Dr. Daniel Costelloe is an Associate Legal Officer at the International Court of Justice in The Hague. Prior to that, he was Counsel in the London office of a leading American law firm, where he practised investment treaty arbitration, international commercial arbitration, international litigation and public international law for seven and a half years. In that role, he worked on proceedings under the ICSID, ICSID Additional Facility, UNCITRAL, LCIA and ICC Rules.
Daniel is the author of Legal Consequences of Peremptory Norms of International Law (Cambridge University Press, 2017) and a co-editor of the Oxford Handbook of Jurisdiction in International Law (Oxford University Press, 2019). He teaches international investment law and regularly lectures on the law of treaties and state succession. Daniel is on the editorial board of the Leiden Journal of International Law.
Daniel is admitted to practice in Washington, D.C., and in New York.
