David Herlihy


David has more than 20 years' experience in international arbitration, with a focus on international commercial arbitration, investment treaty arbitration and public international law. 

He has won some of the largest and most high-profile arbitrations in the world, including two cases accorded “international arbitration team of the year” by Legal Business. He has also been voted as an “MVP” for international arbitration by Law 360 and is recognised as a leader in his field by multiple directories, which describe him as “a superb advocate” and “nothing but exceptional”. David is admitted to practice in Ireland, England and New York. 

David has an undefeated track record of success in investor-state arbitration, acting both for investors and for states over the last two decades, including in several multi-billion euro disputes. Beyond these cases, David has also obtained favourable awards or settlements for clients in dozens of commercial arbitrations under the arbitral rules of the ICC, LCIA, IDRCC, AAA and UNCITRAL.

David is licensed to practice EU law and is highly experienced in that field.  This enables him to advise clients in arbitration and litigation matters with an EU law element.  For example, he currently acts for renewable energy investors in multiple enforcement proceedings involving both EU law and the ICSID Convention.  In addition, David has acted for several of the largest foreign investors in India and has more than 10 years’ experience of advising on disputes arising from those investments, including arbitrations and related litigation in the Indian courts. 

David has particular expertise in disputes relating to the renewable energy, telecoms and technology sectors. 


Representative matters

NextEra Energy Spain Holdings BV (NextEra) in its pending enforcement of an ICSID award against Spain under the Energy Charter Treaty valued at more than €300 million (including interest). This includes obtaining an antisuit injunction from the U.S. District Court restraining attempts by Spain to prevent enforcement of the award in the United States. David was also counsel to NextEra in the underlying ICSID arbitration and annulment proceedings.

A telecommunications investor in its successful arbitration against India under the Netherlands-India BIT, which resulted in India agreeing to ify retroactive withholding tax demands of more than €5 billion (including interest and penalties). David also advised the same company in connection with its defence against India’s application to set aside the BIT award before the Singapore International Commercial Court.

The Kingdom of Bahrain in a pending ICSID arbitration under the Bahrain-Malaysia BIT: Naftiran Intertrade Company Limited v. Kingdom of Bahrain.

The Republic of Cyprus in its successful defence of claims arising out of the Eurozone financial crisis under the Cyprus-Greece BIT, resulting in a full dismissal of claims exceeding €1 billion.

Published Work

  • Co-author, (2018), The Energy Charter Treaty in Arbitration World, 6th Ed, Sweet & Maxwell
  • (2011), Energy Dispute Resolution: Investment Protection, Transit and the Energy Charter Treaty in Ioannis Kardassopoulos v Georgia
  • Co-author, (2005), Most-Favored-Nation Treatment and Dispute Settlement in Investment Arbitration: Just How “Favored” is “Most-Favored”? in ICSID Review - Foreign Investment Law Journal, Volume 20, Issue 1 

Speaking Engagements

  • Moderator, Dublin International Arbitration Day: Enforcement of Intra-EU Arbitration Awards: Latest Developments from the UK, Australia, US, and EU, November 2023
  • Moderator, Dublin International Arbitration Day: Efficiencies in International Arbitration, November 2022
  • Guest Speaker, British Institute of International and Comparative Law, Investment Treaty Forum Seminar: Counterclaims in investment treaty disputes: time for the system to change?, 2019

Leadership Positions And Professional Affiliations

  • Executive Committee Member, Arbitration Ireland



Solicitor (Ireland), 2000

Attorney (New York State), 2002

Solicitor (England and Wales), 2005


BCL, (First Class Honours), National University of Ireland, 1996

LLM New York University School of Law, 2002



English, Spanish
A&O Shearman was formed on May 1, 2024 by the combination of Shearman & Sterling LLP and Allen & Overy LLP and their respective affiliates (the legacy firms). Any matters referred to above may include matters undertaken by one or more of the legacy firms rather than A&O Shearman.