Company Ltd. [2021] IECA 162 (Personal Liability of Directors for alleged torts of a company )

Heanue v Mayo Co. Co and others (Court of Appeal) [2019] IECA 9 (Indemnity claim between insurers in a maritime dispute)

 KBC Bank Ireland Ltd. V Bruce Blake (High Court) [2019] IEHC 252 (rectification of a multi million euro guarantee)

 Blue Diamond Sports Limited v Bank of Ireland (High Court) [2018] IEHC 655 (Injunction to restrain termination of banking relationship – Money Laundering – Payment Services Directive)

 National Asset Loan Management DAC v Thomas Anderson (High Court) [2018] IEHC 593 (Construction of a guarantee)

 In the Matter of Irish Asphalt Ltd. (High Court) [2017] IEHC 524 (Winding up petition – ulterior motive – abuse of process)

 Carpenter v Stoneavon and Deloitte and Touche (High Court) [2016] IEHC 304 (Entitlement to make a lodgement after mediation in an accountant’s professional negligence action)

 In re a Bankrupt, Anthony Casey (Unreported, High Court, McGovern J., 10 July, 2014) (Application to set aside an adjudication in bankruptcy)

Danske Bank A/S v Walsh and others (Unreported, High Court, Herbert J., 26 April, 2013) (Guarantee – Non Est Factum – Undue Influence)

O’Neill v McDonald and others (Unreported, High Court, Bermingham J., 22 March, 2013) (Claim against solicitor for opposing party in proceedings – Extent of absolute privilege afforded by Defamation Act, 2009 – Duty of care to opposing side in litigation)

Moran v Allied Irish Banks plc (Unreported, High Court, Commercial, McGovern J., July, 2012) (Construction of mortgage deeds, and applicability of the Land and Conveyancing Law Reform Act 2009)

John McAuley v Aer Lingus plc. (Unreported, High Court, Hedigan J., 24 March, 2011) (Whether Montreal Convention precludes an action outside the relief envisaged in the Convention itself)

Bank of Scotland v James Mansfield (Unreported, High Court, Commercial, Kelly J., 21 December, 2011) (Application for summary judgment for liability as guarantor in excess of €200 million – legal issues raised as to set off, the statute of frauds, ingredients required for a contract of loan)

Moore v Moore [2011] 1 I.R. 623 (High Court) (whether registration of title conclusive evidence of title, adverse possession, mistake or fraud in registration)

Mulvaney v Betfair [2011] 1 I.R. 85 (High Court) (Liability of defendant for material posted on website – immunity from suit under the e-commerce directive)

Kane Motors Ltd. v. Opel Ireland Ltd. (Unreported, High Court, Laffoy J., 21 February, 2011) (Commercial Agency – whether proceedings ought to be dismissed for delay)

Anglo Irish Bank Corporation plc v Brendan McGrath (Unreported, High Court, Commercial, Kelly J., 21 December, 2005) (Guarantee – Rule in Holme v Brunskill – Factual matrix)

Cooper-Flynn v RTE [2004] 2 I.R. 72 (Supreme Court) (Direction to a civil jury on majority required on an issue paper – admission of hearsay evidence – whether a retrial ought be ordered)

Harrisrange Ltd. v Duncan [2003] 4 I.R. 1 (High Court) (Construction of the Landlord and Tenant Act, 1980)


Currently acting as arbitrator in insurance disputes concerning business interruption insurance arising out of COVID, as counsel in a €50 million claim involving an Agreement for Lease, and in several multi million euro arbitrations in respect of insurance liabilities for defective building works.

Recently appeared in a dispute concerning the liability of a building contractor for pyritic damage with a claim value > €5 million.

Recently appeared before CAS on behalf of the Football Association of Ireland in a match fixing dispute (CAS 2018/A/6075 Igor Labuts v. Football Association of Ireland)

Represented an international beverages company in a multi-million euro dispute with a local distributor

Represented a public body in a major dispute concerning public works with a value >€30 million

Represented a property fund in a property dispute with a major tenant

Represented the landlord of a business park in a dispute with tenants concerning dilapidations

Represented the owner of a business park in a dispute with tenants concerning the calculation of service charges

Advised a wind farm operator in a multi-million euro dispute with the turbine manufacturer governed by ICC Rules

Represented a commercial property owner in a multi-million euro construction dispute with the developer

Represented a public body in an infrastructure dispute with an international company where the value of the disputed contract was >€100 million

Represented a property fund in a multi-million euro dispute with a major international financial services company in relation to the interpretation of a rent review clause in a lease

Represented the National Governing Body of a sport in a dispute concerning the composition of the Executive Committee and registration of athletes for Olympic qualifications


Commissioner for Environmental Information v Coillte and People over Wind [2023] IEHC 327 (Interaction between Access to Environmental Information Regulations and Freedom of Information Acts)

Friends of the Irish Environment v Legal Aid Board [2023] IECA 19 (Application of Legal Aid Scheme to Companies – Statutory interpretation – EU Charter of Fundamental Rights – Aarhus Convention)

Baynes v Financial Services and Pensions Ombudsman [2022] IEHC 678 (Limitation Periods for complaints to the FSPO)

Kane v Gallagher [2021] IEHC 794 (Coroner’s Court – Fair Procedures)

Ahmed v FTP, Ireland and the AG [2021] IECA 214 – (Constitutionality of professional regulatory legislative scheme which precludes an appeal from decision of a tribunal)

Klohn v An Bord Pleanala (Court of Justice, 10 March, 2021 Case C739/19) – (Application of Lawyers Services Directive – Cross Border Provision of Litigation Services)

 Friends of the Irish Environment v Legal Aid Board [2020] IEHC 454 (Application of Legal Aid Scheme to Companies – Statutory interpretation – EU Charter of Fundamental Rights – Aarhus Convention)

 Right to Know CLG v Commissioner for Environmental Information [2020] IEHC 392 (Test to be applied by the Commissioner – Mootness – approach of the CJEU and the Irish Courts)

 Redmond v Commissioner for Environmental Information, [2021] I.R. 695  (Construction of EU Environmental Regulations)

Pharmaceutical Assistants Association v PSI, Minister for Health, Ireland and others [2019] IEHC 663 (Application to have Judicial Review points heard separately to Constitutional Issues)

Klohn v An Bord Pleanala (Supreme Court, 31 July, 2019) (Right of German lawyer to appear before Irish Supreme Court)

Bebenek v Minister for Justice (High Court) [2019] IEHC 154 (Inherent Power of the High Court to discipline solicitor and barrister)

Khashaba v Medical Council [2016] IESC 10 (Application of Professional Qualification Directive to Montserrat)

Corbally v Medical Council [2015] 2 I.R. 304] Supreme Court (Medical Practitioners Act – Meaning of Poor Professional Performance)

 Akpekpe v Medical Council and others (Unreported, High Court, Kearns P., 26 April, 2013) (Whether the absence of a right of an appeal from a decision of the Medical Council to impose a sanction of advice was a breach of the applicant’s constitutional or ECHR rights)

 Flynn v Medical Council [2012] 3 I.R. 236 (High Court) (Amenability of decisions of a screening committee to judicial review, and obligation for such a committee to give reasons)

 An Bord Altranais v A. O’C (Unreported, Supreme Court, Denham C.J., 21 December, 2011) (Factors to be considered in suspending a professional pending an inquiry, notice required before a decision to initiate proceedings)

 Hemat v Medical Council [2010] 3 I.R. 122 (Supreme Court) (Whether defendant an association of undertakings for the purpose of competition law)

 Shine v Medical Council [2009] 1 I.R. 283 (Supreme Court) (Whether grounds upon which leave granted can be expanded – principles – double jeopardy)

 Prendiville v Medical Council [2008] 3 I.R. 122 (High Court) (Statutory construction – obligation to give reasons – composition of the Council considering sanction – whether legal advice should be given in public – appropriate test to be applied to the applicant’s conduct)


Patrick Costello v the Government of Ireland, Ireland and the Attorney General: Obstacles to the Ratification of CETA in the Irish Constitutional Context, ICSID Review – Foreign Investment Law Journal, 2023;

Ratification of the ISDS Provisions in CETA – Current Court and Legislative Challenges – An Overview”, European Investment Law and Arbitration Review, Vol 7 (2022), Chapter 6.

Arbitration in Derivatives Contracts“, (with Hayley O’Donnell BL) (2022), 39, Journal of International Arbitration, Issue 1, pp. 61-78

“Ecoswiss: Weakening the UNCITRAL Model Law?” (with Sarah Daly BL), (2006) Irish Journal of European Law 259.

“Independent News and Media v Ireland. The Judgment of the European Court of Human Rights”, Bar Review, (2005) 10 (4) BR 117

“Recent developments in Privacy and Breach of Confidence”, Bar Review, (2001) 7 (2) BR 102

“Irish Libel Law and the European Convention on Human Rights”, Bar Review, (2000) 5 (8) BR 410

Speaker at EUBA & Arbitration Ireland seminar on ‘Costello v Ireland: CETA and International Arbitration.’, 24 March, 2023

Moderator, Panel Discussion, Young Practitioners Forum, Dublin International Arbitration Day, Arbitration Ireland, 17 November, 2022

“Updates on Registration, Appeals and the EU Directive on Mutual Recognition of Professional Qualifications”, CMG Professional Regulation Conference, 2022, 17 November, 2022

“The interaction between medical negligence litigation, medical misconduct, inquiries and inquests”, 24 October, 2022, Clinical Litigation Unit Conference, State Claims Agency.

Co-Arbitrator, LSE-LCIA London Vis Pre-Moot, 7 March, 2021.

Panellist, New York State Bar Association Webinar, Ireland for Law : Corporate Restructuring, IP/Data Protection, and Derivatives in Europe after Brexit, 19 November, 2020.

Co-Arbitrator, Dublin FDI Pre-Moot, 30 October, 2020.

Chair of Webinar on Conduct of an International Arbitration, organised by Arbitration Ireland and the Arbitration Committee of the Bar of Ireland, 30 June, 2020

Chair of the Young Practitioners Seminar at Dublin International Arbitration Day, 15 November, 2019.

Speaker at the Joint Conference of the EU Bar Association and the Barreau de Paris, Commercial Dispute Resolution in Europe after Brexit, Maison du Barreau, Paris, 9 November, 2019.

Panel Moderator, Choice of law in commercial contracts: the perspective of corporate counsel, Dublin International Arbitration Day, 16 November, 2018.

Promoting Irish Law, Opportunities and Challenges post Brexit, Law Reform Commission Annual Conference, Dublin, 14 November, 2018.

Vues comparées sur la composition des tribunaux arbitraux, Société de Législation Comparée/FBLS, Paris, 28 May, 2018.

Impact of Brexit on Attorneys, their practices and their clients. Where are the likely winners? New York State Bar Association, International Section, Spring Meeting, 2017, Dublin, 21 April, 2017.

Arbitration – Which seat to choose? Franco-British Lawyers Association/ CIArb (London Branch), London, 13 March, 2017.

Chair, Asia-Pacific Forum for International Arbitration session on Guerrilla Tactics, Dublin, 17 October, 2016.

“Practical Matters for Plaintiffs in Multiparty Construction Disputes”, Paper Delivered to the Construction Bar Association, 10 December, 2014.

“Good Practice – Structuring Reports and Evidence”, Paper Delivered to Expert Witness Conference, 12 November, 2014, Royal Marine Hotel, Dun Laoghaire, Co. Dublin.

Professional Regulation in 2012 and Beyond”, Paper Delivered to Conference on Professional Regulation in Ireland, Burlington Hotel, 23 June, 2012.




01-817 2725
The Law Library
145-151 Church Street Dublin 7

Download Profile

Find a Barrister, Mediator or Arbitrator

Advanced Search