Dr. Daniel G. Costelloe

Daniel Costelloe is counsel in the Litigation/Controversy Department, and is a member of the International Arbitration Practice Group. Dr. Costelloe focuses his practice on international arbitration matters across a range of industries, including oil and gas, financial services and automotive. He has represented clients in arbitrations under a variety of arbitral rules and has particular experience with the ICC, ICSID and LCIA Rules. He also advises clients on public international law issues and in arbitration-related court proceedings.

Dr. Costelloe has also acted in pro bono matters with the Media Legal Defence Initiative, notably involving a challenge before the East African Court of Justice to a national law's compatibility with a state's treaty obligations. He has also advised a pro bono client on the international lawfulness of courts established by non-state actors.

Dr. Costelloe publishes on various topics within the field of public international law and has taught classes in public international law and guest classes on the law of treaties.

Professional Activities

  • American Society of International Law
  • Chatham House, Royal Institute of International Affairs


Honors & Awards

Insights & News


  • Education

    • PhD, Law, University of Cambridge, 2014

      WM Tapp Studentship in Law, Managing Editor and Blog Editor, Cambridge Journal of International and Comparative Law
    • LLM, Harvard Law School, 2010

      Line Editor, Harvard International Law Journal
    • LLB (Law with French Law), University College London, 2009

      first class Andrews Medal, Hurst Prize, Richardson Prize
  • Admissions

    • New York

  • Languages

    • German

    • French