Duncan Speller is a partner in the firm's Litigation Department, and Co-Chair of Willkie’s Arbitration Practice Group. Duncan is based in the London office, where he practices International Arbitration and English High Court Litigation.

Duncan is an English barrister. He has significant experience in international arbitration and has successfully represented clients as an advocate on some of the most challenging, high-value and complex cases over the past decade. Duncan has represented clients in over one hundred and fifty institutional and ad hoc arbitrations, sited in both common and civil law jurisdictions, including England, New York, Hong Kong, Singapore, France, Switzerland, Sweden, Austria and Germany.

Duncan also has substantial experience of international commercial litigation in both the English Court of Appeal and in the Commercial and Chancery Divisions of the High Court. He has particular experience of arbitration and litigation concerning aviation, oil and gas, insurance and reinsurance, private equity, telecommunications, banking and competition law issues.

Duncan sits as an arbitrator and has been appointed as arbitrator or emergency arbitrator by multiple arbitral institutions.


Prior to joining Willkie, Duncan was a partner at WilmerHale for over eight years.

  • Duncan is recognised in Chambers UK (2024) and Chambers Global (2024) for International Arbitration. A client reported to Chambers that he has "flawless judgement and a very enviable work ethic" and is "very persuasive, tactical and is a great presenter."
  • Ranked as a "Leading Individual" for International Arbitration by The Legal 500 UK (2024).
  • Featured in Who's Who Legal: Arbitration and named a leading arbitrator in the 2017–2022 editions of Who's Who Legal: Arbitration - Future Leaders - a guide profiling the foremost practitioners in the arbitration community. Duncan was cited as being an “outstanding lawyer” who possesses a “super brain,” “a smart, hardworking and very impressive advocate,” "phenomenal; extremely effective and doing exceptionally well," with one source stating, "He has one of the most exceptional legal minds I have ever come across. He is, quite simply, brilliant. If you have a dispute, he should be your first choice."
  • Selected for inclusion in the 2024, 2023, 2022, and 2020 editions of The Best Lawyers in the United Kingdom for his work in international arbitration.
  • Listed as a leader in aviation in the 2011–2014 editions of The Legal 500 UK. Duncan was cited for his vast experience with aviation disputes and recognised as a "key figure" of WilmerHale's top tier UK aviation team. He was also recommended for dispute resolution: international arbitration in the 2013, 2016 and 2018 editions.

Duncan was called to the Bar of England and Wales by Lincoln’s Inn in November 2001. He has taught commercial law, the conflict of laws and EU law at the University of Cambridge.

Selected Publications

  • International Arbitration Review (England and Wales chapter), Law Business Review, 2014-2021
  • Oil and Gas Arbitration in the Asia-Pacific Region, Asia-Pacific Economic Review, 2019-2020
  • The Guide to M&A Arbitration (United Kingdom chapter), Global Arbitration Review, 2019-2020
  • The Choice of a Foreign Seat in Domestic Disputes – An Opportunity for One More Step Forward in India’s Journey to Establish Itself As An Arbitration Friendly Jurisdiction? Indian Journal of International Arbitration, January 2018
  • Handbuch Internationales Wirtschaftsrecht, (England and Wales chapter), Otto Schmidt, 2017
  • Onderneming en ADR (chapter on Arbitrability of Corporate Disputes Under English Law), Kluwer, 2011
  • A Practical Guide to International Commercial Arbitration, Sweet & Maxwell, 2010

Selected Speaking Engagements

  • English Law Day in Kyiv: “Third Party Funding in International Arbitration” (5 May 2021)
  • International Arbitration Symposium: “Institutional Rules: What is Happening? Improvement or Harmonization?” (4 March 2021)
  • SIDRA/BIICL Webinar: “Implications of China’s Doctrine of State Immunity on Belt and Road Disputes” (5 November 2020)
  • Indian Council of Arbitration: Preliminary Determinations in International Arbitration – New Delhi, India (February 2020)
  • WilmerHale and Kabine Law Office: "Arbitrations Involving States and State-Owned Entities" – Istanbul, Turkey (12 December 2019)
  • WilmerHale and International Business Legal Associates: “Arbitrations Involving States and State-Owned Entities” – Jordan (10 December 2019)
  • Young ICC Skills Training Workshop on Cross-Examination – Kyiv, Ukraine (11 October 2019)
  • CAM-CCBC: Seminar on Cross-Examination – Sao Paulo, Brazil (August 2019)
  • CAM-CCBC Annual Congress: Third Party Funding in International Arbitration – Rio de Janeiro, Brazil (August 2019)
  • Asia ADR Week 2019 - The Kintsukuroi Perspective: “The Asian ADR Revolution” – Kuala Lumpur, Malaysia (June 2019)
  • Panel Discussion: “Latest Developments in Turkish Arbitration and Dispute Resolution” – London, UK (June 2019)
  • Panel Discussion: “Arbitration of Sino-Brazilian Disputes” – London, UK (October 2018)
  • 4th Annual Cambridge Arbitration Day: “The Ethics of Counsel in International Arbitration: Is There a Need for Regulation?” – University of Cambridge, UK (March 2017)
  • Stockholm Arbitration Summit: “The Role of Law” – Stockholm, Sweden (May 2014)
  • American Bar Association: Section of International Law 2014 Spring Meeting: “The Good, the Bad and the Ugly: Intersection of Civil Law and Common Law Deposition Styles in Cross-Border Matters” – New York, USA (April 2014)
  • Tbilisi Arbitration Conference: “Recurring Concerns in Arbitration Proceedings: Consolidation of Claims & Finality of Arbitral Awards” – Tbilisi, Georgia (February 2014)
  • ASA Below 40 Conference: “The Interface Between Arbitration and Criminal Law: Selection of Issues” – Zurich, Switzerland (October 2010)
  • AIJA 48th Congress: “Summary Judgement and Expedited Proceedings: Is Mainstream International Commercial Arbitration Ready for the Next Step?” – South Carolina, USA (August 2010)
  • AIJA/ICDR Annual Arbitration Conference: “Insolvency and Arbitration” – London, UK (June 2010)

Duncan has advised on the following selected significant matters*:

  • Successfully representing an Asian client in pursuing claims in a post-closing M&A dispute in an ICC arbitration seated in Hong Kong and governed by English law. The client obtained an award in the hundreds of millions of dollars and was awarded its costs.
  • Successfully represented a European multinational in pursuing claims under multiple gas supply agreements in parallel ad hoc arbitrations in London. The client secured a very favorable settlement after victories on interim applications.
  • Successfully represented the client in a complex jurisdictional dispute in Dynasty Company for Oil and Gas Trading v The Kurdistan Regional Government of Iraq and Dr Ashti Hawrami [2021] EWHC 952 (Comm), which was listed in The Lawyer’s Top 20 cases to watch in 2021. Claims quantified at over $1.6 billion were dismissed on jurisdictional grounds.
  • Successfully representing a state entity in defending claims quantified in the billions of dollars in an LCIA arbitration seated in London and parallel proceedings in the English and Dubai International Finance Centre Courts. Duncan’s team was nominated by The American Lawyer and Legal 500 as Transatlantic Dispute Resolution Team of the Year for its role on this matter.
  • Successfully represented a leading European company in pursuing claims against a North American company in an NAI arbitration seated in Amsterdam. The client obtained an award in its favor of over $450 million in addition to costs and interest.
  • Successfully representing a multinational company in defeating claims in excess of Euro 35 million in an arbitration sited in Munich under the DIS Rules. The claims were dismissed in their entirety and the client was awarded its costs.
  • Successfully representing an Asian airline in pursuing substantial claims under aircraft lease agreements in an LCIA arbitration sited in London.
  • Successfully representing the contractor in two parallel ICC arbitrations governed by English law and sited in Stockholm with an amount in excess of US$ 80 million arising out of a construction contract.
  • Successfully representing a North American company in a series of ad hoc arbitrations sited in London and Bermuda concerning insurance coverage disputes governed by New York law.
  • Successfully representing a Russian investment bank in an ICC arbitration in relation to an investment in the Russian oil industry.
  • Successfully representing a North American company in an ICC arbitration concerning contracts for the supply of capital goods for an oil field in Central Asia.
  • Successfully representing a hedge fund in pursuing claims in the English Commercial Court arising from a default under a Euro 350 million bond. The client obtained summary judgment in its favor and was awarded indemnity costs.
  • Successfully representing a North American company in a technically complex dispute in the Commercial Court in London arising out of a joint collaboration agreement.
  • Advising the shareholders in a telecommunications joint venture on their position in relation to concurrent proceedings in two Caribbean jurisdictions and two Swiss sited arbitrations.
  • Advising a European oil company in relation to a number of disputes arising under Production Sharing Contracts concerning oil fields in India.

*Duncan advised on some of these matters prior to joining Willkie.



Inns of Court School of Law, 2001 University of Oxford, B.C.L., 2000 University of Cambridge, B.A., 1999

Bar Admissions

England & Wales