Mark has acted as lead counsel in dozens of high-value commercial disputes under US, English, French and numerous other governing laws. His experience spans complex matters involving supply agreements, joint ventures, IP licensing, corporate and shareholder disputes, banking and finance, construction and engineering contracts, mining, and insurance and reinsurance. Notable representations include Areva SAS in its long-running dispute against Finnish utility TVO over nuclear power plant construction, and United Group in an arbitration against the Republic of Serbia over actions taken against UG’s telecoms subsidiary.

Mark has served as lead advocate in dozens of high-value cross-border investment arbitrations under various bilateral and multilateral investment treaties, raising complex issues of public and private international law. Several disputes have involved EU law issues, including the enforcement of intra-EU investment treaty awards in US and other courts. His landmark representations include Cairn Energy in its $1 billion+ recovery against the Republic of India and the Yukos shareholders in their $50 billion award against the Russian Federation. Mark also brings unique expertise from representing the United States government in investment treaty disputes during his tenure at the US State Department. He has taught international investment law at Sciences Po Law School in Paris for 14 years.

Mark has specialized in international arbitration for 27 years, acting as counsel or arbitrator in approximately 100 disputes across Western and Eastern Europe, Asia, the Middle East, and North and South America. His practice encompasses both commercial and investment treaty arbitrations under all major arbitral institutions and rules. He has been involved in numerous high-value, landmark cases and regularly sits as arbitrator. Mark's unique background includes four years representing the United States in investment treaty disputes at the State Department, giving him rare insight from both private practice and sovereign perspectives.

• Lead counsel for claimant in an ICSID arbitration, United Group et al. v Republic of Serbia, concerning state measures taken against a telecommunications subsidiary.  US $350 million in dispute.  
• Co-lead counsel (with Lord Wolfson) for respondent in a SIAC arbitration involving a loan for a cross-border investment in Indonesia made by a Middle Eastern bank.  English and Indonesian law applied. US $650 million in dispute. 
• Lead counsel for claimant in an UNCITRAL arbitration, Cairn Energy LLC et al. v Republic of India, concerning retrospective taxation measures imposed on the claimant's Indian subsidiary.  US $1.4 billion in dispute.   Full damages and costs awarded.  This dispute involved enforcement proceedings across eight jurisdictions around the world, including before the US District Court for the Southern District of New York. 
• Arbitrator in a proceeding under the Swiss Arbitration Rules  and Swiss law concerning alleged mismanagement of funds by fund managers in Switzerland. US $100 million in dispute.
• Co-lead counsel (with Roderick Cordara KC) for claimants in an ICSID arbitration, Alverley Investments Ltd. et al. v Romania, concerning a real estate development project in Bucharest. EUR 1.5 billion in dispute.  Romanian law applied.
• Lead counsel for claimant in an ICSID arbitration, Rasia FZE et al. v Republic of Armenia, concerning the expropriation of a railway and roadway infrastructure project. US $350 million in dispute.
• Arbitrator in an ICC arbitration concerning a contractual dispute over the construction of a telecommunications network in Afghanistan. US $50 million in dispute.
• Co-lead counsel for respondent in an ICC arbitration between a US oil storage company and a Chinese-owned oil trading firm.  US $100 million in dispute.  Claims fully dismissed with costs awarded.
• Counsel for claimant in a JAMS arbitration between a US networking equipment manufacturer and a US semiconductor manufacturer concerning the supply of microchips and routers. US $500 million in dispute.
• Counsel (on a team led by Emmanuel Gaillard) for Electricité de France (EDF) as claimant in a UNCITRAL arbitration brought under the Energy Charter Treaty against the Republic of Hungary arising from the termination of Power Purchase Agreements.  Hungarian law applied.
• Counsel to a Swedish national as claimant in an ICC arbitration seated in New York and applying New York law, under an agreement among related companies and their individual owners over the allocation of proceeds obtained in a successful ICSID arbitration against Romania.  US $100 million in dispute.
• Counsel in an UNCITRAL arbitration on behalf of a Spanish company concerning swap contracts for the delivery of LNG from the Caribbean to the Iberian Peninsula. US $500 million in dispute.  Involved enforcement proceedings before the US District Court for the Southern District of New York.  New York law applied.
• Counsel to a US shipping company against Greek investors in a proceeding before the US District Court for the Southern District of New York to vacate a JAMS arbitration award.  This dispute Involved related proceedings before an LCIA tribunal seated in London governed by English law, US bankruptcy court proceedings applying US federal law, and courts in the BVI and Greece applying BVI and Greek law respectively. 
• Counsel in an ICSID arbitration between a Hong Kong company and a Middle Eastern State concerning the revocation of a telecommunications licence and the expropriation of a telecoms business. US $400 million in dispute.  Saudi law applied.
• Lead counsel in an LMAA arbitration under a charterparty governed by English law that was disrupted by the Covid-19 pandemic.  Full damages and costs awarded.
• Counsel in an LCIA arbitration concerning the termination of a telecommunications service agreement in Greece.  Greek law applied.  US $20 million in dispute.
• Counsel in an ICC arbitration concerning the construction of an LNG facility in Louisiana, United States.  Louisiana law applied.
• Counsel in an ICC arbitration between a French aircraft manufacturer and an engine manufacturer concerning delays in the delivery of aircraft engines. US $800 million in dispute.  New York law applied.
• Counsel in a CPR arbitration concerning the supply and sale of generic prescription drugs. US $200 million in dispute.  Delaware law applied. 
• Counsel to a French chemical company as respondent in a series of related ICC arbitrations in Paris, Geneva and London against the French subsidiary of a large US chemical concern. The disputes arose under a joint venture agreement relating to a facility in northern France that manufactures chemical product used in nylon.  French law applied.  The claims were fully dismissed and near-full costs were awarded.
• Counsel for a French chemical company in an application before US federal court pursuant to 28 USC § 1782 to obtain discovery in aid of a foreign proceeding.  Kansas law applied.
• Counsel in an ICC arbitration concerning the sale to a US company of a producer and promoter of live entertainment in Latin America. US $150 million in dispute.  Mexican law applied.
• Counsel in an UNCITRAL arbitration between shareholders of the Yukos Oil Company and the Russian Federation under the Energy Charter Treaty concerning the expropriation of Yukos through taxation and other measures. US $50 billion awarded.  
• Counsel in an ICC arbitration between a French nuclear power company and a Finnish utility concerning the construction of a nuclear power plant in Finland.  EUR 6.1 billion in dispute.  Finnish law governed. 
• Lead counsel on behalf of an Italian company as claimant in an ICC arbitration in Paris against a German company over the sale and acquisition of a US manufacturing company.  German law applied.
• Arbitrator in an ICC arbitration between a Japanese supplier and a French company over a supply agreement in Europe governed by French law.
• Counsel for a major French pharmaceutical company in an ICC arbitration against three subsidiaries of a global healthcare company arising from a Manufacturing Right Purchase and Licence Agreement. US $70 million in dispute.
• Counsel to a French aviation company as claimant in an ICC arbitration in Geneva against a US engine parts supplier arising out of the respondent’s refusal to ship parts.  This dispute involved proceedings before the US District Court for the Northern District of New York to obtain a temporary restraining order commanding the US supplier to resume deliveries.
• Counsel for a US agribusiness company as respondent in an ICC arbitration initiated by European agribusiness companies.  The dispute related to rights to use proprietary biotechnology related to genetically-modified crops.   
• Counsel in an UNCITRAL arbitration, Methanex v United States of America.  This US $970 million dispute involved the Canadian corporation’s challenging to California's ban on the gasoline additive MTBE, claiming that environmental regulation violated investment protections under the NAFTA.  The tribunal dismissed all claims and ordered Methanex to pay the United States' legal fees of $4 million.
• Counsel in an UNCITRAL arbitration, Glamis Gold Ltd. v United States of America.  This US $200 million in dispute involved a challenge by the Canadian mining company to federal and state regulatory measures that prevented it from mining gold in southeastern California, claiming that the regulations expropriated its mineral rights and denied fair and equitable treatment under NAFTA.  The California regulations required backfilling and grading for mining operations in the vicinity of Native American sacred sites.  The tribunal ultimately dismissed all of Glamis's claims.
• Counsel in UNCITRAL proceedings, In re Consolidated Softwood Lumber, concerning antidumping and countervailing duties imposed on softwood lumber imports from Canada to the United States. US $500 million was in dispute.
• Counsel in an UNCITRAL arbitration, Canfor Corp. v United States of America, concerning antidumping and countervailing duties imposed on softwood lumber imports from Canada to the United States. US $250 million was in dispute.
• Counsel in an UNCITRAL arbitration, Tembec Corp. v United States of America, concerning antidumping and countervailing duties imposed on softwood lumber imports from Canada to the United States. US $100 million was in dispute.
• Counsel to a US reinsurance pool manager as respondent in an $400 million ARIAS arbitration in the US, Bermuda and the United Kingdom.  US $400 million in dispute. The arbitration involved complex disputes arising from the 1999 collapse spanning the US, the United Kingdom and Bermuda.  The dispute involved a workers' compensation reinsurance pool managed by Unicover (later renamed Cragwood), with claims brought by pool members against their retrocessionaires over coverage obligations and pool liabilities.   The tribunal dismissed all claims against the client.  The case involved intricate reinsurance and retrocessional coverage issues stemming from the pools' collapse.

• “Third-Party Funding of International Arbitration in New York”, Chapter in International Commercial Arbitration in New York (James H. Carter and John Fellas, eds., Oxford University Press, forthcoming 2025)
• “DC Circuit OKs Enforcement of Intra-EU Awards, Does Not Decide If Other Treaties' Awards May Be Enforced,” Law.com (September 26, 2024) (with Alex G. Leventhal)
• '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,” Law.com (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,” Chapter in International Arbitration and the Rule of Law: Essays in Honour of Mr. Fali S Nariman (Permanent Court of Arbitration, 2021) (with Daniel Purisch)
• “First Impressions of a Virtual Hearing at ICSID,” ICSID Review—Foreign Investment Law Journal (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)

New York University School of Law, J.D., 1998 - Editor-in-Chief, Journal of International Law & Politics                       

Johns Hopkins University School of Advanced International Studies, M.A., International Law & Economics, 1995 - Colgate University, B.A., English Literature, 1989

Admitted to practice before the bars of New York, England & Wales and Paris. 

Fellow, Chartered Institute of Arbitrators

Sciences Po Law School, Paris, Visiting Lecturer, Investment Treaty Arbitration, 2011-present

CPR Institute for Dispute Resolution, European Advisory Board Member, 2015-present

• “Mark McNeill is absolutely top class, both in his strategic and subject matter advice, but also in his written work and advocacy”. Legal 500 (2020)
•  “An excellent strategist and great with clients”.  Whos Who Legal 2020
• 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”.