Attorney Detail Banner
Back to Attorneys
McNeill, Mark
Direct Tel: +1 212-849-7351, Direct Tel: +1 646-995-9294, Direct Fax: +1 212-849-7100
New York
Tel: +1 212 849 7000 Fax: +1 212 849 7100
Tel: +44 20 7653 2000 Fax: +44 20 7653 2100

Mark McNeill heads the firm’s International Arbitration practice in New York.  For over two decades he has acted as advocate in numerous high-value, complex commercial and investment treaty arbitrations under the auspices of all the major arbitration institutions and rules, including the ICC, LCIA, ICSID, SCC, AAA, ICDR, Swiss Chamber of Commerce, UNCITRAL, DIS and LMAA.  He also sits as an arbitrator and serves as an expert witness on international arbitration issues.

Mark’s experience spans various subject matters, including oil & gas, joint ventures, post-M&A disputes, construction contracts, pharmaceuticals, intellectual property, technology, nuclear power, taxation, mining & metals, telecommunications, insurance and global enforcement of arbitration awards.

Mark recently obtained an award for a client in an arbitration against the Republic of India for $1.7 billion (principal and interest).  He previously represented shareholders in the former Yukos Oil Company against the Russian Federation in relation to the expropriation of their investment resulting in an award of over $50 billion, the largest arbitral award ever.   

Mark previously worked in the Office of the Legal Adviser of the U.S. Department of State where he represented the United States in investor-State arbitrations submitted under the North American Free Trade Agreement (NAFTA) and participated in the drafting of US investment treaties.

For the past 10 years, Mark has lectured on international investment arbitration at Sciences Po Law School in Paris.

Mark is admitted to practice in New York State, Paris (Avocat) and England & Wales (SolicitorAdvocate with Higher Rights of Audience).

Mark is consistently highly rated in the most prominent legal directories in the areas of international arbitration:  Legal 500 (2020) notes that "Mark McNeill is absolutely top class, both in his strategic and subject matter advice, but also in his written work and advocacy".   Who’s Who Legal (2020) ranks Mr. McNeill as a Thought Leader in International Arbitration and notes that he is "an excellent strategist and great with clients".  Chambers & Partners US (2021) notes that "Mark is a great strategist and advocate, and is phenomenal at cross-examination."; "He is a seasoned practitioner and is an excellent lawyer"; "He demonstrates a highly client-focused approach and incredible attention toward winning."  Chambers & Partners Global (2020) notes that Mark "receives consistently positive feedback", and that clients praise his advocacy skills, stating that he is "very sharp" and is "very talented".


  • United Group
  • Cairn Energy PLC
  • Rasia FZE
  • Areva SA
  • Sanofi SA
  • Solvay SA
  • Alverley Investments Ltd


  • Cairn Energy PLC in an arbitration against the Republic of India.  In 2020, the tribunal issued a decision awarding Cairn $1.7 billion (principal and interest).  The claims were submitted under the UNCITRAL Rules and the UK-India Bilateral Investment Treaty and related to retrospective taxation measures.
  • Alverley Investments Limited and Germen Properties Ltd as Claimants in an ICSID arbitration against Romania (ICSID Case No. ARB/18/30). The dispute relates to a multi-billion euro real estate project in northern Bucharest. The claims are brought under the Cyprus-Romania bilateral investment treaty.
  • Rasia FZE Claimant in an ICSID arbitration against the Republic of Armenia under the U.S.-Armenia bilateral investment treaty (ICSID Case No. ARB/18/28). The dispute arose out of concessions to develop a rail network and a high-speed road in Southern Armenia. Over $260 million is at stake.
  • United Group B.V. et al in an ICSID arbitration against the Republic of Serbia (ICSID Case No. ARB/21/5).  The matter relates to governmental measures taken against UG’s telecoms subsidiary, Serbia Broadband–srpske kablovske mreže d.o.o.  Approximately $300 million is in dispute.
  • The majority shareholders in the former Yukos Oil Company in three UNCITRAL arbitrations against the Russian Federation. The claims were brought under the Energy Charter Treaty. The Tribunal ordered Russia to pay over $50 billion in damages, the largest arbitral award in history.
  • A French-German consortium as Claimant in an ICC arbitration in Stockholm against a Finnish utility company. The dispute arose from an agreement for the construction of a nuclear power plant in Finland. Finnish law governed and the language of the proceedings was English. Over €6.1 billion was at stake.
  • Electricité de France (EDF) as Claimant in a UNCITRAL arbitration against the Republic of Hungary. The dispute arose from termination of the Power Purchase Agreements put in place during the privatization of the electricity sector. The claims were brought under the Energy Charter Treaty.
  • A North American agribusiness company as Respondent in an ICC arbitration initiated by European agribusiness companies. The dispute related to rights to use proprietary biotechnology.
  • A European pharmaceutical company as Claimant in an ICC arbitration in Paris against three subsidiaries of a global health care company. The dispute arose from a Manufacturing Right Purchase and License Agreement. French law applied.
  • Three European chemical companies in a series of ICC arbitrations in Paris, Geneva and London against the European subsidiaries of a large North American chemical concern. The disputes arose from a joint venture agreement formed to manufacture a product used for the production of nylon.
  • A European aviation company, Claimant in an ICC arbitration in Geneva against a North American parts supplier. The dispute arose out of an agreement for the supply of airplane components.
  • The United States in several arbitrations under Chapter Eleven of the NAFTA, including Methanex Corp. v. United States of America ($970 million claim challenging California’s regulations banning a gasoline additive); Glamis Gold Ltd. v. United States of America (mining claims); In re Consolidated Softwood Lumber Proceedings ($500 million claim relating to antidumping and countervailing duty measures).
  • New York University School of Law
    (J.D., 1998)
    • Journal of International Law & Politics:
      • Editor-in-Chief
  • Johns Hopkins University School of Advanced International Studies
    (M.A., International Law & Economics, 1995)
  • Colgate University
    (B.A., English Literature, 1989)
  • The State Bar of New York
  • Avocat, Barreau de Paris
  • Solicitor-Advocate, Senior Courts of England and Wales
  • United States Court of Appeals:
    • Second Circuit
  • United States District Court:
    • Southern District of New York
    • Eastern District of New York
  • Honorary Overseas Member of the Commercial Bar Association (COMBAR) (association of English barristers)
  • Japanese
  • French
  • Shearman & Sterling:
    • Partner, 2010-2019
    • Counsel, 2007-2009
    • Associate, 1999-2002
  • Office of the Legal Adviser – United States Department of State:
    • Attorney-Adviser, International Claims and Investments Disputes, 2003-2006
  • Simpson Thacher & Bartlett LLP
    • Associate, 1998-1999


  • Recognized for Who’s Who Legal: Arbitration, 2023, 2024
  • Ranked by Lawdragon 500 Leading Global Litigators Guide for International Arbitration, 2023-2024
  • Ranked by Legal 500 USA Dispute Resolution: International Arbitration “Recommended Lawyer”, 2023
  • Ranked by Chambers, International Arbitration: Counsel USA Nationwide Band 5, 2023, 2024
  • Recognized for Lawdragon 500 Leading Energy Lawyers, Global Energy Disputes & Litigation, 2023
  • Recognized for Chambers Global USA: International Arbitration: Counsel – Band 6, 2023
  • Named Litigator of the Week by The American Lawyer in September 2022
  • 'Micula v. Romania': DC Circuit Offers Hint of What’s to Come for Intra-EU Awards, National Law Journal (June 7, 2024) (with Alex G. Leventhal)
  • “'Blasket Renewable v. Spain': DC District Court Issues Conflicting Decision Regarding the Enforceability of Intra-EU Awards,” (April 12, 2023) (with Alex G. Leventhal)
  • “NextEra v. Spain: DC District Court Rekindles Hope for Enforcing Intra-EU Investor-State Awards in the US,” National Law Journal (March 7, 2023) (with Alex G. Leventhal)
  • “L’état, C’est Moi: State-Owned Enterprises as Claimants in Investment Arbitration,” INTERNATIONAL ARBITRATION AND THE RULE OF LAW: ESSAYS IN HONOUR OF MR. FALI S. NARIMAN (International Bureau of the Permanent Court of Arbitration, 2021) (with Daniel Purisch)
  • “First Impressions of a Virtual Hearing at ICSID,” ICSID Review—Foreign Investment Law Journal (Winter/Spring 2021) (with Jeremy Sharpe & Chester Brown)
  • International Arbitration and the Rule of Law: Essays in honour of Mr Fali S Nariman: International Commercial Arbitration in India: Some Reflections on Practice and Policy (January 2021)
  • “The Energy Charter Treaty,” in Arbitration under International Investment Agreements: A Guide to the Key Issues 31 (K. Yannaca-Small ed., OUP, 2nd ed. 2018) (with E. Gaillard)
  • “Investor-State Arbitration: Striking a Balance Between Investor Protections and States’ Regulatory
  • Imperatives,” in Contemporary Issues in International Arbitration and Mediation – The Fordham Papers 2013, at 270 (A.W. Rovine ed., 2014)
  • “The Doctrine of Separability and Consent to Arbitrate,” 24(3) Arbitration International 475 (2008) (with Ben Juratowitch)
  • “ICSID and Investor-State Arbitration Under Fire: The Rejection by Latin American States,” International Bar Association, Section of International Law, International Investment and Development Committee Newsletter, Vol. 1, Issue 1, at 3 (2008) (with M.N. Hodgson)
  • Sciences Po Law School, Paris, Visiting Lecturer [Investment Treaty Law], 2011-present
  • American University Washington College of Law, Visiting Lecturer [Investment Treaty Law], 2006
  • CPR Institute for Dispute Resolution, European Advisory Board Member, 2015-present | Panel of Distinguished Neutrals, 2015-present
  • Chartered Institute of Arbitrators, Faculty, 2012-present
  • Institute for Transnational Arbitration, Advisory Board Member
  • British Institute of International and Comparative Law, Investment Treaty Forum, Member