Leon Ioannou is a common law-trained lawyer in Hughes Hubbard & Reed's Paris office. Leon's practice focuses on international commercial and investment treaty arbitration, particularly in the construction, energy (nuclear, oil and gas), utilities, telecommunications, pharmaceutical, banking and finance, and corporate and legal services industries. He has conducted proceedings under most of the major arbitral institutional rules as well as ad hoc proceedings under the United Nations Commission on International Trade Law (UNCITRAL) Rules. He has worked on disputes governed by common law and by civil law.

Leon is ranked in the Who's Who Legal: Arbitration – Future Leaders 2017, 2018, 2019, 2020 and 2021 guides as one of the world's leading arbitration experts under 45. He speaks and lectures regularly on theoretical and practical aspects of international arbitration.

Leon also has experience conducting international corporate internal investigations, particularly in relation to the U.S. Foreign Corrupt Practices Act (FCPA), and providing advice on general corporate matters. Previously, Leon worked as an in-house financial analyst at some of Australia’s largest companies.

Highlighted Publications

“What’s French for backflip? French decision overturned to align with legislation and earlier jurisprudence on enforcement” (September 2018) IBA Arbitration Newsletter
"Coming Up From Down Under: A Look at Australia’s Changing Anti-Bribery Framework" (26 June 2018) 26 International Review of Compliance and Business Ethics 33
"How Far Do Your Arms Reach? A Brief Case Study on the Extraterritoriality of Anti-Bribery Laws" (29 March 2018) 13 International Review of Compliance and Business Ethics 38
"France returns to its past position on enforcement against diplomatic assets" (2017) 22(1) Arbitration News (International Bar Association Legal Practice Division) 51
"What’s French for backflip? French decision overturned to align with legislation and earlier jurisprudence on enforcement" (September 2017) IBA Arbitration Newsletter
"Recent decision confirms France's readiness to enforce international arbitral awards annulled at place of arbitration" (2006) Bulletin n°17 de l’International Bar Association Legal Practice Division Arbitration Committee
"Separability Saved: U.S. Supreme Court Eliminates Threat to International Arbitration" (2006) 21(3) Mealey's International Arbitration Report 25
"Loosening up, but not too much: enforcement against diplomatic assets in France" (2016) 21(1) Arbitration News (International Bar Association Legal Practice Division) 53

Professional Activities

Member, ICC Australia Arbitrator Nominations Committee
Member of the Global Advisory Board, Young & International division of the International Centre for Dispute Resolution

Highlighted Matters

Five UNCITRAL arbitrations in The Hague governed by public international law and with over US$ 1 billion at stake arising out of the Russian Federation’s annexation of Crimea in 2014
Multi-billion dollar ICC arbitration in Sweden governed by English law over the construction of a nuclear power plant
Multi-billion Euro ICC arbitration in France governed by French law over the construction of an oil refinery
Three ICSID arbitrations with over US$ 1 billion at stake against Argentina governed by public international law over investments in the utilities sector
Two US$ 500 million UNCITRAL arbitrations in Brussels governed by English law over contracts in the oil and gas sector, including multi-jurisdictional litigation relating to interim relief and actions against third parties
€ 500 million ICC arbitration in Switzerland governed by Swiss law over a contract for the sale and purchase of an international pharmaceutical company
€ 220 million UNCITRAL arbitration in London governed by English law over the commissioning of a power plant in Eastern Europe and the eventual termination of the EPC Contract
€ 150 million UNCITRAL arbitration in Geneva governed by public international law over a public infrastructure investment in and against an Asian country
US$ 130 million ICC arbitration in Mexico City governed by Mexican law concerning the construction of underwater oil pipelines in the Gulf of Mexico
€ 50 million ICSID arbitration against Serbia governed by public international law over investments in the agricultural and fertiliser industry
LCIA arbitration in London governed by English law over a payment dispute in connection with a deep sea gas development project in the South China Sea
ICC arbitration in Vienna governed by English law over the construction of an arena in Eastern Europe
ICC arbitration in Paris governed by French law over payment disputes under multiple sales consultancy agreements
Ad hoc arbitration in Greece governed by Greek law in connection with the construction of a motorway
UNCITRAL arbitration in London governed by English law over a payment dispute under a legal services agreement
Arbitration in Budapest under the arbitration rules of the Hungarian Chamber of Commerce over recovery of a bank loan following bankruptcy
ICC arbitration governed by an Asian law over a public infrastructure construction in Far East Asia
UNCITRAL arbitration in Brussels governed by general principles of law over a payment dispute under a legal services agreement
ICC arbitration in Switzerland governed by Swiss law over the termination of sale-and-purchase agreements
Pre-ICC arbitration representation of an energy company concerning the development of oil and gas fields offshore Africa
Pre-ICC arbitration representation of an energy company concerning a dispute over the construction of a gas facility in Central Asia
Pre-arbitration representation of a construction company concerning a dispute over the construction of a power plant in South America
Pre-ICC arbitration representation of an office services company concerning a dispute over a share purchase agreement
Secretary to tribunal in ICC arbitration in Paris governed by English law and the Vienna Convention for the International Sale of Goods over a price dispute for the sale of fuel